Refactor controllers and exception handling (#8)

* Refactored exceptions and responses

* Extracted exceptions to external api library

* Refactored exceptions and extracted models to external library

* Fixed test after refactor

* Extracted validator to api library

* Implemented session error handler

* Upgraded notifications

* Implemented global exception handler for control panel

api/build.gradle

@@ -0,0 +1,16 @@
+plugins {
+    id 'java'
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testImplementation platform('org.junit:junit-bom:5.9.1')
+    testImplementation 'org.junit.jupiter:junit-jupiter'
+}
+
+test {
+    useJUnitPlatform()
+}

api/src/main/java/ru/dragonestia/picker/api/exception/ApiException.java

@@ -0,0 +1,10 @@
+package ru.dragonestia.picker.api.exception;
+
+import java.util.Map;
+
+public abstract class ApiException extends RuntimeException {
+
+    public abstract String getErrorId();
+
+    public abstract void appendDetailsToErrorResponse(Map<String, String> details);
+}

api/src/main/java/ru/dragonestia/picker/api/exception/ExceptionFactory.java

@@ -0,0 +1,36 @@
+package ru.dragonestia.picker.api.exception;
+
+import ru.dragonestia.picker.api.repository.response.ErrorResponse;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Function;
+
+public class ExceptionFactory {
+
+    private final static Map<String, Constructor> factory = init();
+
+    private ExceptionFactory() {}
+
+    private static Map<String, Constructor> init() {
+        var factory = new HashMap<String, Constructor>();
+
+        factory.put(InvalidNodeIdentifierException.ERROR_ID, InvalidNodeIdentifierException::new);
+        factory.put(InvalidRoomIdentifierException.ERROR_ID, InvalidRoomIdentifierException::new);
+        factory.put(InvalidUsernamesException.ERROR_ID, InvalidUsernamesException::new);
+        factory.put(NodeAlreadyExistException.ERROR_ID, NodeAlreadyExistException::new);
+        factory.put(NodeNotFoundException.ERROR_ID, NodeNotFoundException::new);
+        factory.put(NoRoomsAvailableException.ERROR_ID, NoRoomsAvailableException::new);
+        factory.put(RoomAlreadyExistException.ERROR_ID, RoomAlreadyExistException::new);
+        factory.put(RoomAreFullException.ERROR_ID, RoomAreFullException::new);
+        factory.put(RoomNotFoundException.ERROR_ID, RoomNotFoundException::new);
+
+        return factory;
+    }
+
+    public static ApiException of(ErrorResponse errorResponse) {
+        return factory.get(errorResponse.errorId()).apply(errorResponse);
+    }
+
+    private interface Constructor extends Function<ErrorResponse, ApiException> {}
+}

api/src/main/java/ru/dragonestia/picker/api/exception/InvalidNodeIdentifierException.java

@@ -0,0 +1,39 @@
+package ru.dragonestia.picker.api.exception;
+
+import ru.dragonestia.picker.api.repository.response.ErrorResponse;
+
+import java.util.Map;
+
+public final class InvalidNodeIdentifierException extends ApiException {
+
+    public static final String ERROR_ID = "err.node.invalid_identifier";
+
+    private final String nodeId;
+
+    public InvalidNodeIdentifierException(String nodeId) {
+        this.nodeId = nodeId;
+    }
+
+    public InvalidNodeIdentifierException(ErrorResponse errorResponse) {
+        this(errorResponse.details().get("identifier"));
+    }
+
+    @Override
+    public String getMessage() {
+        return "Invalid node identifier. Taken '" + nodeId + "'";
+    }
+
+    public String getNodeId() {
+        return nodeId;
+    }
+
+    @Override
+    public String getErrorId() {
+        return ERROR_ID;
+    }
+
+    @Override
+    public void appendDetailsToErrorResponse(Map<String, String> details) {
+        details.put("identifier", getNodeId());
+    }
+}

api/src/main/java/ru/dragonestia/picker/api/exception/InvalidRoomIdentifierException.java

@@ -0,0 +1,46 @@
+package ru.dragonestia.picker.api.exception;
+
+import ru.dragonestia.picker.api.repository.response.ErrorResponse;
+
+import java.util.Map;
+
+public final class InvalidRoomIdentifierException extends ApiException {
+
+    public static final String ERROR_ID = "err.room.invalid_identifier";
+
+    private final String nodeId;
+    private final String roomId;
+
+    public InvalidRoomIdentifierException(String nodeId, String roomId) {
+        this.nodeId = nodeId;
+        this.roomId = roomId;
+    }
+
+    public InvalidRoomIdentifierException(ErrorResponse errorResponse) {
+        this(errorResponse.details().get("nodeId"), errorResponse.details().get("roomId"));
+    }
+
+    @Override
+    public String getMessage() {
+        return "Invalid room identifier. Taken '" + roomId + "'";
+    }
+
+    public String getRoomId() {
+        return roomId;
+    }
+
+    public String getNodeId() {
+        return nodeId;
+    }
+
+    @Override
+    public String getErrorId() {
+        return ERROR_ID;
+    }
+
+    @Override
+    public void appendDetailsToErrorResponse(Map<String, String> details) {
+        details.put("nodeId", getNodeId());
+        details.put("roomId", getRoomId());
+    }
+}

api/src/main/java/ru/dragonestia/picker/api/exception/InvalidUsernamesException.java

@@ -0,0 +1,50 @@
+package ru.dragonestia.picker.api.exception;
+
+import ru.dragonestia.picker.api.repository.response.ErrorResponse;
+
+import java.util.*;
+import java.util.function.Function;
+
+public final class InvalidUsernamesException extends ApiException {
+
+    public static final String ERROR_ID = "err.user.invalid_identifier";
+
+    private final List<String> givenUsernames;
+    private final List<String> invalidUsernames;
+
+    public InvalidUsernamesException(List<String> givenUsernames, List<String> invalidUsernames) {
+        this.givenUsernames = givenUsernames;
+        this.invalidUsernames = invalidUsernames;
+    }
+
+    public InvalidUsernamesException(ErrorResponse errorResponse) {
+        this(Arrays.stream(errorResponse.details().get("givenUsernames").split(",")).toList(),
+                Arrays.stream(errorResponse.details().get("invalidUsernames").split(",")).toList());
+    }
+
+    @Override
+    public String getMessage() {
+        return "Users with invalid identifiers were found";
+    }
+
+    public List<String> getGivenUsernames() {
+        return givenUsernames;
+    }
+
+    public List<String> getInvalidUsernames() {
+        return invalidUsernames;
+    }
+
+    @Override
+    public String getErrorId() {
+        return ERROR_ID;
+    }
+
+    @Override
+    public void appendDetailsToErrorResponse(Map<String, String> details) {
+        Function<Collection<String>, String> toString = input -> String.join(",", input);
+
+        details.put("givenUsernames", toString.apply(getGivenUsernames()));
+        details.put("invalidUsernames", toString.apply(getInvalidUsernames()));
+    }
+}

api/src/main/java/ru/dragonestia/picker/api/exception/NoRoomsAvailableException.java

@@ -0,0 +1,39 @@
+package ru.dragonestia.picker.api.exception;
+
+import ru.dragonestia.picker.api.repository.response.ErrorResponse;
+
+import java.util.Map;
+
+public final class NoRoomsAvailableException extends ApiException {
+
+    public static final String ERROR_ID = "err.room.no_available";
+
+    private final String nodeId;
+
+    public NoRoomsAvailableException(String nodeId) {
+        this.nodeId = nodeId;
+    }
+
+    public NoRoomsAvailableException(ErrorResponse errorResponse) {
+        this(errorResponse.details().get("nodeId"));
+    }
+
+    @Override
+    public String getMessage() {
+        return "There are no rooms available in node '" + nodeId + "'";
+    }
+
+    public String getNodeId() {
+        return nodeId;
+    }
+
+    @Override
+    public String getErrorId() {
+        return ERROR_ID;
+    }
+
+    @Override
+    public void appendDetailsToErrorResponse(Map<String, String> details) {
+        details.put("nodeId", getNodeId());
+    }
+}

api/src/main/java/ru/dragonestia/picker/api/exception/NodeAlreadyExistException.java

@@ -0,0 +1,39 @@
+package ru.dragonestia.picker.api.exception;
+
+import ru.dragonestia.picker.api.repository.response.ErrorResponse;
+
+import java.util.Map;
+
+public final class NodeAlreadyExistException extends ApiException {
+
+    public static final String ERROR_ID = "err.node.already_exists";
+
+    private final String nodeId;
+
+    public NodeAlreadyExistException(String nodeId) {
+        this.nodeId = nodeId;
+    }
+
+    public NodeAlreadyExistException(ErrorResponse errorResponse) {
+        this(errorResponse.details().get("nodeId"));
+    }
+
+    @Override
+    public String getMessage() {
+        return "Node with identifier '" + nodeId + "' is already exists";
+    }
+
+    public String getNodeId() {
+        return nodeId;
+    }
+
+    @Override
+    public String getErrorId() {
+        return ERROR_ID;
+    }
+
+    @Override
+    public void appendDetailsToErrorResponse(Map<String, String> details) {
+        details.put("nodeId", getNodeId());
+    }
+}

api/src/main/java/ru/dragonestia/picker/api/exception/NodeNotFoundException.java

@@ -0,0 +1,39 @@
+package ru.dragonestia.picker.api.exception;
+
+import ru.dragonestia.picker.api.repository.response.ErrorResponse;
+
+import java.util.Map;
+
+public final class NodeNotFoundException extends ApiException {
+
+    public static final String ERROR_ID = "err.node.not_found";
+
+    private final String nodeId;
+
+    public NodeNotFoundException(String nodeId) {
+        this.nodeId = nodeId;
+    }
+
+    public NodeNotFoundException(ErrorResponse errorResponse) {
+        this(errorResponse.details().get("node"));
+    }
+
+    @Override
+    public String getMessage() {
+        return "Node '" + nodeId + "' does not found";
+    }
+
+    public String getNodeId() {
+        return nodeId;
+    }
+
+    @Override
+    public String getErrorId() {
+        return ERROR_ID;
+    }
+
+    @Override
+    public void appendDetailsToErrorResponse(Map<String, String> details) {
+        details.put("node", getNodeId());
+    }
+}

api/src/main/java/ru/dragonestia/picker/api/exception/RoomAlreadyExistException.java

@@ -0,0 +1,47 @@
+package ru.dragonestia.picker.api.exception;
+
+import ru.dragonestia.picker.api.repository.response.ErrorResponse;
+
+import java.util.Map;
+
+public final class RoomAlreadyExistException extends ApiException {
+
+    public static final String ERROR_ID = "err.room.already_exists";
+
+    private final String nodeId;
+    private final String roomId;
+
+    public RoomAlreadyExistException(String nodeId, String roomId) {
+        this.nodeId = nodeId;
+        this.roomId = roomId;
+    }
+
+    public RoomAlreadyExistException(ErrorResponse errorResponse) {
+        this(errorResponse.details().get("nodeId"),
+                errorResponse.details().get("roomId"));
+    }
+
+    @Override
+    public String getMessage() {
+        return "Room with identifier '" + roomId + "' in node '" + nodeId + "' is already exists";
+    }
+
+    public String getNodeId() {
+        return nodeId;
+    }
+
+    public String getRoomId() {
+        return roomId;
+    }
+
+    @Override
+    public String getErrorId() {
+        return ERROR_ID;
+    }
+
+    @Override
+    public void appendDetailsToErrorResponse(Map<String, String> details) {
+        details.put("nodeId", getNodeId());
+        details.put("roomId", getRoomId());
+    }
+}

api/src/main/java/ru/dragonestia/picker/api/exception/RoomAreFullException.java

@@ -0,0 +1,47 @@
+package ru.dragonestia.picker.api.exception;
+
+import ru.dragonestia.picker.api.repository.response.ErrorResponse;
+
+import java.util.Map;
+
+public final class RoomAreFullException extends ApiException {
+
+    public static final String ERROR_ID = "err.room.are_full";
+
+    private final String nodeId;
+    private final String roomId;
+
+    public RoomAreFullException(String nodeId, String roomId) {
+        this.nodeId = nodeId;
+        this.roomId = roomId;
+    }
+
+    public RoomAreFullException(ErrorResponse errorResponse) {
+        this(errorResponse.details().get("nodeId"),
+                errorResponse.details().get("roomId"));
+    }
+
+    @Override
+    public String getMessage() {
+        return "Room with identifier '" + roomId + "' in node '" + nodeId + "' are full";
+    }
+
+    public String getNodeId() {
+        return nodeId;
+    }
+
+    public String getRoomId() {
+        return roomId;
+    }
+
+    @Override
+    public String getErrorId() {
+        return ERROR_ID;
+    }
+
+    @Override
+    public void appendDetailsToErrorResponse(Map<String, String> details) {
+        details.put("nodeId", getNodeId());
+        details.put("roomId", getRoomId());
+    }
+}

api/src/main/java/ru/dragonestia/picker/api/exception/RoomNotFoundException.java

@@ -0,0 +1,47 @@
+package ru.dragonestia.picker.api.exception;
+
+import ru.dragonestia.picker.api.repository.response.ErrorResponse;
+
+import java.util.Map;
+
+public final class RoomNotFoundException extends ApiException {
+
+    public static final String ERROR_ID = "err.room.not_found";
+
+    private final String nodeId;
+    private final String roomId;
+
+    public RoomNotFoundException(String nodeId, String roomId) {
+        this.nodeId = nodeId;
+        this.roomId = roomId;
+    }
+
+    public RoomNotFoundException(ErrorResponse errorResponse) {
+        this(errorResponse.details().get("nodeId"),
+                errorResponse.details().get("roomId"));
+    }
+
+    @Override
+    public String getMessage() {
+        return "Room '" + roomId + "' in node '" + nodeId + "' does not found";
+    }
+
+    public String getNodeId() {
+        return nodeId;
+    }
+
+    public String getRoomId() {
+        return roomId;
+    }
+
+    @Override
+    public String getErrorId() {
+        return ERROR_ID;
+    }
+
+    @Override
+    public void appendDetailsToErrorResponse(Map<String, String> details) {
+        details.put("node", getNodeId());
+        details.put("room", getRoomId());
+    }
+}

api/src/main/java/ru/dragonestia/picker/api/model/Node.java

@@ -0,0 +1,39 @@
+package ru.dragonestia.picker.api.model;
+
+import ru.dragonestia.picker.api.model.type.PickingMode;
+
+public class Node {
+
+    private String id;
+    private PickingMode mode;
+
+    private Node() {}
+
+    public Node(String id, PickingMode mode) {
+        this.id = id;
+        this.mode = mode;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public PickingMode getMode() {
+        return mode;
+    }
+
+    @Override
+    public int hashCode() {
+        return id.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object object) {
+        if (object == this) return true;
+        if (object == null) return false;
+        if (object instanceof Node other) {
+            return id.equals(other.id);
+        }
+        return false;
+    }
+}

api/src/main/java/ru/dragonestia/picker/api/model/Room.java

@@ -0,0 +1,73 @@
+package ru.dragonestia.picker.api.model;
+
+import java.beans.Transient;
+
+public class Room {
+
+    public final static int INFINITE_SLOTS = -1;
+
+    private String id;
+    private String nodeId;
+    private int slots;
+    private String payload;
+    private boolean locked = false;
+
+    private Room() {}
+
+    public Room(String id, String nodeId, int slots, String payload) {
+        this.id = id;
+        this.nodeId = nodeId;
+        this.slots = slots;
+        this.payload = payload;
+    }
+
+    public Room(String id, Node node, int limit, String payload) {
+        this(id, node.getId(), limit, payload);
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public String getNodeId() {
+        return nodeId;
+    }
+
+    public int getSlots() {
+        return slots;
+    }
+
+    public String getPayload() {
+        return payload;
+    }
+
+    public boolean isLocked() {
+        return locked;
+    }
+
+    public void setLocked(boolean value) {
+        locked = value;
+    }
+
+    @Transient
+    public boolean isUnlimited() {
+        return slots == INFINITE_SLOTS;
+    }
+
+    @Override
+    public int hashCode() {
+        return id.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object object) {
+        if (object == this) return true;
+        if (object == null) return false;
+        if (object instanceof Room other) {
+            return id.equals(other.id);
+        }
+        return false;
+    }
+
+    public record Short(String id, int slots, boolean locked) {}
+}

api/src/main/java/ru/dragonestia/picker/api/model/User.java

@@ -1,8 +1,18 @@
-package ru.dragonestia.picker.cp.model;
+package ru.dragonestia.picker.api.model;
 
-import lombok.NonNull;
+public class User {
 
-public record User(@NonNull String id) {
+    private String id;
+
+    private User() {}
+
+    public User(String id) {
+        this.id = id;
+    }
+
+    public String getId() {
+        return id;
+    }
 
     @Override
     public int hashCode() {

api/src/main/java/ru/dragonestia/picker/api/model/type/PickingMode.java

@@ -1,14 +1,17 @@
-package ru.dragonestia.picker.cp.model.type;
+package ru.dragonestia.picker.api.model.type;
 
-import lombok.Getter;
-import lombok.RequiredArgsConstructor;
-
-@Getter
-@RequiredArgsConstructor
 public enum PickingMode {
     SEQUENTIAL_FILLING("Sequential filling"),
     ROUND_ROBIN("Round Robin"),
     LEAST_PICKED("Least Picked");
 
     private final String name;
+
+    PickingMode(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
 }

api/src/main/java/ru/dragonestia/picker/api/repository/NodeRepository.java

@@ -0,0 +1,19 @@
+package ru.dragonestia.picker.api.repository;
+
+import ru.dragonestia.picker.api.exception.InvalidNodeIdentifierException;
+import ru.dragonestia.picker.api.exception.NodeAlreadyExistException;
+import ru.dragonestia.picker.api.model.Node;
+
+import java.util.List;
+import java.util.Optional;
+
+public interface NodeRepository {
+
+    void register(Node node) throws InvalidNodeIdentifierException, NodeAlreadyExistException;
+
+    List<Node> all();
+
+    Optional<Node> find(String nodeId);
+
+    void remove(String nodeId);
+}

api/src/main/java/ru/dragonestia/picker/api/repository/RoomRepository.java

@@ -0,0 +1,23 @@
+package ru.dragonestia.picker.api.repository;
+
+import ru.dragonestia.picker.api.exception.*;
+import ru.dragonestia.picker.api.model.Node;
+import ru.dragonestia.picker.api.model.Room;
+
+import java.util.List;
+import java.util.Optional;
+
+public interface RoomRepository {
+
+    void register(Room room) throws NodeNotFoundException, InvalidRoomIdentifierException, RoomAlreadyExistException;
+
+    void remove(Room room) throws NodeNotFoundException;
+
+    void remove(Node node, Room.Short room) throws NodeNotFoundException;
+
+    List<Room.Short> all(Node node) throws NodeNotFoundException;
+
+    Optional<Room> find(Node node, String roomId) throws NodeNotFoundException;
+
+    void lock(Room room, boolean value) throws NodeNotFoundException, RoomNotFoundException;
+}

api/src/main/java/ru/dragonestia/picker/api/repository/UserRepository.java

@@ -0,0 +1,19 @@
+package ru.dragonestia.picker.api.repository;
+
+import ru.dragonestia.picker.api.exception.NodeNotFoundException;
+import ru.dragonestia.picker.api.exception.RoomAreFullException;
+import ru.dragonestia.picker.api.exception.RoomNotFoundException;
+import ru.dragonestia.picker.api.model.Room;
+import ru.dragonestia.picker.api.model.User;
+
+import java.util.Collection;
+import java.util.List;
+
+public interface UserRepository {
+
+    void linkWithRoom(Room room, Collection<User> users, boolean force) throws NodeNotFoundException, RoomNotFoundException, RoomAreFullException;
+
+    void unlinkFromRoom(Room room, Collection<User> users) throws NodeNotFoundException, RoomNotFoundException;
+
+    List<User> all(Room room) throws NodeNotFoundException, RoomNotFoundException;
+}

api/src/main/java/ru/dragonestia/picker/api/repository/response/ErrorResponse.java

@@ -0,0 +1,5 @@
+package ru.dragonestia.picker.api.repository.response;
+
+import java.util.Map;
+
+public record ErrorResponse(String errorId, String message, Map<String, String> details) {}

api/src/main/java/ru/dragonestia/picker/api/repository/response/LinkUsersWithRoomResponse.java

@@ -0,0 +1,3 @@
+package ru.dragonestia.picker.api.repository.response;
+
+public record LinkUsersWithRoomResponse(int usedSlots, int totalSlots) {}

api/src/main/java/ru/dragonestia/picker/api/repository/response/NodeDetailsResponse.java

@@ -0,0 +1,5 @@
+package ru.dragonestia.picker.api.repository.response;
+
+import ru.dragonestia.picker.api.model.Node;
+
+public record NodeDetailsResponse(Node node) {}

api/src/main/java/ru/dragonestia/picker/api/repository/response/NodeListResponse.java

@@ -0,0 +1,7 @@
+package ru.dragonestia.picker.api.repository.response;
+
+import ru.dragonestia.picker.api.model.Node;
+
+import java.util.List;
+
+public record NodeListResponse(List<Node> nodes) {}

api/src/main/java/ru/dragonestia/picker/api/repository/response/RoomInfoResponse.java

@@ -0,0 +1,5 @@
+package ru.dragonestia.picker.api.repository.response;
+
+import ru.dragonestia.picker.api.model.Room;
+
+public record RoomInfoResponse(Room room) {}

api/src/main/java/ru/dragonestia/picker/api/repository/response/RoomListResponse.java

@@ -0,0 +1,7 @@
+package ru.dragonestia.picker.api.repository.response;
+
+import ru.dragonestia.picker.api.model.Room;
+
+import java.util.List;
+
+public record RoomListResponse(String node, List<Room.Short> rooms) {}

api/src/main/java/ru/dragonestia/picker/api/repository/response/RoomUserListResponse.java

@@ -1,6 +1,6 @@
-package ru.dragonestia.picker.controller.response;
+package ru.dragonestia.picker.api.repository.response;
 
-import ru.dragonestia.picker.model.User;
+import ru.dragonestia.picker.api.model.User;
 
 import java.util.List;
 

api/src/main/java/ru/dragonestia/picker/api/utils/ValidateIdentifier.java

@@ -0,0 +1,18 @@
+package ru.dragonestia.picker.api.utils;
+
+public class ValidateIdentifier {
+
+    private ValidateIdentifier() {}
+
+    public static boolean forNode(String nodeId) {
+        return nodeId.matches("^[a-z\\d-]+$");
+    }
+
+    public static boolean forRoom(String roomId) {
+        return roomId.matches("^[a-z\\d-]+$");
+    }
+
+    public static boolean forUser(String username) {
+        return username.matches("^[aA-zZ\\d-.\\s:@_;]+$");
+    }
+}

app/build.gradle

@@ -10,6 +10,7 @@ configurations {
 }
 
 dependencies {
+    implementation project(":api")
     implementation 'org.springframework.boot:spring-boot-starter-security'
     implementation 'org.springframework.boot:spring-boot-starter-web'
 

app/src/main/java/ru/dragonestia/picker/config/TestConfig.java

@@ -7,11 +7,11 @@ import org.springframework.context.annotation.Profile;
 import org.springframework.lang.NonNull;
 import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+import ru.dragonestia.picker.api.model.type.PickingMode;
 import ru.dragonestia.picker.interceptor.DebugInterceptor;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.Node;
 import ru.dragonestia.picker.model.User;
-import ru.dragonestia.picker.model.type.PickingMode;
 import ru.dragonestia.picker.model.type.SlotLimit;
 import ru.dragonestia.picker.repository.RoomRepository;
 import ru.dragonestia.picker.repository.NodeRepository;

app/src/main/java/ru/dragonestia/picker/controller/ExceptionHandlerController.java

@@ -0,0 +1,65 @@
+package ru.dragonestia.picker.controller;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.RestControllerAdvice;
+import ru.dragonestia.picker.api.exception.*;
+import ru.dragonestia.picker.api.repository.response.ErrorResponse;
+
+import java.util.HashMap;
+
+@RestControllerAdvice
+public class ExceptionHandlerController {
+
+    @ExceptionHandler(NodeNotFoundException.class)
+    ResponseEntity<?> nodeNotFound(NodeNotFoundException ex) {
+        return create(404, ex);
+    }
+
+    @ExceptionHandler(RoomNotFoundException.class)
+    ResponseEntity<?> roomNotFound(RoomNotFoundException ex) {
+        return create(404, ex);
+    }
+
+    @ExceptionHandler(InvalidUsernamesException.class)
+    ResponseEntity<?> invalidUsernames(InvalidUsernamesException ex) {
+        return create(400, ex);
+    }
+
+    @ExceptionHandler(InvalidNodeIdentifierException.class)
+    ResponseEntity<?> invalidNodeIdentifier(InvalidNodeIdentifierException ex) {
+        return create(400, ex);
+    }
+
+    @ExceptionHandler(InvalidRoomIdentifierException.class)
+    ResponseEntity<?> invalidRoomIdentifier(InvalidRoomIdentifierException ex) {
+        return create(400, ex);
+    }
+
+    @ExceptionHandler(NodeAlreadyExistException.class)
+    ResponseEntity<?> nodeAlreadyExists(NodeAlreadyExistException ex) {
+        return create(400, ex);
+    }
+
+    @ExceptionHandler(RoomAlreadyExistException.class)
+    ResponseEntity<?> roomAlreadyExists(RoomAlreadyExistException ex) {
+        return create(400, ex);
+    }
+
+    @ExceptionHandler(RoomAreFullException.class)
+    ResponseEntity<?> roomAreFull(RoomAreFullException ex) {
+        return create(400, ex);
+    }
+
+    @ExceptionHandler(NoRoomsAvailableException.class)
+    ResponseEntity<?> noRoomsAvailable(NoRoomsAvailableException ex) {
+        return create(400, ex);
+    }
+
+    private ResponseEntity<ErrorResponse> create(int code, ApiException ex) {
+        var details = new HashMap<String, String>();
+        ex.appendDetailsToErrorResponse(details);
+
+        return ResponseEntity.status(code).body(new ErrorResponse(ex.getErrorId(), ex.getMessage(), details));
+    }
+}

app/src/main/java/ru/dragonestia/picker/controller/NodeController.java

@@ -1,22 +1,18 @@
 package ru.dragonestia.picker.controller;
 
 import lombok.RequiredArgsConstructor;
-import org.springframework.http.HttpStatusCode;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.*;
-import ru.dragonestia.picker.controller.response.NodeDetailsResponse;
-import ru.dragonestia.picker.controller.response.NodeListResponse;
-import ru.dragonestia.picker.controller.response.NodeRegisterResponse;
+import ru.dragonestia.picker.api.exception.NodeNotFoundException;
+import ru.dragonestia.picker.api.model.type.PickingMode;
+import ru.dragonestia.picker.api.repository.response.NodeDetailsResponse;
+import ru.dragonestia.picker.api.repository.response.NodeListResponse;
 import ru.dragonestia.picker.model.Node;
-import ru.dragonestia.picker.model.Room;
-import ru.dragonestia.picker.model.User;
-import ru.dragonestia.picker.model.type.PickingMode;
 import ru.dragonestia.picker.service.NodeService;
 import ru.dragonestia.picker.service.RoomService;
 import ru.dragonestia.picker.util.NamingValidator;
 
-import java.util.LinkedList;
-import java.util.Optional;
+import java.util.Arrays;
 
 @RestController
 @RequestMapping("/nodes")
@@ -25,47 +21,35 @@ public class NodeController {
 
     private final NodeService nodeService;
     private final RoomService roomService;
+    private final NamingValidator namingValidator;
 
     @GetMapping
     NodeListResponse allNodes() {
-        return new NodeListResponse(nodeService.all());
+        return new NodeListResponse(nodeService.all().stream().map(Node::toResponseObject).toList());
     }
 
     @PostMapping
-    NodeRegisterResponse registerNode(@RequestParam(name = "nodeId") String nodeId,
+    ResponseEntity<?> registerNode(@RequestParam(name = "nodeId") String nodeId,
                                       @RequestParam(name = "method") PickingMode method) {
 
-        try {
-            nodeService.create(new Node(nodeId, method));
-        } catch (IllegalArgumentException ex) {
-            return new NodeRegisterResponse(false, ex.getMessage());
-        } catch (Error error) {
-            new NodeRegisterResponse(false, error.getMessage());
-        }
-
-        return new NodeRegisterResponse(true, "");
+        nodeService.create(new Node(nodeId, method));
+        return ResponseEntity.ok().build();
     }
 
     @GetMapping("/{nodeId}")
     ResponseEntity<NodeDetailsResponse> nodeDetails(@PathVariable("nodeId") String nodeId) {
-        if (!NamingValidator.validateNodeId(nodeId)) {
-            return new ResponseEntity<>(HttpStatusCode.valueOf(404));
-        }
+        namingValidator.validateNodeId(nodeId);
 
-        var nodeOpt = nodeService.find(nodeId);
-        return nodeOpt.map(node -> ResponseEntity.ok(new NodeDetailsResponse(node)))
-                .orElseGet(() -> new ResponseEntity<>(HttpStatusCode.valueOf(404)));
+        return nodeService.find(nodeId)
+                .map(node -> ResponseEntity.ok(new NodeDetailsResponse(node.toResponseObject())))
+                .orElseThrow(() -> new NodeNotFoundException(nodeId));
     }
 
     @DeleteMapping("/{nodeId}")
     ResponseEntity<?> removeNode(@PathVariable("nodeId") String nodeId) {
-        if (!NamingValidator.validateNodeId(nodeId)) {
-            return ResponseEntity.ok().build();
-        }
-
-        var nodeOpt = nodeService.find(nodeId);
-        nodeOpt.ifPresent(nodeService::remove);
+        namingValidator.validateNodeId(nodeId);
 
+        nodeService.find(nodeId).ifPresent(nodeService::remove);
         return ResponseEntity.ok().build();
     }
 
@@ -73,30 +57,11 @@ public class NodeController {
     ResponseEntity<?> pickRoom(@PathVariable("nodeId") String nodeId,
                                @RequestParam(name = "userIds") String userIds) {
 
-        if (!NamingValidator.validateNodeId(nodeId)) {
-            return new ResponseEntity<>(HttpStatusCode.valueOf(404));
-        }
+        namingValidator.validateNodeId(nodeId);
 
-        var nodeOpt = nodeService.find(nodeId);
-        if (nodeOpt.isEmpty()) {
-            return new ResponseEntity<>(HttpStatusCode.valueOf(404));
-        }
-
-        var node = nodeOpt.get();
-
-        var list = new LinkedList<User>();
-        for (var username: userIds.split(",")) { // TODO: create warnings about invalid usernames
-            if (!NamingValidator.validateUserId(username)) continue;
-
-            list.add(new User(username));
-        }
-
-        Room room;
-        try {
-            room = roomService.pickAvailable(node, list);
-        } catch (RuntimeException ex) {
-            return new ResponseEntity<>(HttpStatusCode.valueOf(409));
-        }
+        var node = nodeService.find(nodeId).orElseThrow(() -> new NodeNotFoundException(nodeId));
+        var users = namingValidator.validateUserIds(Arrays.stream(userIds.split(",")).toList());
+        var room = roomService.pickAvailable(node, users);
 
         return ResponseEntity.ok(room); // TODO: make other json schema
     }

app/src/main/java/ru/dragonestia/picker/controller/RoomController.java

@@ -4,17 +4,16 @@ import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.*;
-import ru.dragonestia.picker.controller.response.RoomInfoResponse;
-import ru.dragonestia.picker.controller.response.RoomListResponse;
-import ru.dragonestia.picker.controller.response.RoomRegisterResponse;
+import ru.dragonestia.picker.api.exception.NodeNotFoundException;
+import ru.dragonestia.picker.api.exception.RoomNotFoundException;
+import ru.dragonestia.picker.api.repository.response.RoomInfoResponse;
+import ru.dragonestia.picker.api.repository.response.RoomListResponse;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.type.SlotLimit;
 import ru.dragonestia.picker.service.RoomService;
 import ru.dragonestia.picker.service.NodeService;
 import ru.dragonestia.picker.util.NamingValidator;
 
-import java.util.Objects;
-
 @Log4j2
 @RestController
 @RequestMapping("/nodes/{nodeId}/rooms")
@@ -23,49 +22,40 @@ public class RoomController {
 
     private final NodeService nodeService;
     private final RoomService roomService;
+    private final NamingValidator namingValidator;
 
     @GetMapping
     ResponseEntity<RoomListResponse> all(@PathVariable(name = "nodeId") String nodeId) {
-        var nodeOpt = nodeService.find(nodeId);
-        return nodeOpt.map(node -> ResponseEntity.ok(new RoomListResponse(nodeId,
-                roomService.all(node).stream()
-                        .map(room -> new RoomListResponse.RoomDTO(room.getId(), room.getSlots().getSlots(), room.isLocked()))
-                        .toList()
-        ))).orElseGet(() -> ResponseEntity.notFound().build());
+
+        return nodeService.find(nodeId)
+                .map(node -> ResponseEntity.ok(new RoomListResponse(nodeId,
+                        roomService.all(node).stream()
+                                .map(room -> new ru.dragonestia.picker.api.model.Room.Short(room.getId(), room.getSlots().getSlots(), room.isLocked()))
+                                .toList()
+                ))).orElseThrow(() -> new NodeNotFoundException(nodeId));
     }
 
     @PostMapping
-    ResponseEntity<RoomRegisterResponse> register(@PathVariable(name = "nodeId") String nodeId,
-                                                  @RequestParam(name = "roomId") String roomId,
-                                                  @RequestParam(name = "slots") int slots,
-                                                  @RequestParam(name = "payload") String payload,
-                                                  @RequestParam(name = "locked", defaultValue = "false") boolean locked) {
+    ResponseEntity<?> register(@PathVariable(name = "nodeId") String nodeId,
+                               @RequestParam(name = "roomId") String roomId,
+                               @RequestParam(name = "slots") int slots,
+                               @RequestParam(name = "payload") String payload,
+                               @RequestParam(name = "locked", defaultValue = "false") boolean locked) {
 
-        var nodeOpt = nodeService.find(nodeId);
-
-        if (nodeOpt.isEmpty()) {
-            return ResponseEntity.status(404)
-                    .body(new RoomRegisterResponse(false, "Node does not exist"));
-        }
-
-        var room = Room.create(roomId, nodeOpt.get(), SlotLimit.of(slots), payload);
+        var node = nodeService.find(nodeId).orElseThrow(() -> new NodeNotFoundException(nodeId));
+        var room = Room.create(roomId, node, SlotLimit.of(slots), payload);
         room.setLocked(locked);
-        try {
-            roomService.create(room);
-            return ResponseEntity.ok(new RoomRegisterResponse(true, ""));
-        } catch (Error error) {
-            return ResponseEntity.status(400).body(new RoomRegisterResponse(false, error.getMessage()));
-        } catch (Exception ex) {
-            return ResponseEntity.status(500).body(new RoomRegisterResponse(false, ex.getMessage()));
-        }
+        roomService.create(room);
+
+        return ResponseEntity.ok().build();
     }
 
     @DeleteMapping("/{roomId}")
     ResponseEntity<?> remove(@PathVariable("nodeId") String nodeId,
                              @PathVariable("roomId") String roomId) {
-        if (!NamingValidator.validateNodeId(nodeId) || !NamingValidator.validateRoomId(roomId)) {
-            return ResponseEntity.ok().build();
-        }
+
+        namingValidator.validateNodeId(nodeId);
+        namingValidator.validateRoomId(nodeId, roomId);
 
         var nodeOpt = nodeService.find(nodeId);
         nodeOpt.flatMap(node -> roomService.find(node, roomId))
@@ -77,40 +67,26 @@ public class RoomController {
     @GetMapping("/{roomId}")
     ResponseEntity<RoomInfoResponse> info(@PathVariable("nodeId") String nodeId,
                                           @PathVariable("roomId") String roomId) {
-        if (!NamingValidator.validateNodeId(nodeId) || !NamingValidator.validateRoomId(roomId)) {
-            return ResponseEntity.ok().build();
-        }
 
-        var nodeOpt = nodeService.find(nodeId);
-        if (nodeOpt.isEmpty()) {
-            return ResponseEntity.notFound().build();
-        }
+        namingValidator.validateNodeId(nodeId);
+        namingValidator.validateRoomId(nodeId, roomId);
 
-        var roomOpt = roomService.find(Objects.requireNonNull(nodeOpt.get()), roomId);
-        return roomOpt.map(room -> ResponseEntity.ok(new RoomInfoResponse(room)))
-                .orElseGet(() -> ResponseEntity.notFound().build());
+        var node = nodeService.find(nodeId).orElseThrow(() -> new NodeNotFoundException(nodeId));
+        return roomService.find(node, roomId)
+                .map(room -> ResponseEntity.ok(new RoomInfoResponse(room.toResponseObject())))
+                .orElseThrow(() -> new RoomNotFoundException(nodeId, roomId));
     }
 
-    @PostMapping("/{roomId}/lock")
+    @PutMapping("/{roomId}/lock")
     ResponseEntity<Boolean> lockBucket(@PathVariable("nodeId") String nodeId,
-                                 @PathVariable("roomId") String roomId,
-                                 @RequestParam(name = "newState") boolean value) {
+                                       @PathVariable("roomId") String roomId,
+                                       @RequestParam(name = "newState") boolean value) {
 
-        if (!NamingValidator.validateNodeId(nodeId) || !NamingValidator.validateRoomId(roomId)) {
-            return ResponseEntity.notFound().build();
-        }
+        namingValidator.validateNodeId(nodeId);
+        namingValidator.validateRoomId(nodeId, roomId);
 
-        var nodeOpt = nodeService.find(nodeId);
-        if (nodeOpt.isEmpty()) {
-            return ResponseEntity.notFound().build();
-        }
-
-        var roomOpt = roomService.find(Objects.requireNonNull(nodeOpt.get()), roomId);
-        if (roomOpt.isEmpty()) {
-            return ResponseEntity.notFound().build();
-        }
-
-        var room = roomOpt.get();
+        var node = nodeService.find(nodeId).orElseThrow(() -> new NodeNotFoundException(nodeId));
+        var room = roomService.find(node, roomId).orElseThrow(() -> new RoomNotFoundException(nodeId, roomId));
         room.setLocked(value);
         return ResponseEntity.ok(true);
     }

app/src/main/java/ru/dragonestia/picker/controller/UserRoomController.java

@@ -3,8 +3,10 @@ package ru.dragonestia.picker.controller;
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.*;
-import ru.dragonestia.picker.controller.response.RoomUserListResponse;
-import ru.dragonestia.picker.controller.response.LinkUsersWithRoomResponse;
+import ru.dragonestia.picker.api.exception.NodeNotFoundException;
+import ru.dragonestia.picker.api.exception.RoomNotFoundException;
+import ru.dragonestia.picker.api.repository.response.LinkUsersWithRoomResponse;
+import ru.dragonestia.picker.api.repository.response.RoomUserListResponse;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.Node;
 import ru.dragonestia.picker.model.User;
@@ -13,8 +15,7 @@ import ru.dragonestia.picker.service.NodeService;
 import ru.dragonestia.picker.service.UserService;
 import ru.dragonestia.picker.util.NamingValidator;
 
-import java.util.LinkedList;
-import java.util.Objects;
+import java.util.Arrays;
 
 @RequiredArgsConstructor
 @RestController
@@ -24,21 +25,15 @@ public class UserRoomController {
     private final NodeService nodeService;
     private final RoomService roomService;
     private final UserService userService;
+    private final NamingValidator namingValidator;
 
     @GetMapping
     ResponseEntity<RoomUserListResponse> usersInsideRoom(@PathVariable(name = "nodeId") String nodeId,
-                                                         @PathVariable(name = "roomId") String bucketId) {
-
-        Room room;
-        try {
-            var temp = getNodeAndRoom(nodeId, bucketId);
-            room = temp.room();
-        } catch (Error error) {
-            return ResponseEntity.notFound().build();
-        }
+                                                         @PathVariable(name = "roomId") String roomId) {
 
+        var room = getNodeAndRoom(nodeId, roomId).room();
         var users = userService.getRoomUsers(room);
-        return ResponseEntity.ok(new RoomUserListResponse(room.getSlots().getSlots(), users.size(), users));
+        return ResponseEntity.ok(new RoomUserListResponse(room.getSlots().getSlots(), users.size(), users.stream().map(User::toResponseObject).toList()));
     }
 
     @PostMapping
@@ -47,28 +42,10 @@ public class UserRoomController {
                                                                @RequestParam(name = "userIds") String userIds,
                                                                @RequestParam(name = "force") boolean force) {
 
-        Room room;
-        try {
-            var temp = getNodeAndRoom(nodeId, roomId);
-            room = temp.room();
-        } catch (Error error) {
-            return ResponseEntity.status(404).body(new LinkUsersWithRoomResponse(false, error.getMessage(), -1, -1));
-        }
-
-        var list = new LinkedList<User>();
-        for (var username: userIds.split(",")) { // TODO: create warnings about invalid usernames
-            if (!NamingValidator.validateUserId(username)) continue;
-
-            list.add(new User(username));
-        }
-
-        try {
-            int usedSlots = userService.linkUsersWithRoom(room, list, force);
-
-            return ResponseEntity.ok(new LinkUsersWithRoomResponse(true, "Success", usedSlots, room.getSlots().getSlots()));
-        } catch (Error error) {
-            return ResponseEntity.status(400).body(new LinkUsersWithRoomResponse(false, error.getMessage(), -1, -1));
-        }
+        var room = getNodeAndRoom(nodeId, roomId).room();
+        var users = namingValidator.validateUserIds(Arrays.stream(userIds.split(",")).toList());
+        var usedSlots = userService.linkUsersWithRoom(room, users, force);
+        return ResponseEntity.ok(new LinkUsersWithRoomResponse(usedSlots, room.getSlots().getSlots()));
     }
 
     @DeleteMapping
@@ -76,43 +53,21 @@ public class UserRoomController {
                                 @PathVariable(name = "roomId") String roomId,
                                 @RequestParam(name = "userIds") String userIds) {
 
-        Room room;
-        try {
-            var temp = getNodeAndRoom(nodeId, roomId);
-            room = temp.room();
-
-            var list = new LinkedList<User>();
-            for (var username: userIds.split(",")) { // TODO: create warnings about invalid usernames
-                if (!NamingValidator.validateUserId(username)) continue;
-
-                list.add(new User(username));
-            }
-
-            userService.unlinkUsersFromRoom(room, list);
-        } catch (Error error) {
-            return ResponseEntity.notFound().build();
-        }
-
+        var room = getNodeAndRoom(nodeId, roomId).room();
+        var users = namingValidator.validateUserIds(Arrays.stream(userIds.split(",")).toList());
+        userService.unlinkUsersFromRoom(room, users);
         return ResponseEntity.ok().build();
     }
 
     private record NodeAndRoom(Node node, Room room) {}
 
     private NodeAndRoom getNodeAndRoom(String nodeId, String roomId) {
-        if (!NamingValidator.validateNodeId(nodeId) || !NamingValidator.validateRoomId(roomId)) {
-            throw new Error();
-        }
+        namingValidator.validateNodeId(nodeId);
+        namingValidator.validateRoomId(nodeId, roomId);
 
-        var nodeOpt = nodeService.find(nodeId);
-        if (nodeOpt.isEmpty()) {
-            throw new Error();
-        }
+        var node = nodeService.find(nodeId).orElseThrow(() -> new NodeNotFoundException(nodeId));
+        var room = roomService.find(node, roomId).orElseThrow(() -> new RoomNotFoundException(nodeId, roomId));
 
-        var roomOpt = roomService.find(Objects.requireNonNull(nodeOpt.get()), roomId);
-        if (roomOpt.isEmpty()) {
-            throw new Error();
-        }
-
-        return new NodeAndRoom(nodeOpt.get(), roomOpt.get());
+        return new NodeAndRoom(node, room);
     }
 }

app/src/main/java/ru/dragonestia/picker/controller/response/LinkUsersWithRoomResponse.java

@@ -1,3 +0,0 @@
-package ru.dragonestia.picker.controller.response;
-
-public record LinkUsersWithRoomResponse(boolean success, String message, int usedSlots, int totalSlots) {}

app/src/main/java/ru/dragonestia/picker/controller/response/NodeDetailsResponse.java

@@ -1,5 +0,0 @@
-package ru.dragonestia.picker.controller.response;
-
-import ru.dragonestia.picker.model.Node;
-
-public record NodeDetailsResponse(Node node) {}

app/src/main/java/ru/dragonestia/picker/controller/response/NodeListResponse.java

@@ -1,7 +0,0 @@
-package ru.dragonestia.picker.controller.response;
-
-import ru.dragonestia.picker.model.Node;
-
-import java.util.List;
-
-public record NodeListResponse(List<Node> nodes) {}

app/src/main/java/ru/dragonestia/picker/controller/response/NodeRegisterResponse.java

@@ -1,3 +0,0 @@
-package ru.dragonestia.picker.controller.response;
-
-public record NodeRegisterResponse(boolean success, String message) {}

app/src/main/java/ru/dragonestia/picker/controller/response/RoomInfoResponse.java

@@ -1,5 +0,0 @@
-package ru.dragonestia.picker.controller.response;
-
-import ru.dragonestia.picker.model.Room;
-
-public record RoomInfoResponse(Room room) {}

app/src/main/java/ru/dragonestia/picker/controller/response/RoomListResponse.java

@@ -1,8 +0,0 @@
-package ru.dragonestia.picker.controller.response;
-
-import java.util.List;
-
-public record RoomListResponse(String node, List<RoomDTO> rooms) {
-
-    public record RoomDTO(String id, int slots, boolean locked) {}
-}

app/src/main/java/ru/dragonestia/picker/controller/response/RoomRegisterResponse.java

@@ -1,3 +0,0 @@
-package ru.dragonestia.picker.controller.response;
-
-public record RoomRegisterResponse(boolean success, String message) {}

app/src/main/java/ru/dragonestia/picker/model/Node.java

@@ -1,7 +1,7 @@
 package ru.dragonestia.picker.model;
 
 import lombok.NonNull;
-import ru.dragonestia.picker.model.type.PickingMode;
+import ru.dragonestia.picker.api.model.type.PickingMode;
 
 public record Node(@NonNull String id, @NonNull PickingMode mode) {
 
@@ -19,4 +19,8 @@ public record Node(@NonNull String id, @NonNull PickingMode mode) {
         }
         return false;
     }
+
+    public ru.dragonestia.picker.api.model.Node toResponseObject() {
+        return new ru.dragonestia.picker.api.model.Node(id, mode);
+    }
 }

app/src/main/java/ru/dragonestia/picker/model/Room.java

@@ -43,4 +43,10 @@ public class Room {
         }
         return false;
     }
+
+    public ru.dragonestia.picker.api.model.Room toResponseObject() {
+        var result = new ru.dragonestia.picker.api.model.Room(id, nodeId, slots.getSlots(), payload);
+        result.setLocked(locked);
+        return result;
+    }
 }

app/src/main/java/ru/dragonestia/picker/model/User.java

@@ -18,4 +18,8 @@ public record User(@NonNull String id) {
         }
         return false;
     }
+
+    public ru.dragonestia.picker.api.model.User toResponseObject() {
+        return new ru.dragonestia.picker.api.model.User(id);
+    }
 }

app/src/main/java/ru/dragonestia/picker/model/type/PickingMode.java

@@ -1,7 +0,0 @@
-package ru.dragonestia.picker.model.type;
-
-public enum PickingMode {
-    SEQUENTIAL_FILLING,
-    ROUND_ROBIN,
-    LEAST_PICKED,
-}

app/src/main/java/ru/dragonestia/picker/repository/NodeRepository.java

@@ -1,5 +1,6 @@
 package ru.dragonestia.picker.repository;
 
+import ru.dragonestia.picker.api.exception.NodeAlreadyExistException;
 import ru.dragonestia.picker.model.Node;
 
 import java.util.List;
@@ -7,7 +8,7 @@ import java.util.Optional;
 
 public interface NodeRepository {
 
-    void create(Node node);
+    void create(Node node) throws NodeAlreadyExistException;
 
     void delete(Node node);
 

app/src/main/java/ru/dragonestia/picker/repository/RoomRepository.java

@@ -1,5 +1,6 @@
 package ru.dragonestia.picker.repository;
 
+import ru.dragonestia.picker.api.exception.RoomAlreadyExistException;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.Node;
 import ru.dragonestia.picker.model.User;
@@ -10,7 +11,7 @@ import java.util.Optional;
 
 public interface RoomRepository {
 
-    void create(Room room);
+    void create(Room room) throws RoomAlreadyExistException;
 
     void remove(Room room);
 

app/src/main/java/ru/dragonestia/picker/repository/UserRepository.java

@@ -1,5 +1,6 @@
 package ru.dragonestia.picker.repository;
 
+import ru.dragonestia.picker.api.exception.RoomAreFullException;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.User;
 
@@ -9,7 +10,7 @@ import java.util.Map;
 
 public interface UserRepository {
 
-    Map<User, Boolean> linkWithRoom(Room room, Collection<User> users, boolean force);
+    Map<User, Boolean> linkWithRoom(Room room, Collection<User> users, boolean force) throws RoomAreFullException;
 
     int unlinkWithRoom(Room room, Collection<User> users);
 

app/src/main/java/ru/dragonestia/picker/repository/impl/NodeRepositoryImpl.java

@@ -2,6 +2,7 @@ package ru.dragonestia.picker.repository.impl;
 
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Repository;
+import ru.dragonestia.picker.api.exception.NodeAlreadyExistException;
 import ru.dragonestia.picker.model.Node;
 import ru.dragonestia.picker.repository.RoomRepository;
 import ru.dragonestia.picker.repository.NodeRepository;
@@ -22,10 +23,10 @@ public class NodeRepositoryImpl implements NodeRepository {
     private final Map<String, Node> nodeMap = new ConcurrentHashMap<>();
 
     @Override
-    public void create(Node node) {
+    public void create(Node node) throws NodeAlreadyExistException {
         synchronized (nodeMap) {
             if (nodeMap.containsKey(node.id())) {
-                throw new IllegalArgumentException("Node with id '" + node.id() + "' already exists");
+                throw new NodeAlreadyExistException(node.id());
             }
 
             nodeMap.put(node.id(), node);

app/src/main/java/ru/dragonestia/picker/repository/impl/PickerRepository.java

@@ -2,9 +2,9 @@ package ru.dragonestia.picker.repository.impl;
 
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Component;
+import ru.dragonestia.picker.api.model.type.PickingMode;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.User;
-import ru.dragonestia.picker.model.type.PickingMode;
 import ru.dragonestia.picker.repository.UserRepository;
 import ru.dragonestia.picker.repository.impl.picker.*;
 

app/src/main/java/ru/dragonestia/picker/repository/impl/RoomRepositoryImpl.java

@@ -2,6 +2,7 @@ package ru.dragonestia.picker.repository.impl;
 
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Repository;
+import ru.dragonestia.picker.api.exception.RoomAlreadyExistException;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.Node;
 import ru.dragonestia.picker.model.User;
@@ -21,7 +22,7 @@ public class RoomRepositoryImpl implements RoomRepository {
     private final Map<Node, Rooms> node2roomsMap = new ConcurrentHashMap<>();
 
     @Override
-    public void create(Room room) {
+    public void create(Room room) throws RoomAlreadyExistException {
         var nodeId = room.getNodeId();
 
         synchronized (node2roomsMap) {
@@ -35,7 +36,7 @@ public class RoomRepositoryImpl implements RoomRepository {
 
             var rooms = node2roomsMap.get(node.get());
             if (rooms.containsKey(room.getId())) {
-                throw new IllegalArgumentException("Room already exists");
+                throw new RoomAlreadyExistException(room.getNodeId(), room.getId());
             }
             rooms.put(room.getId(), new RoomContainer(room, new AtomicInteger(0)));
             pickerRepository.find(room.getNodeId()).add(room);

app/src/main/java/ru/dragonestia/picker/repository/impl/UserRepositoryImpl.java

@@ -2,10 +2,9 @@ package ru.dragonestia.picker.repository.impl;
 
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Repository;
+import ru.dragonestia.picker.api.exception.RoomAreFullException;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.User;
-import ru.dragonestia.picker.model.type.PickingMode;
-import ru.dragonestia.picker.repository.NodeRepository;
 import ru.dragonestia.picker.repository.UserRepository;
 import ru.dragonestia.picker.repository.impl.cache.NodeId2PickerModeCache;
 import ru.dragonestia.picker.repository.impl.picker.LeastPickedPicker;
@@ -23,7 +22,7 @@ public class UserRepositoryImpl implements UserRepository {
     private final Map<NodeRoomPath, Set<User>> roomUsers = new ConcurrentHashMap<>();
 
     @Override
-    public Map<User, Boolean> linkWithRoom(Room room, Collection<User> users, boolean force) {
+    public Map<User, Boolean> linkWithRoom(Room room, Collection<User> users, boolean force) throws RoomAreFullException {
         var result = new HashMap<User, Boolean>();
 
         synchronized (usersMap) {
@@ -39,7 +38,7 @@ public class UserRepositoryImpl implements UserRepository {
                 }
 
                 if (room.getSlots().getSlots() < usersSet.size() + users.size()) {
-                    throw new Error("Room are full");
+                    throw new RoomAreFullException(room.getNodeId(), room.getId());
                 }
             }
 

app/src/main/java/ru/dragonestia/picker/repository/impl/picker/LeastPickedPicker.java

@@ -1,8 +1,8 @@
 package ru.dragonestia.picker.repository.impl.picker;
 
+import ru.dragonestia.picker.api.model.type.PickingMode;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.User;
-import ru.dragonestia.picker.model.type.PickingMode;
 import ru.dragonestia.picker.repository.UserRepository;
 import ru.dragonestia.picker.repository.impl.collection.DynamicSortedMap;
 

app/src/main/java/ru/dragonestia/picker/repository/impl/picker/RoomPicker.java

@@ -1,8 +1,8 @@
 package ru.dragonestia.picker.repository.impl.picker;
 
+import ru.dragonestia.picker.api.model.type.PickingMode;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.User;
-import ru.dragonestia.picker.model.type.PickingMode;
 
 public interface RoomPicker extends Picker<Room, User> {
 

app/src/main/java/ru/dragonestia/picker/repository/impl/picker/RoundRobinPicker.java

@@ -1,8 +1,8 @@
 package ru.dragonestia.picker.repository.impl.picker;
 
+import ru.dragonestia.picker.api.model.type.PickingMode;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.User;
-import ru.dragonestia.picker.model.type.PickingMode;
 import ru.dragonestia.picker.repository.UserRepository;
 import ru.dragonestia.picker.repository.impl.collection.QueuedLinkedList;
 

app/src/main/java/ru/dragonestia/picker/repository/impl/picker/SequentialFillingPicker.java

@@ -1,8 +1,8 @@
 package ru.dragonestia.picker.repository.impl.picker;
 
+import ru.dragonestia.picker.api.model.type.PickingMode;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.User;
-import ru.dragonestia.picker.model.type.PickingMode;
 import ru.dragonestia.picker.repository.UserRepository;
 
 import java.util.Collection;

app/src/main/java/ru/dragonestia/picker/service/NodeService.java

@@ -1,5 +1,7 @@
 package ru.dragonestia.picker.service;
 
+import ru.dragonestia.picker.api.exception.InvalidNodeIdentifierException;
+import ru.dragonestia.picker.api.exception.NodeAlreadyExistException;
 import ru.dragonestia.picker.model.Node;
 
 import java.util.List;
@@ -7,7 +9,7 @@ import java.util.Optional;
 
 public interface NodeService {
 
-    void create(Node node);
+    void create(Node node) throws InvalidNodeIdentifierException, NodeAlreadyExistException;
 
     void remove(Node node);
 

app/src/main/java/ru/dragonestia/picker/service/RoomService.java

@@ -1,5 +1,7 @@
 package ru.dragonestia.picker.service;
 
+import ru.dragonestia.picker.api.exception.InvalidRoomIdentifierException;
+import ru.dragonestia.picker.api.exception.RoomAlreadyExistException;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.Node;
 import ru.dragonestia.picker.model.User;
@@ -9,7 +11,7 @@ import java.util.Optional;
 
 public interface RoomService {
 
-    void create(Room room);
+    void create(Room room) throws InvalidRoomIdentifierException, RoomAlreadyExistException;
 
     void remove(Room room);
 

app/src/main/java/ru/dragonestia/picker/service/UserService.java

@@ -1,5 +1,6 @@
 package ru.dragonestia.picker.service;
 
+import ru.dragonestia.picker.api.exception.RoomAreFullException;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.User;
 
@@ -10,7 +11,7 @@ public interface UserService {
 
     List<Room> getUserRooms(User user);
 
-    int linkUsersWithRoom(Room room, Collection<User> users, boolean force);
+    int linkUsersWithRoom(Room room, Collection<User> users, boolean force) throws RoomAreFullException;
 
     void unlinkUsersFromRoom(Room room, Collection<User> users);
 

app/src/main/java/ru/dragonestia/picker/service/impl/NodeServiceImpl.java

@@ -2,6 +2,8 @@ package ru.dragonestia.picker.service.impl;
 
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
+import ru.dragonestia.picker.api.exception.InvalidNodeIdentifierException;
+import ru.dragonestia.picker.api.exception.NodeAlreadyExistException;
 import ru.dragonestia.picker.model.Node;
 import ru.dragonestia.picker.repository.NodeRepository;
 import ru.dragonestia.picker.service.NodeService;
@@ -15,13 +17,11 @@ import java.util.Optional;
 public class NodeServiceImpl implements NodeService {
 
     private final NodeRepository nodeRepository;
+    private final NamingValidator namingValidator;
 
     @Override
-    public void create(Node node) {
-        if (!NamingValidator.validateNodeId(node.id())) {
-            throw new Error("Invalid node id format");
-        }
-
+    public void create(Node node) throws InvalidNodeIdentifierException, NodeAlreadyExistException {
+        namingValidator.validateNodeId(node.id());
         nodeRepository.create(node);
     }
 

app/src/main/java/ru/dragonestia/picker/service/impl/RoomServiceImpl.java

@@ -2,6 +2,8 @@ package ru.dragonestia.picker.service.impl;
 
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
+import ru.dragonestia.picker.api.exception.InvalidRoomIdentifierException;
+import ru.dragonestia.picker.api.exception.RoomAlreadyExistException;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.Node;
 import ru.dragonestia.picker.model.User;
@@ -17,13 +19,11 @@ import java.util.Optional;
 public class RoomServiceImpl implements RoomService {
 
     private final RoomRepository roomRepository;
+    private final NamingValidator namingValidator;
 
     @Override
-    public void create(Room room) {
-        if (!NamingValidator.validateRoomId(room.getId())) {
-            throw new Error("Invalid room id format");
-        }
-
+    public void create(Room room) throws InvalidRoomIdentifierException, RoomAlreadyExistException {
+        namingValidator.validateRoomId(room.getNodeId(), room.getId());
         roomRepository.create(room);
     }
 

app/src/main/java/ru/dragonestia/picker/util/NamingValidator.java

@@ -1,19 +1,51 @@
 package ru.dragonestia.picker.util;
 
-import lombok.experimental.UtilityClass;
+import org.springframework.stereotype.Component;
+import ru.dragonestia.picker.api.exception.InvalidNodeIdentifierException;
+import ru.dragonestia.picker.api.exception.InvalidRoomIdentifierException;
+import ru.dragonestia.picker.api.exception.InvalidUsernamesException;
+import ru.dragonestia.picker.api.utils.ValidateIdentifier;
+import ru.dragonestia.picker.model.User;
 
-@UtilityClass
+import java.util.LinkedList;
+import java.util.List;
+
+@Component
 public class NamingValidator {
 
-    public boolean validateNodeId(String input) {
-        return input.matches("^[a-z\\d-]+$");
+    public void validateNodeId(String input) throws InvalidNodeIdentifierException {
+        if (ValidateIdentifier.forNode(input)) return;
+
+        throw new InvalidNodeIdentifierException(input);
     }
 
-    public boolean validateRoomId(String input) {
-        return input.matches("^[a-z\\d-]+$");
+    public void validateRoomId(String nodeId, String input) throws InvalidRoomIdentifierException {
+        if (ValidateIdentifier.forRoom(input)) return;
+
+        throw new InvalidRoomIdentifierException(nodeId, input);
     }
 
-    public boolean validateUserId(String input) {
-        return input.matches("^[aA-zZ\\d-.\\s:/@%?!~$)(+=_|;*]+$");
+    private boolean validateUserId(String input) {
+        return ValidateIdentifier.forUser(input);
+    }
+
+    public List<User> validateUserIds(List<String> input) throws InvalidUsernamesException {
+        var users = new LinkedList<User>();
+        var invalid = new LinkedList<String>();
+
+        for (var username: input) {
+            if (validateUserId(username)) {
+                users.add(new User(username));
+                continue;
+            }
+
+            invalid.add(username);
+        }
+
+        if (!invalid.isEmpty()) {
+            throw new InvalidUsernamesException(input, invalid);
+        }
+
+        return users;
     }
 }

app/src/test/java/ru/dragonestia/picker/config/FillingNodesConfig.java

@@ -3,10 +3,10 @@ package ru.dragonestia.picker.config;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.TestConfiguration;
 import org.springframework.context.annotation.Bean;
+import ru.dragonestia.picker.api.model.type.PickingMode;
 import ru.dragonestia.picker.model.Node;
 import ru.dragonestia.picker.model.Room;
 import ru.dragonestia.picker.model.User;
-import ru.dragonestia.picker.model.type.PickingMode;
 import ru.dragonestia.picker.model.type.SlotLimit;
 import ru.dragonestia.picker.repository.NodeRepository;
 import ru.dragonestia.picker.repository.RoomRepository;

control-panel/build.gradle

@@ -23,8 +23,11 @@ ext {
 }
 
 dependencies {
+    implementation project(":api")
+
     implementation 'com.vaadin:vaadin-spring-boot-starter'
     compileOnly 'org.projectlombok:lombok'
+
     annotationProcessor 'org.projectlombok:lombok'
     testImplementation 'org.springframework.boot:spring-boot-starter-test'
 }

control-panel/src/main/java/ru/dragonestia/picker/cp/component/AddUsers.java

@@ -9,18 +9,15 @@ import com.vaadin.flow.component.html.Div;
 import com.vaadin.flow.component.html.H2;
 import com.vaadin.flow.component.icon.Icon;
 import com.vaadin.flow.component.icon.VaadinIcon;
-import com.vaadin.flow.component.notification.Notification;
-import com.vaadin.flow.component.notification.NotificationVariant;
 import com.vaadin.flow.component.orderedlayout.VerticalLayout;
 import com.vaadin.flow.component.textfield.TextField;
 import lombok.Getter;
-import ru.dragonestia.picker.cp.model.Room;
-import ru.dragonestia.picker.cp.model.User;
+import ru.dragonestia.picker.api.model.Room;
+import ru.dragonestia.picker.api.model.User;
 
 import java.util.Collection;
 import java.util.List;
 import java.util.function.BiConsumer;
-import java.util.function.Consumer;
 
 public class AddUsers extends Details {
 
@@ -79,8 +76,7 @@ public class AddUsers extends Details {
         try {
             onCommit.accept(readAllUsers(), ignoreSlots.getValue());
         } catch (Error error) {
-            Notification.show(error.getMessage(), 3000, Notification.Position.TOP_END)
-                    .addThemeVariants(NotificationVariant.LUMO_ERROR);
+            Notifications.error(error.getMessage());
         }
 
         clear();

control-panel/src/main/java/ru/dragonestia/picker/cp/component/NavPath.java

@@ -10,7 +10,7 @@ import com.vaadin.flow.component.orderedlayout.HorizontalLayout;
 
 public class NavPath extends HorizontalLayout{
 
-    public NavPath(Point root, Point... points) {
+    private NavPath(Point root, Point... points) {
         setWidth("100%");
         setAlignItems(Alignment.CENTER);
         getStyle().set("background-color", "#F3F3F3")
@@ -58,5 +58,20 @@ public class NavPath extends HorizontalLayout{
         return button;
     }
 
-    public record Point(String name, String uri) {}
+    public static NavPath rootNodes() {
+        return new NavPath(new NavPath.Point("Nodes", "/nodes"));
+    }
+
+    public static NavPath toNode(String nodeId) {
+        return new NavPath(new NavPath.Point("Nodes", "/nodes"),
+                new NavPath.Point(nodeId, "/nodes/" + nodeId));
+    }
+
+    public static NavPath toRoom(String nodeId, String roomId) {
+        return new NavPath(new NavPath.Point("Nodes", "/nodes"),
+                new NavPath.Point(nodeId, "/nodes/" + nodeId),
+                new NavPath.Point(roomId, "/nodes/" + nodeId + "/rooms/" + roomId));
+    }
+
+    private record Point(String name, String uri) {}
 }

control-panel/src/main/java/ru/dragonestia/picker/cp/component/NodeList.java

@@ -1,5 +1,6 @@
 package ru.dragonestia.picker.cp.component;
 
+import com.vaadin.flow.component.Html;
 import com.vaadin.flow.component.button.Button;
 import com.vaadin.flow.component.button.ButtonVariant;
 import com.vaadin.flow.component.dialog.Dialog;
@@ -8,13 +9,11 @@ import com.vaadin.flow.component.html.H2;
 import com.vaadin.flow.component.html.Paragraph;
 import com.vaadin.flow.component.icon.Icon;
 import com.vaadin.flow.component.icon.VaadinIcon;
-import com.vaadin.flow.component.notification.Notification;
-import com.vaadin.flow.component.notification.NotificationVariant;
 import com.vaadin.flow.component.orderedlayout.HorizontalLayout;
 import com.vaadin.flow.component.orderedlayout.VerticalLayout;
 import com.vaadin.flow.component.textfield.TextField;
 import lombok.Setter;
-import ru.dragonestia.picker.cp.model.Node;
+import ru.dragonestia.picker.api.model.Node;
 
 import java.util.List;
 import java.util.function.Consumer;
@@ -51,14 +50,14 @@ public class NodeList extends VerticalLayout {
         var temp = input.trim();
 
         nodesGrid.setItems(cachedNodes.stream()
-                .filter(node -> node.id().startsWith(temp))
+                .filter(node -> node.getId().startsWith(temp))
                 .toList());
     }
 
     private Grid<Node> createGrid() {
         var grid = new Grid<>(Node.class, false);
-        grid.addColumn(Node::id).setHeader("Identifier");
-        grid.addColumn(node -> node.mode().getName()).setHeader("Mode");
+        grid.addColumn(Node::getId).setHeader("Identifier");
+        grid.addColumn(node -> node.getMode().getName()).setHeader("Mode");
         grid.addComponentColumn(this::createManageButtons).setHeader("Manage");
         return grid;
     }
@@ -84,29 +83,28 @@ public class NodeList extends VerticalLayout {
     }
 
     private void clickDetailsButton(Node node) {
-        getUI().ifPresent(ui -> ui.navigate("/nodes/" + node.id()));
+        getUI().ifPresent(ui -> ui.navigate("/nodes/" + node.getId()));
     }
 
     private void clickRemoveButton(Node node) {
         var dialog = new Dialog("Confirm node deletion");
-        dialog.add(new Paragraph("Confirm that you want to delete node. Enter '" + node.id() + "' to field below and confirm."));
+        dialog.add(new Html("<p>Confirm that you want to delete node. Enter <b><u>" + node.getId() + "</u></b> to field below and confirm.</p>"));
 
         var inputField = new TextField();
+        inputField.setWidth("100%");
         dialog.add(inputField);
 
         { // confirm
             var button = new Button("Confirm");
             button.addThemeVariants(ButtonVariant.LUMO_PRIMARY, ButtonVariant.LUMO_ERROR);
             button.addClickListener(event -> {
-                if (!node.id().equals(inputField.getValue())) {
-                    Notification.show("Invalid input", 3000, Notification.Position.TOP_END)
-                            .addThemeVariants(NotificationVariant.LUMO_ERROR);
+                if (!node.getId().equals(inputField.getValue())) {
+                    Notifications.error("Invalid input");
                     return;
                 }
 
                 removeNode(node);
-                Notification.show("Node '" + node.id() + "' was successfully removed!", 3000, Notification.Position.TOP_END)
-                        .addThemeVariants(NotificationVariant.LUMO_SUCCESS);
+                Notifications.success("Node <b>" + node.getId() + "</b> was successfully removed!");
                 dialog.close();
             });
 
@@ -129,7 +127,7 @@ public class NodeList extends VerticalLayout {
 
     private void removeNode(Node node) {
         if (removeMethod != null) {
-            removeMethod.accept(node.id());
+            removeMethod.accept(node.getId());
         }
     }
 }

control-panel/src/main/java/ru/dragonestia/picker/cp/component/Notifications.java

@@ -0,0 +1,53 @@
+package ru.dragonestia.picker.cp.component;
+
+import com.vaadin.flow.component.Html;
+import com.vaadin.flow.component.button.Button;
+import com.vaadin.flow.component.button.ButtonVariant;
+import com.vaadin.flow.component.icon.Icon;
+import com.vaadin.flow.component.icon.VaadinIcon;
+import com.vaadin.flow.component.notification.Notification;
+import com.vaadin.flow.component.notification.NotificationVariant;
+import com.vaadin.flow.component.orderedlayout.HorizontalLayout;
+import lombok.experimental.UtilityClass;
+
+@UtilityClass
+public class Notifications {
+
+    public Notification success(String text) {
+        var notification = create(VaadinIcon.CHECK_CIRCLE, text);
+        notification.addThemeVariants(NotificationVariant.LUMO_SUCCESS);
+        notification.open();
+        return notification;
+    }
+
+    public Notification warn(String text) {
+        var notification = create(VaadinIcon.WARNING, text);
+        notification.addThemeVariants(NotificationVariant.LUMO_WARNING);
+        notification.open();
+        return notification;
+    }
+
+    public Notification error(String text) {
+        var notification = create(VaadinIcon.WARNING, text);
+        notification.addThemeVariants(NotificationVariant.LUMO_ERROR);
+        notification.open();
+        return notification;
+    }
+
+    private Notification create(VaadinIcon icon, String text) {
+        var layout = new HorizontalLayout();
+        layout.add(new Icon(icon));
+        layout.add(new Html("<span>" + text + "</span>"));
+
+        var notification = new Notification();
+        notification.setDuration(5000);
+        notification.setPosition(Notification.Position.TOP_END);
+
+        var closeButton = new Button(VaadinIcon.CLOSE_SMALL.create(), event -> notification.close());
+        closeButton.addThemeVariants(ButtonVariant.LUMO_TERTIARY_INLINE);
+        layout.add(closeButton);
+
+        notification.add(layout);
+        return notification;
+    }
+}

control-panel/src/main/java/ru/dragonestia/picker/cp/component/RegisterNode.java

@@ -7,8 +7,6 @@ import com.vaadin.flow.component.button.ButtonVariant;
 import com.vaadin.flow.component.details.Details;
 import com.vaadin.flow.component.html.H2;
 import com.vaadin.flow.component.html.Span;
-import com.vaadin.flow.component.notification.Notification;
-import com.vaadin.flow.component.notification.NotificationVariant;
 import com.vaadin.flow.component.orderedlayout.VerticalLayout;
 import com.vaadin.flow.component.radiobutton.RadioButtonGroup;
 import com.vaadin.flow.component.radiobutton.RadioGroupVariant;
@@ -16,8 +14,8 @@ import com.vaadin.flow.component.textfield.Autocomplete;
 import com.vaadin.flow.component.textfield.TextField;
 import com.vaadin.flow.data.renderer.ComponentRenderer;
 import org.springframework.lang.Nullable;
-import ru.dragonestia.picker.cp.model.Node;
-import ru.dragonestia.picker.cp.model.type.PickingMode;
+import ru.dragonestia.picker.api.model.Node;
+import ru.dragonestia.picker.api.model.type.PickingMode;
 
 import java.util.function.Function;
 
@@ -91,8 +89,7 @@ public class RegisterNode extends Details {
                 error = "Invalid node id format";
             }
 
-            Notification.show(error, 3000, Notification.Position.TOP_END)
-                    .addThemeVariants(NotificationVariant.LUMO_ERROR);
+            Notifications.error(error);
             return;
         }
 
@@ -100,13 +97,11 @@ public class RegisterNode extends Details {
         var response = onSubmit.apply(node);
         clear();
         if (response.error()) {
-            Notification.show(response.reason(), 3000, Notification.Position.TOP_END)
-                    .addThemeVariants(NotificationVariant.LUMO_ERROR);
+            Notifications.error(response.reason());
             return;
         }
 
-        Notification.show("Node was successfully registered", 3000, Notification.Position.TOP_END)
-                .addThemeVariants(NotificationVariant.LUMO_SUCCESS);
+        Notifications.success("Node was successfully registered");
     }
 
     public record Response(boolean error, @Nullable String reason) {}

control-panel/src/main/java/ru/dragonestia/picker/cp/component/RegisterRoom.java

@@ -6,16 +6,13 @@ import com.vaadin.flow.component.button.ButtonVariant;
 import com.vaadin.flow.component.checkbox.Checkbox;
 import com.vaadin.flow.component.details.Details;
 import com.vaadin.flow.component.html.H2;
-import com.vaadin.flow.component.notification.Notification;
-import com.vaadin.flow.component.notification.NotificationVariant;
 import com.vaadin.flow.component.orderedlayout.VerticalLayout;
 import com.vaadin.flow.component.textfield.Autocomplete;
 import com.vaadin.flow.component.textfield.TextArea;
 import com.vaadin.flow.component.textfield.TextField;
 import org.springframework.lang.Nullable;
-import ru.dragonestia.picker.cp.model.Room;
-import ru.dragonestia.picker.cp.model.Node;
-import ru.dragonestia.picker.cp.model.type.SlotLimit;
+import ru.dragonestia.picker.api.model.Node;
+import ru.dragonestia.picker.api.model.Room;
 
 import java.util.function.Function;
 
@@ -45,7 +42,7 @@ public class RegisterRoom extends Details {
     private TextField createNodeIdentifierField() {
         var field = new TextField("Node identifier");
         field.setMinWidth(20, Unit.REM);
-        field.setValue(node.id());
+        field.setValue(node.getId());
         field.setReadOnly(true);
         return field;
     }
@@ -106,23 +103,20 @@ public class RegisterRoom extends Details {
                 error = "Invalid room id format";
             }
 
-            Notification.show(error, 3000, Notification.Position.TOP_END)
-                    .addThemeVariants(NotificationVariant.LUMO_ERROR);
+            Notifications.error(error);
             return;
         }
 
-        var room = Room.create(nodeIdentifier, node, SlotLimit.unlimited(), payloadField.getValue());
+        var room = new Room(nodeIdentifier, node, Room.INFINITE_SLOTS, payloadField.getValue());
         room.setLocked(lockedField.getValue());
         var response = onSubmit.apply(room);
         clear();
         if (response.error()) {
-            Notification.show(response.reason(), 3000, Notification.Position.TOP_END)
-                    .addThemeVariants(NotificationVariant.LUMO_ERROR);
+            Notifications.error(response.reason());
             return;
         }
 
-        Notification.show("Room was successfully registered", 3000, Notification.Position.TOP_END)
-                .addThemeVariants(NotificationVariant.LUMO_SUCCESS);
+        Notifications.success("Room was successfully registered");
     }
 
     public record Response(boolean error, @Nullable String reason) {}

control-panel/src/main/java/ru/dragonestia/picker/cp/component/RoomList.java

@@ -1,5 +1,6 @@
 package ru.dragonestia.picker.cp.component;
 
+import com.vaadin.flow.component.Html;
 import com.vaadin.flow.component.button.Button;
 import com.vaadin.flow.component.button.ButtonVariant;
 import com.vaadin.flow.component.dialog.Dialog;
@@ -10,13 +11,11 @@ import com.vaadin.flow.component.html.Paragraph;
 import com.vaadin.flow.component.html.Span;
 import com.vaadin.flow.component.icon.Icon;
 import com.vaadin.flow.component.icon.VaadinIcon;
-import com.vaadin.flow.component.notification.Notification;
-import com.vaadin.flow.component.notification.NotificationVariant;
 import com.vaadin.flow.component.orderedlayout.HorizontalLayout;
 import com.vaadin.flow.component.orderedlayout.VerticalLayout;
 import com.vaadin.flow.component.textfield.TextField;
 import lombok.Setter;
-import ru.dragonestia.picker.cp.model.dto.RoomDTO;
+import ru.dragonestia.picker.api.model.Room;
 
 import java.util.List;
 import java.util.function.Consumer;
@@ -24,12 +23,12 @@ import java.util.function.Consumer;
 public class RoomList extends VerticalLayout {
 
     private final String nodeIdentifier;
-    private final Grid<RoomDTO> roomsGrid;
+    private final Grid<Room.Short> roomsGrid;
     private final TextField searchField;
-    private List<RoomDTO> cachedRooms;
-    @Setter private Consumer<RoomDTO> removeMethod;
+    private List<Room.Short> cachedRooms;
+    @Setter private Consumer<Room.Short> removeMethod;
 
-    public RoomList(String nodeIdentifier, List<RoomDTO> buckets) {
+    public RoomList(String nodeIdentifier, List<Room.Short> buckets) {
         this.nodeIdentifier = nodeIdentifier;
         cachedRooms = buckets;
 
@@ -57,9 +56,9 @@ public class RoomList extends VerticalLayout {
                 .toList());
     }
 
-    private Grid<RoomDTO> createGrid() {
-        var grid = new Grid<>(RoomDTO.class, false);
-        grid.addColumn(RoomDTO::id).setHeader("Identifier");
+    private Grid<Room.Short> createGrid() {
+        var grid = new Grid<>(Room.Short.class, false);
+        grid.addColumn(Room.Short::id).setHeader("Identifier");
         grid.addComponentColumn(room -> {
             var result = new Span();
             if (room.slots() == -1) {
@@ -84,7 +83,7 @@ public class RoomList extends VerticalLayout {
         return grid;
     }
 
-    private HorizontalLayout createManageButtons(RoomDTO room) {
+    private HorizontalLayout createManageButtons(Room.Short room) {
         var layout = new HorizontalLayout();
 
         {
@@ -104,18 +103,19 @@ public class RoomList extends VerticalLayout {
         return layout;
     }
 
-    private void clickDetailsButton(RoomDTO bucket) {
+    private void clickDetailsButton(Room.Short bucket) {
         getUI().ifPresent(ui -> {
             ui.navigate("/nodes/" + nodeIdentifier +
                     "/rooms/" + bucket.id());
         });
     }
 
-    private void clickRemoveButton(RoomDTO bucket) {
+    private void clickRemoveButton(Room.Short bucket) {
         var dialog = new Dialog("Confirm bucket deletion");
-        dialog.add(new Paragraph("Confirm that you want to delete bucket. Enter '" + bucket.id() + "' to field below and confirm."));
+        dialog.add(new Html("<p>Confirm that you want to delete bucket. Enter <b><u>" + bucket.id() + "</u></b> to field below and confirm.</p>"));
 
         var inputField = new TextField();
+        inputField.setWidth("100%");
         dialog.add(inputField);
 
         { // confirm
@@ -123,14 +123,12 @@ public class RoomList extends VerticalLayout {
             button.addThemeVariants(ButtonVariant.LUMO_PRIMARY, ButtonVariant.LUMO_ERROR);
             button.addClickListener(event -> {
                 if (!bucket.id().equals(inputField.getValue())) {
-                    Notification.show("Invalid input", 3000, Notification.Position.TOP_END)
-                            .addThemeVariants(NotificationVariant.LUMO_ERROR);
+                    Notifications.error("Invalid input");
                     return;
                 }
 
                 removeBucket(bucket);
-                Notification.show("Bucket '" + bucket.id() + "' was successfully removed!", 3000, Notification.Position.TOP_END)
-                        .addThemeVariants(NotificationVariant.LUMO_SUCCESS);
+                Notifications.success("Bucket <b>" + bucket.id() + "</b> was successfully removed!");
                 dialog.close();
             });
 
@@ -146,12 +144,12 @@ public class RoomList extends VerticalLayout {
         dialog.open();
     }
 
-    public void update(List<RoomDTO> buckets) {
+    public void update(List<Room.Short> buckets) {
         cachedRooms = buckets;
         applySearch(searchField.getValue());
     }
 
-    private void removeBucket(RoomDTO bucket) {
+    private void removeBucket(Room.Short bucket) {
         if (removeMethod != null) {
             removeMethod.accept(bucket);
         }

control-panel/src/main/java/ru/dragonestia/picker/cp/component/UserList.java

@@ -4,8 +4,8 @@ import com.vaadin.flow.component.grid.ColumnTextAlign;
 import com.vaadin.flow.component.grid.Grid;
 import com.vaadin.flow.component.html.Span;
 import com.vaadin.flow.component.orderedlayout.VerticalLayout;
-import ru.dragonestia.picker.cp.model.Room;
-import ru.dragonestia.picker.cp.model.User;
+import ru.dragonestia.picker.api.model.Room;
+import ru.dragonestia.picker.api.model.User;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -28,7 +28,7 @@ public class UserList extends VerticalLayout {
 
     private Grid<User> createUsersGrid() {
         var grid = new Grid<User>();
-        grid.addColumn(User::id).setHeader("User Identifier").setFooter(totalUsers);
+        grid.addColumn(User::getId).setHeader("User Identifier").setFooter(totalUsers);
         grid.addColumn(user -> 0).setTextAlign(ColumnTextAlign.CENTER).setHeader("Linked with rooms") // TODO
                 .setFooter(occupancy);
         grid.addComponentColumn(user -> new Span("buttons")).setHeader("Manage"); // TODO
@@ -39,6 +39,12 @@ public class UserList extends VerticalLayout {
         cachedUsers = users;
         usersGrid.setItems(users);
         totalUsers.setText("Total users: " + users.size());
-        occupancy.setText("Occupancy: %s".formatted(room.getUsingPercentage(users.size())));
+        occupancy.setText("Occupancy: %s".formatted(getUsingPercentage(room, users.size())));
+    }
+
+    private String getUsingPercentage(Room room, int usedSlots) {
+        if (room.isUnlimited()) return "0%";
+        double percent = usedSlots / (double) room.getSlots() * 100;
+        return ((int) percent) + "%";
     }
 }

control-panel/src/main/java/ru/dragonestia/picker/cp/config/RestApiConfig.java

@@ -17,7 +17,7 @@ public class RestApiConfig {
     }
 
     @Bean
-    Supplier<RestTemplate> restTemplate(@Autowired RestTemplateBuilder builder) {
+    Supplier<RestTemplate> restTemplateSupplier(@Autowired RestTemplateBuilder builder) {
         return builder::build;
     }
 }

control-panel/src/main/java/ru/dragonestia/picker/cp/error/ApplicationErrorHandler.java

@@ -0,0 +1,37 @@
+package ru.dragonestia.picker.cp.error;
+
+import com.vaadin.flow.component.UI;
+import com.vaadin.flow.server.Command;
+import com.vaadin.flow.server.ErrorEvent;
+import com.vaadin.flow.server.ErrorHandler;
+import lombok.extern.log4j.Log4j2;
+import ru.dragonestia.picker.api.exception.ApiException;
+import ru.dragonestia.picker.cp.component.Notifications;
+
+@Log4j2
+public class ApplicationErrorHandler implements ErrorHandler {
+
+    @Override
+    public void error(ErrorEvent errorEvent) {
+        if (UI.getCurrent() == null) {
+            log.throwing(errorEvent.getThrowable());
+            return;
+        }
+
+        if (errorEvent.getThrowable() instanceof ApiException ex) {
+            execute(() -> {
+                Notifications.error(ex.getMessage());
+            });
+            return;
+        }
+
+        execute(() -> {
+            Notifications.error("Internal server error");
+        });
+        log.throwing(errorEvent.getThrowable());
+    }
+
+    private void execute(Command command) {
+        UI.getCurrent().access(command);
+    }
+}

control-panel/src/main/java/ru/dragonestia/picker/cp/listener/VaadinEventListener.java

@@ -0,0 +1,19 @@
+package ru.dragonestia.picker.cp.listener;
+
+import com.vaadin.flow.server.ServiceInitEvent;
+import com.vaadin.flow.server.VaadinServiceInitListener;
+import com.vaadin.flow.spring.annotation.SpringComponent;
+import lombok.extern.log4j.Log4j2;
+import ru.dragonestia.picker.cp.error.ApplicationErrorHandler;
+
+@Log4j2
+@SpringComponent
+public class VaadinEventListener implements VaadinServiceInitListener {
+
+    @Override
+    public void serviceInit(ServiceInitEvent event) {
+        event.getSource().addSessionInitListener(e -> {
+            e.getSession().setErrorHandler(new ApplicationErrorHandler());
+        });
+    }
+}

control-panel/src/main/java/ru/dragonestia/picker/cp/model/Node.java

@@ -1,24 +0,0 @@
-package ru.dragonestia.picker.cp.model;
-
-import lombok.NonNull;
-import ru.dragonestia.picker.cp.model.type.PickingMode;
-
-import java.io.Serializable;
-
-public record Node(@NonNull String id, @NonNull PickingMode mode) implements Serializable {
-
-    @Override
-    public int hashCode() {
-        return id.hashCode();
-    }
-
-    @Override
-    public boolean equals(Object object) {
-        if (object == this) return true;
-        if (object == null) return false;
-        if (object instanceof Node other) {
-            return id.equals(other.id);
-        }
-        return false;
-    }
-}

control-panel/src/main/java/ru/dragonestia/picker/cp/model/Room.java

@@ -1,71 +0,0 @@
-package ru.dragonestia.picker.cp.model;
-
-import com.fasterxml.jackson.annotation.JsonCreator;
-import com.fasterxml.jackson.annotation.JsonProperty;
-import lombok.Getter;
-import ru.dragonestia.picker.cp.model.type.SlotLimit;
-
-import java.net.URI;
-
-@Getter
-public class Room {
-
-    private final String id;
-    private final String nodeId;
-    private final SlotLimit slots;
-    private final String payload;
-    private boolean locked = false;
-
-    @JsonCreator
-    private Room(@JsonProperty("id") String id,
-                 @JsonProperty("nodeIdentifier") String nodeId,
-                 @JsonProperty("slots") SlotLimit slots,
-                 @JsonProperty("payload") String payload,
-                 @JsonProperty("locked") boolean locked) {
-
-        this.id = id;
-        this.nodeId = nodeId;
-        this.slots = slots;
-        this.payload = payload;
-        this.locked = locked;
-    }
-
-    public static Room create(String roomId, Node node, SlotLimit limit, String payload) {
-        return new Room(roomId, node.id(), limit, payload, false);
-    }
-
-    public void setLocked(boolean value) {
-        locked = value;
-    }
-
-    public boolean isAvailable(int usedSlots, int requiredSlots) {
-        if (locked) return false;
-        if (slots.isUnlimited()) return true;
-        return slots.slots() >= usedSlots + requiredSlots;
-    }
-
-    @Override
-    public int hashCode() {
-        return id.hashCode();
-    }
-
-    @Override
-    public boolean equals(Object object) {
-        if (object == this) return true;
-        if (object == null) return false;
-        if (object instanceof Room other) {
-            return id.equals(other.id);
-        }
-        return false;
-    }
-
-    public URI createApiURI() {
-        return URI.create("/nodes/" + nodeId + "/rooms/" + id);
-    }
-
-    public String getUsingPercentage(int used) {
-        if (getSlots().isUnlimited()) return "0%";
-        double percent = used / (double) getSlots().slots() * 100;
-        return ((int) percent) + "%";
-    }
-}

control-panel/src/main/java/ru/dragonestia/picker/cp/model/dto/RoomDTO.java

@@ -1,16 +0,0 @@
-package ru.dragonestia.picker.cp.model.dto;
-
-import ru.dragonestia.picker.cp.model.Node;
-
-import java.net.URI;
-
-public record RoomDTO(String id, int slots, boolean locked) {
-
-    public URI uriAPI(Node node) {
-        return uriAPI(node.id());
-    }
-
-    public URI uriAPI(String nodeId) {
-        return URI.create("/nodes/" + nodeId + "/rooms/" + id);
-    }
-}

control-panel/src/main/java/ru/dragonestia/picker/cp/model/type/SlotLimit.java

@@ -1,21 +0,0 @@
-package ru.dragonestia.picker.cp.model.type;
-
-import java.beans.Transient;
-
-public record SlotLimit(int slots) {
-
-    private final static int UNLIMITED_VALUE = -1;
-
-    public static SlotLimit unlimited() {
-        return new SlotLimit(UNLIMITED_VALUE);
-    }
-
-    public static SlotLimit of(int slots) {
-        return new SlotLimit(slots);
-    }
-
-    @Transient
-    public boolean isUnlimited() {
-        return slots == UNLIMITED_VALUE;
-    }
-}

control-panel/src/main/java/ru/dragonestia/picker/cp/page/HomePage.java

@@ -3,10 +3,11 @@ package ru.dragonestia.picker.cp.page;
 import com.vaadin.flow.component.html.H1;
 import com.vaadin.flow.component.html.Paragraph;
 import com.vaadin.flow.component.orderedlayout.VerticalLayout;
-import com.vaadin.flow.router.Route;
+import com.vaadin.flow.router.*;
+import ru.dragonestia.picker.api.exception.NodeNotFoundException;
 
 @Route("/")
-public class HomePage extends VerticalLayout {
+public class HomePage extends VerticalLayout implements BeforeEnterObserver {
 
     public HomePage() {
         super();
@@ -14,4 +15,9 @@ public class HomePage extends VerticalLayout {
         add(new H1("Hello world!"));
         add(new Paragraph("Hello world!"));
     }
+
+    @Override
+    public void beforeEnter(BeforeEnterEvent beforeEnterEvent) {
+        throw new NodeNotFoundException("gdfsg");
+    }
 }

control-panel/src/main/java/ru/dragonestia/picker/cp/page/NodeDetailsPage.java

@@ -4,72 +4,54 @@ import com.vaadin.flow.component.Html;
 import com.vaadin.flow.component.html.H2;
 import com.vaadin.flow.component.html.Hr;
 import com.vaadin.flow.component.html.Paragraph;
-import com.vaadin.flow.component.notification.Notification;
-import com.vaadin.flow.component.notification.NotificationVariant;
 import com.vaadin.flow.component.orderedlayout.VerticalLayout;
 import com.vaadin.flow.router.BeforeEnterEvent;
 import com.vaadin.flow.router.BeforeEnterObserver;
 import com.vaadin.flow.router.PageTitle;
 import com.vaadin.flow.router.Route;
 import lombok.Getter;
+import lombok.RequiredArgsConstructor;
 import org.springframework.beans.factory.annotation.Autowired;
+import ru.dragonestia.picker.api.model.Node;
+import ru.dragonestia.picker.api.model.Room;
+import ru.dragonestia.picker.api.repository.NodeRepository;
+import ru.dragonestia.picker.api.repository.RoomRepository;
+import ru.dragonestia.picker.cp.component.Notifications;
 import ru.dragonestia.picker.cp.component.RoomList;
 import ru.dragonestia.picker.cp.component.NavPath;
 import ru.dragonestia.picker.cp.component.RegisterRoom;
-import ru.dragonestia.picker.cp.model.Node;
-import ru.dragonestia.picker.cp.model.dto.RoomDTO;
-import ru.dragonestia.picker.cp.repository.RoomRepository;
-import ru.dragonestia.picker.cp.repository.NodeRepository;
+import ru.dragonestia.picker.cp.util.RouteParamsExtractor;
 
 import java.util.List;
 
 @Getter
+@RequiredArgsConstructor
 @PageTitle("Rooms")
 @Route("/nodes/:nodeId")
 public class NodeDetailsPage extends VerticalLayout implements BeforeEnterObserver {
 
     private final NodeRepository nodeRepository;
     private final RoomRepository roomRepository;
+    private final RouteParamsExtractor paramsExtractor;
+
     private Node node;
     private RegisterRoom registerRoom;
     private RoomList roomList;
 
-    public NodeDetailsPage(@Autowired NodeRepository nodeRepository,
-                           @Autowired RoomRepository roomRepository) {
-
-        this.nodeRepository = nodeRepository;
-        this.roomRepository = roomRepository;
-    }
-
     @Override
     public void beforeEnter(BeforeEnterEvent event) {
-        var nodeIdOpt = event.getRouteParameters().get("nodeId");
-        if (nodeIdOpt.isEmpty()) {
-            getUI().ifPresent(ui -> ui.navigate("/nodes"));
-            return;
-        }
-        var nodeId = nodeIdOpt.get();
-        add(new NavPath(new NavPath.Point("Nodes", "/nodes"), new NavPath.Point(nodeId, "/nodes/" + nodeId)));
-
-        var nodeOpt = nodeRepository.find(nodeId);
-        if (nodeOpt.isEmpty()) {
-            add(new H2("Error 404"));
-            add(new Paragraph("Node not found"));
-            Notification.show("Node '" + nodeId + "' does not exist", 3000, Notification.Position.TOP_END)
-                    .addThemeVariants(NotificationVariant.LUMO_ERROR);
-            return;
-        }
-        node = nodeOpt.get();
+        node = paramsExtractor.extractNodeId(event);
 
         initComponents(node, roomRepository.all(node));
     }
 
-    private void initComponents(Node node, List<RoomDTO> rooms) {
+    private void initComponents(Node node, List<Room.Short> rooms) {
+        add(NavPath.toNode(node.getId()));
         printNodeDetails(node);
         add(new Hr());
-        add(registerRoom = new RegisterRoom(node, (bucket) -> {
+        add(registerRoom = new RegisterRoom(node, (room) -> {
             try {
-                roomRepository.register(bucket);
+                roomRepository.register(room);
                 return new RegisterRoom.Response(false,  null);
             } catch (Error error) {
                 return new RegisterRoom.Response(true,  error.getMessage());
@@ -78,9 +60,9 @@ public class NodeDetailsPage extends VerticalLayout implements BeforeEnterObserv
             }
         }));
         add(new Hr());
-        add(roomList = new RoomList(node.id(), rooms));
-        roomList.setRemoveMethod(bucket -> {
-            roomRepository.remove(node, bucket);
+        add(roomList = new RoomList(node.getId(), rooms));
+        roomList.setRemoveMethod(room -> {
+            roomRepository.remove(node, room);
             roomList.update(roomRepository.all(node));
         });
     }
@@ -89,8 +71,8 @@ public class NodeDetailsPage extends VerticalLayout implements BeforeEnterObserv
         add(new H2("Node details"));
 
         var layout = new VerticalLayout();
-        layout.add(new Html("<span>Identifier: <b>" + node.id() + "</b></span>"));
-        layout.add(new Html("<span>Mode: <b>" + node.mode().getName() + "</b></span>"));
+        layout.add(new Html("<span>Identifier: <b>" + node.getId() + "</b></span>"));
+        layout.add(new Html("<span>Mode: <b>" + node.getMode().getName() + "</b></span>"));
 
         add(layout);
     }

control-panel/src/main/java/ru/dragonestia/picker/cp/page/NodesPage.java

@@ -7,10 +7,11 @@ import com.vaadin.flow.router.Route;
 import lombok.Getter;
 import lombok.extern.log4j.Log4j2;
 import org.springframework.beans.factory.annotation.Autowired;
+import ru.dragonestia.picker.api.exception.ApiException;
+import ru.dragonestia.picker.api.repository.NodeRepository;
 import ru.dragonestia.picker.cp.component.NavPath;
 import ru.dragonestia.picker.cp.component.NodeList;
 import ru.dragonestia.picker.cp.component.RegisterNode;
-import ru.dragonestia.picker.cp.repository.NodeRepository;
 
 @Log4j2
 @Getter
@@ -26,7 +27,7 @@ public class NodesPage extends VerticalLayout {
         super();
         this.nodeRepository = nodeRepository;
 
-        add(new NavPath(new NavPath.Point("Nodes", "/nodes")));
+        add(NavPath.rootNodes());
         add(registerNode = createRegisterNodeElement());
         add(new Hr());
         add(nodeList = createNodeListElement());
@@ -41,10 +42,7 @@ public class NodesPage extends VerticalLayout {
             try {
                 nodeRepository.register(node);
                 return new RegisterNode.Response(false, "");
-            } catch (Error ex) {
-                return new RegisterNode.Response(true, ex.getMessage());
-            } catch (RuntimeException ex) {
-                log.throwing(ex);
+            } catch (ApiException ex) {
                 return new RegisterNode.Response(true, ex.getMessage());
             } finally {
                 nodeList.update(nodeRepository.all());

control-panel/src/main/java/ru/dragonestia/picker/cp/page/RoomDetailsPage.java

@@ -8,28 +8,30 @@ import com.vaadin.flow.component.html.Hr;
 import com.vaadin.flow.component.html.Paragraph;
 import com.vaadin.flow.component.icon.Icon;
 import com.vaadin.flow.component.icon.VaadinIcon;
-import com.vaadin.flow.component.notification.Notification;
-import com.vaadin.flow.component.notification.NotificationVariant;
 import com.vaadin.flow.component.orderedlayout.VerticalLayout;
 import com.vaadin.flow.component.textfield.TextArea;
 import com.vaadin.flow.router.BeforeEnterEvent;
 import com.vaadin.flow.router.BeforeEnterObserver;
 import com.vaadin.flow.router.PageTitle;
 import com.vaadin.flow.router.Route;
+import lombok.RequiredArgsConstructor;
 import org.springframework.beans.factory.annotation.Autowired;
+import ru.dragonestia.picker.api.model.Node;
+import ru.dragonestia.picker.api.model.Room;
+import ru.dragonestia.picker.api.model.User;
+import ru.dragonestia.picker.api.repository.NodeRepository;
+import ru.dragonestia.picker.api.repository.RoomRepository;
+import ru.dragonestia.picker.api.repository.UserRepository;
 import ru.dragonestia.picker.cp.component.AddUsers;
 import ru.dragonestia.picker.cp.component.NavPath;
+import ru.dragonestia.picker.cp.component.Notifications;
 import ru.dragonestia.picker.cp.component.UserList;
-import ru.dragonestia.picker.cp.model.Room;
-import ru.dragonestia.picker.cp.model.Node;
-import ru.dragonestia.picker.cp.model.User;
-import ru.dragonestia.picker.cp.repository.RoomRepository;
-import ru.dragonestia.picker.cp.repository.NodeRepository;
-import ru.dragonestia.picker.cp.repository.UserRepository;
+import ru.dragonestia.picker.cp.util.RouteParamsExtractor;
 
 import java.util.Collection;
 import java.util.concurrent.atomic.AtomicBoolean;
 
+@RequiredArgsConstructor
 @PageTitle("Room details")
 @Route("/nodes/:nodeId/rooms/:roomId")
 public class RoomDetailsPage extends VerticalLayout implements BeforeEnterObserver {
@@ -37,6 +39,8 @@ public class RoomDetailsPage extends VerticalLayout implements BeforeEnterObserv
     private final NodeRepository nodeRepository;
     private final RoomRepository roomRepository;
     private final UserRepository userRepository;
+    private final RouteParamsExtractor paramsExtractor;
+
     private Node node;
     private Room room;
     private AddUsers addUsers;
@@ -44,57 +48,16 @@ public class RoomDetailsPage extends VerticalLayout implements BeforeEnterObserv
     private Button lockRoomButton;
     private VerticalLayout roomInfo;
 
-    @Autowired
-    public RoomDetailsPage(NodeRepository nodeRepository, RoomRepository roomRepository, UserRepository userRepository) {
-        this.nodeRepository = nodeRepository;
-        this.roomRepository = roomRepository;
-        this.userRepository = userRepository;
-    }
-
     @Override
     public void beforeEnter(BeforeEnterEvent event) {
-        var nodeIdOpt = event.getRouteParameters().get("nodeId");
-        if (nodeIdOpt.isEmpty()) {
-            getUI().ifPresent(ui -> ui.navigate("/nodes"));
-            return;
-        }
-
-        var roomIdOpt = event.getRouteParameters().get("roomId");
-        if (roomIdOpt.isEmpty()) {
-            getUI().ifPresent(ui -> ui.navigate("/rooms/" + nodeIdOpt.get()));
-            return;
-        }
-
-        var nodeId = nodeIdOpt.get();
-        var roomId = roomIdOpt.get();
-        add(new NavPath(new NavPath.Point("Nodes", "/nodes"),
-                new NavPath.Point(nodeId, "/nodes/" + nodeId),
-                new NavPath.Point(roomId, "/nodes/" + nodeId + "/rooms/" + roomId)));
-
-        var nodeOpt = nodeRepository.find(nodeId);
-        if (nodeOpt.isEmpty()) {
-            add(new H2("Error 404"));
-            add(new Paragraph("Node not found!"));
-            Notification.show("Node '" + nodeId + "' does not exist", 3000, Notification.Position.TOP_END)
-                    .addThemeVariants(NotificationVariant.LUMO_ERROR);
-            return;
-        }
-        node = nodeOpt.get();
-
-        var bucketOpt = roomRepository.find(node, roomId);
-        if (bucketOpt.isEmpty()) {
-            add(new H2("Error 404"));
-            add(new Paragraph("Room not found!"));
-            Notification.show("Room '" + nodeId + "' does not exist", 3000, Notification.Position.TOP_END)
-                    .addThemeVariants(NotificationVariant.LUMO_ERROR);
-            return;
-        }
-        room = bucketOpt.get();
+        node = paramsExtractor.extractNodeId(event);
+        room = paramsExtractor.extractRoomId(event, node);
 
         init();
     }
 
     private void init() {
+        add(NavPath.toRoom(node.getId(), room.getId()));
         add(new H2("Room details"));
         printRoomDetails();
         add(new Hr());
@@ -108,7 +71,7 @@ public class RoomDetailsPage extends VerticalLayout implements BeforeEnterObserv
         roomInfo.removeAll();
         roomInfo.add(new Html("<span>Node identifier: <b>" + room.getNodeId() + "</b></span>"));
         roomInfo.add(new Html("<span>Room identifier: <b>" + room.getId() + "</b></span>"));
-        roomInfo.add(new Html("<span>Slots: <b>" + (room.getSlots().isUnlimited()? "Unlimited" : room.getSlots().slots()) + "</b></span>"));
+        roomInfo.add(new Html("<span>Slots: <b>" + (room.isUnlimited()? "Unlimited" : room.getSlots()) + "</b></span>"));
         roomInfo.add(new Html("<span>Locked: <b>" + (room.isLocked()? "Yes" : "No") + "</b></span>"));
     }
 
@@ -139,20 +102,13 @@ public class RoomDetailsPage extends VerticalLayout implements BeforeEnterObserv
 
     private void changeBucketLockedState() {
         var newValue = !room.isLocked();
-        try {
-            roomRepository.lock(room, newValue);
-        } catch (Error error) {
-            Notification.show(error.getMessage(), 3000, Notification.Position.TOP_END)
-                    .addThemeVariants(NotificationVariant.LUMO_ERROR);
-            return;
-        }
+        roomRepository.lock(room, newValue);
 
         room.setLocked(newValue);
         setLockRoomButtonState();
         updateRoomInfo();
 
-        Notification.show("Success", 3000, Notification.Position.TOP_END)
-                .addThemeVariants(NotificationVariant.LUMO_SUCCESS);
+        Notifications.success("Success");
     }
 
     private void appendUsers(Room room, Collection<User> users, boolean ignoreLimitation) {
@@ -160,7 +116,7 @@ public class RoomDetailsPage extends VerticalLayout implements BeforeEnterObserv
 
         var newUsers = users.stream()
                 .filter(user -> {
-                    if (user.id().matches("^[aA-zZ\\d-.\\s:/@%?!~$)(+=_|;*]+$")) {
+                    if (user.getId().matches("^[aA-zZ\\d-.\\s:/@%?!~$)(+=_|;*]+$")) {
                         return true;
                     }
 
@@ -173,15 +129,12 @@ public class RoomDetailsPage extends VerticalLayout implements BeforeEnterObserv
 
         if (validationFail.get()) {
             if (newUsers.isEmpty()) {
-                Notification.show("All users entered were added because they do not comply with the rule for writing the user identifier", 3000, Notification.Position.TOP_END)
-                        .addThemeVariants(NotificationVariant.LUMO_ERROR);
+                Notifications.error("All users entered were added because they do not comply with the rule for writing the user identifier");
             } else {
-                Notification.show("Not all users entered were added because they do not comply with the rule for writing the user identifier", 3000, Notification.Position.TOP_END)
-                        .addThemeVariants(NotificationVariant.LUMO_WARNING);
+                Notifications.warn("Not all users entered were added because they do not comply with the rule for writing the user identifier");
             }
         } else {
-            Notification.show("Success", 3000, Notification.Position.TOP_END)
-                    .addThemeVariants(NotificationVariant.LUMO_SUCCESS);
+            Notifications.success("Success");
         }
     }
 }

control-panel/src/main/java/ru/dragonestia/picker/cp/page/plug/ErrorPlug.java

@@ -0,0 +1,15 @@
+package ru.dragonestia.picker.cp.page.plug;
+
+import com.vaadin.flow.component.Html;
+import com.vaadin.flow.component.html.H1;
+import com.vaadin.flow.component.orderedlayout.VerticalLayout;
+import ru.dragonestia.picker.cp.component.NavPath;
+
+public abstract class ErrorPlug extends VerticalLayout {
+
+    public void init(NavPath path, String title, String description) {
+        add(path);
+        add(new H1(title));
+        add(new Html("<p>" + description + "</p>"));
+    }
+}

control-panel/src/main/java/ru/dragonestia/picker/cp/page/plug/InvalidNodeIdentifierPlug.java

@@ -0,0 +1,20 @@
+package ru.dragonestia.picker.cp.page.plug;
+
+import com.vaadin.flow.router.BeforeEnterEvent;
+import com.vaadin.flow.router.ErrorParameter;
+import com.vaadin.flow.router.HasErrorParameter;
+import jakarta.servlet.http.HttpServletResponse;
+import ru.dragonestia.picker.api.exception.InvalidNodeIdentifierException;
+import ru.dragonestia.picker.cp.component.NavPath;
+
+public class InvalidNodeIdentifierPlug extends ErrorPlug implements HasErrorParameter<InvalidNodeIdentifierException> {
+
+    @Override
+    public int setErrorParameter(BeforeEnterEvent beforeEnterEvent, ErrorParameter<InvalidNodeIdentifierException> errorParameter) {
+        var ex = errorParameter.getException();
+        var nodeId = ex.getNodeId();
+
+        init(NavPath.toNode(nodeId), "Error 400", ex.getMessage());
+        return HttpServletResponse.SC_NOT_FOUND;
+    }
+}

control-panel/src/main/java/ru/dragonestia/picker/cp/page/plug/InvalidRoomIdentifierPlug.java

@@ -0,0 +1,21 @@
+package ru.dragonestia.picker.cp.page.plug;
+
+import com.vaadin.flow.router.BeforeEnterEvent;
+import com.vaadin.flow.router.ErrorParameter;
+import com.vaadin.flow.router.HasErrorParameter;
+import jakarta.servlet.http.HttpServletResponse;
+import ru.dragonestia.picker.api.exception.InvalidRoomIdentifierException;
+import ru.dragonestia.picker.cp.component.NavPath;
+
+public class InvalidRoomIdentifierPlug extends ErrorPlug implements HasErrorParameter<InvalidRoomIdentifierException> {
+
+    @Override
+    public int setErrorParameter(BeforeEnterEvent event, ErrorParameter<InvalidRoomIdentifierException> errorParameter) {
+        var ex = errorParameter.getException();
+        var nodeId = ex.getNodeId();
+        var roomId = ex.getRoomId();
+
+        init(NavPath.toRoom(nodeId, roomId), "Error 400", ex.getMessage());
+        return HttpServletResponse.SC_NOT_FOUND;
+    }
+}

control-panel/src/main/java/ru/dragonestia/picker/cp/page/plug/NodeNotFoundPlug.java

@@ -0,0 +1,20 @@
+package ru.dragonestia.picker.cp.page.plug;
+
+import com.vaadin.flow.router.BeforeEnterEvent;
+import com.vaadin.flow.router.ErrorParameter;
+import com.vaadin.flow.router.HasErrorParameter;
+import jakarta.servlet.http.HttpServletResponse;
+import ru.dragonestia.picker.api.exception.NodeNotFoundException;
+import ru.dragonestia.picker.cp.component.NavPath;
+
+public class NodeNotFoundPlug extends ErrorPlug implements HasErrorParameter<NodeNotFoundException> {
+
+    @Override
+    public int setErrorParameter(BeforeEnterEvent beforeEnterEvent, ErrorParameter<NodeNotFoundException> errorParameter) {
+        var ex = errorParameter.getException();
+        var nodeId = ex.getNodeId();
+
+        init(NavPath.toNode(nodeId), "Error 404", ex.getMessage());
+        return HttpServletResponse.SC_NOT_FOUND;
+    }
+}

control-panel/src/main/java/ru/dragonestia/picker/cp/page/plug/RoomNotFoundPlug.java

@@ -0,0 +1,21 @@
+package ru.dragonestia.picker.cp.page.plug;
+
+import com.vaadin.flow.router.BeforeEnterEvent;
+import com.vaadin.flow.router.ErrorParameter;
+import com.vaadin.flow.router.HasErrorParameter;
+import jakarta.servlet.http.HttpServletResponse;
+import ru.dragonestia.picker.api.exception.RoomNotFoundException;
+import ru.dragonestia.picker.cp.component.NavPath;
+
+public class RoomNotFoundPlug extends ErrorPlug implements HasErrorParameter<RoomNotFoundException> {
+
+    @Override
+    public int setErrorParameter(BeforeEnterEvent beforeEnterEvent, ErrorParameter<RoomNotFoundException> errorParameter) {
+        var ex = errorParameter.getException();
+        var nodeId = ex.getNodeId();
+        var roomId = ex.getRoomId();
+
+        init(NavPath.toRoom(nodeId, roomId), "Error 404", ex.getMessage());
+        return HttpServletResponse.SC_NOT_FOUND;
+    }
+}

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/NodeRepository.java

@@ -1,17 +0,0 @@
-package ru.dragonestia.picker.cp.repository;
-
-import ru.dragonestia.picker.cp.model.Node;
-
-import java.util.List;
-import java.util.Optional;
-
-public interface NodeRepository {
-
-    void register(Node node);
-
-    List<Node> all();
-
-    Optional<Node> find(String nodeId);
-
-    void remove(String nodeId);
-}

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/RoomRepository.java

@@ -1,23 +0,0 @@
-package ru.dragonestia.picker.cp.repository;
-
-import ru.dragonestia.picker.cp.model.Room;
-import ru.dragonestia.picker.cp.model.Node;
-import ru.dragonestia.picker.cp.model.dto.RoomDTO;
-
-import java.util.List;
-import java.util.Optional;
-
-public interface RoomRepository {
-
-    List<RoomDTO> all(Node node);
-
-    void register(Room room);
-
-    void remove(Room room);
-
-    void remove(Node node, RoomDTO bucket);
-
-    Optional<Room> find(Node node, String roomId);
-
-    void lock(Room room, boolean value);
-}

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/UserRepository.java

@@ -1,16 +0,0 @@
-package ru.dragonestia.picker.cp.repository;
-
-import ru.dragonestia.picker.cp.model.Room;
-import ru.dragonestia.picker.cp.model.User;
-
-import java.util.Collection;
-import java.util.List;
-
-public interface UserRepository {
-
-    void linkWithRoom(Room room, Collection<User> users, boolean force);
-
-    void unlinkFromRoom(Room room, Collection<User> users);
-
-    List<User> all(Room room);
-}

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/impl/NodeRepositoryImpl.java

@@ -3,13 +3,15 @@ package ru.dragonestia.picker.cp.repository.impl;
 import com.vaadin.flow.spring.annotation.SpringComponent;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
-import ru.dragonestia.picker.cp.model.Node;
-import ru.dragonestia.picker.cp.repository.NodeRepository;
-import ru.dragonestia.picker.cp.repository.impl.response.NodeDetailsResponse;
-import ru.dragonestia.picker.cp.repository.impl.response.NodeListResponse;
-import ru.dragonestia.picker.cp.repository.impl.response.NodeRegisterResponse;
+import org.springframework.http.HttpMethod;
+import ru.dragonestia.picker.api.exception.InvalidNodeIdentifierException;
+import ru.dragonestia.picker.api.exception.NodeAlreadyExistException;
+import ru.dragonestia.picker.api.exception.NodeNotFoundException;
+import ru.dragonestia.picker.api.repository.response.NodeDetailsResponse;
+import ru.dragonestia.picker.api.repository.response.NodeListResponse;
+import ru.dragonestia.picker.api.model.Node;
+import ru.dragonestia.picker.api.repository.NodeRepository;
 
-import java.net.URI;
 import java.util.List;
 import java.util.Optional;
 
@@ -21,41 +23,30 @@ public class NodeRepositoryImpl implements NodeRepository {
     private final RestUtil rest;
 
     @Override
-    public void register(Node node) {
-        NodeRegisterResponse response;
-        try {
-            response = rest.post(URI.create("nodes"),
-                    NodeRegisterResponse.class,
-                    params -> {
-                        params.put("nodeId", node.id());
-                        params.put("method", node.mode().name());
-                    });
-        } catch (Exception ex) {
-            throw new RuntimeException("Internal error", ex);
-        }
-
-        if (!response.success()) {
-            throw new Error(response.message());
-        }
+    public void register(Node node) throws InvalidNodeIdentifierException, NodeAlreadyExistException {
+        rest.query("nodes", HttpMethod.POST, params -> {
+            params.put("nodeId", node.getId());
+            params.put("method", node.getMode().name());
+        });
     }
 
     @Override
     public List<Node> all() {
-        return rest.get(URI.create("nodes"), NodeListResponse.class).nodes();
+        return rest.query("nodes", HttpMethod.GET, NodeListResponse.class, params -> {}).nodes();
     }
 
     @Override
     public Optional<Node> find(String nodeId) {
         try {
-            var response = rest.get(URI.create("nodes/" + nodeId), NodeDetailsResponse.class);
+            var response = rest.query("nodes/" + nodeId, HttpMethod.GET, NodeDetailsResponse.class, params -> {});
             return Optional.of(response.node());
-        } catch (Exception ex) {
+        } catch (NodeNotFoundException ex) {
             return Optional.empty();
         }
     }
 
     @Override
     public void remove(String nodeId) {
-        rest.delete(URI.create("nodes/" + nodeId), params -> {});
+        rest.query("nodes/" + nodeId, HttpMethod.DELETE, params -> {});
     }
 }

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/impl/RestUtil.java

@@ -1,15 +1,15 @@
 package ru.dragonestia.picker.cp.repository.impl;
 
 import lombok.RequiredArgsConstructor;
-import org.springframework.http.ResponseEntity;
+import org.springframework.http.HttpMethod;
 import org.springframework.stereotype.Component;
+import org.springframework.web.client.HttpClientErrorException;
 import org.springframework.web.client.RestTemplate;
+import ru.dragonestia.picker.api.exception.ExceptionFactory;
+import ru.dragonestia.picker.api.repository.response.ErrorResponse;
 
 import java.net.URI;
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Objects;
+import java.util.*;
 import java.util.function.Consumer;
 import java.util.function.Supplier;
 
@@ -18,67 +18,41 @@ import java.util.function.Supplier;
 public class RestUtil {
 
     private final URI serverUrl;
-    private final Supplier<RestTemplate> restTemplate;
+    private final Supplier<RestTemplate> restTemplateSupplier;
 
-    public <T> T get(URI uri, Class<T> responseType) {
-        var template = restTemplate.get();
-        return Objects.requireNonNull(template.getForObject(serverUrl.resolve(uri), responseType));
+    public void query(String uri, HttpMethod method) {
+        query(uri, method, ParamsConsumer.NONE);
     }
 
-    public <T> ResponseEntity<T> getEntity(URI uri, Class<T> responseType) {
-        var template = restTemplate.get();
-        return template.getForEntity(serverUrl.resolve(uri), responseType);
-    }
-
-    public <T> T get(URI uri, Class<T> responseType, Consumer<Map<String, String>> paramsConsumer) {
+    public void query(String uri, HttpMethod method, ParamsConsumer paramsConsumer) {
         var params = new HashMap<String, String>();
         paramsConsumer.accept(params);
 
-        var template = restTemplate.get();
-        return Objects.requireNonNull(template.getForObject(buildPath(uri, params.keySet()),
-                responseType,
-                params));
+        var template = restTemplateSupplier.get();
+        try {
+            template.exchange(buildPath(uri, params.keySet()), method, null, String.class, params);
+        } catch (HttpClientErrorException ex) {
+            throw ExceptionFactory.of(Objects.requireNonNull(ex.getResponseBodyAs(ErrorResponse.class)));
+        }
     }
 
-    public <T> T post(URI uri, Class<T> responseType, Consumer<Map<String, String>> paramsConsumer) {
+    public <T> T query(String uri, HttpMethod method, Class<T> clazz) {
+        return query(uri, method, clazz, ParamsConsumer.NONE);
+    }
+
+    public <T> T query(String uri, HttpMethod method, Class<T> clazz, ParamsConsumer paramsConsumer) {
         var params = new HashMap<String, String>();
         paramsConsumer.accept(params);
 
-        var template = restTemplate.get();
-        return Objects.requireNonNull(template.postForObject(buildPath(uri, params.keySet()),
-                null,
-                responseType,
-                params));
+        var template = restTemplateSupplier.get();
+        try {
+            return template.exchange(buildPath(uri, params.keySet()), method, null, clazz, params).getBody();
+        } catch (HttpClientErrorException ex) {
+            throw ExceptionFactory.of(Objects.requireNonNull(ex.getResponseBodyAs(ErrorResponse.class)));
+        }
     }
 
-    public <T> ResponseEntity<T> postEntity(URI uri, Class<T> responseType, Consumer<Map<String, String>> paramsConsumer) {
-        var params = new HashMap<String, String>();
-        paramsConsumer.accept(params);
-
-        var template = restTemplate.get();
-        return template.postForEntity(buildPath(uri, params.keySet()),
-                null,
-                responseType,
-                params);
-    }
-
-    public void put(URI uri, Consumer<Map<String, String>> paramsConsumer) {
-        var params = new HashMap<String, String>();
-        paramsConsumer.accept(params);
-
-        var template = restTemplate.get();
-        template.put(buildPath(uri, params.keySet()), params);
-    }
-
-    public void delete(URI uri, Consumer<Map<String, String>> paramsConsumer) {
-        var params = new HashMap<String, String>();
-        paramsConsumer.accept(params);
-
-        var template = restTemplate.get();
-        template.delete(buildPath(uri, params.keySet()), params);
-    }
-
-    private String buildPath(URI uri, Collection<String> paramKeys) {
+    private String buildPath(String uri, Collection<String> paramKeys) {
         var path = new StringBuilder(serverUrl.resolve(uri) + "?");
         int left = paramKeys.size();
         for (var key: paramKeys) {
@@ -92,4 +66,9 @@ public class RestUtil {
         }
         return path.toString();
     }
+
+    public interface ParamsConsumer extends Consumer<Map<String, String>> {
+
+        ParamsConsumer NONE = map -> {};
+    }
 }

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/impl/RoomRepositoryImpl.java

@@ -3,18 +3,18 @@ package ru.dragonestia.picker.cp.repository.impl;
 import com.vaadin.flow.spring.annotation.SpringComponent;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
-import org.springframework.web.client.HttpClientErrorException;
-import ru.dragonestia.picker.cp.model.Room;
-import ru.dragonestia.picker.cp.model.Node;
-import ru.dragonestia.picker.cp.model.dto.RoomDTO;
-import ru.dragonestia.picker.cp.repository.RoomRepository;
-import ru.dragonestia.picker.cp.repository.impl.response.RoomInfoResponse;
-import ru.dragonestia.picker.cp.repository.impl.response.RoomListResponse;
-import ru.dragonestia.picker.cp.repository.impl.response.RoomRegisterResponse;
+import org.springframework.http.HttpMethod;
+import ru.dragonestia.picker.api.exception.InvalidRoomIdentifierException;
+import ru.dragonestia.picker.api.exception.NodeNotFoundException;
+import ru.dragonestia.picker.api.exception.RoomAlreadyExistException;
+import ru.dragonestia.picker.api.exception.RoomNotFoundException;
+import ru.dragonestia.picker.api.model.Node;
+import ru.dragonestia.picker.api.model.Room;
+import ru.dragonestia.picker.api.repository.RoomRepository;
+import ru.dragonestia.picker.api.repository.response.RoomInfoResponse;
+import ru.dragonestia.picker.api.repository.response.RoomListResponse;
 
-import java.net.URI;
 import java.util.List;
-import java.util.Objects;
 import java.util.Optional;
 
 @Log4j2
@@ -25,76 +25,44 @@ public class RoomRepositoryImpl implements RoomRepository {
     private final RestUtil rest;
 
     @Override
-    public List<RoomDTO> all(Node node) {
-        var entity = rest.getEntity(URI.create("/nodes/" + node.id() + "/rooms"),
-                RoomListResponse.class);
-
-        if (entity.getStatusCode().value() == 404) {
-            throw new Error("Node with identifier '" + node.id() + "' does not exists'");
-        }
-
-        if (!entity.hasBody()) {
-            throw new Error("Room list did not present");
-        }
-
-        return Objects.requireNonNull(entity.getBody()).rooms();
+    public void register(Room room) throws NodeNotFoundException, InvalidRoomIdentifierException, RoomAlreadyExistException {
+        rest.query("/nodes/" + room.getNodeId() + "/rooms", HttpMethod.POST, params -> {
+            params.put("roomId", room.getId());
+            params.put("slots", Integer.toString(room.getSlots()));
+            params.put("payload", room.getPayload());
+            params.put("locked", Boolean.toString(room.isLocked()));
+        });
     }
 
     @Override
-    public void register(Room room) {
+    public void remove(Room room) throws NodeNotFoundException {
+        rest.query("/nodes/" + room.getNodeId() + "/rooms/" + room.getId(), HttpMethod.DELETE, params -> {});
+    }
+
+    @Override
+    public void remove(Node node, Room.Short room) throws NodeNotFoundException {
+        rest.query("/nodes/" + node.getId() + "/rooms/" + room.id(), HttpMethod.DELETE, params -> {});
+    }
+
+    @Override
+    public List<Room.Short> all(Node node) throws NodeNotFoundException {
+        return rest.query("/nodes/" + node.getId() + "/rooms", HttpMethod.GET, RoomListResponse.class, params -> {}).rooms();
+    }
+
+    @Override
+    public Optional<Room> find(Node node, String roomId) throws NodeNotFoundException {
         try {
-            var response = rest.post(URI.create("/nodes/" + room.getNodeId() + "/rooms"),
-                    RoomRegisterResponse.class,
-                    params -> {
-                        params.put("roomId", room.getId());
-                        params.put("slots", Integer.toString(room.getSlots().slots()));
-                        params.put("payload", room.getPayload());
-                        params.put("locked", Boolean.toString(room.isLocked()));
-                    });
-
-            if (response.success()) return;
-            throw new Error(response.message());
-        } catch (HttpClientErrorException ex) {
-            var response = ex.getResponseBodyAs(RoomRegisterResponse.class);
-
-            if (response != null) {
-                throw new Error(response.message());
-            }
-
-            log.throwing(ex);
-            throw new Error("Internal error. Check logs");
-        }
-    }
-
-    @Override
-    public void remove(Room room) {
-        rest.delete(URI.create("/nodes/" + room.getNodeId() + "/rooms/" + room.getId()), params -> {});
-    }
-
-    @Override
-    public void remove(Node node, RoomDTO room) {
-        rest.delete(URI.create("/nodes/" + node.id() + "/rooms/" + room.id()), params -> {});
-    }
-
-    @Override
-    public Optional<Room> find(Node node, String roomId) {
-        try {
-            var response = rest.get(URI.create("/nodes/" + node.id() + "/rooms/" + roomId), RoomInfoResponse.class, map -> {});
+            var response = rest.query("/nodes/" + node.getId() + "/rooms/" + roomId, HttpMethod.GET, RoomInfoResponse.class, map -> {});
             return Optional.of(response.room());
-        } catch (Exception ex) {
+        } catch (RoomNotFoundException ex) {
             return Optional.empty();
         }
     }
 
     @Override
-    public void lock(Room room, boolean value) {
-        try {
-            rest.post(URI.create(room.createApiURI() + "/lock"), Boolean.class, params -> {
-                params.put("newState", Boolean.toString(value));
-            });
-        } catch (Exception ex) {
-            log.throwing(ex);
-            throw new Error("Error when changing room locked state");
-        }
+    public void lock(Room room, boolean value) throws NodeNotFoundException, RoomNotFoundException {
+        rest.query("/nodes/%s/rooms/%s/lock".formatted(room.getNodeId(), room.getId()), HttpMethod.PUT, params -> {
+            params.put("newState", Boolean.toString(value));
+        });
     }
 }

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/impl/UserRepositoryImpl.java

@@ -3,13 +3,15 @@ package ru.dragonestia.picker.cp.repository.impl;
 import com.vaadin.flow.spring.annotation.SpringComponent;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
-import ru.dragonestia.picker.cp.model.Room;
-import ru.dragonestia.picker.cp.model.User;
-import ru.dragonestia.picker.cp.repository.UserRepository;
-import ru.dragonestia.picker.cp.repository.impl.response.LinkUsersWithRoomResponse;
-import ru.dragonestia.picker.cp.repository.impl.response.RoomUserListResponse;
+import org.springframework.http.HttpMethod;
+import ru.dragonestia.picker.api.exception.NodeNotFoundException;
+import ru.dragonestia.picker.api.exception.RoomAreFullException;
+import ru.dragonestia.picker.api.exception.RoomNotFoundException;
+import ru.dragonestia.picker.api.model.Room;
+import ru.dragonestia.picker.api.model.User;
+import ru.dragonestia.picker.api.repository.UserRepository;
+import ru.dragonestia.picker.api.repository.response.RoomUserListResponse;
 
-import java.net.URI;
 import java.util.Collection;
 import java.util.List;
 
@@ -21,47 +23,29 @@ public class UserRepositoryImpl implements UserRepository {
     private final RestUtil rest;
 
     @Override
-    public void linkWithRoom(Room room, Collection<User> users, boolean force) {
-        try {
-            var response = rest.post(URI.create("/nodes/%s/rooms/%s/users".formatted(room.getNodeId(), room.getId())),
-                    LinkUsersWithRoomResponse.class,
-                    params -> {
-                        params.put("userIds", String.join(",", users.stream().map(User::id).toList()));
-                        params.put("force", Boolean.toString(force));
-                    }
-            );
-
-            if (!response.success()) {
-                throw new Error(response.message());
-            }
-        } catch (Exception ex) {
-            log.throwing(ex);
-            throw new Error("Internal error");
-        }
+    public void linkWithRoom(Room room, Collection<User> users, boolean force) throws NodeNotFoundException, RoomNotFoundException, RoomAreFullException {
+        rest.query("/nodes/%s/rooms/%s/users".formatted(room.getNodeId(), room.getId()),
+                HttpMethod.POST,
+                params -> {
+                    params.put("userIds", String.join(",", users.stream().map(User::getId).toList()));
+                    params.put("force", Boolean.toString(force));
+                });
     }
 
     @Override
-    public void unlinkFromRoom(Room room, Collection<User> users) {
-        try {
-            rest.delete(URI.create("/nodes/%s/rooms/%s/users".formatted(room.getNodeId(), room.getId())),
-                    params -> params.put("userIds", String.join(",", users.stream().map(User::id).toList())));
-        } catch (Exception ex) {
-            log.throwing(ex);
-            throw new Error("Internal error");
-        }
+    public void unlinkFromRoom(Room room, Collection<User> users) throws NodeNotFoundException, RoomNotFoundException {
+        rest.query("/nodes/%s/rooms/%s/users".formatted(room.getNodeId(), room.getId()),
+                HttpMethod.DELETE,
+                params -> {
+                    params.put("userIds", String.join(",", users.stream().map(User::getId).toList()));
+                });
     }
 
     @Override
-    public List<User> all(Room room) {
-        try {
-            var response = rest.get(URI.create("/nodes/%s/rooms/%s/users".formatted(room.getNodeId(), room.getId())),
-                    RoomUserListResponse.class,
-                    params -> {});
-
-            return response.users();
-        } catch (Exception ex) {
-            log.throwing(ex);
-            throw new Error("Internal error");
-        }
+    public List<User> all(Room room) throws NodeNotFoundException, RoomNotFoundException {
+        return rest.query("/nodes/%s/rooms/%s/users".formatted(room.getNodeId(), room.getId()),
+                HttpMethod.GET,
+                RoomUserListResponse.class,
+                params -> {}).users();
     }
 }

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/impl/response/LinkUsersWithRoomResponse.java

@@ -1,3 +0,0 @@
-package ru.dragonestia.picker.cp.repository.impl.response;
-
-public record LinkUsersWithRoomResponse(boolean success, String message, int usedSlots, int totalSlots) {}

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/impl/response/NodeDetailsResponse.java

@@ -1,5 +0,0 @@
-package ru.dragonestia.picker.cp.repository.impl.response;
-
-import ru.dragonestia.picker.cp.model.Node;
-
-public record NodeDetailsResponse(Node node) {}

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/impl/response/NodeListResponse.java

@@ -1,7 +0,0 @@
-package ru.dragonestia.picker.cp.repository.impl.response;
-
-import ru.dragonestia.picker.cp.model.Node;
-
-import java.util.List;
-
-public record NodeListResponse(List<Node> nodes) {}

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/impl/response/NodeRegisterResponse.java

@@ -1,3 +0,0 @@
-package ru.dragonestia.picker.cp.repository.impl.response;
-
-public record NodeRegisterResponse(boolean success, String message) {}

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/impl/response/RoomInfoResponse.java

@@ -1,5 +0,0 @@
-package ru.dragonestia.picker.cp.repository.impl.response;
-
-import ru.dragonestia.picker.cp.model.Room;
-
-public record RoomInfoResponse(Room room) {}

control-panel/src/main/java/ru/dragonestia/picker/cp/repository/impl/response/RoomListResponse.java

@@ -1,7 +0,0 @@
-package ru.dragonestia.picker.cp.repository.impl.response;
-
-import ru.dragonestia.picker.cp.model.dto.RoomDTO;
-
-import java.util.List;
-
-public record RoomListResponse(String node, List<RoomDTO> rooms) {}