Add desktop chat

.gitignore

@@ -44,3 +44,4 @@ connectionpetstore.properties
 # Log files
 *.log
 log.txt
+*.class

src/main/java/module-info.java

@@ -25,6 +25,7 @@ module org.example.petshopdesktop {
     opens org.example.petshopdesktop.api.dto.inventory to com.fasterxml.jackson.databind;
     opens org.example.petshopdesktop.api.dto.appointment to com.fasterxml.jackson.databind;
     opens org.example.petshopdesktop.api.dto.adoption to com.fasterxml.jackson.databind;
+    opens org.example.petshopdesktop.api.dto.chat to com.fasterxml.jackson.databind;
     opens org.example.petshopdesktop.api.dto.sale to com.fasterxml.jackson.databind;
     opens org.example.petshopdesktop.api.dto.user to com.fasterxml.jackson.databind;
     opens org.example.petshopdesktop.api.dto.analytics to com.fasterxml.jackson.databind;
@@ -33,4 +34,4 @@ module org.example.petshopdesktop {
     exports org.example.petshopdesktop;
     exports org.example.petshopdesktop.controllers;
     exports org.example.petshopdesktop.auth;
-}
+}

src/main/java/org/example/petshopdesktop/api/ChatRealtimeClient.java

@@ -0,0 +1,336 @@
+package org.example.petshopdesktop.api;
+
+import org.example.petshopdesktop.api.dto.chat.ConversationResponse;
+import org.example.petshopdesktop.api.dto.chat.MessageRequest;
+import org.example.petshopdesktop.api.dto.chat.MessageResponse;
+import org.example.petshopdesktop.auth.UserSession;
+
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.WebSocket;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.time.Duration;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionStage;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.Consumer;
+
+public class ChatRealtimeClient implements WebSocket.Listener {
+    private static final ChatRealtimeClient INSTANCE = new ChatRealtimeClient();
+
+    private final HttpClient httpClient;
+    private final StringBuilder frameBuffer = new StringBuilder();
+    private final AtomicInteger subscriptionCounter = new AtomicInteger(1);
+    private final Map<String, String> destinationBySubscription = new HashMap<>();
+    private final Object lock = new Object();
+
+    private WebSocket webSocket;
+    private boolean connecting;
+    private boolean connected;
+    private boolean conversationsSubscribed;
+    private Long selectedConversationId;
+    private String conversationsSubscriptionId;
+    private String conversationMessagesSubscriptionId;
+    private Consumer<ConversationResponse> conversationListener;
+    private Consumer<MessageResponse> messageListener;
+    private Consumer<String> statusListener;
+
+    private ChatRealtimeClient() {
+        this.httpClient = HttpClient.newBuilder()
+                .connectTimeout(Duration.ofSeconds(10))
+                .build();
+    }
+
+    public static ChatRealtimeClient getInstance() {
+        return INSTANCE;
+    }
+
+    public void setConversationListener(Consumer<ConversationResponse> conversationListener) {
+        this.conversationListener = conversationListener;
+    }
+
+    public void setMessageListener(Consumer<MessageResponse> messageListener) {
+        this.messageListener = messageListener;
+    }
+
+    public void setStatusListener(Consumer<String> statusListener) {
+        this.statusListener = statusListener;
+    }
+
+    public void connect() {
+        String token = UserSession.getInstance().getJwtToken();
+        if (token == null || token.isBlank()) {
+            publishStatus("Chat disconnected");
+            return;
+        }
+
+        synchronized (lock) {
+            if (connected || connecting) {
+                return;
+            }
+            connecting = true;
+        }
+
+        String wsUrl = ApiConfig.getInstance().getBaseUrl()
+                .replaceFirst("^http://", "ws://")
+                .replaceFirst("^https://", "wss://") + "/ws/chat";
+
+        publishStatus("Connecting chat...");
+
+        httpClient.newWebSocketBuilder()
+                .connectTimeout(Duration.ofSeconds(10))
+                .buildAsync(URI.create(wsUrl), this)
+                .thenAccept(socket -> {
+                    synchronized (lock) {
+                        webSocket = socket;
+                    }
+                    socket.sendText("CONNECT\naccept-version:1.2\nhost:localhost\nAuthorization:Bearer " + token + "\n\n\0", true);
+                })
+                .exceptionally(ex -> {
+                    synchronized (lock) {
+                        resetConnectionState();
+                    }
+                    publishStatus("Chat unavailable");
+                    return null;
+                });
+    }
+
+    public void disconnect() {
+        WebSocket socket;
+        synchronized (lock) {
+            socket = webSocket;
+            resetConnectionState();
+            selectedConversationId = null;
+            conversationsSubscribed = false;
+        }
+        if (socket != null) {
+            socket.sendText("DISCONNECT\n\n\0", true);
+            socket.sendClose(WebSocket.NORMAL_CLOSURE, "bye");
+        }
+        publishStatus("Chat disconnected");
+    }
+
+    public void subscribeToConversations() {
+        synchronized (lock) {
+            conversationsSubscribed = true;
+        }
+        connect();
+        synchronized (lock) {
+            if (connected && conversationsSubscriptionId == null) {
+                conversationsSubscriptionId = subscribeLocked("/topic/chat/conversations");
+            }
+        }
+    }
+
+    public void subscribeToConversation(Long conversationId) {
+        synchronized (lock) {
+            selectedConversationId = conversationId;
+        }
+        connect();
+        synchronized (lock) {
+            if (connected) {
+                applySelectedConversationSubscriptionLocked();
+            }
+        }
+    }
+
+    public boolean isConnected() {
+        synchronized (lock) {
+            return connected;
+        }
+    }
+
+    public boolean sendMessage(Long conversationId, String content) {
+        String token = UserSession.getInstance().getJwtToken();
+        if (token == null || token.isBlank()) {
+            publishStatus("Chat send failed");
+            return false;
+        }
+        String body;
+        try {
+            body = ApiClient.getInstance().getObjectMapper().writeValueAsString(new MessageRequest(content));
+        } catch (Exception e) {
+            publishStatus("Chat send failed");
+            return false;
+        }
+
+        synchronized (lock) {
+            if (!connected || webSocket == null) {
+                connect();
+                return false;
+            }
+            webSocket.sendText(
+                    "SEND\ndestination:/app/chat/conversations/" + conversationId + "/messages\nAuthorization:Bearer " + token + "\ncontent-type:application/json\ncontent-length:" + body.getBytes(StandardCharsets.UTF_8).length + "\n\n" + body + "\0",
+                    true
+            );
+            return true;
+        }
+    }
+
+    private String subscribeLocked(String destination) {
+        String subscriptionId = "sub-" + subscriptionCounter.getAndIncrement();
+        destinationBySubscription.put(subscriptionId, destination);
+        webSocket.sendText("SUBSCRIBE\nid:" + subscriptionId + "\ndestination:" + destination + "\n\n\0", true);
+        return subscriptionId;
+    }
+
+    private void unsubscribeLocked(String subscriptionId) {
+        destinationBySubscription.remove(subscriptionId);
+        if (webSocket != null) {
+            webSocket.sendText("UNSUBSCRIBE\nid:" + subscriptionId + "\n\n\0", true);
+        }
+    }
+
+    private void applySubscriptionsLocked() {
+        if (webSocket == null || !connected) {
+            return;
+        }
+        if (conversationsSubscribed && conversationsSubscriptionId == null) {
+            conversationsSubscriptionId = subscribeLocked("/topic/chat/conversations");
+        }
+        applySelectedConversationSubscriptionLocked();
+    }
+
+    private void applySelectedConversationSubscriptionLocked() {
+        if (webSocket == null || !connected) {
+            return;
+        }
+
+        String destination = selectedConversationId == null ? null : "/topic/chat/conversations/" + selectedConversationId;
+        if (destination == null) {
+            if (conversationMessagesSubscriptionId != null) {
+                unsubscribeLocked(conversationMessagesSubscriptionId);
+                conversationMessagesSubscriptionId = null;
+            }
+            return;
+        }
+
+        if (conversationMessagesSubscriptionId != null) {
+            String currentDestination = destinationBySubscription.get(conversationMessagesSubscriptionId);
+            if (destination.equals(currentDestination)) {
+                return;
+            }
+            unsubscribeLocked(conversationMessagesSubscriptionId);
+        }
+
+        conversationMessagesSubscriptionId = subscribeLocked(destination);
+    }
+
+    private void resetConnectionState() {
+        webSocket = null;
+        connecting = false;
+        connected = false;
+        destinationBySubscription.clear();
+        conversationsSubscriptionId = null;
+        conversationMessagesSubscriptionId = null;
+    }
+
+    private void handleFrame(String frame) {
+        String normalized = frame.replace("\r\n", "\n");
+        int separator = normalized.indexOf("\n\n");
+        String headerPart = separator >= 0 ? normalized.substring(0, separator) : normalized;
+        String bodyPart = separator >= 0 ? normalized.substring(separator + 2) : "";
+        String[] headerLines = headerPart.split("\n");
+        if (headerLines.length == 0) {
+            return;
+        }
+
+        String command = headerLines[0];
+        Map<String, String> headers = new HashMap<>();
+        for (int i = 1; i < headerLines.length; i++) {
+            int idx = headerLines[i].indexOf(':');
+            if (idx > 0) {
+                headers.put(headerLines[i].substring(0, idx), headerLines[i].substring(idx + 1));
+            }
+        }
+
+        if ("CONNECTED".equals(command)) {
+            synchronized (lock) {
+                connecting = false;
+                connected = true;
+                applySubscriptionsLocked();
+            }
+            publishStatus("Chat connected");
+            return;
+        }
+
+        if ("MESSAGE".equals(command)) {
+            String destination;
+            synchronized (lock) {
+                destination = destinationBySubscription.get(headers.get("subscription"));
+            }
+            try {
+                if (destination != null && destination.startsWith("/topic/chat/conversations/")) {
+                    MessageResponse message = ApiClient.getInstance().getObjectMapper().readValue(bodyPart, MessageResponse.class);
+                    if (messageListener != null) {
+                        messageListener.accept(message);
+                    }
+                } else {
+                    ConversationResponse conversation = ApiClient.getInstance().getObjectMapper().readValue(bodyPart, ConversationResponse.class);
+                    if (conversationListener != null) {
+                        conversationListener.accept(conversation);
+                    }
+                }
+            } catch (Exception e) {
+                publishStatus("Chat update failed");
+            }
+            return;
+        }
+
+        if ("ERROR".equals(command)) {
+            publishStatus("Chat error");
+        }
+    }
+
+    private void publishStatus(String status) {
+        if (statusListener != null) {
+            statusListener.accept(status);
+        }
+    }
+
+    @Override
+    public void onOpen(WebSocket webSocket) {
+        webSocket.request(1);
+    }
+
+    @Override
+    public CompletionStage<?> onText(WebSocket webSocket, CharSequence data, boolean last) {
+        synchronized (lock) {
+            frameBuffer.append(data);
+            int delimiter;
+            while ((delimiter = frameBuffer.indexOf("\0")) >= 0) {
+                String frame = frameBuffer.substring(0, delimiter);
+                frameBuffer.delete(0, delimiter + 1);
+                handleFrame(frame);
+            }
+        }
+        webSocket.request(1);
+        return CompletableFuture.completedFuture(null);
+    }
+
+    @Override
+    public CompletionStage<?> onBinary(WebSocket webSocket, ByteBuffer data, boolean last) {
+        webSocket.request(1);
+        return CompletableFuture.completedFuture(null);
+    }
+
+    @Override
+    public CompletionStage<?> onClose(WebSocket webSocket, int statusCode, String reason) {
+        synchronized (lock) {
+            resetConnectionState();
+        }
+        publishStatus("Chat disconnected");
+        return CompletableFuture.completedFuture(null);
+    }
+
+    @Override
+    public void onError(WebSocket webSocket, Throwable error) {
+        synchronized (lock) {
+            resetConnectionState();
+        }
+        publishStatus("Chat unavailable");
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/chat/ConversationRequest.java

@@ -0,0 +1,20 @@
+package org.example.petshopdesktop.api.dto.chat;
+
+public class ConversationRequest {
+    private String message;
+
+    public ConversationRequest() {
+    }
+
+    public ConversationRequest(String message) {
+        this.message = message;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/chat/ConversationResponse.java

@@ -0,0 +1,72 @@
+package org.example.petshopdesktop.api.dto.chat;
+
+import java.time.LocalDateTime;
+
+public class ConversationResponse {
+    private Long id;
+    private Long customerId;
+    private Long staffId;
+    private String status;
+    private String lastMessage;
+    private LocalDateTime createdAt;
+    private LocalDateTime updatedAt;
+
+    public ConversationResponse() {
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    public Long getStaffId() {
+        return staffId;
+    }
+
+    public void setStaffId(Long staffId) {
+        this.staffId = staffId;
+    }
+
+    public String getStatus() {
+        return status;
+    }
+
+    public void setStatus(String status) {
+        this.status = status;
+    }
+
+    public String getLastMessage() {
+        return lastMessage;
+    }
+
+    public void setLastMessage(String lastMessage) {
+        this.lastMessage = lastMessage;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/chat/MessageRequest.java

@@ -0,0 +1,20 @@
+package org.example.petshopdesktop.api.dto.chat;
+
+public class MessageRequest {
+    private String content;
+
+    public MessageRequest() {
+    }
+
+    public MessageRequest(String content) {
+        this.content = content;
+    }
+
+    public String getContent() {
+        return content;
+    }
+
+    public void setContent(String content) {
+        this.content = content;
+    }
+}

src/main/java/org/example/petshopdesktop/api/dto/chat/MessageResponse.java

@@ -0,0 +1,63 @@
+package org.example.petshopdesktop.api.dto.chat;
+
+import java.time.LocalDateTime;
+
+public class MessageResponse {
+    private Long id;
+    private Long conversationId;
+    private Long senderId;
+    private String content;
+    private LocalDateTime timestamp;
+    private Boolean isRead;
+
+    public MessageResponse() {
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getConversationId() {
+        return conversationId;
+    }
+
+    public void setConversationId(Long conversationId) {
+        this.conversationId = conversationId;
+    }
+
+    public Long getSenderId() {
+        return senderId;
+    }
+
+    public void setSenderId(Long senderId) {
+        this.senderId = senderId;
+    }
+
+    public String getContent() {
+        return content;
+    }
+
+    public void setContent(String content) {
+        this.content = content;
+    }
+
+    public LocalDateTime getTimestamp() {
+        return timestamp;
+    }
+
+    public void setTimestamp(LocalDateTime timestamp) {
+        this.timestamp = timestamp;
+    }
+
+    public Boolean getIsRead() {
+        return isRead;
+    }
+
+    public void setIsRead(Boolean isRead) {
+        this.isRead = isRead;
+    }
+}

src/main/java/org/example/petshopdesktop/api/endpoints/ChatApi.java

@@ -0,0 +1,45 @@
+package org.example.petshopdesktop.api.endpoints;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import org.example.petshopdesktop.api.ApiClient;
+import org.example.petshopdesktop.api.dto.chat.ConversationRequest;
+import org.example.petshopdesktop.api.dto.chat.ConversationResponse;
+import org.example.petshopdesktop.api.dto.chat.MessageRequest;
+import org.example.petshopdesktop.api.dto.chat.MessageResponse;
+
+import java.util.List;
+
+public class ChatApi {
+    private static final ChatApi INSTANCE = new ChatApi();
+    private final ApiClient apiClient;
+
+    private ChatApi() {
+        this.apiClient = ApiClient.getInstance();
+    }
+
+    public static ChatApi getInstance() {
+        return INSTANCE;
+    }
+
+    public List<ConversationResponse> listConversations() throws Exception {
+        String response = apiClient.getRawResponse("/api/v1/chat/conversations");
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<ConversationResponse>>() {});
+    }
+
+    public ConversationResponse createConversation(ConversationRequest request) throws Exception {
+        return apiClient.post("/api/v1/chat/conversations", request, ConversationResponse.class);
+    }
+
+    public ConversationResponse getConversation(Long id) throws Exception {
+        return apiClient.get("/api/v1/chat/conversations/" + id, ConversationResponse.class);
+    }
+
+    public List<MessageResponse> listMessages(Long conversationId) throws Exception {
+        String response = apiClient.getRawResponse("/api/v1/chat/conversations/" + conversationId + "/messages");
+        return apiClient.getObjectMapper().readValue(response, new TypeReference<List<MessageResponse>>() {});
+    }
+
+    public MessageResponse sendMessage(Long conversationId, MessageRequest request) throws Exception {
+        return apiClient.post("/api/v1/chat/conversations/" + conversationId + "/messages", request, MessageResponse.class);
+    }
+}

src/main/java/org/example/petshopdesktop/controllers/ChatController.java

@@ -0,0 +1,341 @@
+package org.example.petshopdesktop.controllers;
+
+import javafx.application.Platform;
+import javafx.collections.FXCollections;
+import javafx.collections.ObservableList;
+import javafx.fxml.FXML;
+import javafx.scene.control.Button;
+import javafx.scene.control.Label;
+import javafx.scene.control.ListCell;
+import javafx.scene.control.ListView;
+import javafx.scene.control.ScrollPane;
+import javafx.scene.control.TextArea;
+import javafx.scene.input.KeyCode;
+import javafx.scene.layout.HBox;
+import javafx.scene.layout.Priority;
+import javafx.scene.layout.Region;
+import javafx.scene.layout.VBox;
+import org.example.petshopdesktop.api.ChatRealtimeClient;
+import org.example.petshopdesktop.api.dto.chat.ConversationResponse;
+import org.example.petshopdesktop.api.dto.chat.MessageRequest;
+import org.example.petshopdesktop.api.dto.chat.MessageResponse;
+import org.example.petshopdesktop.api.dto.common.DropdownOption;
+import org.example.petshopdesktop.api.endpoints.ChatApi;
+import org.example.petshopdesktop.api.endpoints.DropdownApi;
+import org.example.petshopdesktop.auth.UserSession;
+import org.example.petshopdesktop.util.ActivityLogger;
+
+import java.time.format.DateTimeFormatter;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+public class ChatController {
+    private static final DateTimeFormatter TIME_FORMATTER = DateTimeFormatter.ofPattern("MMM d, HH:mm");
+
+    @FXML
+    private ListView<ConversationResponse> lvConversations;
+
+    @FXML
+    private VBox vbMessages;
+
+    @FXML
+    private ScrollPane spMessages;
+
+    @FXML
+    private TextArea txtMessage;
+
+    @FXML
+    private Button btnSend;
+
+    @FXML
+    private Button btnRefresh;
+
+    @FXML
+    private Label lblConversationTitle;
+
+    @FXML
+    private Label lblChatStatus;
+
+    private final ObservableList<ConversationResponse> conversations = FXCollections.observableArrayList();
+    private final Map<Long, String> customerLabels = new HashMap<>();
+    private final ChatRealtimeClient realtimeClient = ChatRealtimeClient.getInstance();
+    private ConversationResponse selectedConversation;
+
+    @FXML
+    public void initialize() {
+        lvConversations.setItems(conversations);
+        lvConversations.setCellFactory(list -> new ListCell<>() {
+            @Override
+            protected void updateItem(ConversationResponse item, boolean empty) {
+                super.updateItem(item, empty);
+                if (empty || item == null) {
+                    setText(null);
+                    setGraphic(null);
+                    return;
+                }
+
+                Label title = new Label(getConversationTitle(item));
+                title.setStyle("-fx-font-weight: bold; -fx-text-fill: #1f2937;");
+                Label preview = new Label(item.getLastMessage() == null ? "" : item.getLastMessage());
+                preview.setStyle("-fx-text-fill: #64748b;");
+                preview.setWrapText(true);
+                Label meta = new Label(buildConversationMeta(item));
+                meta.setStyle("-fx-text-fill: #94a3b8; -fx-font-size: 11px;");
+                VBox box = new VBox(4, title, preview, meta);
+                setGraphic(box);
+            }
+        });
+
+        lvConversations.getSelectionModel().selectedItemProperty().addListener((obs, oldValue, newValue) -> {
+            if (newValue != null) {
+                selectedConversation = newValue;
+                lblConversationTitle.setText(getConversationTitle(newValue));
+                loadMessages(newValue.getId());
+                realtimeClient.subscribeToConversation(newValue.getId());
+            }
+        });
+
+        txtMessage.setOnKeyPressed(event -> {
+            if (event.getCode() == KeyCode.ENTER && event.isControlDown()) {
+                btnSendClicked();
+            }
+        });
+
+        realtimeClient.setConversationListener(conversation -> Platform.runLater(() -> upsertConversation(conversation)));
+        realtimeClient.setMessageListener(message -> Platform.runLater(() -> appendMessageIfSelected(message)));
+        realtimeClient.setStatusListener(status -> Platform.runLater(() -> lblChatStatus.setText(status)));
+        realtimeClient.connect();
+
+        loadCustomers();
+        loadConversations();
+    }
+
+    @FXML
+    void btnRefreshClicked() {
+        loadConversations();
+        if (selectedConversation != null) {
+            loadMessages(selectedConversation.getId());
+        }
+    }
+
+    @FXML
+    void btnSendClicked() {
+        if (selectedConversation == null) {
+            lblChatStatus.setText("Select a conversation");
+            return;
+        }
+
+        String content = txtMessage.getText() == null ? "" : txtMessage.getText().trim();
+        if (content.isEmpty()) {
+            return;
+        }
+
+        txtMessage.clear();
+        boolean sent = realtimeClient.sendMessage(selectedConversation.getId(), content);
+        if (!sent) {
+            sendMessageFallback(selectedConversation.getId(), content);
+        }
+    }
+
+    private void loadCustomers() {
+        new Thread(() -> {
+            try {
+                List<DropdownOption> customers = DropdownApi.getInstance().getCustomers();
+                Map<Long, String> labels = new HashMap<>();
+                for (DropdownOption option : customers) {
+                    labels.put(option.getId(), option.getLabel());
+                }
+                Platform.runLater(() -> {
+                    customerLabels.clear();
+                    customerLabels.putAll(labels);
+                    lvConversations.refresh();
+                    if (selectedConversation != null) {
+                        lblConversationTitle.setText(getConversationTitle(selectedConversation));
+                    }
+                });
+            } catch (Exception e) {
+                Platform.runLater(() -> ActivityLogger.getInstance().logException(
+                        "ChatController.loadCustomers",
+                        e,
+                        "Loading customer labels for chat"));
+            }
+        }).start();
+    }
+
+    private void loadConversations() {
+        new Thread(() -> {
+            try {
+                List<ConversationResponse> response = ChatApi.getInstance().listConversations();
+                response.sort(Comparator.comparing(ChatController::conversationSortTime, Comparator.nullsLast(Comparator.reverseOrder())));
+                Platform.runLater(() -> {
+                    conversations.setAll(response);
+                    restoreSelection();
+                    if (selectedConversation == null && !conversations.isEmpty()) {
+                        lvConversations.getSelectionModel().selectFirst();
+                    }
+                });
+            } catch (Exception e) {
+                Platform.runLater(() -> {
+                    lblChatStatus.setText("Chat unavailable");
+                    ActivityLogger.getInstance().logException(
+                            "ChatController.loadConversations",
+                            e,
+                            "Loading conversations");
+                });
+            }
+        }).start();
+    }
+
+    private void loadMessages(Long conversationId) {
+        new Thread(() -> {
+            try {
+                List<MessageResponse> messages = ChatApi.getInstance().listMessages(conversationId);
+                Platform.runLater(() -> renderMessages(messages));
+            } catch (Exception e) {
+                Platform.runLater(() -> ActivityLogger.getInstance().logException(
+                        "ChatController.loadMessages",
+                        e,
+                        "Loading messages for conversation " + conversationId));
+            }
+        }).start();
+    }
+
+    private void sendMessageFallback(Long conversationId, String content) {
+        new Thread(() -> {
+            try {
+                MessageResponse response = ChatApi.getInstance().sendMessage(conversationId, new MessageRequest(content));
+                Platform.runLater(() -> {
+                    lblChatStatus.setText("Chat fallback active");
+                    appendMessageIfSelected(response);
+                });
+            } catch (Exception e) {
+                Platform.runLater(() -> ActivityLogger.getInstance().logException(
+                        "ChatController.sendMessageFallback",
+                        e,
+                        "Sending chat message for conversation " + conversationId));
+            }
+        }).start();
+    }
+
+    private void renderMessages(List<MessageResponse> messages) {
+        vbMessages.getChildren().clear();
+        for (MessageResponse message : messages) {
+            vbMessages.getChildren().add(createMessageBubble(message));
+        }
+        scrollMessagesToBottom();
+    }
+
+    private void appendMessageIfSelected(MessageResponse message) {
+        upsertConversationForMessage(message);
+        if (selectedConversation != null && selectedConversation.getId().equals(message.getConversationId())) {
+            vbMessages.getChildren().add(createMessageBubble(message));
+            scrollMessagesToBottom();
+        }
+    }
+
+    private void upsertConversation(ConversationResponse conversation) {
+        Optional<ConversationResponse> existing = conversations.stream()
+                .filter(item -> item.getId().equals(conversation.getId()))
+                .findFirst();
+
+        if (existing.isPresent()) {
+            ConversationResponse current = existing.get();
+            int index = conversations.indexOf(current);
+            conversations.set(index, conversation);
+        } else {
+            conversations.add(conversation);
+        }
+
+        conversations.sort(Comparator.comparing(ChatController::conversationSortTime, Comparator.nullsLast(Comparator.reverseOrder())));
+        restoreSelection();
+        lvConversations.refresh();
+    }
+
+    private void upsertConversationForMessage(MessageResponse message) {
+        conversations.stream()
+                .filter(conversation -> conversation.getId().equals(message.getConversationId()))
+                .findFirst()
+                .ifPresent(conversation -> {
+                    conversation.setLastMessage(message.getContent());
+                    conversation.setUpdatedAt(message.getTimestamp());
+                    conversations.sort(Comparator.comparing(ChatController::conversationSortTime, Comparator.nullsLast(Comparator.reverseOrder())));
+                    lvConversations.refresh();
+                });
+    }
+
+    private void restoreSelection() {
+        if (selectedConversation == null) {
+            return;
+        }
+        conversations.stream()
+                .filter(item -> item.getId().equals(selectedConversation.getId()))
+                .findFirst()
+                .ifPresent(match -> {
+                    selectedConversation = match;
+                    lvConversations.getSelectionModel().select(match);
+                });
+    }
+
+    private HBox createMessageBubble(MessageResponse message) {
+        boolean mine = message.getSenderId() != null && message.getSenderId().equals(UserSession.getInstance().getUserId());
+        Label author = new Label(resolveAuthorLabel(message));
+        author.setStyle("-fx-font-weight: bold; -fx-text-fill: " + (mine ? "#ffffff" : "#1f2937") + ";");
+
+        Label content = new Label(message.getContent());
+        content.setWrapText(true);
+        content.setStyle("-fx-text-fill: " + (mine ? "#ffffff" : "#1f2937") + ";");
+
+        String timestampText = message.getTimestamp() == null ? "" : TIME_FORMATTER.format(message.getTimestamp());
+        Label timestamp = new Label(timestampText);
+        timestamp.setStyle("-fx-text-fill: " + (mine ? "#dbeafe" : "#94a3b8") + "; -fx-font-size: 11px;");
+
+        VBox bubble = new VBox(4, author, content, timestamp);
+        bubble.setMaxWidth(420);
+        bubble.setStyle(mine
+                ? "-fx-background-color: #0f766e; -fx-background-radius: 14; -fx-padding: 12;"
+                : "-fx-background-color: #e2e8f0; -fx-background-radius: 14; -fx-padding: 12;");
+
+        Region spacer = new Region();
+        HBox.setHgrow(spacer, Priority.ALWAYS);
+        HBox container = new HBox(12);
+        if (mine) {
+            container.getChildren().addAll(spacer, bubble);
+        } else {
+            container.getChildren().addAll(bubble, spacer);
+        }
+        return container;
+    }
+
+    private String resolveAuthorLabel(MessageResponse message) {
+        Long currentUserId = UserSession.getInstance().getUserId();
+        if (message.getSenderId() != null && message.getSenderId().equals(currentUserId)) {
+            return "You";
+        }
+        if (selectedConversation != null && selectedConversation.getStaffId() != null && selectedConversation.getStaffId().equals(message.getSenderId())) {
+            return "Staff";
+        }
+        return "Customer";
+    }
+
+    private String getConversationTitle(ConversationResponse conversation) {
+        String customerLabel = customerLabels.get(conversation.getCustomerId());
+        return customerLabel != null ? customerLabel : "Customer #" + conversation.getCustomerId();
+    }
+
+    private String buildConversationMeta(ConversationResponse conversation) {
+        String assignee = conversation.getStaffId() == null ? "Unassigned" : "Assigned";
+        String updated = conversation.getUpdatedAt() == null ? "" : TIME_FORMATTER.format(conversation.getUpdatedAt());
+        return assignee + (updated.isBlank() ? "" : " · " + updated);
+    }
+
+    private static java.time.LocalDateTime conversationSortTime(ConversationResponse conversation) {
+        return conversation.getUpdatedAt() != null ? conversation.getUpdatedAt() : conversation.getCreatedAt();
+    }
+
+    private void scrollMessagesToBottom() {
+        Platform.runLater(() -> spMessages.setVvalue(1.0));
+    }
+}

src/main/java/org/example/petshopdesktop/controllers/MainLayoutController.java

@@ -13,6 +13,7 @@ import javafx.scene.image.ImageView;
 import javafx.scene.input.MouseEvent;
 import javafx.scene.layout.StackPane;
 import javafx.stage.Stage;
+import org.example.petshopdesktop.api.ChatRealtimeClient;
 import org.example.petshopdesktop.auth.UserSession;
 import org.example.petshopdesktop.util.ActivityLogger;
 
@@ -185,6 +186,7 @@ public class MainLayoutController {
 
     @FXML
     void btnLogoutClicked(ActionEvent event) {
+        ChatRealtimeClient.getInstance().disconnect();
         UserSession.getInstance().logout();
         try {
             FXMLLoader loader = new FXMLLoader(

src/main/resources/org/example/petshopdesktop/modelviews/chat-view.fxml

@@ -1,18 +1,78 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
 <?import javafx.geometry.Insets?>
+<?import javafx.scene.control.Button?>
 <?import javafx.scene.control.Label?>
+<?import javafx.scene.control.ListView?>
+<?import javafx.scene.control.ScrollPane?>
+<?import javafx.scene.control.Separator?>
+<?import javafx.scene.control.TextArea?>
+<?import javafx.scene.layout.BorderPane?>
+<?import javafx.scene.layout.HBox?>
+<?import javafx.scene.layout.Priority?>
+<?import javafx.scene.layout.Region?>
 <?import javafx.scene.layout.VBox?>
 <?import javafx.scene.text.Font?>
 
-<VBox spacing="20.0" style="-fx-background-color: #f8fafc;" xmlns="http://javafx.com/javafx/21" xmlns:fx="http://javafx.com/fxml/1">
-    <padding>
-        <Insets bottom="20.0" left="20.0" right="20.0" top="20.0" />
-    </padding>
-
-    <Label text="Customer Chat" textFill="#2c3e50">
-        <font>
-            <Font name="System Bold" size="30.0" />
-        </font>
-    </Label>
-</VBox>
+<BorderPane prefHeight="680.0" prefWidth="900.0" style="-fx-background-color: linear-gradient(to bottom right, #f8fafc, #e2e8f0);" xmlns="http://javafx.com/javafx/17" xmlns:fx="http://javafx.com/fxml/1" fx:controller="org.example.petshopdesktop.controllers.ChatController">
+    <left>
+        <VBox prefWidth="290.0" spacing="12.0" style="-fx-background-color: #ffffff; -fx-border-color: #dbe4ee; -fx-border-width: 0 1 0 0;">
+            <padding>
+                <Insets bottom="18.0" left="18.0" right="18.0" top="18.0" />
+            </padding>
+            <children>
+                <HBox alignment="CENTER_LEFT" spacing="10.0">
+                    <children>
+                        <Label text="Chat Inbox" textFill="#1f2937">
+                            <font>
+                                <Font name="System Bold" size="24.0" />
+                            </font>
+                        </Label>
+                        <Region HBox.hgrow="ALWAYS" />
+                        <Button fx:id="btnRefresh" mnemonicParsing="false" onAction="#btnRefreshClicked" style="-fx-background-color: #0f766e; -fx-background-radius: 10; -fx-text-fill: white; -fx-cursor: hand;" text="Refresh">
+                            <padding>
+                                <Insets bottom="8.0" left="14.0" right="14.0" top="8.0" />
+                            </padding>
+                        </Button>
+                    </children>
+                </HBox>
+                <Label fx:id="lblChatStatus" text="Connecting chat..." textFill="#64748b" />
+                <Separator />
+                <ListView fx:id="lvConversations" prefHeight="620.0" style="-fx-background-color: transparent; -fx-border-color: transparent;" VBox.vgrow="ALWAYS" />
+            </children>
+        </VBox>
+    </left>
+    <center>
+        <VBox spacing="14.0">
+            <padding>
+                <Insets bottom="18.0" left="18.0" right="18.0" top="18.0" />
+            </padding>
+            <children>
+                <Label fx:id="lblConversationTitle" text="Select a conversation" textFill="#0f172a">
+                    <font>
+                        <Font name="System Bold" size="24.0" />
+                    </font>
+                </Label>
+                <ScrollPane fx:id="spMessages" fitToWidth="true" hbarPolicy="NEVER" style="-fx-background-color: transparent; -fx-background: transparent;" VBox.vgrow="ALWAYS">
+                    <content>
+                        <VBox fx:id="vbMessages" spacing="10.0" style="-fx-background-color: rgba(255,255,255,0.72); -fx-background-radius: 18; -fx-padding: 18;" />
+                    </content>
+                </ScrollPane>
+                <VBox spacing="10.0" style="-fx-background-color: #ffffff; -fx-background-radius: 16; -fx-padding: 14;">
+                    <children>
+                        <TextArea fx:id="txtMessage" prefRowCount="4" promptText="Reply to the selected conversation..." wrapText="true" />
+                        <HBox alignment="CENTER_RIGHT">
+                            <children>
+                                <Button fx:id="btnSend" mnemonicParsing="false" onAction="#btnSendClicked" style="-fx-background-color: #1d4ed8; -fx-background-radius: 12; -fx-text-fill: white; -fx-cursor: hand;" text="Send Message">
+                                    <padding>
+                                        <Insets bottom="10.0" left="18.0" right="18.0" top="10.0" />
+                                    </padding>
+                                </Button>
+                            </children>
+                        </HBox>
+                    </children>
+                </VBox>
+            </children>
+        </VBox>
+    </center>
+</BorderPane>