feat: add LoginController.java logic for handling UI events

src/main/java/com/university/chat/Client/UI/LoginController.java

@@ -0,0 +1,180 @@
+package com.university.chat.Client.UI;
+
+import com.university.chat.Client.Net.chatClient;
+import com.university.chat.Common.ChatMessage;
+import com.university.chat.Common.MessageType;
+import javafx.application.Platform;
+import javafx.fxml.FXML;
+import javafx.fxml.FXMLLoader;
+import javafx.scene.Parent;
+import javafx.scene.Scene;
+import javafx.scene.control.Alert;
+import javafx.scene.control.Button;
+import javafx.scene.control.TextField;
+import javafx.scene.layout.HBox;
+import javafx.stage.Stage;
+
+public class LoginController {
+
+    @FXML
+    public HBox titleBar;
+
+    private double xOffset = 0;
+    private double yOffset = 0;
+
+    @FXML
+    private TextField usernameField;
+
+    @FXML
+    private Button nameButton;
+
+    private final chatClient client = new chatClient();
+
+    private ChatController chatController;
+
+    @FXML
+    public void initialize() {
+        titleBar.setOnMousePressed(event -> {
+            xOffset = event.getSceneX();
+            yOffset = event.getSceneY();
+        });
+
+        titleBar.setOnMouseDragged(event -> {
+            Stage stage = (Stage) titleBar.getScene().getWindow();
+            stage.setX(event.getScreenX() - xOffset);
+            stage.setY(event.getScreenY() - yOffset);
+        });
+
+    }
+
+    @FXML
+    private void onConnectClicked() {
+        String username = usernameField.getText().trim();
+
+        if (username.isEmpty()) {
+            showError("Username cannot be empty.");
+            return;
+        }
+
+        nameButton.setDisable(true);
+
+        new Thread(() -> {
+            try {
+
+                client.connect("localhost", 9000);
+
+                client.startListening(
+                        this::handleServerMessage,
+                        this::handleConnectionError
+                );
+
+                client.login(username);
+
+            } catch (Exception e) {
+                Platform.runLater(() -> {
+                    showError("Failed to connect to server.\nMake sure the server is running.\n\n" + e.getMessage());
+                    nameButton.setDisable(false);
+                });
+            }
+        }).start();
+    }
+
+
+    private void handleServerMessage(Object obj) {
+        if (obj instanceof ChatMessage msg) {
+
+            if (msg.getType() == MessageType.LOGIN_SUCCESS) {
+                Platform.runLater(() -> {
+                    showInfo("Login successful!");
+                    openChatWindow();
+                });
+            }
+            else if (msg.getType() == MessageType.LOGIN_FAILED) {
+                Platform.runLater(() -> {
+                    showError("Login failed: username taken");
+                    nameButton.setDisable(false);
+                });
+            }
+            else if (msg.getType() == MessageType.USER_LIST) {
+                Platform.runLater(() -> {
+                    if (chatController != null) {
+                        String content = msg.getContent();
+                        java.util.List<String> users = java.util.Arrays.asList(content.split(","));
+                        chatController.updateUsersList(users);
+                    }
+                });
+            }
+            else {
+                Platform.runLater(() -> {
+                    if (chatController != null) {
+                        chatController.sendPublicMessage();
+                    }
+                    System.out.println("Server: " + msg.getContent());
+                });
+            }
+        }
+    }
+
+    private void handleConnectionError(Exception e) {
+        Platform.runLater(() -> showError("Connection lost: " + e.getMessage()));
+    }
+
+
+    private void showError(String text) {
+        Alert alert = new Alert(Alert.AlertType.ERROR);
+        alert.setTitle("Error");
+        alert.setHeaderText(null);
+        alert.setContentText(text);
+        alert.showAndWait();
+    }
+
+    private void showInfo(String text) {
+        Alert alert = new Alert(Alert.AlertType.INFORMATION);
+        alert.setTitle("Info");
+        alert.setHeaderText(null);
+        alert.setContentText(text);
+        alert.showAndWait();
+    }
+
+    private void openChatWindow() {
+        try {
+
+            FXMLLoader loader = new FXMLLoader(
+                    getClass().getResource("chat.fxml")
+            );
+
+            Parent root = loader.load();
+
+            this.chatController = loader.getController();
+            this.chatController.setClient(client);
+
+            Stage stage = (Stage) usernameField.getScene().getWindow();
+
+            stage.setScene(new Scene(root, 900, 600));
+
+            stage.getScene().getStylesheets().add(
+                    getClass().getResource("/chat_style.css").toExternalForm()
+            );
+
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+
+    @FXML
+    private void closeApp() {
+        System.exit(0);
+    }
+
+    @FXML
+    private void minimize() {
+        Stage stage = (Stage) usernameField.getScene().getWindow();
+        stage.setIconified(true);
+    }
+
+    @FXML
+    private void maximize() {
+        Stage stage = (Stage) usernameField.getScene().getWindow();
+        stage.setMaximized(!stage.isMaximized());
+    }
+}