Add exit case and handle exit in main window

src/main/java/victor/Handler.java

@@ -36,11 +36,10 @@ public Handler() {
      * @param request A string containing the user's input to the task bot.
      * @return A string containing the program's response to the user input.
      */
-    public String handleRequest(String request) {
+    public Command handleRequest(String request) {
         Command command = parser.parseInput(request);
         command.setData(taskList);
-        ReturnMessage returnMessage = command.execute();
         command.write(DATA_PATH);
-        return returnMessage.getMessagesAsString();
+        return command;
     }
 }

src/main/java/victor/controls/MainWindow.java

@@ -7,6 +7,8 @@
 import javafx.scene.layout.VBox;
 import javafx.stage.Stage;
 import victor.Handler;
+import victor.commands.Command;
+import victor.messages.ReturnMessage;
 
 /**
  * Controller for the main GUI.
@@ -62,10 +64,12 @@ public void welcomeUser() {
     @FXML
     private void handleUserInput() {
         String input = userInput.getText();
-        if (input.trim().equalsIgnoreCase("bye")) {
+        Command command = handler.handleRequest(input);
+        if (command.isExit()) {
             stage.close();
         }
-        String response = handler.handleRequest(input);
+        ReturnMessage returnMessage = command.execute();
+        String response = returnMessage.getMessagesAsString();
         dialogContainer.getChildren().addAll(
                 DialogBox.getUserDialog(input, userImage),
                 DialogBox.getVictorDialog(response, victorImage)

src/main/java/victor/parser/Parser.java

@@ -33,7 +33,7 @@ public Command parseInput(String input) {
         case "mark" -> new MarkCommand(inputWords);
         case "unmark" -> new UnmarkCommand(inputWords);
         case "list" -> new ListCommand(inputWords);
-        case "bye" -> new ExitCommand(inputWords);
+        case "bye", "exit" -> new ExitCommand(inputWords);
         case "find" -> new FindCommand(inputWords);
         default -> new Command(inputWords);
         };