Implement CommandHistory and testcases

src/main/java/seedu/address/ui/CommandBox.java

@@ -3,6 +3,7 @@
 import javafx.collections.ObservableList;
 import javafx.fxml.FXML;
 import javafx.scene.control.TextField;
+import javafx.scene.input.KeyCode;
 import javafx.scene.layout.Region;
 import seedu.address.logic.commands.CommandResult;
 import seedu.address.logic.commands.exceptions.CommandException;
@@ -18,9 +19,13 @@ public class CommandBox extends UiPart<Region> {
 
     private final CommandExecutor commandExecutor;
 
+    private CommandHistory commandHistory = new CommandHistory();
+
     @FXML
     private TextField commandTextField;
 
+
+
     /**
      * Creates a {@code CommandBox} with the given {@code CommandExecutor}.
      */
@@ -31,6 +36,28 @@ public CommandBox(CommandExecutor commandExecutor) {
         commandTextField.textProperty().addListener((unused1, unused2, unused3) -> setStyleToDefault());
     }
 
+    /**
+     * initialize() method from javaFx, used to check for arrow inputs inside the commandTextField
+     */
+    @FXML
+    public void initialize() {
+        commandTextField.setOnKeyPressed(event -> {
+            if (event.getCode() == KeyCode.UP) {
+                String previousCommand = commandHistory.getPreviousCommand();
+                if (previousCommand != null) {
+                    commandTextField.setText(previousCommand);
+                    commandTextField.positionCaret(previousCommand.length()); // Move cursor to end
+                }
+            } else if (event.getCode() == KeyCode.DOWN) {
+                String nextCommand = commandHistory.getNextCommand();
+                if (nextCommand != null) {
+                    commandTextField.setText(nextCommand);
+                    commandTextField.positionCaret(nextCommand.length()); // Move cursor to end
+                }
+            }
+        });
+    }
+
     /**
      * Handles the Enter button pressed event.
      */
@@ -46,7 +73,9 @@ private void handleCommandEntered() {
             commandTextField.setText("");
         } catch (CommandException | ParseException e) {
             setStyleToIndicateCommandFailure();
+            return;
         }
+        commandHistory.addCommand(commandText);
     }
 
     /**

src/main/java/seedu/address/ui/CommandHistory.java

@@ -1,19 +1,24 @@
 package seedu.address.ui;
 import java.util.ArrayList;
 
-
 /**
  * Container for previous commands
  */
 public class CommandHistory {
     private ArrayList<String> commandHistory = new ArrayList<>();
     private int currentHistoryIndex = -1;
 
+    /**
+     * Adds a command to the ArrayList
+     */
     public void addCommand(String command) {
         commandHistory.add(command);
         currentHistoryIndex = commandHistory.size(); // Reset index to point after the latest command
     }
 
+    /**
+     * Retrieves the previous command from the ArrayList, outputs null if already at the front of the arraylist
+     */
     public String getPreviousCommand() {
         if (currentHistoryIndex > 0) {
             currentHistoryIndex--;
@@ -22,11 +27,14 @@ public String getPreviousCommand() {
         return null; // No previous command
     }
 
+    /**
+     * Retrieves the next command from the ArrayList, outputs null if already at the end of the arraylist
+     */
     public String getNextCommand() {
         if (currentHistoryIndex < commandHistory.size() - 1) {
             currentHistoryIndex++;
             return commandHistory.get(currentHistoryIndex);
         }
         return null; // No next command
     }
-}
+}

src/main/java/seedu/address/ui/MainWindow.java

@@ -121,6 +121,8 @@ void fillInnerParts() {
 
         CommandBox commandBox = new CommandBox(this::executeCommand);
         commandBoxPlaceholder.getChildren().add(commandBox.getRoot());
+
+
     }
 
     /**

src/test/java/seedu/address/ui/CommandHistoryTest.java

@@ -0,0 +1,67 @@
+package seedu.address.ui;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class CommandHistoryTest {
+
+    private CommandHistory commandHistory;
+
+    @BeforeEach
+    public void setUp() {
+        commandHistory = new CommandHistory();
+    }
+
+    @Test
+    public void testAddCommand() {
+        commandHistory.addCommand("first command");
+        commandHistory.addCommand("second command");
+
+        // Moving back in history
+        assertEquals("second command", commandHistory.getPreviousCommand());
+        assertEquals("first command", commandHistory.getPreviousCommand());
+
+        // Should return null as there's no more previous command
+        assertNull(commandHistory.getPreviousCommand());
+    }
+
+    @Test
+    public void testNextCommand() {
+        commandHistory.addCommand("first command");
+        commandHistory.addCommand("second command");
+
+        // Go back twice to previous commands
+        commandHistory.getPreviousCommand();
+        commandHistory.getPreviousCommand();
+
+        // Moving forward in history
+        assertEquals("second command", commandHistory.getNextCommand());
+        assertNull(commandHistory.getNextCommand()); // No further next command after latest
+    }
+
+    @Test
+    public void testEmptyHistory() {
+        // Initially, history should return null when getting previous/next command
+        assertNull(commandHistory.getPreviousCommand());
+        assertNull(commandHistory.getNextCommand());
+    }
+
+    @Test
+    public void testMixedNavigation() {
+        commandHistory.addCommand("first command");
+        commandHistory.addCommand("second command");
+        commandHistory.addCommand("third command");
+
+        // Navigate through commands
+        assertEquals("third command", commandHistory.getPreviousCommand());
+        assertEquals("second command", commandHistory.getPreviousCommand());
+
+        // Moving forward should bring back "third command"
+        assertEquals("third command", commandHistory.getNextCommand());
+
+        // After the latest command, there should be no more next command
+        assertNull(commandHistory.getNextCommand());
+    }
+}