Merge 9293b8a into a6225fc

src/main/java/seedu/exercise/logic/commands/AddCommand.java

@@ -9,13 +9,14 @@
 import static seedu.exercise.logic.parser.CliSyntax.PREFIX_UNIT;
 
 import seedu.exercise.logic.commands.exceptions.CommandException;
+import seedu.exercise.logic.commands.history.EventHistory;
 import seedu.exercise.model.Model;
 import seedu.exercise.model.exercise.Exercise;
 
 /**
  * Adds an exercise to the exercise book.
  */
-public class AddCommand extends Command {
+public class AddCommand extends Command implements UndoableCommand {
 
     public static final String COMMAND_WORD = "add";
 
@@ -41,13 +42,22 @@ public class AddCommand extends Command {
     private final Exercise toAdd;
 
     /**
-     * Creates an AddCommand to add the specified {@code Person}
+     * Creates an AddCommand to add the specified {@code Exercise}
      */
     public AddCommand(Exercise exercise) {
         requireNonNull(exercise);
         toAdd = exercise;
     }
 
+    /**
+     * Returns the exercise to be added to the Exercise Book.
+     *
+     * @return exercise that is passed into constructor of AddCommand
+     */
+    public Exercise getExercise() {
+        return toAdd;
+    }
+
     @Override
     public CommandResult execute(Model model) throws CommandException {
         requireNonNull(model);
@@ -57,6 +67,7 @@ public CommandResult execute(Model model) throws CommandException {
         }
 
         model.addExercise(toAdd);
+        EventHistory.getInstance().addCommandToUndoStack(this);
         return new CommandResult(String.format(MESSAGE_SUCCESS, toAdd));
     }
 

src/main/java/seedu/exercise/logic/commands/DeleteCommand.java

@@ -7,13 +7,14 @@
 import seedu.exercise.commons.core.Messages;
 import seedu.exercise.commons.core.index.Index;
 import seedu.exercise.logic.commands.exceptions.CommandException;
+import seedu.exercise.logic.commands.history.EventHistory;
 import seedu.exercise.model.Model;
 import seedu.exercise.model.exercise.Exercise;
 
 /**
  * Deletes a exercise identified using it's displayed index from the exercise book.
  */
-public class DeleteCommand extends Command {
+public class DeleteCommand extends Command implements UndoableCommand {
 
     public static final String COMMAND_WORD = "delete";
 
@@ -25,6 +26,7 @@ public class DeleteCommand extends Command {
     public static final String MESSAGE_DELETE_EXERCISE_SUCCESS = "Deleted Exercise: %1$s";
 
     private final Index targetIndex;
+    private Exercise exerciseToDelete;
 
     public DeleteCommand(Index targetIndex) {
         this.targetIndex = targetIndex;
@@ -39,11 +41,21 @@ public CommandResult execute(Model model) throws CommandException {
             throw new CommandException(Messages.MESSAGE_INVALID_EXERCISE_DISPLAYED_INDEX);
         }
 
-        Exercise exerciseToDelete = lastShownList.get(targetIndex.getZeroBased());
+        exerciseToDelete = lastShownList.get(targetIndex.getZeroBased());
         model.deleteExercise(exerciseToDelete);
+        EventHistory.getInstance().addCommandToUndoStack(this);
         return new CommandResult(String.format(MESSAGE_DELETE_EXERCISE_SUCCESS, exerciseToDelete));
     }
 
+    /**
+     * Returns the exercise to be deleted from Exercise Book.
+     *
+     * @return exercise referred to by targetIndex
+     */
+    public Exercise getExercise() {
+        return exerciseToDelete;
+    }
+
     @Override
     public boolean equals(Object other) {
         return other == this // short circuit if same object

src/main/java/seedu/exercise/logic/commands/RedoCommand.java

@@ -0,0 +1,35 @@
+package seedu.exercise.logic.commands;
+
+import static java.util.Objects.requireNonNull;
+
+import seedu.exercise.logic.commands.exceptions.CommandException;
+import seedu.exercise.logic.commands.history.Event;
+import seedu.exercise.logic.commands.history.EventHistory;
+import seedu.exercise.model.Model;
+
+/**
+ * Undoes the last executed command.
+ */
+public class RedoCommand extends Command {
+
+    public static final String COMMAND_WORD = "redo";
+
+    public static final String MESSAGE_SUCCESS = "Action redone: \n%1$s";
+    public static final String MESSAGE_EMPTY_REDO_STACK = "There is no command to redo";
+
+    @Override
+    public CommandResult execute(Model model) throws CommandException {
+        requireNonNull(model);
+        EventHistory actionHistory = EventHistory.getInstance();
+
+        if (actionHistory.isRedoStackEmpty()) {
+            throw new CommandException(MESSAGE_EMPTY_REDO_STACK);
+        }
+
+        Event eventToRedo = actionHistory.redo();
+        eventToRedo.redo(model);
+        return new CommandResult(
+                String.format(MESSAGE_SUCCESS, eventToRedo));
+    }
+
+}

src/main/java/seedu/exercise/logic/commands/UndoCommand.java

@@ -0,0 +1,37 @@
+package seedu.exercise.logic.commands;
+
+import static java.util.Objects.requireNonNull;
+
+import seedu.exercise.logic.commands.exceptions.CommandException;
+import seedu.exercise.logic.commands.history.Event;
+import seedu.exercise.logic.commands.history.EventHistory;
+import seedu.exercise.model.Model;
+
+/**
+ * Undoes the last executed command.
+ */
+public class UndoCommand extends Command {
+
+    public static final String COMMAND_WORD = "undo";
+    public static final String MESSAGE_USAGE = COMMAND_WORD
+            + ": Undoes the latest command called.\n"
+            + "Example: " + COMMAND_WORD;
+    public static final String MESSAGE_SUCCESS = "Command undone: \n%1$s";
+    public static final String MESSAGE_EMPTY_UNDO_STACK = "There is no command to undo";
+
+    @Override
+    public CommandResult execute(Model model) throws CommandException {
+        requireNonNull(model);
+        EventHistory commandHistory = EventHistory.getInstance();
+
+        if (commandHistory.isUndoStackEmpty()) {
+            throw new CommandException(MESSAGE_EMPTY_UNDO_STACK);
+        }
+
+        Event eventToUndo = commandHistory.undo();
+        eventToUndo.undo(model);
+
+        return new CommandResult(String.format(MESSAGE_SUCCESS, eventToUndo));
+    }
+
+}

src/main/java/seedu/exercise/logic/commands/UndoableCommand.java

@@ -0,0 +1,7 @@
+package seedu.exercise.logic.commands;
+
+/**
+ * Represents a command that can be undone.
+ */
+public interface UndoableCommand {
+}

src/main/java/seedu/exercise/logic/commands/history/AddEvent.java

@@ -0,0 +1,58 @@
+package seedu.exercise.logic.commands.history;
+
+import seedu.exercise.model.Model;
+import seedu.exercise.model.exercise.Exercise;
+
+/**
+ * Represents a particular add event that can be redone or or undone.
+ */
+public class AddEvent implements Event {
+
+    private static final String EVENT_DESCRIPTION = "Add exercise: %1$s";
+
+    /**
+     * The exercise that has been added during the event.
+     */
+    private final Exercise exercise;
+
+    /**
+     * Creates an AddEvent to store the particular event of an exercise being added to the exercise book.
+     *
+     * @param exercise the exercise that has been added in this instance of AddEvent.
+     */
+    AddEvent(Exercise exercise) {
+        this.exercise = exercise;
+    }
+
+    @Override
+    public void undo(Model model) {
+        model.deleteExercise(exercise);
+    }
+
+    @Override
+    public void redo(Model model) {
+        model.addExercise(exercise);
+    }
+
+    /**
+     * Returns the exercise that was added.
+     *
+     * @return exercise that is passed into constructor of AddEvent
+     */
+    public Exercise getExercise() {
+        return exercise;
+    }
+
+    @Override
+    public String toString() {
+        return String.format(EVENT_DESCRIPTION, exercise);
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        return other == this // short circuit if same object
+                || (other instanceof AddEvent // instanceof handles nulls
+                && exercise.equals(((AddEvent) other).getExercise()));
+    }
+
+}

src/main/java/seedu/exercise/logic/commands/history/DeleteEvent.java

@@ -0,0 +1,58 @@
+package seedu.exercise.logic.commands.history;
+
+import seedu.exercise.model.Model;
+import seedu.exercise.model.exercise.Exercise;
+
+/**
+ * Represents a particular delete event that can be redone or or undone.
+ */
+public class DeleteEvent implements Event {
+
+    private static final String EVENT_DESCRIPTION = "Delete exercise: %1$s";
+
+    /**
+     * The exercise that has been deleted during the event.
+     */
+    private final Exercise exercise;
+
+    /**
+     * Creates a DeleteEvent to store the particular event of an exercise being deleted from the exercise book.
+     *
+     * @param exercise the exercise that has been deleted in this instance of DeleteEvent.
+     */
+    DeleteEvent(Exercise exercise) {
+        this.exercise = exercise;
+    }
+
+    @Override
+    public void undo(Model model) {
+        model.addExercise(exercise);
+    }
+
+    @Override
+    public void redo(Model model) {
+        model.deleteExercise(exercise);
+    }
+
+    /**
+     * Returns the exercise that was deleted.
+     *
+     * @return exercise that is passed into constructor of DeleteEvent
+     */
+    public Exercise getExercise() {
+        return exercise;
+    }
+
+    @Override
+    public String toString() {
+        return String.format(EVENT_DESCRIPTION, exercise);
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        return other == this // short circuit if same object
+                || (other instanceof DeleteEvent // instanceof handles nulls
+                && exercise.equals(((DeleteEvent) other).getExercise()));
+    }
+
+}

src/main/java/seedu/exercise/logic/commands/history/Event.java

@@ -0,0 +1,23 @@
+package seedu.exercise.logic.commands.history;
+
+import seedu.exercise.model.Model;
+
+/**
+ * Represents an Event that can be undone or redone.
+ */
+public interface Event {
+
+    /**
+     * Executes the reverse of the event.
+     *
+     * @param model {@code Model} which the command should operate on.
+     */
+    void undo(Model model);
+
+    /**
+     * Executes the event again.
+     *
+     * @param model {@code Model} which the command should operate on.
+     */
+    void redo(Model model);
+}

src/main/java/seedu/exercise/logic/commands/history/EventFactory.java

@@ -0,0 +1,34 @@
+package seedu.exercise.logic.commands.history;
+
+import seedu.exercise.logic.commands.AddCommand;
+import seedu.exercise.logic.commands.DeleteCommand;
+import seedu.exercise.logic.commands.UndoableCommand;
+import seedu.exercise.model.exercise.Exercise;
+
+/**
+ * A utility class to generate specific Event objects depending on requirements.
+ */
+public class EventFactory {
+
+    /**
+     * Generate an Event object that can execute the behaviour of a given Command as well
+     * as its opposite behaviour.
+     *
+     * @param command a command to be represented with using an Event object
+     * @return an Event that can be undone or redone
+     */
+    static Event commandToEvent(UndoableCommand command) {
+        if (command instanceof AddCommand) {
+            Exercise exercise = ((AddCommand) command).getExercise();
+            return new AddEvent(exercise);
+
+        } else if (command instanceof DeleteCommand) {
+            Exercise exercise = ((DeleteCommand) command).getExercise();
+            return new DeleteEvent(exercise);
+
+        } else {
+            return null;
+        }
+    }
+
+}