Poor implementation of Undo Memento Pattern.

src/seedu/addressbook/commands/CommandResult.java

@@ -1,5 +1,6 @@
 package seedu.addressbook.commands;
 
+import seedu.addressbook.data.AddressBook;
 import seedu.addressbook.data.person.ReadOnlyPerson;
 
 import java.util.List;
@@ -15,15 +16,28 @@ public class CommandResult {
 
     /** The list of persons that was produced by the command */
     private final List<? extends ReadOnlyPerson> relevantPersons;
+
+    private final AddressBook state;
+    private boolean isUndone;
 
     public CommandResult(String feedbackToUser) {
         this.feedbackToUser = feedbackToUser;
         relevantPersons = null;
+        state = null;
     }
 
     public CommandResult(String feedbackToUser, List<? extends ReadOnlyPerson> relevantPersons) {
         this.feedbackToUser = feedbackToUser;
         this.relevantPersons = relevantPersons;
+        state = null;
+    }
+
+    public CommandResult(String feedbackToUser, AddressBook state, boolean undoneStatus) {
+        this.feedbackToUser = feedbackToUser;
+        this.relevantPersons = null;
+        this.state = state;
+        isUndone = undoneStatus;
+        System.out.println("isUndone " + isUndone);
     }
 
     /**
@@ -32,5 +46,15 @@ public CommandResult(String feedbackToUser, List<? extends ReadOnlyPerson> relev
     public Optional<List<? extends ReadOnlyPerson>> getRelevantPersons() {
         return Optional.ofNullable(relevantPersons);
     }
-
+
+    /**
+     *  Returns previous state of addressBook to command command result, if succeeded
+     */
+    public AddressBook getRevertState() {
+        return state;
+    }
+
+    public boolean getUndoStatus() {
+        return isUndone;
+    }
 }

src/seedu/addressbook/commands/UndoCommand.java

@@ -0,0 +1,56 @@
+package seedu.addressbook.commands;
+
+import seedu.addressbook.data.AddressBook;
+import seedu.addressbook.data.person.UniquePersonList;
+import seedu.addressbook.data.person.UniquePersonList.DuplicatePersonException;
+import seedu.addressbook.data.tag.UniqueTagList;
+import seedu.addressbook.data.tag.UniqueTagList.DuplicateTagException;
+import seedu.addressbook.logic.Logic;
+import seedu.addressbook.revision_control.CareTaker;
+import seedu.addressbook.revision_control.Originator;
+
+/**
+ * Undo most recently successful command which mutates the data of AddressBook.
+ */
+public class UndoCommand extends Command {
+
+    public static final String COMMAND_WORD = "undo";
+
+    public static final String MESSAGE_USAGE = COMMAND_WORD + ":\n"
+            + "Undo your most recent command which mutates the data such as add,delete,edit,clear" + "Example: "
+            + COMMAND_WORD;
+
+    public static final String MESSAGE_SUCCESS = "Your AddressBook action has been reverted successfully";
+
+    private Originator originator;
+    private CareTaker careTaker;
+
+
+    /**
+     * To request logic to give additional input for executing Undo.
+     */
+    public UndoCommand(Logic logic) {
+
+    }
+
+    public UndoCommand(Originator originator, CareTaker careTaker, int numCmd, int numUndo) {
+        this.originator = originator;
+        this.careTaker = careTaker;
+
+    }
+
+    @Override
+    public CommandResult execute() {
+
+        /*
+         * new AddressBook(new UniquePersonList(personList), new UniqueTagList(tagList))
+         * 
+         */
+        originator.getStateFromMemento(careTaker.get(0)); // does not work when ported here
+        return new CommandResult(String.format(MESSAGE_SUCCESS), 
+                new AddressBook(new UniquePersonList( originator.getState().getAllPersons()),        
+                        new UniqueTagList(originator.getState().getAllTags())),// does not work.
+                                                 true); 
+    }
+
+}

src/seedu/addressbook/logic/Logic.java

@@ -2,10 +2,16 @@
 
 import seedu.addressbook.commands.Command;
 import seedu.addressbook.commands.CommandResult;
+import seedu.addressbook.commands.UndoCommand;
 import seedu.addressbook.data.AddressBook;
 import seedu.addressbook.data.person.ReadOnlyPerson;
+import seedu.addressbook.data.person.UniquePersonList;
+import seedu.addressbook.data.tag.UniqueTagList;
 import seedu.addressbook.parser.Parser;
+import seedu.addressbook.revision_control.CareTaker;
+import seedu.addressbook.revision_control.Originator;
 import seedu.addressbook.storage.StorageFile;
+import seedu.addressbook.storage.jaxb.AdaptedAddressBook;
 
 import java.util.Collections;
 import java.util.List;
@@ -19,26 +25,45 @@ public class Logic {
 
     private StorageFile storage;
     private AddressBook addressBook;
+    private Originator originator;
+    private CareTaker careTaker;
+    private int numCmd = 0;
+    private int numUndo = 0;
 
     /** The list of person shown to the user most recently.  */
     private List<? extends ReadOnlyPerson> lastShownList = Collections.emptyList();
 
     public Logic() throws Exception{
         setStorage(initializeStorage());
         setAddressBook(storage.load());
+        originator = new Originator();
+        setCareTaker();
+
     }
 
     Logic(StorageFile storageFile, AddressBook addressBook){
         setStorage(storageFile);
         setAddressBook(addressBook);
-    }
+        originator = new Originator();
+        setCareTaker();
+    }    
 
     void setStorage(StorageFile storage){
         this.storage = storage;
     }
 
     void setAddressBook(AddressBook addressBook){
         this.addressBook = addressBook;
+    }    
+
+    /**
+     * Sets the careTaker to be the initial state upon starting the program.
+     * CareTaker and originator will reset on every startup.
+     */
+    void setCareTaker() {
+        careTaker = new CareTaker();
+        originator.setState(addressBook);
+        careTaker.add(originator.saveStateToMemento());
     }
 
     /**
@@ -52,6 +77,14 @@ private StorageFile initializeStorage() throws StorageFile.InvalidStorageFilePat
     public String getStorageFilePath() {
         return storage.getPath();
     }
+
+    public Originator getOriginator() {
+        return originator;
+    }
+
+    public CareTaker getCareTaker() {
+        return careTaker;
+    }
 
     /**
      * Unmodifiable view of the current last shown list.
@@ -70,6 +103,9 @@ protected void setLastShownList(List<? extends ReadOnlyPerson> newList) {
      */
     public CommandResult execute(String userCommandText) throws Exception {
         Command command = new Parser().parseCommand(userCommandText);
+        if (isUndo(command)) {            
+            command = new UndoCommand(originator, careTaker, numCmd, numUndo);
+        }
         CommandResult result = execute(command);
         recordResult(result);
         return result;
@@ -84,8 +120,32 @@ public CommandResult execute(String userCommandText) throws Exception {
      */
     private CommandResult execute(Command command) throws Exception {
         command.setData(addressBook, lastShownList);
+        numCmd++;
         CommandResult result = command.execute();
+        //TODO: save only if execute successfully mutates the data.
         storage.save(addressBook);
+        if (!result.getUndoStatus()) {
+            originator.setState(addressBook);
+            System.out.println(originator.getState() + " 1");
+            careTaker.add(originator.saveStateToMemento());
+            System.out.println(result.getUndoStatus());
+        }
+        else  {
+            // logic issues with num counter
+            numUndo++;           
+            System.out.println(careTaker.mementoList.size());
+            System.out.println(originator.getState() + " 2");
+
+            /*
+             originator.getStateFromMemento(careTaker.get(0));
+             addressBook = new AddressBook(new UniquePersonList( originator.getState().getAllPersons()),        
+                                           new UniqueTagList(originator.getState().getAllTags()));// works for delete, To convert to command
+             */
+
+            //AddressBook(UniquePersonList persons, UniqueTagList tags)
+        }
+
+
         return result;
     }
 
@@ -96,4 +156,8 @@ private void recordResult(CommandResult result) {
             lastShownList = personList.get();
         }
     }
+
+    private boolean isUndo(Command command) {
+        return (command.getClass().equals( new UndoCommand(null).getClass()) ? true : false);
+    }
 }

src/seedu/addressbook/parser/Parser.java

@@ -2,7 +2,6 @@
 
 import seedu.addressbook.commands.*;
 import seedu.addressbook.data.exception.IllegalValueException;
-
 import java.util.*;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -93,6 +92,9 @@ public Command parseCommand(String userInput) {
 
             case ExitCommand.COMMAND_WORD:
                 return new ExitCommand();
+
+            case UndoCommand.COMMAND_WORD:
+                return new UndoCommand(null);
 
             case HelpCommand.COMMAND_WORD: // Fallthrough
             default:
@@ -276,5 +278,4 @@ private Command prepareFind(String args) {
         return new FindCommand(keywordSet);
     }
 
-
 }

src/seedu/addressbook/revision_control/CareTaker.java

@@ -0,0 +1,20 @@
+package seedu.addressbook.revision_control;
+
+import java.util.ArrayList;
+
+public class CareTaker {
+
+    public ArrayList<Memento> mementoList;
+
+    public CareTaker() {
+        mementoList = new ArrayList<Memento>();
+    }
+
+    public void add(Memento state) {
+        mementoList.add(state);
+    }
+
+    public Memento get(int index) {
+        return mementoList.get(index);
+    }
+}

src/seedu/addressbook/revision_control/Memento.java

@@ -0,0 +1,18 @@
+package seedu.addressbook.revision_control;
+
+import seedu.addressbook.data.AddressBook;
+
+public class Memento {
+
+    private AddressBook state;
+
+
+    public Memento(AddressBook state) {
+        this.state = state;
+    }
+
+    public AddressBook getState() {
+        return state;
+    }
+
+}

src/seedu/addressbook/revision_control/Originator.java

@@ -0,0 +1,25 @@
+package seedu.addressbook.revision_control;
+
+import seedu.addressbook.data.AddressBook;
+
+public class Originator {
+
+    private AddressBook state;
+
+    public void setState(AddressBook state) {
+        this.state = state;
+    }
+
+    public AddressBook getState() {
+        return state;
+    }
+
+    public Memento saveStateToMemento() {
+        return new Memento(state);
+    }
+
+    public void getStateFromMemento(Memento Memento) {
+        state = Memento.getState();
+    }
+
+}