From 821bf0c91623355b391ff13088036ec23811e087 Mon Sep 17 00:00:00 2001
From: Vahagn Khachatryan <vahagn.khachatryan@gmail.com>
Date: Tue, 14 May 2013 09:20:24 +0400
Subject: [PATCH] Missig files from the 'Working Version'.

---
 AndroidManifest.xml                           |  17 +-
 compiler/compiler.cpp                         |   8 +-
 res/layout/menu.xml                           |  15 +-
 src/org/dyndns/vahagn/sokoban/App.java        |  91 +++-
 src/org/dyndns/vahagn/sokoban/MainMenu.java   | 135 +++++-
 src/org/dyndns/vahagn/sokoban/Puzzle.java     | 432 +++++++++++++++---
 .../vahagn/sokoban/PuzzleContainer.java       |  14 +-
 7 files changed, 611 insertions(+), 101 deletions(-)

diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index c9716ab..aecd884 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -7,19 +7,24 @@
 			  android:targetSdkVersion="14"/>
     <application android:label="@string/app_name" 
 				 android:name="org.dyndns.vahagn.sokoban.App"
-				 android:theme="@android:style/Theme.Light">
-        <activity android:name="org.dyndns.vahagn.sokoban.SokobanMenu"
-                  android:label="@string/app_name">
+				 android:icon="@drawable/icon"
+				 android:theme="@android:style/Theme">
+        <activity	android:name="org.dyndns.vahagn.sokoban.MainMenu"
+					android:label="@string/app_name"
+					android:configChanges="keyboardHidden|orientation"
+					android:screenOrientation="portrait" >
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
-        <activity 	android:name="org.dyndns.vahagn.sokoban.PlayActivity"
-					android:label="@string/play_activity">
+        <activity 	android:name="org.dyndns.vahagn.sokoban.play.PlayActivity"
+					android:label="@string/play_activity"
+					android:configChanges="keyboardHidden|orientation"
+					android:screenOrientation="portrait" >
 	        <meta-data
 	            android:name="android.support.PARENT_ACTIVITY"
-	            android:value="org.dyndns.vahagn.sokoban.SokobanMenu" />
+	            android:value="org.dyndns.vahagn.sokoban.MainMenu" />
         </activity>
     </application>
 </manifest> 
diff --git a/compiler/compiler.cpp b/compiler/compiler.cpp
index ad4b882..f857519 100644
--- a/compiler/compiler.cpp
+++ b/compiler/compiler.cpp
@@ -21,8 +21,8 @@ protected:
 		empty = 0,
 		wall,
 		box,
-		hole,
-		box_in_hole,
+		goal,
+		box_in_goal,
 		worker
 	};
 
@@ -69,10 +69,10 @@ public:
 					*it++ = box;
 					break;
 				case '.':
-					*it++ = hole;
+					*it++ = goal;
 					break;
 				case '*':
-					*it++ = box_in_hole;
+					*it++ = box_in_goal;
 					break;
 				case '@':
 					*it++ = worker;
diff --git a/res/layout/menu.xml b/res/layout/menu.xml
index 59fc39a..842b72d 100644
--- a/res/layout/menu.xml
+++ b/res/layout/menu.xml
@@ -2,10 +2,18 @@
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical"
     android:layout_width="fill_parent"
-    android:layout_height="fill_parent"
-	android:background="@drawable/splash"
-    >
+    android:layout_height="fill_parent">
 
+<GridView
+    android:id="@+id/puzzle_grid"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+	android:horizontalSpacing="2mm"
+	android:verticalSpacing="2mm"
+	android:columnWidth="10mm"
+	android:numColumns="auto_fit"
+    android:stretchMode="columnWidth"
+    android:gravity="center" />
 
 <Button
     android:id="@+id/btn_start"
@@ -14,5 +22,6 @@
     android:onClick="onStartCurrentPuzzle"
     android:text="Start" />
 
+
 </LinearLayout>
 
diff --git a/src/org/dyndns/vahagn/sokoban/App.java b/src/org/dyndns/vahagn/sokoban/App.java
index 83ab2ef..8963272 100644
--- a/src/org/dyndns/vahagn/sokoban/App.java
+++ b/src/org/dyndns/vahagn/sokoban/App.java
@@ -1,12 +1,24 @@
 package org.dyndns.vahagn.sokoban;
 
 import android.app.Application;
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
+import android.util.Log;
 
-public class App extends Application {
+public class App extends Application
+{	
+	public static final String TAG = "Sokoban";
+	public static final String PREFS = "org.dyndns.vahagn.sokoban.prefs";
+	static final int MIN_LEVEL = 1;
 	
 	private static App mApp = null;
 	protected PuzzleContainer pc;
-	public int level;
+	protected int current_level;
+	protected int achieved_level;
+	protected int max_level;
+	protected SharedPreferences prefs;
+	protected SharedPreferences.Editor prefsEdit;
 	
 	/* 
 	 * 
@@ -17,21 +29,82 @@ public class App extends Application {
 	    super.onCreate();
 	    mApp = this;
 	    pc = new PuzzleContainer();
-	    level = 0;
+		prefs = getSharedPreferences(PREFS, MODE_PRIVATE);
+		prefsEdit = prefs.edit();
+	    max_level = pc.getCount();
+		current_level = prefs.getInt("current_level", MIN_LEVEL);
+		achieved_level = prefs.getInt("achieved_level", MIN_LEVEL);
 	}
-	
+	//
+	//	This is a singleton object.
+	//
 	public static App theApp()
 	{
 	    return mApp;
 	}
-
-	public PuzzleContainer getPuzzleContainer()
+	//
+	//	Puzzles.
+	//
+	public Puzzle getPuzzle( int level )
 	{
-		return pc;
+		return pc.getPuzzle( level-1 );
 	}
-	
 	public Puzzle getCurrentPuzzle()
 	{
-		return getPuzzleContainer().getPuzzle( level );
+		return getPuzzle( getCurrentLevel() );
 	}
+	//
+	//	Provide amount of puzzles.
+	//
+	public final int getPuzzleCount()
+	{
+		return max_level;
+	}
+	//
+	//	Provide highest solved puzzle.
+	//
+	public final int getAchivedLevel()
+	{
+		return achieved_level;
+	}
+	//
+	//	Provide last played puzzle.
+	//
+	public final int getCurrentLevel()
+	{
+		return current_level;
+	}
+	//
+	//	Set the current puzzle level. It deons't alter 
+	//
+	public void setCurrentLevel( int l )
+	{
+		if ( current_level != l )
+		{
+			current_level = l;
+			prefsEdit.putInt("current_level", current_level);
+			prefsEdit.apply();
+			if ( !prefs.edit().commit() )
+				Log.d(TAG, "prefs.edit().commit() failed.");
+		}
+	}
+	//
+	//	Advances current level. It also reviews achived level if the
+	//	new level is bigger than achieved level.
+	//
+	public void advanceCurrentLevel()
+	{
+		int new_level = current_level+1;
+		if ( new_level == max_level )
+			new_level = MIN_LEVEL;
+		if ( new_level > achieved_level )
+		{
+			achieved_level = new_level;
+			prefsEdit.putInt("achieved_level", achieved_level);
+			//	Don't call apply() here since the call below 
+			//	to setCurrentLevel() will do that.
+		}
+		setCurrentLevel(new_level);
+	}
+
 }
diff --git a/src/org/dyndns/vahagn/sokoban/MainMenu.java b/src/org/dyndns/vahagn/sokoban/MainMenu.java
index b2b3a0d..e6039d7 100644
--- a/src/org/dyndns/vahagn/sokoban/MainMenu.java
+++ b/src/org/dyndns/vahagn/sokoban/MainMenu.java
@@ -1,33 +1,135 @@
 package org.dyndns.vahagn.sokoban;
 
+import org.dyndns.vahagn.sokoban.play.PlayActivity;
 import android.app.Activity;
+import android.content.Context;
 import android.content.Intent;
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.graphics.Rect;
 import android.view.View;
 import android.os.Bundle;
 import android.util.Log;
+import android.util.TypedValue;
+import android.view.Display;
+import android.view.ViewGroup;
+import android.view.Window;
+import android.widget.AdapterView;
+import android.widget.AdapterView.OnItemClickListener;
+import android.widget.BaseAdapter;
+import android.widget.GridView;
+import android.widget.ImageView;
 import static org.dyndns.vahagn.sokoban.App.theApp;
 
-public class SokobanMenu extends Activity
+public class MainMenu extends Activity
 {
 	protected final String TAG = "SokobanMenu";
 	protected final String LEVEL= "org.dyndns.vahagn.sokoban.LEVEL";
+	protected GridView puzzle_grid;
     
 	/** Called when the activity is first created. */
     @Override
     public void onCreate(Bundle savedInstanceState)
     {
-    	Log.d(TAG, "onCreate: " + savedInstanceState );
+        requestWindowFeature(Window.FEATURE_NO_TITLE);
     	
         super.onCreate(savedInstanceState);
         setContentView(R.layout.menu);
-        
-        try {
-		} catch (Exception e) {
-			// TODO Auto-generated catch block
-			e.printStackTrace();
-		}
+		
+		puzzle_grid = (GridView)findViewById(R.id.puzzle_grid);
+		puzzle_grid.setAdapter( new PuzzlesAdapter(this) );
+		//puzzle_grid.addView(puzzle_grid);
+		puzzle_grid.setOnItemClickListener(new OnItemClickListener() {
+			public void onItemClick(AdapterView<?> parent, View v, int position, long id)
+			{
+				onPuzzleClicked(v,(int)id);
+			}
+		});
     }
    
+	public class PuzzlesAdapter extends BaseAdapter
+	{
+		private Context mContext;
+		private int icon_size;
+		private int text_x;
+		private int text_y;
+		private Bitmap lock_icon;
+		private Bitmap unlock_icon;
+		private Paint paint;
+
+		public PuzzlesAdapter(Context c)
+		{
+			mContext = c;
+			icon_size = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_MM, 10, getResources().getDisplayMetrics() );
+			int text_size = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_MM, 4, getResources().getDisplayMetrics() );
+			text_x = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_MM, 9, getResources().getDisplayMetrics() );
+			text_y = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_MM, 9, getResources().getDisplayMetrics() );
+			
+			Bitmap lock_icon_tmp = BitmapFactory.decodeResource( getResources(), R.drawable.lock );
+			lock_icon = Bitmap.createBitmap(icon_size,icon_size,Bitmap.Config.ARGB_8888);
+			Canvas lock_canvas = new Canvas(lock_icon);
+			lock_canvas.drawBitmap(lock_icon_tmp, 
+				new Rect(0,0,lock_icon_tmp.getWidth()-1,lock_icon_tmp.getHeight()-1), 
+				new Rect(0,0,icon_size, icon_size),
+				null);
+		
+			Bitmap unlock_icon_tmp = BitmapFactory.decodeResource( getResources(), R.drawable.unlock );
+			unlock_icon = Bitmap.createBitmap(icon_size,icon_size,Bitmap.Config.ARGB_8888);
+			Canvas unlock_canvas = new Canvas(unlock_icon);
+			unlock_canvas.drawBitmap(unlock_icon_tmp, 
+				new Rect(0,0,unlock_icon_tmp.getWidth()-1,unlock_icon_tmp.getHeight()-1), 
+				new Rect(0,0,icon_size, icon_size),
+				null);
+			
+			paint = new Paint();
+			paint.setColor( Color.WHITE );
+			paint.setTextSize( text_size );
+			paint.setTextAlign(Paint.Align.RIGHT);
+		}
+
+		public int getCount()
+		{
+			return theApp().getPuzzleCount();
+		}
+
+		public Object getItem(int position)
+		{
+			return null;
+		}
+
+		public long getItemId(int position)
+		{
+			return position+1;
+		}
+
+		// create a new ImageView for each item referenced by the Adapter
+		public View getView(int position, View convertView, ViewGroup parent)
+		{
+			ImageView imageView;
+			if (convertView == null)
+			{  // if it's not recycled, initialize some attributes
+				imageView = new ImageView(mContext);
+				imageView.setLayoutParams(new GridView.LayoutParams(icon_size, icon_size));
+				imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
+			//	imageView.setPadding(8, 8, 8, 8);
+			}
+			else
+				imageView = (ImageView) convertView;
+
+			int id = (int)getItemId(position);
+			Bitmap icon = ( id <= theApp().getAchivedLevel() ) 
+					? unlock_icon.copy(Bitmap.Config.ARGB_8888,true)
+					: lock_icon.copy(Bitmap.Config.ARGB_8888,true);
+			Canvas canvas = new Canvas(icon);
+			canvas.drawText( Integer.toString(id), text_x, text_y, paint);
+			imageView.setImageBitmap(icon);
+			return imageView;
+		}
+	}
+	
     @Override
     public void onStart()
     {
@@ -83,11 +185,20 @@ public class SokobanMenu extends Activity
        // setContentView(R.layout-l.menu);
     }
     
-    public void onStartCurrentPuzzle( View v)
+    public void onStartCurrentPuzzle(View v)
     {
-    	Intent intent = new Intent(this, PlayActivity.class);
-		
+    	Intent intent = new Intent(this, PlayActivity.class);		
     	startActivity( intent );
-    	Log.d(TAG, "onStartCurrentPuzzle: " );
+    }
+
+	public void onPuzzleClicked(View v, int level )
+    {
+		if ( level <= theApp().getAchivedLevel() )
+		{
+			theApp().setCurrentLevel(level);
+
+			Intent intent = new Intent(this, PlayActivity.class);
+			startActivity( intent );
+		}
     }
 }
diff --git a/src/org/dyndns/vahagn/sokoban/Puzzle.java b/src/org/dyndns/vahagn/sokoban/Puzzle.java
index c079397..e41252d 100644
--- a/src/org/dyndns/vahagn/sokoban/Puzzle.java
+++ b/src/org/dyndns/vahagn/sokoban/Puzzle.java
@@ -2,73 +2,51 @@ package org.dyndns.vahagn.sokoban;
 
 //import java.lang.Exception;
 import java.io.*;
+import static java.lang.Math.*;
 import android.util.Log;
+import android.graphics.Point;
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.List;
+import static org.dyndns.vahagn.sokoban.App.TAG;
 
 public class Puzzle
 {
-	public enum symbole
-	{
-		FLOOR,
-		WALL,
-		BOX,
-		HOLE,
-		BOX_IN_HOLE,
-		WORKER;
-		
-		public static int MAX_COUNT()
-		{
-			return 6;
-		}
-	};
+	public final static int FLOOR = 0x0;
+	public final static int GOAL = 0x1;
+	public final static int FLOOR_MASK = ~(GOAL | FLOOR);
+	public final static int WALL = 0x2;
+	public final static int BOX = 0x4;
+	public final static int BINGO = BOX | GOAL;
+	public final static int WORKER = 0x8;
+	public final static int WORKER_NORTH = 0x00 | WORKER;
+	public final static int WORKER_SOUTH = 0x10 | WORKER;
+	public final static int WORKER_WEST = 0x20 | WORKER;
+	public final static int WORKER_EAST = 0x30 | WORKER;
+	public final static int WORKER_MASK = WORKER_EAST | WORKER_WEST | WORKER_SOUTH | WORKER_NORTH;
+	public final static int SELECTED = 0x40;
+	public final static int MAX_COUNT = 0x80-1;
 
-	protected static final String TAG = "Puzzle";
 	protected int columns;
 	protected int rows;
-	protected symbole [] board;
+	protected int box_count;
+
+	protected int [] board;
+	protected int worker_x;
+	protected int worker_y;
+	protected int selected_x;
+	protected int selected_y;
+	protected int bingos;
 
 	public Puzzle( InputStream is )
 	{
 		load( is );
 	}
 	
-	private void load( InputStream is )
-	{try{
-		columns = is.read();
-		rows = is.read();
-		byte [] b = new byte [columns*rows];
-		board = new symbole[columns*rows];
-		is.read( b, 0, columns*rows);
-		for( int i = 0; i < b.length; ++i )
-		{
-			switch( b[i] )
-			{
-				case 0:
-					board[i] = symbole.FLOOR;
-					break;
-				case 1:
-					board[i] = symbole.WALL;
-					break;
-				case 2:
-					board[i] = symbole.BOX;
-					break;
-				case 3:
-					board[i] = symbole.HOLE;
-					break;
-				case 4:
-					board[i] = symbole.BOX_IN_HOLE;
-					break;
-				case 5:
-					board[i] = symbole.WORKER;
-					break;
-				default:
-			}
-		}
-	}
-	catch ( Exception e )
-	{
-		Log.d( TAG, "load()", e);
-	}}
-	
+	//////////////////////////////////////////////////////////////////////////
+	//
+	//	Low level helper functions.
+	//
 	
 	public final int getColumnCount()
 	{
@@ -80,15 +58,347 @@ public class Puzzle
 	}
 	public static int getSymCount()
 	{
-		return symbole.MAX_COUNT();
+		return MAX_COUNT;
 	}
 	
-	/*
-	 *  r- row
-	 *  c- column
-	 */
-	public final symbole getSym( int r, int c )
+	public final int getIndex( int x, int y )
 	{
-		return board[r*columns+c];
+		return y*columns+x;
+	}
+	public final int getX( int idx )
+	{
+		return idx % columns;
+	}
+	public final int getY( int idx )
+	{
+		return idx / columns;
+	}
+
+	public final int getSym( int x, int y )
+	{
+		return board[getIndex(x,y)];
+	}
+	public void setSym( int x, int y, int v )
+	{
+		board[getIndex(x,y)]=v;
+	}
+	
+	public static boolean isEmpty( int v )
+	{
+		return (v & FLOOR_MASK) == 0;
+	}
+	public static boolean hasBox( int v )
+	{
+		return (v & BOX) != 0;
+	}
+	public static boolean hasWorker( int v )
+	{
+		return (v & WORKER) != 0;
+	}
+
+	public final int getWorkerX()
+	{
+		return worker_x;
+	}
+
+	public final int getWorkerY()
+	{
+		return worker_y;
+	}
+
+	public final boolean isSelected()
+	{
+		return selected_x != -1;
+	}
+	
+	public final boolean isSelected( int x, int y )
+	{
+		return selected_x == x && selected_y == y;
+	}
+
+	public final int getSelectedX()
+	{
+		return selected_x;
+	}
+
+	public final int getSelectedY()
+	{
+		return selected_y;
+	}
+
+	public final boolean isValid( int x, int y )
+	{
+		return ( 0 <= x && 0 <= y
+			&& x < getColumnCount()
+			&& y < getRowCount() );
+	}
+
+	public final boolean isOneStep( int x, int y )
+	{
+		return isValid(x,y) 
+				&& (abs(worker_x-x )+abs(worker_y-y) == 1);
+	}
+
+	public final boolean isDone()
+	{
+		return bingos == box_count;
+	}
+
+	//////////////////////////////////////////////////////////////////////////
+	//
+	//	Loading.
+	//
+	private void load( InputStream is )
+	{try{
+		columns = is.read();
+		rows = is.read();
+		box_count = 0;
+		bingos = 0;
+		selected_x = -1;
+		selected_y = -1;
+		board = new int[columns*rows];
+		byte [] b = new byte [columns*rows];
+		is.read( b, 0, columns*rows);
+		for( int i = 0; i < b.length; ++i )
+		{
+			switch( b[i] )
+			{
+				case 0:
+					board[i] = FLOOR;
+					break;
+				case 1:
+					board[i] = WALL;
+					break;
+				case 2:
+					board[i] = BOX;
+					++box_count;
+					break;
+				case 3:
+					board[i] = GOAL;
+					break;
+				case 4:
+					board[i] = BINGO;
+					++box_count;
+					++bingos;
+					break;
+				case 5:
+					board[i] = WORKER;
+					worker_x = getX(i);
+					worker_y = getY(i);
+					break;
+				default:
+			}
+		}
+	}
+	catch ( Exception e )
+	{
+		Log.d( TAG, "load()", e);
+	}}
+
+	//////////////////////////////////////////////////////////////////////////
+	//
+	//	Move worker.
+	//
+	
+	public boolean walk( int x, int y)
+	{
+		//
+		//	Check that this is one step away.
+		//
+		if ( !isOneStep(x,y) )
+			return false;
+		//
+		//	Check that this is empty space.
+		//
+		int v = getSym(x,y);
+		if ( !isEmpty(v) )
+			return false;
+		//
+		//	If something is selected then unselect first.
+		//
+		if ( isSelected() )
+			unselect();
+		//
+		//	Find direction to move.
+		//
+		int worker;
+		if ( worker_x < x )
+			worker = WORKER_WEST;
+		else if ( worker_x > x )
+			worker = WORKER_EAST;
+		else if ( worker_y > y )
+			worker = WORKER_SOUTH;
+		else
+			worker = WORKER_NORTH;
+		//
+		//	Move worker marker from current position to asked position.
+		//
+		setSym(worker_x,worker_y,getSym(worker_x,worker_y)&~WORKER_MASK);
+		worker_x =x;
+		worker_y =y;
+		setSym(worker_x,worker_y,getSym(worker_x,worker_y)|worker);
+		return true;
+	}
+
+	public boolean select( int x, int y)
+	{
+		//
+		//	Check that this is one step away.
+		//
+		if ( !isOneStep(x,y) )
+			return false;
+		//
+		//	Check that this is empty space.
+		//
+		int v = getSym(x,y);
+		if ( !hasBox(v) )
+			return false;
+		//
+		//	If something is selected then unselect first.
+		//
+		if ( isSelected() )
+			unselect();
+		//
+		//	Find direction to move.
+		//
+		int worker;
+		if ( worker_x < x )
+			worker = WORKER_WEST;
+		else if ( worker_x > x )
+			worker = WORKER_EAST;
+		else if ( worker_y > y )
+			worker = WORKER_SOUTH;
+		else
+			worker = WORKER_NORTH;
+		//
+		//	Move worker marker from current position to asked position.
+		//
+		selected_x =x;
+		selected_y =y;
+		setSym(worker_x,worker_y,getSym(worker_x,worker_y)&~WORKER_MASK|worker|SELECTED);
+		setSym(selected_x,selected_y,getSym(selected_x,selected_y)|SELECTED);
+		return true;
+	}
+
+	public boolean unselect()
+	{
+		//
+		//	If not selected then do nothing.
+		//
+		if ( !isSelected() )
+			return false;
+		//
+		//	Move worker marker from current position to asked position.
+		//
+		setSym(worker_x,worker_y,getSym(worker_x,worker_y)&~SELECTED);
+		setSym(selected_x,selected_y,getSym(selected_x,selected_y)&~SELECTED);
+		selected_x =-1;
+		selected_y =-1;
+		return true;
+	}
+
+	public boolean push(int x, int y)
+	{
+		//
+		//	If not selected then do nothing.
+		//
+		if ( !isSelected() )
+			return false;
+		//
+		//	Check that we go to the selected direction.
+		//
+		if ( selected_x != x && selected_y != y )
+			return false;
+		//
+		//	Check that this is a box that we move.
+		//
+		int v = getSym(x,y);
+		if ( !hasBox(v) )
+			return false;
+		//
+		//	Check that the next space to the box is empty.
+		//w - 2*(w-x) = 2x -w
+		int next_x = 2*x - worker_x;
+		int next_y = 2*y - worker_y;
+		int next_v = getSym(next_x,next_y);
+		if ( !isEmpty(next_v) )
+			return false;
+		//
+		//	Ok, looks we can move the box. Do it actually.
+		//
+		unselect();
+		setSym(x,y,getSym(x,y)&~BOX);
+		setSym(next_x,next_y,getSym(next_x,next_y)|BOX);
+		walk(x,y);
+		select(next_x,next_y);
+		//
+		//	Keep track of box count in place.
+		//
+		if ( (v & GOAL) != 0 )
+			--bingos;
+		if ( (next_v & GOAL) != 0 )
+			++bingos;
+		return true;
+	}
+
+	//////////////////////////////////////////////////////////////////////////
+	//
+	//	Undo/Redo.
+	//
+	
+	protected class State
+	{
+		public int [] board;
+		public int worker_x;
+		public int worker_y;
+		public int selected_x;
+		public int selected_y;
+		public int bingos;
+		
+		public State(Puzzle puzzle)
+		{
+			board = puzzle.board.clone();
+			worker_x = puzzle.worker_x;
+			worker_y = puzzle.worker_y;
+			selected_x = puzzle.selected_x;
+			selected_y = puzzle.selected_y;
+			bingos = puzzle.bingos;
+		}
+		
+		public void restore(Puzzle puzzle)
+		{
+			puzzle.board = board;
+			puzzle.worker_x = worker_x;
+			puzzle.worker_y = worker_y;
+			puzzle.selected_x = selected_x;
+			puzzle.selected_y = selected_y;
+			puzzle.bingos = bingos;
+		}
+	}
+	protected LinkedList<State> undoStack = new LinkedList<State>();
+	
+	//
+	//	Save this state to be able to restore later.
+	//
+	public void save()
+	{
+		State s = new State(this);
+		undoStack.addFirst(s);
+	}
+	//
+	//	Restore state.
+	//
+	public void restore()
+	{
+		State s = undoStack.removeFirst();
+		if ( s != null )
+			s.restore(this);
+	}
+	//
+	//	Check if there are items in the undo stack.
+	//
+	public final boolean isUndoable()
+	{
+		return undoStack.size() != 0; 
 	}
 }
diff --git a/src/org/dyndns/vahagn/sokoban/PuzzleContainer.java b/src/org/dyndns/vahagn/sokoban/PuzzleContainer.java
index ce5d53f..a9cb00e 100644
--- a/src/org/dyndns/vahagn/sokoban/PuzzleContainer.java
+++ b/src/org/dyndns/vahagn/sokoban/PuzzleContainer.java
@@ -7,8 +7,6 @@ import android.util.Log;
 
 public class PuzzleContainer
 {
-	protected final String TAG = "PuzzleContainer";
-	
 	protected int count;
 	
 	/*
@@ -41,11 +39,13 @@ public class PuzzleContainer
 	}
 	catch ( java.lang.Exception e )
 	{
-		Log.d(TAG, "Exception: " + e.getMessage() );
+		//Log.d(TAG, "Exception: " + e.getMessage() );
 		e.printStackTrace();
 		return null;
 	}}
-	
+	//
+	//	Retrive amount of puzzles.
+	//
 	public int getCount()
 	{try{
 		if ( count == 0 )
@@ -57,11 +57,13 @@ public class PuzzleContainer
 	}
 	catch ( java.lang.Exception e )
 	{
-		Log.d(TAG, "Exception: " + e.getMessage() );
+		//Log.d(TAG, "Exception: " + e.getMessage() );
 		e.printStackTrace();
 		return 0;
 	}}
-	
+	//
+	//	Helper function to read little endian 32bit integer.
+	//
 	protected int read_i32( InputStream is ) throws IOException
 	{
 		int i = is.read();