/*

 File: iSudoku.js 

 Abstract: JavaScript for the index.html file

           Demonstrates use of Puzzle2x2 object that implements a 2x2 Sudoku game.

 Version: <1.0>

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 */

document.puzzle = null;

function Puzzle2x2() {

    this.badSquares = new Object();

    this.board = new Object();

    this.mask = new Object();

    this.solved = false;

    this.width = 2;

    this.height = 2;

    this.maximumValue = this.width * this.height;

    // Load board

    for (var i = 0; i < this.maximumValue; i++) {

        for (var j = 0; j < this.maximumValue; j++) {

            this.board[i+","+j] = arguments[i * this.maximumValue + j];

        }

    }

    // Load mask

    for (var i = this.maximumValue; i < arguments.length; i++) {

        this.mask[arguments[i]] = 1;

    }

}

/* Utility function for going from a tuple (2,2, e.g.) to the DOM ID */

Puzzle2x2.prototype.tupleToID = function(tuple) {

    var id = "cell" + parseInt(tuple.substring(0, tuple.indexOf(','))) + ":";

    id += parseInt(tuple.substring(tuple.indexOf(',') + 1));

    return id;

}

/* Utility function for going from a DOM ID ("cell2:2", e.g.) to a tuple */

Puzzle2x2.prototype.IDToTuple = function(id) {

    var tuple = parseInt(id.substring(4, id.indexOf(":"))) + ",";

    tuple += parseInt(id.substring(id.indexOf(":") + 1));

    return tuple;

}

/* Set up digits on the board */

Puzzle2x2.prototype.setup = function() {

   for (var i = 0; i < this.maximumValue; i++) {

        for (var j = 0; j < this.maximumValue; j++) {

            var tuple = i + "," + j;

            var element = document.getElementById(this.tupleToID(tuple));

            if (this.mask[tuple]) { 

                element.style.backgroundColor = '#dddddd';

                element.textContent = this.board[tuple];

                element.onclick = null;

            }

            else {

                element.style.backgroundColor = 'white';

                element.textContent = ' ';

                element.onclick = function() { document.puzzle.choose(this.id); };

            }

        }

    }

}

/* Displays the the content of the file associated with chooser-iframe

chooser-iframe loads iSudokuChooser.html by default */

Puzzle2x2.prototype.choose = function(id) {

    var chooser = document.getElementById('chooser-iframe');

    chooser.style.position = 'absolute';

    chooser.style.zIndex = '1';

    chooser.style.display = 'block';

    chooser.contentDocument.id = id;

}

/*Set chooser-iframe to display iSudokuSuccess.html   */

Puzzle2x2.prototype.success = function(){

    var chooser = document.getElementById('chooser-iframe');

    var lastId=chooser.contentDocument.id;

    chooser.setAttribute("src", "iSudokuSuccess.html");

    this.choose(lastId);

}

/* Displays a congratulation message if the player successfully filled out the board*/

Puzzle2x2.prototype.gameOver = function() {

    for (var i = 0; i < this.maximumValue; i++) {

        for (var j = 0; j < this.maximumValue; j++) {

            var id = this.tupleToID(i + "," + j);

            document.getElementById(id).onclick = null;

        }

    }

    this.success();

}

/*  Returns true if a player succesfully filled out the board */

Puzzle2x2.prototype.isSolved = function() {

    return this.solved;

}

/* Sets a value at a given cell of the board */  

Puzzle2x2.prototype.setValue = function(position, value) {

    document.getElementById(position).textContent = value;

    if (value) {

        var oldBadSquares = this.badSquares;

        this.badSquares = new Object();

        // Revalidate the whole board

        this.validate("0,0"); 

        this.validate("1,2"); 

        this.validate("2,1"); 

        this.validate("3,3");

        // Iterate through the previous bad squares and reset them to

        // to a normal background if they aren't in the new listing of

        // bad squares. 

        for (var tuple in oldBadSquares) {

            if (! this.badSquares[tuple]) {

                var elementID = this.tupleToID(tuple);

                document.getElementById(elementID).style.backgroundColor = 'white';

            }

        }

        // Iterate through our new bad squares and make sure that we 

        // mark any squares not previously in our bad squares as red.

        // We also adjust our bad square count for use later.

        var countBadSquares = 0;

        for (var tuple in this.badSquares) {

            countBadSquares++;

            if (! oldBadSquares[tuple]) {

                var elementID = this.tupleToID(tuple);

                document.getElementById(elementID).style.backgroundColor = 'red';

            }

        }

        // If we have no bad squares then we check to ensure that every 

        // square is filled.  If it is, then they game is done.  If not,

        // the game continues!

        if (countBadSquares == 0) {

            var isDone = true;

            for (var i = 0; i < this.maximumValue; i++) {

                for (var j = 0; j < this.maximumValue; j++) {

                    var tuple = i + "," + j;

                    if (this.board[tuple] != document.getElementById(this.tupleToID(tuple)).textContent) {

                        isDone = false;

                    }

                }

            }

            if (isDone) {

                this.solved = true;

                this.gameOver();

            }

        }

    }

}

/* Check each row and column for duplicated values */

Puzzle2x2.prototype.validate = function(tuple) {

    var box = parseInt(tuple.substring(0, tuple.indexOf(',')));

    var square = parseInt(tuple.substring(tuple.indexOf(',') + 1));

    // Validate square

    this.validateTuple(box + ",0", box + ",1", box + ",2", box + ",3");

    // Validate row;

    var rowBox = (box % 2 == 0) ? (box + 1) : (box - 1);

    var rowSquare = (square % 2 == 0) ? (square + 1) : (square - 1);

    this.validateTuple(box + "," + square, box + "," + rowSquare, rowBox + "," + square, rowBox + "," + rowSquare);

    // Validate column

    var colBox = (box % 2 == 0) ? (box + 2) % 4 : (box + 2) % 4;

    var colSquare = (square % 2 == 0) ? (square + 2) % 4 : (square + 2) % 4;

    this.validateTuple(box + "," + square, box + "," + colSquare, colBox + "," + square, colBox + "," + colSquare);

}

/* Compare two values  */

Puzzle2x2.prototype.validateTuple = function() {

    var check = new Array();

    for (var i = 0; i < arguments.length; i++) {

        var element = document.getElementById(this.tupleToID(arguments[i]));

        if (element && element.textContent && element.textContent != ' ') {

            var value = element.textContent;

            if (! check[value]) {

                check[value] = new Array();

            }

            check[value][check[value].length] = element;

        }

    }

    for (var i in check) {

        if (check[i].length > 1) {

            for (var j = 0; j < check[i].length; j++) {

                var element = check[i][j];

                var tuple = this.IDToTuple(element.id);

                if (! this.mask[tuple]) {

                    this.badSquares[tuple]++;

                }

            }

        }

    }

}

var games = new Array();

games[0] = "new Puzzle2x2(1,2,4,3,3,4,2,1,3,4,2,1,1,2,4,3,'0,0','1,2','2,1','3,3')";

games[1] = "new Puzzle2x2(2,1,3,4,4,3,1,2,4,3,1,2,2,1,3,4,'0,3','1,1','2,2','3,0')";

games[2] = "new Puzzle2x2(4,3,2,1,2,1,4,3,3,4,1,2,1,2,3,4,'1,1','0,2','2,1','3,2')";

games[3] = "new Puzzle2x2(3,4,1,2,1,2,3,4,4,3,2,1,2,1,4,3,'0,0','1,3','2,3','3,0')";

games[4] = "new Puzzle2x2(2,3,4,1,4,1,2,3,3,2,1,4,1,4,3,2,'0,1','1,2','2,3','3,0')";

var lastGameIndex = -1;

/* Used to create a board  with random numbers for the iSudoku game */

function setupPuzzle() {

    var gameIndex = Math.floor(Math.random() * games.length);

    while (gameIndex == lastGameIndex) {

         gameIndex = Math.floor(Math.random() * games.length);     

    }

    lastGameIndex = gameIndex;

    document.puzzle = eval(games[gameIndex]);

    document.puzzle.setup();

}