"use strict";

/** @fileOverview Game/world rules. */

/** @namespace */

var board = {};

board.create = function() {

    var brd = [];

    for (var i = 0; i < 4; i++) {

        brd[i] = [];

        for (var j = 0; j < 4; j++) {

            brd[i][j] = 0;

        }

    }

    return brd;

}

board.copy = function(from, to) {

    for (var i = 0; i < 4; i++) {

        for (var j = 0; j < 4; j++) {

            to[i][j] = from[i][j];

        }

    }

}

board.freeCnt = function(brd) {

    var cnt = 0;

    for (var i = 0; i < 4; i++) {

        for (var j = 0; j < 4; j++) {

            if (brd[i][j] === 0)

                cnt++;

        }

    }

    return cnt;

}

board.gameOver = function(brd) {

    if (board.freeCnt(brd) > 0)

        return false;

    for (var i = 0; i < 4; i++) {

        for (var j = 0; j < 3; j++) {

            if (brd[i][j] === brd[i][j+1])

                return false;

        }

    }

    for (var j = 0; j < 4; j++) {

        for (var i = 0; i < 3; i++) {

            if (brd[i][j] === brd[i+1][j])

                return false;

        }

    }

    return true;

}

board.putRandom = function(brd) {

    var cnt = board.freeCnt(brd);

    if (cnt === 0)

        throw Error('You forget detect game over!');

    cnt = Math.floor(Math.random() * cnt)+1;

exit:

    for (var i = 0; i < 4; i++) {

        for (var j = 0; j < 4; j++) {

            if (brd[i][j] !== 0)

                continue;

            if (cnt === 1) {

                brd[i][j] = (Math.random() > .9) ? 2 : 1;

                break exit;

            }

            cnt--;

        }

    }

}

/* http://www.reddit.com/r/2048/comments/214njx/highest_possible_score_for_2048_warning_math */

var boardScoreTbl = [0];

for (var i = 1, exp = 2; i < 16; i++, exp *= 2) {

    boardScoreTbl[i] = (i-1)*exp;

}

board.score = function(brd) {

    var score = 0;

    var max = 0;

    for (var i = 0; i < 4; i++) {

        for (var j = 0; j < 4; j++) {

            var val = brd[i][j];

            score += boardScoreTbl[val];

            if (max < val)

                max = val;

        }

    }

    return {score: score, max: max};

}

/** @namespace */

board.row = {};

board.row.init = function() {

    return {stack: [], curr: 0};

}

board.row.push = function(state, val) {

    if (val === 0)

        return;

    if (state.curr === 0) {

        state.curr = val;

        return;

    }

    if (state.curr === val) {

        state.stack.push(state.curr+1);

        state.curr = 0;

    } else {

        state.stack.push(state.curr);

        state.curr = val;

    }

}

board.row.finish = function(state) {

    if (state.curr !== 0)

        state.stack.push(state.curr);

}

/** @namespace */

board.move = {};

board.move.up = board.move.upOrig = function(brd) {

    var updated = false;

    for (var j = 0; j < 4; j++) {

        var state = board.row.init();

        for (var i = 0; i < 4; i++) {

            board.row.push(state, brd[i][j]);

        }

        board.row.finish(state);

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

            if (brd[i][j] !== state.stack[i])

                updated = true;

            brd[i][j] = state.stack[i];

        }

        for (; i < 4; i++) {

            if (brd[i][j] !== 0)

                updated = true;

            brd[i][j] = 0;

        }

    }

    return updated;

};

board.move.down = board.move.downOrig = function(brd) {

    var updated = false;

    for (var j = 0; j < 4; j++) {

        var state = board.row.init();

        for (var i = 3; i >= 0; i--) {

            board.row.push(state, brd[i][j]);

        }

        board.row.finish(state);

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

            if (brd[3-i][j] !== state.stack[i])

                updated = true;

            brd[3-i][j] = state.stack[i];

        }

        for (; i < 4; i++) {

            if (brd[3-i][j] !== 0)

                updated = true;

            brd[3-i][j] = 0;

        }

    }

    return updated;

};

board.move.left = board.move.leftOrig = function(brd) {

    var updated = false;

    for (var i = 0; i < 4; i++) {

        var state = board.row.init();

        for (var j = 0; j < 4; j++) {

            board.row.push(state, brd[i][j]);

        }

        board.row.finish(state);

        for (var j = 0; j < state.stack.length; j++) {

            if (brd[i][j] !== state.stack[j])

                updated = true;

            brd[i][j] = state.stack[j];

        }

        for (; j < 4; j++) {

            if (brd[i][j] !== 0)

                updated = true;

            brd[i][j] = 0;

        }

    }

    return updated;

};

board.move.right = board.move.rightOrig = function(brd) {

    var updated = false;

    for (var i = 0; i < 4; i++) {

        var state = board.row.init();

        for (var j = 3; j >= 0; j--) {

            board.row.push(state, brd[i][j]);

        }

        board.row.finish(state);

        for (var j = 0; j < state.stack.length; j++) {

            if (brd[i][3-j] !== state.stack[j])

                updated = true;

            brd[i][3-j] = state.stack[j];

        }

        for (; j < 4; j++) {

            if (brd[i][3-j] !== 0)

                updated = true;

            brd[i][3-j] = 0;

        }

    }

    return updated;

};

/* Restore after testing board.js moves. */

board.move.restore = function() {

    board.move.up = board.move.upOrig;

    board.move.down = board.move.downOrig;

    board.move.left = board.move.leftOrig;

    board.move.right = board.move.rightOrig;

}

/* For testing board.js moves. */

board.move.replaceMoveByBoardJS = function(brdEngine, dir) {

    return function(brd) {

        var engOrigBrd = new brdEngine(brd);

        var engBrd = new brdEngine();

        var changed = engOrigBrd[dir](engBrd);

        var newBrd = engBrd.exportTo();

        var changed2 = board.move[dir+"Orig"](brd);

        for (var i = 0; i < 4; i++) {

            for (var j = 0; j < 4; j++) {

                if (newBrd[i][j] !== brd[i][j]) {

                    console.log("[%d][%d] original: %o, expected: %o, actual: %o", i, j, engOrigBrd.exportTo(), brd, newBrd);

                    return false;

                }

            }

        }

        if (changed2 !== changed) {

            console.log("original: %o, changed: %o, changed2: %o", engOrigBrd.exportTo(), changed, changed2);

            return false;

        }

        return changed;

    }

}

board.move.replaceByBoardJS = function(brdEngine) {

    // console.log("x2: %o", brdEngine);

    board.move.up = board.move.replaceMoveByBoardJS(brdEngine, "up");

    board.move.down = board.move.replaceMoveByBoardJS(brdEngine, "down");

    board.move.left = board.move.replaceMoveByBoardJS(brdEngine, "left");

    board.move.right = board.move.replaceMoveByBoardJS(brdEngine, "right");

}