window.onload = function() {
    var oUi = new GameUi();
    var oCtrl = new GameCtrl(oUi);
    oUi.setCtrl(oCtrl);
    oCtrl.startGame();
}

/*----------------------------------------*/

/*my little tool*/
var Tool = {
    getE: function(/*string*/sName) {
        var sType = sName[0];
        sName = sName.split(sType)[1];
        switch(sType) {
            case '#':
                return document.getElementById(sName);
            case '.':
                var aResult = new Array();
                var aObj = document.getElementsByTagName('*');
                for(var i = aObj.length - 1; i >= 0; i--) {
                    if(aObj[i].className && aObj[i].className.indexOf(sName) != -1) {
                        aResult.push(aObj[i]);
                    }
                }
                return aResult;
            default:
                return document.getElementsByTagName(sName);
        }
    }
};

/*---------------------------------------*/
function GameUi() {
    var oCtrl,
        aBlocks,
        sPlayerStyle,
        sAiStyle;

    var init = function() {
            aBlocks = Tool.getE('.block');
        },
        startGame = function() {
            clean();
            startScreen();
        },
        startScreen = function() {
            var oScreen = Tool.getE('#start_screen');
                selectO = Tool.getE('#selectO'),
                selectX = Tool.getE('#selectX');
            oScreen.style['display'] = 'block';
            selectX.onmouseover = function() {
                selectO.className = '';
                this.className = 'current';
            }
            selectO.onmouseover = function() {
                selectX.className = '';
                this.className = 'current';
            }
            selectX.onclick = function() {
                sPlayerStyle = 'x';
                sAiStyle = 'o';
                oScreen.style['display'] = 'none';
                setupListener();
            }
            selectO.onclick = function() {
                sPlayerStyle = 'o';
                sAiStyle = 'x';
                oScreen.style['display'] = 'none';
                oCtrl.nextStep();
                setupListener();
            }
        },
        setupListener = function() {
            for (var i = aBlocks.length - 1; i >= 0; i--) {
                (function(index) {
                    aBlocks[index].onclick = function() {
                        if (aBlocks[index].innerHTML != '') return;
                        draw('player', index);
                        oCtrl.setChessboard(index, -1);
                        oCtrl.nextStep();
                    }
                })(i);
            }
        },
        endGame = function() {
            endScreen();
        },
        endScreen = function() {
            var oScreen = Tool.getE('#end_screen');
            var oEndInfo = Tool.getE('#end_info');
            switch(oCtrl.getWinner()) {
                case 'ai':
                    oEndInfo.innerHTML = 'LOST';
                    break;
                case 'player':
                    oEndInfo.innerHTML = 'WIN';
                    break;
                case 'no':
                    oEndInfo.innerHTML = 'ITE';
                    break;
            }
            oScreen.style['display'] = 'block';
            var btnRestart = Tool.getE('#btn_restart');
            btnRestart.onclick = function() {
                oScreen.style['display'] = 'none';
                oCtrl.startGame();
            }
        },
        draw = function(/*string*/role, /*num*/index) {
            var obj = aBlocks[index];
            switch (role) {
                case 'ai':
                    obj.innerHTML = '<div class="' + sAiStyle +'"></div>';
                    break;
                case 'player':
                    obj.innerHTML = '<div class="' + sPlayerStyle +'"></div>';
                    break;
                default:
                    break;
            }
        },
        clean = function() {
            for (var i = aBlocks.length - 1; i >= 0; i--) {
                aBlocks[i].innerHTML = '';
            }
        };
    init();

    return {
        setCtrl: function(_oCtrl) {
            oCtrl = _oCtrl;
        },
        startGame: function() {
            startGame();
        },
        endGame: function() {
            endGame();
        },
        draw: function(/*string*/role, /*obj*/obj) {
            draw(/*string*/role, /*obj*/obj);
        }
    }
}

/*-----------------------------------*/

function GameCtrl(/*obj*/_oUi) {
    var oUi,
        winner,
        aChessboard,
        aWinCondition;

    var init = function() {
            oUi = _oUi;
            aChessboard = [0,0,0,0,0,0,0,0,0],
            aWinCondition = [[0,1,2],[3,4,5],[6,7,8],[0,3,6],[1,4,7],[2,5,8],[0,4,8],[2,4,6]];
        },
        checkOver = function() {
            for (var i = aWinCondition.length - 1; i >= 0; i--) {
                if (aChessboard[aWinCondition[i][0]] + aChessboard[aWinCondition[i][1]] + aChessboard[aWinCondition[i][2]] == 3) {
                    winner = 'ai';
                    oUi.endGame();
                    return true;
                }
                if (aChessboard[aWinCondition[i][0]] + aChessboard[aWinCondition[i][1]] + aChessboard[aWinCondition[i][2]] == -3) {
                    winner = 'player';
                    oUi.endGame();
                    return true;
                }
            }
            var count = 0;
            for (var i = aWinCondition.length - 1; i >= 0; i--) {
                if (aChessboard[i] != 0) count++;
            }
            if (count == 8) {
                winner = 'no';
                oUi.endGame();
                return true;
            }
            return false;
        },
        nextStep = function() {
            if (!checkOver()) {
                var nMax = null, nMaxSub, aChessboards = new Array();
                for (var i = 8; i >= 0; i--) {

                    for (var i2 = 8; i2 >= 0; i2--) {
                        if (aChessboard[i2] != 0) continue;
                        aChessboard[i2] = 1;
                        for (var k = aWinCondition.length - 1; k >= 0; k--) {
                            if (aChessboard[aWinCondition[k][0]] + aChessboard[aWinCondition[k][1]] +
                                aChessboard[aWinCondition[k][2]] == 3) {
                                //aChessboard[i] = 1;//change chessboard
                                console.log(i2)
                                oUi.draw('ai', i2);
                                checkOver();
                                return;
                            }
                        }
                        aChessboard[i2] = 0;
                    }

                    if (aChessboard[i] != 0) continue;
                    aChessboard[i] = 1;
                    /*if(checkSame(aChessboards, aChessboard)) {
                        break;
                    } else {
                        aChessboards.push(aChessboard);
                    }*/

                    var aTempCb = aChessboard.concat();
                    var nMin = null;
                    var aTempCbs = new Array();
                    for (var j = 8; j >= 0; j--) {
                        if (aTempCb[j] != 0) continue;
                        aTempCb[j] = -1;//guess
                        for (var k = aWinCondition.length - 1; k >= 0; k--) {
                            if (aTempCb[aWinCondition[k][0]] + aTempCb[aWinCondition[k][1]] +
                                aTempCb[aWinCondition[k][2]] == -3) {
                                aChessboard[j] = 1;//change chessboard
                                aChessboard[i] = 0;
                                oUi.draw('ai', j);
                                checkOver();
                                return;
                            }
                        }
                        /*if(checkSame(aTempCbs, aTempCb)) {
                            break;
                        } else {
                            aTempCbs.push(aTempCb);
                        }*/

                        var nMax2 = 0, nMin2 = 0,
                            aTempCbMax = aTempCb.concat(),
                            aTempCbMin = aTempCb.concat();
                        for (var l = 8; l >= 0; l--) {
                            if (aTempCbMax[l] == 0) {
                                aTempCbMax[l] = 1;
                            }
                            if (aTempCbMin[l] == 0) {
                                aTempCbMin[l] = -1;
                            }
                        }
                        for (var m = aWinCondition.length - 1; m >= 0; m--) {
                            if (aTempCbMax[aWinCondition[m][0]] + aTempCbMax[aWinCondition[m][1]] + aTempCbMax[aWinCondition[m][2]] == 3)
                                nMax2++;
                            if (aTempCbMin[aWinCondition[m][0]] + aTempCbMin[aWinCondition[m][1]] + aTempCbMin[aWinCondition[m][2]] == -3) {
                                nMin2++;
                            }
                        }
                        var nDiff = nMax2 - nMin2;

                        if (nMin == null) {
                            nMin = nDiff;
                        } else {
                            nMin = nMin > nDiff ? nDiff : nMin;
                        }
                        aTempCb[j] = 0;
                    }

                    if (nMax == null) {
                        nMax = nMin;
                        nMaxSub = i;
                    } else {
                        if (nMax < nMin) {
                            nMax = nMin;
                            nMaxSub = i;
                        }
                    }
                    aChessboard[i] = 0;
                }
                aChessboard[nMaxSub] = 1;
                oUi.draw('ai', nMaxSub);
                checkOver();
            } else {

            }
        }
    init();

    return {
        startGame: function() {
            aChessboard = [0,0,0,0,0,0,0,0,0];
            oUi.startGame();
        },
        nextStep: function(/*num*/nPlayerStep) {
            nextStep();
        },
        setChessboard: function(/*num*/index, /*num*/val) {
            aChessboard[index] = val;
        },
        getWinner: function() {
            return winner;
        }
    }
}