function Square(x, y, player) {
    this.player = player;
    this.x = x;
    this.y = y;
};

Square.prototype = {
    getPlayer : function () {
        return this.player;
    },

    setPlayer : function (player) {
        this.player = player;
    },

    getX : function () {
        return this.x;
    },

    getY : function () {
        return this.y;
    }
};

function Line () {
    this.squares = [];
};

Line.prototype = {
    first : function () {
        return this.squares[0];
    },

    last : function () {
        return this.squares[this.squares.length - 1];
    },

    addSquare : function (square) {
        this.squares.push(square);
    },

    winsFor : function () {
        let current = null;
        let last = null;

        for (let i = 0; i < this.squares.length; i++) {
            current = this.squares[i].getPlayer();
            if (i > 0 && current != last) {
                last = null;
                break;
        	}
            else {
                last = current;
            }
        }
        return last;
    },

    clear : function () {
        this.squares = [];
    }
};

function Board(players, sideSize) {
    this._init(players, sideSize);
};

Board.prototype = {

    _init : function(players, sideSize) {
        this.squares = [];
        this.sideSize = sideSize;
        this.winner = null;
        this.playerPos = 0;
        this.players = players;

        for (var i = 0; i < sideSize; i++) {
            this.squares[i] = [];
            for (var j = 0; j < sideSize; j++) {
                this.squares[i][j] = new Square(i, j, null);
            }
        }
    },

    switchPlayer : function() {
        this.playerPos = this.playerPos + 1;
        if (this.playerPos >= this.players.length) {
            this.playerPos = 0;
        }
    },

    getNextPlayer : function() {
        return this.players[this.playerPos];
    },

    makeMove : function(x, y, player) {
        this.squares[x][y].setPlayer(player);
        let line = this.getWinningLine();
        return line;
    },

    canMove : function(x, y) {
        return !this.winner && this.squares[x][y].getPlayer() == null;
    },

    getWinningLine : function () {
        let line = new Line();
        let x = 0;
        let y = 0;

        // check columns
        while (this.winner == null && x < this.sideSize) {
            line.clear();
            for (y = 0; y < this.sideSize; y++) {
	            line.addSquare(this.squares[x][y]);
	        }
            this.winner = line.winsFor();
            x++;
        }

        // check rows
        y = 0;
        while (this.winner == null && y < this.sideSize) {
            line.clear();
            for (x = 0; x < this.sideSize; x++) {
                line.addSquare(this.squares[x][y]);
            }
            this.winner = line.winsFor();
            y++;
        }

        // check bottom right to top left diagonal
        if (this.winner == null) {
            line.clear();
            for (x = 0, y = 0; x < this.sideSize && y < this.sideSize; x++, y++) {
                line.addSquare(this.squares[x][y]);
            }
            this.winner = line.winsFor();
        }

        // check bottom left to top right diagonal
        if (this.winner == null) {
            line.clear();
            for (x = 0, y = this.sideSize - 1; x < this.sideSize && y >= 0; x++, y--) {
                line.addSquare(this.squares[x][y]);
            }
            this.winner = line.winsFor();
        }

        return line;
    }

};