jQuery(function () {
  // Game model object
  var field = new (function () {
    this.moves = 0;
    this.cells = [ [0,0,0,0], [0,0,0,0], [0,0,0,0], [0,0,0,0] ];
    this.isFree = function (row, col) {
      return -1 < col && 4 > col && -1 < row && 4 > row && 16 == this.cells[row][col];
    };
    this.isSolved = function () {
      for (var i = 15; i > -1; i--) {
        if ((i + 1) != this.cells[(i - (i % 4)) / 4][i % 4]) {
          return false;
        }
      }
      return true;
    };
    this.move = function (p) {
      var d = [[-1, 0], [1, 0], [0, -1], [0, 1]];
      if (16 != this.cells[p.row][p.col]) {
        for (var k in d) {
          if (this.isFree(p.row + d[k][1], p.col + d[k][0])) {
            this.cells[p.row + d[k][1]][p.col + d[k][0]] = this.cells[p.row][p.col];
            this.cells[p.row][p.col] = 16;
            p.col += d[k][0];
            p.row += d[k][1];
            return ++this.moves;
          }
        }
      }
      return false;
    };
    this.reset = function () {
      var a, b, c, d, i, v = [];
      for (i = 0; i < 16; v.push(++i));
      var t = [a = [-4, -3, 1], b = [1, 5, 4], c = [4, 3, -1], d = [-1, -5, -4]];
      var ts = [[b],[b,c],[b,c],[c],[a,b],t,t,[c,d],[a,b],t,t,[c,d],[a],[a,d],[a,d],[d]];
      var i, cSet, sT, fc = 15, d;
      for (i = 0; i < 150; i++) {
        sT = ts[fc][Math.round(Math.random() * (ts[fc].length - 1))];
        d = (Math.round(Math.random())) ? [2,0] : [0,2];
        v[fc] = v[sT[d[0]] + fc];
        v[sT[d[0]] + fc] = v[sT[1] + fc];
        v[sT[1] + fc] = v[sT[d[1]] + fc]
        fc += sT[d[1]];
      }
      v[fc] = 16;
      for (i = 0; i < 16; i++) {
        this.cells[(i - (i % 4)) / 4][i % 4] = v[i];
      }
      this.moves = 0;
    };
  })();
  // Constants
  var cSize = 44;
  var cellCss = {'background-color' : '#fff', 'color' : '#aaa', 'border-color' : '#aaa'};
  var cellNCss = [];
  // jQuery part
  var lock = false, game15 = $('#game15').get(0), offset = {'left' : game15.offsetLeft + 75, 'top' : game15.offsetTop + 5};
  $('#shuffle').click(function () {
    if (lock) return;
    field.reset();
    $('#moves').html('0');
    $('#game15-field').empty();
    for (var col = 0; col < 4; col++) {
      for (var row = 0; row < 4; row++) {
        !field.isFree(row, col) && ($('#game15-field').get(0).appendChild(
          $("<div class='game-cell game-cell-" + field.cells[row][col] + "'>" + field.cells[row][col] + "</div>")
            .css(cellCss).css(cellNCss[field.cells[row][col]-1]||{}).css({'left' : col * cSize + offset.left, 'top' : row * cSize + offset.top})
            .click(function () {
              if (!lock && field.move(this._p)) {
                lock = true;
                $('#moves').html('' + field.moves);
                $(this).animate(
                  {'left' : this._p.col * cSize + offset.left, 'top' : this._p.row * cSize + offset.top },
                  300, '', function () {
                    lock = false;
                    field.isSolved() && confirm('Puzzle is solved! Play again?') && $('#shuffle').click();
                  });
              }
            }).get(0))._p = {'row': row, 'col': col});
      }
    }
  }).click();
});