function Grid(size,previousState){this.size=size;this.cells=previousState?this.fromState(previousState):this.empty();}
Grid.prototype.empty=function(){var cells=[];for(var x=0;x<this.size;x++){var row=cells[x]=[];for(var y=0;y<this.size;y++){row.push(null);}}
return cells;};Grid.prototype.fromState=function(state){var cells=[];for(var x=0;x<this.size;x++){var row=cells[x]=[];for(var y=0;y<this.size;y++){var tile=state[x][y];row.push(tile?new Tile(tile.position,tile.value):null);}}
return cells;};Grid.prototype.randomAvailableCell=function(){var cells=this.availableCells();if(cells.length){return cells[Math.floor(Math.random()*cells.length)];}};Grid.prototype.availableCells=function(){var cells=[];this.eachCell(function(x,y,tile){if(!tile){cells.push({x:x,y:y});}});return cells;};Grid.prototype.eachCell=function(callback){for(var x=0;x<this.size;x++){for(var y=0;y<this.size;y++){callback(x,y,this.cells[x][y]);}}};Grid.prototype.cellsAvailable=function(){return!!this.availableCells().length;};Grid.prototype.cellAvailable=function(cell){return!this.cellOccupied(cell);};Grid.prototype.cellOccupied=function(cell){return!!this.cellContent(cell);};Grid.prototype.cellContent=function(cell){if(this.withinBounds(cell)){return this.cells[cell.x][cell.y];}else{return null;}};Grid.prototype.insertTile=function(tile){this.cells[tile.x][tile.y]=tile;};Grid.prototype.removeTile=function(tile){this.cells[tile.x][tile.y]=null;};Grid.prototype.withinBounds=function(position){return position.x>=0&&position.x<this.size&&position.y>=0&&position.y<this.size;};Grid.prototype.serialize=function(){var cellState=[];for(var x=0;x<this.size;x++){var row=cellState[x]=[];for(var y=0;y<this.size;y++){row.push(this.cells[x][y]?this.cells[x][y].serialize():null);}}
return{size:this.size,cells:cellState};};