package
{
    import flash.display.Sprite;
    import flash.events.MouseEvent;
 
    public class GridView2 extends Sprite
    {
        private var _cellSize:int = 20;
        private var _grid:Grid;
                 
        public function GridView2(grid:Grid)
        {
            _grid = grid;
            for(var i:int = 0; i < _grid.numCols; i++)
            {
                for(var j:int = 0; j < _grid.numRows; j++)
                {
                    //为每个节点设置不同的“代价权重因子”
                    var mult:Number = Math.sin(i * .50) + Math.cos(j * .2 + i * .05);
                    _grid.getNode(i, j).costMultiplier = Math.abs(mult) + 1;
                }
            }
            drawGrid();
            findPath();
            addEventListener(MouseEvent.CLICK, onGridClick);
        }
         
        //画网格
        public function drawGrid():void
        {
            graphics.clear();
            for(var i:int = 0; i < _grid.numCols; i++)
            {
                for(var j:int = 0; j < _grid.numRows; j++)
                {
                    var node:Node = _grid.getNode(i, j);
                    graphics.lineStyle(0);
                    graphics.beginFill(getColor(node));
                    graphics.drawRect(i * _cellSize, j * _cellSize, _cellSize, _cellSize);
                }
            }
        }
         
        //取得单元格的颜色(与权重因子关联，costMultiplier越小，颜色越深)
        private function getColor(node:Node):uint
        {
            if(!node.walkable) return 0;
            if(node == _grid.startNode) return 0x666666;
            if(node == _grid.endNode) return 0x666666;
            var shade:Number = 300 - 70 * node.costMultiplier;
            return shade << 16 | shade << 8 | shade;
        }
         
        //单元格点击时，切换节点为普通节点或障碍物节点
        private function onGridClick(event:MouseEvent):void
        {
            var xpos:int = Math.floor(event.localX / _cellSize);
            var ypos:int = Math.floor(event.localY / _cellSize);
             
            _grid.setWalkable(xpos, ypos, !_grid.getNode(xpos, ypos).walkable);
            drawGrid();
            findPath();
        }
         
        //找路
        private function findPath():void
        {
            var astar:AStar = new AStar();
            if(astar.findPath(_grid))
            {
                //showVisited(astar);
                showPath(astar);
            }
        }
         
         
        private function showVisited(astar:AStar):void
        {
            var visited:Array = astar.visited;
            for(var i:int = 0; i < visited.length; i++)
            {
                graphics.beginFill(0xcccccc);
                graphics.drawRect(visited[i].x * _cellSize, visited[i].y * _cellSize, _cellSize, _cellSize);
                graphics.endFill();
            }
        }
         
         
        private function showPath(astar:AStar):void
        {
            var path:Array = astar.path;
            for(var i:int = 0; i < path.length; i++)
            {
                graphics.lineStyle(0);
                graphics.beginFill(0);
                graphics.drawCircle(path[i].x * _cellSize + _cellSize / 2,
                    path[i].y * _cellSize + _cellSize / 2,
                    _cellSize / 3);
            }
        }
    }
}