/**
 * @author       Richard Davey <rich@photonstorm.com>
 * @copyright    2018 Photon Storm Ltd.
 * @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
 */

var SnapFloor = require('../../math/snap/SnapFloor');
var SnapCeil = require('../../math/snap/SnapCeil');

/**
 * Returns the tiles in the given layer that are within the camera's viewport. This is used internally.
 *
 * @function Phaser.Tilemaps.Components.CullTiles
 * @private
 * @since 3.0.0
 *
 * @param {Phaser.Tilemaps.LayerData} layer - The Tilemap Layer to act upon.
 * @param {Phaser.Cameras.Scene2D.Camera} [camera] - The Camera to run the cull check against.
 * @param {array} [outputArray] - [description]
 *
 * @return {Phaser.Tilemaps.Tile[]} An array of Tile objects.
 */
var CullTiles = function (layer, camera, outputArray, renderOrder)
{
    if (outputArray === undefined) { outputArray = []; }
    if (renderOrder === undefined) { renderOrder = 0; }

    outputArray.length = 0;

    var tilemap = layer.tilemapLayer.tilemap;
    var tilemapLayer = layer.tilemapLayer;

    var mapData = layer.data;
    var mapWidth = layer.width;
    var mapHeight = layer.height;

    //  We need to use the tile sizes defined for the map as a whole, not the layer,
    //  in order to calculate the bounds correctly. As different sized tiles may be
    //  placed on the grid and we cannot trust layer.baseTileWidth to give us the true size.
    var tileW = Math.floor(tilemap.tileWidth * tilemapLayer.scaleX);
    var tileH = Math.floor(tilemap.tileHeight * tilemapLayer.scaleY);

    var drawLeft = 0;
    var drawRight = mapWidth;
    var drawTop = 0;
    var drawBottom = mapHeight;

    if (!tilemapLayer.skipCull && tilemapLayer.scrollFactorX === 1 && tilemapLayer.scrollFactorY === 1)
    {
        //  Camera world view bounds, snapped for scaled tile size
        //  Cull Padding values are given in tiles, not pixels

        var boundsLeft = SnapFloor(camera.worldView.x - tilemapLayer.x, tileW, 0, true) - tilemapLayer.cullPaddingX;
        var boundsRight = SnapCeil(camera.worldView.right - tilemapLayer.x, tileW, 0, true) + tilemapLayer.cullPaddingX;
        var boundsTop = SnapFloor(camera.worldView.y - tilemapLayer.y, tileH, 0, true) - tilemapLayer.cullPaddingY;
        var boundsBottom = SnapCeil(camera.worldView.bottom - tilemapLayer.y, tileH, 0, true) + tilemapLayer.cullPaddingY;

        drawLeft = Math.max(0, boundsLeft);
        drawRight = Math.min(mapWidth, boundsRight);
        drawTop = Math.max(0, boundsTop);
        drawBottom = Math.min(mapHeight, boundsBottom);
    }

    var x;
    var y;
    var tile;

    if (renderOrder === 0)
    {
        //  right-down

        for (y = drawTop; y < drawBottom; y++)
        {
            for (x = drawLeft; x < drawRight; x++)
            {
                tile = mapData[y][x];
    
                if (!tile || tile.index === -1 || !tile.visible || tile.alpha === 0)
                {
                    continue;
                }
    
                outputArray.push(tile);
            }
        }
    }
    else if (renderOrder === 1)
    {
        //  left-down

        for (y = drawTop; y < drawBottom; y++)
        {
            for (x = drawRight; x >= drawLeft; x--)
            {
                tile = mapData[y][x];
    
                if (!tile || tile.index === -1 || !tile.visible || tile.alpha === 0)
                {
                    continue;
                }
    
                outputArray.push(tile);
            }
        }
    }
    else if (renderOrder === 2)
    {
        //  right-up

        for (y = drawBottom; y >= drawTop; y--)
        {
            for (x = drawLeft; x < drawRight; x++)
            {
                tile = mapData[y][x];
    
                if (!tile || tile.index === -1 || !tile.visible || tile.alpha === 0)
                {
                    continue;
                }
    
                outputArray.push(tile);
            }
        }
    }
    else if (renderOrder === 3)
    {
        //  left-up

        for (y = drawBottom; y >= drawTop; y--)
        {
            for (x = drawRight; x >= drawLeft; x--)
            {
                tile = mapData[y][x];
    
                if (!tile || tile.index === -1 || !tile.visible || tile.alpha === 0)
                {
                    continue;
                }
    
                outputArray.push(tile);
            }
        }
    }

    tilemapLayer.tilesDrawn = outputArray.length;
    tilemapLayer.tilesTotal = mapWidth * mapHeight;

    return outputArray;
};

module.exports = CullTiles;