/**
 * Constructor.
 *
 * @param parent
 * @constructor
 */
Phaser.Plugin.PathFinderPlugin = function (parent) {

    if (typeof EasyStar !== 'object') {
        throw new Error("Easystar is not defined!");
    }

    this.parent = parent;
    this._easyStar = new EasyStar.js();
    this._grid = null;
    this._callback = null;
    this._prepared = false;
    this._walkables = [0];

};

Phaser.Plugin.PathFinderPlugin.prototype = Object.create(Phaser.Plugin.prototype);
Phaser.Plugin.PathFinderPlugin.prototype.constructor = Phaser.Plugin.PathFinderPlugin;

/**
 * Set Grid for Pathfinding.
 *
 * @param grid          Mapdata as a two dimensional array.
 * @param walkables     Tiles which are walkable. Every other tile is marked as blocked.
 * @param iterationsPerCount
 */
Phaser.Plugin.PathFinderPlugin.prototype.setGrid = function (grid, walkables, iterationsPerCount) {
    iterationsPerCount = iterationsPerCount || null;

    this._grid = [];
    for (var i = 0; i < grid.length; i++)
    {
        this._grid[i] = []
        for (var j = 0; j < grid[i].length; j++)
        {
            if (grid[i][j])
                this._grid[i][j] = grid[i][j].index
            else
                this._grid[i][j] = 0
        }
    }
    this._walkables = walkables;

    this._easyStar.setGrid(this._grid);
    this._easyStar.setAcceptableTiles(this._walkables);

    // initiate all walkable tiles with cost 1 so they will be walkable even if they are not on the grid map, jet.
    for (var i = 0; i < walkables.length; i++)
    {
        this.setTileCost(walkables[i], 1);
    }

    if (iterationsPerCount !== null) {
        this._easyStar.setIterationsPerCalculation(iterationsPerCount);
    }
};

/**
 * Sets the tile cost for a particular tile type.
 *
 * @param {Number} The tile type to set the cost for.
 * @param {Number} The multiplicative cost associated with the given tile.
 */
Phaser.Plugin.PathFinderPlugin.prototype.setTileCost = function (tileType, cost) {
    this._easyStar.setTileCost(tileType, cost);
}

/**
 * Set callback function (Uh, really?)
 * @param callback
 */
Phaser.Plugin.PathFinderPlugin.prototype.setCallbackFunction = function (callback) {
    this._callback = callback;
};

/**
 * Prepare pathcalculation for easystar.
 *
 * @param from  array 0: x-coords, 1: y-coords ([x,y])
 * @param to    array 0: x-coords, 1: y-coords ([x,y])
 */
Phaser.Plugin.PathFinderPlugin.prototype.preparePathCalculation = function (from, to) {
    if (this._callback === null || typeof this._callback !== "function") {
        throw new Error("No Callback set!");
    }

    var startX = from[0],
        startY = from[1],
        destinationX = to[0],
        destinationY = to[1];

    this._easyStar.findPath(startX, startY, destinationX, destinationY, this._callback);
    this._prepared = true;
};

/**
 * Start path calculation.
 */
Phaser.Plugin.PathFinderPlugin.prototype.calculatePath = function () {
    if (this._prepared === null) {
        throw new Error("no Calculation prepared!");
    }

    this._easyStar.calculate();
};