/**
*  
* @module Kiwi
* @submodule Renderers
* 
*/

module Kiwi.Renderers {

	/**
	* Encapsulates a WebGL Element Array Buffer
	* @class GLElementArrayBuffer
	* @constructor
	* @namespace Kiwi.Renderers
	* @param gl {WebGLRenderingContent}
	* @param [_itemSize] {number}
	* @param [_indices] {number[]}
	* @param [init=true] {boolean}
	* @return {GLElementArrayBuffer}
	*/
	export class GLElementArrayBuffer {

		constructor(gl: WebGLRenderingContext, _itemSize?: number, _indices?: number[], init: boolean = true) {

			this.indices = _indices || GLElementArrayBuffer.square;
			this.itemSize = _itemSize || 1;
			this.numItems = this.indices.length / this.itemSize;
			if (init) {
				this.buffer = this.init(gl);
			}
		}

		/**
		* An array of indices
		* @property indices
		* @type number[]
		* @public
		*/
		public indices: number[];

		/**
		* The Element Array Buffer object
		* @property buffer
		* @type WebGLBuffer
		* @public
		*/
		public buffer: WebGLBuffer;

		/**
		* The size of each buffer item
		* @property itemSize
		* @type number
		* @public
		*/
		public itemSize: number;

		/**
		* The numbe of items in the buffer
		* @property numItems
		* @type number
		* @public
		*/
		public numItems: number;

		/**
		* Clears the indices array.
		* @method clear
		* @public
		*/
		public clear() {
			this.indices = new Array();
		}

		/**
		* Initialises the Element Array Buffer
		* @method init
		* @param gl {WebGLRenderingContext}
		* @return {WebGLBuffer}
		* @public
		*/
		public init(gl: WebGLRenderingContext): WebGLBuffer {
			var buffer: WebGLBuffer = gl.createBuffer();
			gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, buffer);
			gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(this.indices), gl.STATIC_DRAW);

			return buffer;
		}

		/**
		* Refreshes the Element Array Buffer
		* @method refresh
		* @param gl {WebGLRenderingContext}
		* @param indices {number[]} 
		* @return {WebGLBuffer}
		* @public
		*/
		public refresh(gl: WebGLRenderingContext,indices:number[]): WebGLBuffer {
			this.numItems = this.indices.length / this.itemSize;
			gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.buffer);
			gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(this.indices), gl.STATIC_DRAW);

			return this.buffer;
		}

		/**
		* The required indices for a single quad.
		* @property square 
		* @static
		* @type number[]
		* @default [0,1,2,0,2,3]
		* @public
		*/
		public static square: number[] = [
			0, 1, 2,
			0, 2, 3
		];

	}

}