var PrimitiveShader = require('../shader/PrimitiveShader'),
    ComplexPrimitiveShader = require('../shader/ComplexPrimitiveShader'),
    PixiShader = require('../shader/PixiShader'),
    PixiFastShader = require('../shader/PixiFastShader'),
    StripShader = require('../shader/StripShader');

/**
 * @class
 * @namespace PIXI
 * @private
 */
function WebGLShaderManager() {
    /**
     * @member {number}
     */
    this.maxAttibs = 10;

    /**
     * @member {Array}
     */
    this.attribState = [];

    /**
     * @member {Array}
     */
    this.tempAttribState = [];

    for (var i = 0; i < this.maxAttibs; i++) {
        this.attribState[i] = false;
    }

    /**
     * @member {Array}
     */
    this.stack = [];
}

WebGLShaderManager.prototype.constructor = WebGLShaderManager;
module.exports = WebGLShaderManager;

/**
 * Initialises the context and the properties.
 *
 * @param gl {WebGLContext} the current WebGL drawing context
 */
WebGLShaderManager.prototype.setContext = function (gl) {
    this.gl = gl;

    // the next one is used for rendering primitives
    this.primitiveShader = new PrimitiveShader(gl);

    // the next one is used for rendering triangle strips
    this.complexPrimitiveShader = new ComplexPrimitiveShader(gl);

    // this shader is used for the default sprite rendering
    this.defaultShader = new PixiShader(gl);

    // this shader is used for the fast sprite rendering
    this.fastShader = new PixiFastShader(gl);

    // the next one is used for rendering triangle strips
    this.stripShader = new StripShader(gl);
    this.setShader(this.defaultShader);
};

/**
 * Takes the attributes given in parameters.
 *
 * @param attribs {Array} attribs
 */
WebGLShaderManager.prototype.setAttribs = function (attribs) {
    // reset temp state
    var i;

    for (i = 0; i < this.tempAttribState.length; i++) {
        this.tempAttribState[i] = false;
    }

    // set the new attribs
    for (i = 0; i < attribs.length; i++) {
        var attribId = attribs[i];
        this.tempAttribState[attribId] = true;
    }

    var gl = this.gl;

    for (i = 0; i < this.attribState.length; i++) {
        if (this.attribState[i] !== this.tempAttribState[i]) {
            this.attribState[i] = this.tempAttribState[i];

            if (this.tempAttribState[i]) {
                gl.enableVertexAttribArray(i);
            }
            else {
                gl.disableVertexAttribArray(i);
            }
        }
    }
};

/**
 * Sets the current shader.
 *
 * @param shader {Any}
 */
WebGLShaderManager.prototype.setShader = function (shader) {
    if (this._currentId === shader._UID) {
        return false;
    }

    this._currentId = shader._UID;

    this.currentShader = shader;

    this.gl.useProgram(shader.program);
    this.setAttribs(shader.attributes);

    return true;
};

/**
 * Destroys this object.
 *
 */
WebGLShaderManager.prototype.destroy = function () {
    this.attribState = null;

    this.tempAttribState = null;

    this.primitiveShader.destroy();

    this.complexPrimitiveShader.destroy();

    this.defaultShader.destroy();

    this.fastShader.destroy();

    this.stripShader.destroy();

    this.gl = null;
};