var compileProgram = require('./shader/compileProgram'),
	extractAttributes = require('./shader/extractAttributes'),
	extractUniforms = require('./shader/extractUniforms'),
	setPrecision = require('./shader/setPrecision'),
	generateUniformAccessObject = require('./shader/generateUniformAccessObject');

/**
 * Helper class to create a webGL Shader
 *
 * @class
 * @memberof PIXI.glCore
 * @param gl {WebGLRenderingContext}
 * @param vertexSrc {string|string[]} The vertex shader source as an array of strings.
 * @param fragmentSrc {string|string[]} The fragment shader source as an array of strings.
 * @param precision {string} The float precision of the shader. Options are 'lowp', 'mediump' or 'highp'.
 * @param attributeLocations {object} A key value pair showing which location eact attribute should sit eg {position:0, uvs:1}
 */
var Shader = function(gl, vertexSrc, fragmentSrc, precision, attributeLocations)
{
	/**
	 * The current WebGL rendering context
	 *
	 * @member {WebGLRenderingContext}
	 */
	this.gl = gl;

	if(precision)
	{
		vertexSrc = setPrecision(vertexSrc, precision);
		fragmentSrc = setPrecision(fragmentSrc, precision);
	}

	/**
	 * The shader program
	 *
	 * @member {WebGLProgram}
	 */
	// First compile the program..
	this.program = compileProgram(gl, vertexSrc, fragmentSrc, attributeLocations);

	/**
	 * The attributes of the shader as an object containing the following properties
	 * {
	 * 	type,
	 * 	size,
	 * 	location,
	 * 	pointer
	 * }
	 * @member {Object}
	 */
	// next extract the attributes
	this.attributes = extractAttributes(gl, this.program);

    this.uniformData = extractUniforms(gl, this.program);

	/**
	 * The uniforms of the shader as an object containing the following properties
	 * {
	 * 	gl,
	 * 	data
	 * }
	 * @member {Object}
	 */
	this.uniforms = generateUniformAccessObject( gl, this.uniformData );

	this.uniformGroups = {};
};
/**
 * Uses this shader
 */
Shader.prototype.bind = function()
{
	this.gl.useProgram(this.program);
};

/**
 * Destroys this shader
 * TODO
 */
Shader.prototype.destroy = function()
{
	this.attributes = null;
	this.uniformData = null;
	this.uniforms = null;

	var gl = this.gl;
	gl.deleteProgram(this.program);
};


module.exports = Shader;