/*
 OpenGL ES 2.0 / WebGL helper functions
 */

/*
 * According to the WebGL specification ( For further info see:s http://www.khronos.org/registry/webgl/specs/latest/webgl.idl ),
 * the API should work with objects like WebGLTexture, WebGLBuffer, WebGLRenderBuffer, WebGLFramebuffer, WebGLProgram, WebGLShader.
 * OpenGL ES 2.0 doesn't have "objects" concepts: Instead it uses ids (GLints). So, these objects are emulated in this thin wrapper.
 */


var gl = gl || {};

//
// Create functions
//
gl.createTexture = function() {
	// Returns a "WebGLTexture" object
	var ret = gl._createTexture();
	return { texture_id:ret };
};

gl.createBuffer = function() {
	// Returns a "WebGLBuffer" object
	var ret = gl._createBuffer();
	return { buffer_id:ret };
};

gl.createRenderbuffer = function() {
	// Returns a "WebGLRenderBuffer" object
	var ret = gl._createRenderuffer();
	return { renderbuffer_id:ret};
};

gl.createFramebuffer = function() {
	// Returns a "WebGLFramebuffer" object
	var ret = gl._createFramebuffer();
	return {framebuffer_id:ret};
};

gl.createProgram = function() {
	// Returns a "WebGLProgram" object
	var ret = gl._createProgram();
	return {program_id:ret};
};

gl.createShader = function(shaderType) {
	// Returns a "WebGLShader" object
	var ret = gl._createShader(shaderType);
	return {shader_id:ret};
};

//
// Delete Functions
//
gl.deleteTexture = function(texture) {
	var texture_id = texture.texture_id;
	// Accept numbers too. eg: gl.deleteTexture(0)
	if( typeof texture === 'number' )
		texture_id = texture;

	gl._deleteTexture(texture_id);
};

gl.deleteBuffer = function(bufer) {
	var buffer_id = buffer.buffer_id;
	// Accept numbers too. eg: gl.deleteBuffer(0)
	if( typeof buffer === 'number' )
		buffer_id = buffer;

	gl._deleteBuffer(buffer_id);
};

gl.deleteRenderbuffer = function(bufer) {
	var buffer_id = buffer.renderbuffer_id;
	// Accept numbers too. eg: gl.deleteRenderbuffer(0)
	if( typeof buffer === 'number' )
		buffer_id = buffer;

	gl._deleteRenderbuffer(renderbuffer_id);
};

gl.deleteFramebuffer = function(bufer) {
	var buffer_id = buffer.framebuffer_id;
	// Accept numbers too. eg: gl.deleteFramebuffer(0)
	if( typeof buffer === 'number' )
		buffer_id = buffer;

	gl._deleteFramebuffer(buffer_id);
};

gl.deleteProgram = function(program) {
	var program_id = program.program_id;
	// Accept numbers too. eg: gl.deleteShader(0)
	if( typeof program === 'number' )
		program_id = program;

	gl._deleteProgram(program_id);
};

gl.deleteShader = function(shader) {
	var shader_id = shader.shader_id;
	// Accept numbers too. eg: gl.deleteShader(0)
	if( typeof shader === 'number' )
		shader_id = shader;

	gl._deleteShader(shader_id);
};

//
// Bind Related
//
// void bindTexture(GLenum target, WebGLTexture? texture);
gl.bindTexture = function(target, texture) {

	var texture_id;
	// Accept numbers too. eg: gl.bindTexture(0)
	if( typeof texture === 'number' )
		texture_id = texture;
	else if( texture === null )
		texture_id = 0;
	else
		texture_id = texture.texture_id;

	gl._bindTexture( target, texture_id );
};

// void bindBuffer(GLenum target, WebGLBuffer? buffer);
gl.bindBuffer = function(target, buffer) {
	var buffer_id;
	// Accept numbers too. eg: gl.bindBuffer(0)
	if( typeof buffer === 'number' )
		buffer_id = buffer;
	else if( buffer === null )
		buffer_id = 0;
	else
		buffer_id = buffer.buffer_id;

	gl._bindBuffer(target, buffer_id);
};

// void bindRenderbuffer(GLenum target, WebGLRenderbuffer? renderbuffer);
gl.bindRenderBuffer = function(target, buffer) {
	var buffer_id;

	// Accept numbers too. eg: gl.bindRenderbuffer(0)
	if( typeof buffer === 'number' )
		buffer_id = buffer;
	else if( buffer === null )
		buffer_id = 0;
	else
		buffer_id = buffer.buffer_id;

	gl._bindRenderbuffer(target, buffer_id);
};

// void bindFramebuffer(GLenum target, WebGLFramebuffer? framebuffer);
gl.bindFramebuffer = function(target, buffer) {
	var buffer_id;

	// Accept numbers too. eg: gl.bindFramebuffer(0)
	if( typeof buffer === 'number' )
		buffer_id = buffer;
	else if( buffer === null )
		buffer_id = 0;
	else
		buffer_id = buffer.buffer_id;

	gl._bindFramebuffer(target, buffer_id);
};

//
// Uniform related
//
// any getUniform(WebGLProgram? program, WebGLUniformLocation? location);
gl.getUniform = function(program, location) {
	var program_id;
	var location_id;

	// Accept numbers too. eg: gl.bindFramebuffer(0)
	if( typeof program === 'number' )
		program_id = program;
	else
		program_id = program.program_id;

	if( typeof location === 'number' )
		location_id = location;
	else
		location_id = location.location_id;

	return gl._getUniform(program_id, location_id);
};

// gl.uniformMatrix2fv = function(location, bool, matrix) {
// 	gl._uniformMatrix2fv(program.program_id, bool, matrix);
// };

// gl.uniformMatrix3fv = function(program, bool, matrix) {
// 	gl._uniformMatrix3fv(program.program_id, bool, matrix);
// };

// gl.uniformMatrix4fv = function(program, bool, matrix) {
// 	gl._uniformMatrix4fv(program.program_id, bool, matrix);
// };


//
// Shader related
//
// void compileShader(WebGLShader? shader);
gl.compileShader = function(shader) {
	gl._compileShader( shader.shader_id);
};

// void shaderSource(WebGLShader? shader, DOMString source);
gl.shaderSource = function(shader, source) {
	gl._shaderSource(shader.shader_id, source);
};

// any getShaderParameter(WebGLShader? shader, GLenum pname);
gl.getShaderParameter = function(shader, e) {
	return gl._getShaderParameter(shader.shader_id,e);
};

// DOMString? getShaderInfoLog(WebGLShader? shader);
gl.getShaderInfoLog = function(shader) {
	return gl._getShaderInfoLog(shader.shader_id);
};

//
// program related
//
// void attachShader(WebGLProgram? program, WebGLShader? shader);
gl.attachShader = function(program, shader) {
	var program_id = program.program_id;
	// Accept numbers too. eg: gl.attachShader(17)
	if( typeof program === 'number' )
		program_id = program;

	gl._attachShader(program_id, shader.shader_id);
};

// void linkProgram(WebGLProgram? program);
gl.linkProgram = function(program) {
	var program_id = program.program_id;
	// Accept numbers too. eg: gl.linkProgram(17)
	if( typeof program === 'number' )
		program_id = program;

	gl._linkProgram(program_id);
};


// any getProgramParameter(WebGLProgram? program, GLenum pname);
gl.getProgramParameter = function(program, e) {
	var program_id = program.program_id;
	// Accept numbers too. eg: gl.getProgramParameter(17)
	if( typeof program === 'number' )
		program_id = program;

	return gl._getProgramParameter(program_id, e);
};

// void useProgram(WebGLProgram? program);
gl.useProgram = function(program) {
	var program_id;
	// Accept numbers too. eg: gl.useProgram(17)
	if( typeof program === 'number' )
		program_id = program;
	else
		program_id = program.program_id;

	gl._useProgram (program_id);
};


// [WebGLHandlesContextLoss] GLint getAttribLocation(WebGLProgram? program, DOMString name);
gl.getAttribLocation = function(program, name) {
	var program_id = program.program_id;
	// Accept numbers too. eg: gl.getAttribLocation(17)
	if( typeof program === 'number' )
		program_id = program;

	return gl._getAttribLocation(program_id, name);
};

// WebGLUniformLocation? getUniformLocation(WebGLProgram? program, DOMString name);
gl.getUniformLocation = function(program, name) {
	var program_id = program.program_id;
	// Accept numbers too. eg: gl.getUniformLocation(17)
	if( typeof program === 'number' )
		program_id = program;

	// XXX: it should return an object, not an integer
	return gl._getUniformLocation(program_id,name);
};


// WebGLActiveInfo? getActiveAttrib(WebGLProgram? program, GLuint index);
gl.getActiveAttrib = function(program, index) {
	var program_id = program.program_id;
	// Accept numbers too. eg: gl.getActiveAttrib(17)
	if( typeof program === 'number' )
		program_id = program;

	return gl._getActiveAttrib(program_id, index);
};

// WebGLActiveInfo? getActiveUniform(WebGLProgram? program, GLuint index);
gl.getActiveUniform = function(program, index) {
	var program_id = program.program_id;
	// Accept numbers too. eg: gl.getActiveUniform(17)
	if( typeof program === 'number' )
		program_id = program;

	return gl._getActiveUniform(program_id, index);
};

// sequence<WebGLShader>? getAttachedShaders(WebGLProgram? program);
gl.getAttachedShaders = function(program) {
	var program_id = program.program_id;
	// Accept numbers too. eg: gl.getAttachedShaders(17)
	if( typeof program === 'number' )
		program_id = program;

	return gl._getAttachedShaders(program_id);
};

//
// Texture functions
//

// XXX: Currently only the 1st one is supported
// void texImage2D(GLenum target, GLint level, GLenum internalformat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, ArrayBufferView? pixels);
// void texImage2D(GLenum target, GLint level, GLenum internalformat, GLenum format, GLenum type, ImageData? pixels);
// void texImage2D(GLenum target, GLint level, GLenum internalformat, GLenum format, GLenum type, HTMLImageElement image); // May throw DOMException
// void texImage2D(GLenum target, GLint level, GLenum internalformat, GLenum format, GLenum type, HTMLCanvasElement canvas); // May throw DOMException
// void texImage2D(GLenum target, GLint level, GLenum internalformat, GLenum format, GLenum type, HTMLVideoElement video); // May throw DOMException
gl.texImage2D = function() {
	if( arguments.length !=  9)
		throw "texImage2D: Unsupported number of parameters:" + arguments.length;

	gl._texImage2D.apply(this, arguments);
};

// XXX: Currently only the 1st one is supported
// void texSubImage2D(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, ArrayBufferView? pixels);
// void texSubImage2D(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLenum format, GLenum type, ImageData? pixels);
// void texSubImage2D(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLenum format, GLenum type, HTMLImageElement image); // May throw DOMException
// void texSubImage2D(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLenum format, GLenum type, HTMLCanvasElement canvas); // May throw DOMException
// void texSubImage2D(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLenum format, GLenum type, HTMLVideoElement video); // May throw DOMException
gl.texSubImage2D = function() {
	if( arguments.length !=  9)
		throw "texImage2D: Unsupported number of parameters";

	gl._texSubImage2D.apply(this, arguments);
};

//
// Extensions
//
// From the WebGL spec:
// Returns an object if, and only if, name is an ASCII case-insensitive match [HTML] for one of the names returned from getSupportedExtensions;
// otherwise, returns null. The object returned from getExtension contains any constants or functions provided by the extension.
// A returned object may have no constants or functions if the extension does not define any, but a unique object must still be returned.
// That object is used to indicate that the extension has been enabled.
// XXX: The returned object must return the functions and constants.
gl.getExtension = function(extension) {
	var extensions = gl.getSupportedExtensions();
	if( extensions.indexOf(extension) > -1 )
		return {};
	return null;
};