/**
 * @author thespite / http://www.twitter.com/thespite
 */

import { RGBA_ASTC_4x4_Format, RGBA_ASTC_5x4_Format, RGBA_ASTC_5x5_Format, RGBA_ASTC_6x5_Format, RGBA_ASTC_6x6_Format, RGBA_ASTC_8x5_Format, RGBA_ASTC_8x6_Format, RGBA_ASTC_8x8_Format, RGBA_ASTC_10x5_Format, RGBA_ASTC_10x6_Format, RGBA_ASTC_10x8_Format, RGBA_ASTC_10x10_Format, RGBA_ASTC_12x10_Format, RGBA_ASTC_12x12_Format, RGB_ETC1_Format, RGBA_PVRTC_2BPPV1_Format, RGBA_PVRTC_4BPPV1_Format, RGB_PVRTC_2BPPV1_Format, RGB_PVRTC_4BPPV1_Format, RGBA_S3TC_DXT5_Format, RGBA_S3TC_DXT3_Format, RGBA_S3TC_DXT1_Format, RGB_S3TC_DXT1_Format, DepthFormat, DepthStencilFormat, LuminanceAlphaFormat, LuminanceFormat, RedFormat, RGBAFormat, RGBFormat, AlphaFormat, HalfFloatType, FloatType, UnsignedIntType, IntType, UnsignedShortType, ShortType, ByteType, UnsignedInt248Type, UnsignedShort565Type, UnsignedShort5551Type, UnsignedShort4444Type, UnsignedByteType } from '../../constants.js';

function WebGLUtils( gl, extensions, capabilities ) {

	var isWebGL2 = capabilities.isWebGL2;

	function convert( p ) {

		var extension;

		if ( p === UnsignedByteType ) return gl.UNSIGNED_BYTE;
		if ( p === UnsignedShort4444Type ) return gl.UNSIGNED_SHORT_4_4_4_4;
		if ( p === UnsignedShort5551Type ) return gl.UNSIGNED_SHORT_5_5_5_1;
		if ( p === UnsignedShort565Type ) return gl.UNSIGNED_SHORT_5_6_5;

		if ( p === ByteType ) return gl.BYTE;
		if ( p === ShortType ) return gl.SHORT;
		if ( p === UnsignedShortType ) return gl.UNSIGNED_SHORT;
		if ( p === IntType ) return gl.INT;
		if ( p === UnsignedIntType ) return gl.UNSIGNED_INT;
		if ( p === FloatType ) return gl.FLOAT;

		if ( p === HalfFloatType ) {

			if ( isWebGL2 ) return gl.HALF_FLOAT;

			extension = extensions.get( 'OES_texture_half_float' );

			if ( extension !== null ) {

				return extension.HALF_FLOAT_OES;

			} else {

				return null;

			}

		}

		if ( p === AlphaFormat ) return gl.ALPHA;
		if ( p === RGBFormat ) return gl.RGB;
		if ( p === RGBAFormat ) return gl.RGBA;
		if ( p === LuminanceFormat ) return gl.LUMINANCE;
		if ( p === LuminanceAlphaFormat ) return gl.LUMINANCE_ALPHA;
		if ( p === DepthFormat ) return gl.DEPTH_COMPONENT;
		if ( p === DepthStencilFormat ) return gl.DEPTH_STENCIL;
		if ( p === RedFormat ) return gl.RED;

		if ( p === RGB_S3TC_DXT1_Format || p === RGBA_S3TC_DXT1_Format ||
			p === RGBA_S3TC_DXT3_Format || p === RGBA_S3TC_DXT5_Format ) {

			extension = extensions.get( 'WEBGL_compressed_texture_s3tc' );

			if ( extension !== null ) {

				if ( p === RGB_S3TC_DXT1_Format ) return extension.COMPRESSED_RGB_S3TC_DXT1_EXT;
				if ( p === RGBA_S3TC_DXT1_Format ) return extension.COMPRESSED_RGBA_S3TC_DXT1_EXT;
				if ( p === RGBA_S3TC_DXT3_Format ) return extension.COMPRESSED_RGBA_S3TC_DXT3_EXT;
				if ( p === RGBA_S3TC_DXT5_Format ) return extension.COMPRESSED_RGBA_S3TC_DXT5_EXT;

			} else {

				return null;

			}

		}

		if ( p === RGB_PVRTC_4BPPV1_Format || p === RGB_PVRTC_2BPPV1_Format ||
			p === RGBA_PVRTC_4BPPV1_Format || p === RGBA_PVRTC_2BPPV1_Format ) {

			extension = extensions.get( 'WEBGL_compressed_texture_pvrtc' );

			if ( extension !== null ) {

				if ( p === RGB_PVRTC_4BPPV1_Format ) return extension.COMPRESSED_RGB_PVRTC_4BPPV1_IMG;
				if ( p === RGB_PVRTC_2BPPV1_Format ) return extension.COMPRESSED_RGB_PVRTC_2BPPV1_IMG;
				if ( p === RGBA_PVRTC_4BPPV1_Format ) return extension.COMPRESSED_RGBA_PVRTC_4BPPV1_IMG;
				if ( p === RGBA_PVRTC_2BPPV1_Format ) return extension.COMPRESSED_RGBA_PVRTC_2BPPV1_IMG;

			} else {

				return null;

			}

		}

		if ( p === RGB_ETC1_Format ) {

			extension = extensions.get( 'WEBGL_compressed_texture_etc1' );

			if ( extension !== null ) {

				return extension.COMPRESSED_RGB_ETC1_WEBGL;

			} else {

				return null;

			}

		}

		if ( p === RGBA_ASTC_4x4_Format || p === RGBA_ASTC_5x4_Format || p === RGBA_ASTC_5x5_Format ||
			p === RGBA_ASTC_6x5_Format || p === RGBA_ASTC_6x6_Format || p === RGBA_ASTC_8x5_Format ||
			p === RGBA_ASTC_8x6_Format || p === RGBA_ASTC_8x8_Format || p === RGBA_ASTC_10x5_Format ||
			p === RGBA_ASTC_10x6_Format || p === RGBA_ASTC_10x8_Format || p === RGBA_ASTC_10x10_Format ||
			p === RGBA_ASTC_12x10_Format || p === RGBA_ASTC_12x12_Format ) {

			extension = extensions.get( 'WEBGL_compressed_texture_astc' );

			if ( extension !== null ) {

				// TODO Complete?

				return p;

			} else {

				return null;

			}

		}

		if ( p === UnsignedInt248Type ) {

			if ( isWebGL2 ) return gl.UNSIGNED_INT_24_8;

			extension = extensions.get( 'WEBGL_depth_texture' );

			if ( extension !== null ) {

				return extension.UNSIGNED_INT_24_8_WEBGL;

			} else {

				return null;

			}

		}

	}

	return { convert: convert };

}


export { WebGLUtils };
