/*
 * @author Daosheng Mu / https://github.com/DaoshengMu/
 * @author mrdoob / http://mrdoob.com/
 * @author takahirox / https://github.com/takahirox/
 */

THREE.TGALoader = function ( manager ) {

	this.manager = ( manager !== undefined ) ? manager : THREE.DefaultLoadingManager;

};

THREE.TGALoader.prototype.load = function ( url, onLoad, onProgress, onError ) {

	var scope = this;

	var texture = new THREE.Texture();

	var loader = new THREE.XHRLoader( this.manager );
	loader.setResponseType( 'arraybuffer' );

	loader.load( url, function ( buffer ) {

		texture.image = scope.parse( buffer );
		texture.needsUpdate = true;

		if ( onLoad !== undefined ) {

			onLoad( texture );

		}

	}, onProgress, onError );

	return texture;

};

// reference from vthibault, https://github.com/vthibault/roBrowser/blob/master/src/Loaders/Targa.js
THREE.TGALoader.prototype.parse = function ( buffer ) {

	// TGA Constants
	var TGA_TYPE_NO_DATA = 0,
	TGA_TYPE_INDEXED = 1,
	TGA_TYPE_RGB = 2,
	TGA_TYPE_GREY = 3,
	TGA_TYPE_RLE_INDEXED = 9,
	TGA_TYPE_RLE_RGB = 10,
	TGA_TYPE_RLE_GREY = 11,

	TGA_ORIGIN_MASK = 0x30,
	TGA_ORIGIN_SHIFT = 0x04,
	TGA_ORIGIN_BL = 0x00,
	TGA_ORIGIN_BR = 0x01,
	TGA_ORIGIN_UL = 0x02,
	TGA_ORIGIN_UR = 0x03;


	if ( buffer.length < 19 )
		console.error( 'THREE.TGALoader.parse: Not enough data to contain header.' );

	var content = new Uint8Array( buffer ),
		offset = 0,
		header = {
			id_length:       content[ offset ++ ],
			colormap_type:   content[ offset ++ ],
			image_type:      content[ offset ++ ],
			colormap_index:  content[ offset ++ ] | content[ offset ++ ] << 8,
			colormap_length: content[ offset ++ ] | content[ offset ++ ] << 8,
			colormap_size:   content[ offset ++ ],

			origin: [
				content[ offset ++ ] | content[ offset ++ ] << 8,
				content[ offset ++ ] | content[ offset ++ ] << 8
			],
			width:      content[ offset ++ ] | content[ offset ++ ] << 8,
			height:     content[ offset ++ ] | content[ offset ++ ] << 8,
			pixel_size: content[ offset ++ ],
			flags:      content[ offset ++ ]
		};

	function tgaCheckHeader( header ) {

		switch ( header.image_type ) {

			// Check indexed type
			case TGA_TYPE_INDEXED:
			case TGA_TYPE_RLE_INDEXED:
				if ( header.colormap_length > 256 || header.colormap_size !== 24 || header.colormap_type !== 1 ) {

					console.error( 'THREE.TGALoader.parse.tgaCheckHeader: Invalid type colormap data for indexed type' );

				}
				break;

			// Check colormap type
			case TGA_TYPE_RGB:
			case TGA_TYPE_GREY:
			case TGA_TYPE_RLE_RGB:
			case TGA_TYPE_RLE_GREY:
				if ( header.colormap_type ) {

					console.error( 'THREE.TGALoader.parse.tgaCheckHeader: Invalid type colormap data for colormap type' );

				}
				break;

			// What the need of a file without data ?
			case TGA_TYPE_NO_DATA:
				console.error( 'THREE.TGALoader.parse.tgaCheckHeader: No data' );

			// Invalid type ?
			default:
				console.error( 'THREE.TGALoader.parse.tgaCheckHeader: Invalid type " ' + header.image_type + '"' );

		}

		// Check image width and height
		if ( header.width <= 0 || header.height <= 0 ) {

			console.error( 'THREE.TGALoader.parse.tgaCheckHeader: Invalid image size' );

		}

		// Check image pixel size
		if ( header.pixel_size !== 8  &&
			header.pixel_size !== 16 &&
			header.pixel_size !== 24 &&
			header.pixel_size !== 32 ) {

			console.error( 'THREE.TGALoader.parse.tgaCheckHeader: Invalid pixel size "' + header.pixel_size + '"' );

		}

	}

	// Check tga if it is valid format
	tgaCheckHeader( header );

	if ( header.id_length + offset > buffer.length ) {

		console.error( 'THREE.TGALoader.parse: No data' );

	}

	// Skip the needn't data
	offset += header.id_length;

	// Get targa information about RLE compression and palette
	var use_rle = false,
		use_pal = false,
		use_grey = false;

	switch ( header.image_type ) {

		case TGA_TYPE_RLE_INDEXED:
			use_rle = true;
			use_pal = true;
			break;

		case TGA_TYPE_INDEXED:
			use_pal = true;
			break;

		case TGA_TYPE_RLE_RGB:
			use_rle = true;
			break;

		case TGA_TYPE_RGB:
			break;

		case TGA_TYPE_RLE_GREY:
			use_rle = true;
			use_grey = true;
			break;

		case TGA_TYPE_GREY:
			use_grey = true;
			break;

	}

	// Parse tga image buffer
	function tgaParse( use_rle, use_pal, header, offset, data ) {

		var pixel_data,
			pixel_size,
			pixel_total,
			palettes;

		pixel_size = header.pixel_size >> 3;
		pixel_total = header.width * header.height * pixel_size;

		 // Read palettes
		 if ( use_pal ) {

			 palettes = data.subarray( offset, offset += header.colormap_length * ( header.colormap_size >> 3 ) );

		 }

		 // Read RLE
		 if ( use_rle ) {

			 pixel_data = new Uint8Array( pixel_total );

			var c, count, i;
			var shift = 0;
			var pixels = new Uint8Array( pixel_size );

			while ( shift < pixel_total ) {

				c     = data[ offset ++ ];
				count = ( c & 0x7f ) + 1;

				// RLE pixels.
				if ( c & 0x80 ) {

					// Bind pixel tmp array
					for ( i = 0; i < pixel_size; ++ i ) {

						pixels[ i ] = data[ offset ++ ];

					}

					// Copy pixel array
					for ( i = 0; i < count; ++ i ) {

						pixel_data.set( pixels, shift + i * pixel_size );

					}

					shift += pixel_size * count;

				} else {

					// Raw pixels.
					count *= pixel_size;
					for ( i = 0; i < count; ++ i ) {

						pixel_data[ shift + i ] = data[ offset ++ ];

					}
					shift += count;

				}

			}

		 } else {

			// RAW Pixels
			pixel_data = data.subarray(
				 offset, offset += ( use_pal ? header.width * header.height : pixel_total )
			);

		 }

		 return {
			pixel_data: pixel_data,
			palettes: palettes
		 };

	}

	function tgaGetImageData8bits( imageData, y_start, y_step, y_end, x_start, x_step, x_end, image, palettes ) {

		var colormap = palettes;
		var color, i = 0, x, y;
		var width = header.width;

		for ( y = y_start; y !== y_end; y += y_step ) {

			for ( x = x_start; x !== x_end; x += x_step, i ++ ) {

				color = image[ i ];
				imageData[ ( x + width * y ) * 4 + 3 ] = 255;
				imageData[ ( x + width * y ) * 4 + 2 ] = colormap[ ( color * 3 ) + 0 ];
				imageData[ ( x + width * y ) * 4 + 1 ] = colormap[ ( color * 3 ) + 1 ];
				imageData[ ( x + width * y ) * 4 + 0 ] = colormap[ ( color * 3 ) + 2 ];

			}

		}

		return imageData;

	}

	function tgaGetImageData16bits( imageData, y_start, y_step, y_end, x_start, x_step, x_end, image ) {

		var color, i = 0, x, y;
		var width = header.width;

		for ( y = y_start; y !== y_end; y += y_step ) {

			for ( x = x_start; x !== x_end; x += x_step, i += 2 ) {

				color = image[ i + 0 ] + ( image[ i + 1 ] << 8 ); // Inversed ?
				imageData[ ( x + width * y ) * 4 + 0 ] = ( color & 0x7C00 ) >> 7;
				imageData[ ( x + width * y ) * 4 + 1 ] = ( color & 0x03E0 ) >> 2;
				imageData[ ( x + width * y ) * 4 + 2 ] = ( color & 0x001F ) >> 3;
				imageData[ ( x + width * y ) * 4 + 3 ] = ( color & 0x8000 ) ? 0 : 255;

			}

		}

		return imageData;

	}

	function tgaGetImageData24bits( imageData, y_start, y_step, y_end, x_start, x_step, x_end, image ) {

		var i = 0, x, y;
		var width = header.width;

		for ( y = y_start; y !== y_end; y += y_step ) {

			for ( x = x_start; x !== x_end; x += x_step, i += 3 ) {

				imageData[ ( x + width * y ) * 4 + 3 ] = 255;
				imageData[ ( x + width * y ) * 4 + 2 ] = image[ i + 0 ];
				imageData[ ( x + width * y ) * 4 + 1 ] = image[ i + 1 ];
				imageData[ ( x + width * y ) * 4 + 0 ] = image[ i + 2 ];

			}

		}

		return imageData;

	}

	function tgaGetImageData32bits( imageData, y_start, y_step, y_end, x_start, x_step, x_end, image ) {

		var i = 0, x, y;
		var width = header.width;

		for ( y = y_start; y !== y_end; y += y_step ) {

			for ( x = x_start; x !== x_end; x += x_step, i += 4 ) {

				imageData[ ( x + width * y ) * 4 + 2 ] = image[ i + 0 ];
				imageData[ ( x + width * y ) * 4 + 1 ] = image[ i + 1 ];
				imageData[ ( x + width * y ) * 4 + 0 ] = image[ i + 2 ];
				imageData[ ( x + width * y ) * 4 + 3 ] = image[ i + 3 ];

			}

		}

		return imageData;

	}

	function tgaGetImageDataGrey8bits( imageData, y_start, y_step, y_end, x_start, x_step, x_end, image ) {

		var color, i = 0, x, y;
		var width = header.width;

		for ( y = y_start; y !== y_end; y += y_step ) {

			for ( x = x_start; x !== x_end; x += x_step, i ++ ) {

				color = image[ i ];
				imageData[ ( x + width * y ) * 4 + 0 ] = color;
				imageData[ ( x + width * y ) * 4 + 1 ] = color;
				imageData[ ( x + width * y ) * 4 + 2 ] = color;
				imageData[ ( x + width * y ) * 4 + 3 ] = 255;

			}

		}

		return imageData;

	}

	function tgaGetImageDataGrey16bits( imageData, y_start, y_step, y_end, x_start, x_step, x_end, image ) {

		var i = 0, x, y;
		var width = header.width;

		for ( y = y_start; y !== y_end; y += y_step ) {

			for ( x = x_start; x !== x_end; x += x_step, i += 2 ) {

				imageData[ ( x + width * y ) * 4 + 0 ] = image[ i + 0 ];
				imageData[ ( x + width * y ) * 4 + 1 ] = image[ i + 0 ];
				imageData[ ( x + width * y ) * 4 + 2 ] = image[ i + 0 ];
				imageData[ ( x + width * y ) * 4 + 3 ] = image[ i + 1 ];

			}

		}

		return imageData;

	}

	function getTgaRGBA( data, width, height, image, palette ) {

		var x_start,
			y_start,
			x_step,
			y_step,
			x_end,
			y_end;

		switch ( ( header.flags & TGA_ORIGIN_MASK ) >> TGA_ORIGIN_SHIFT ) {
			default:
			case TGA_ORIGIN_UL:
				x_start = 0;
				x_step = 1;
				x_end = width;
				y_start = 0;
				y_step = 1;
				y_end = height;
				break;

			case TGA_ORIGIN_BL:
				x_start = 0;
				x_step = 1;
				x_end = width;
				y_start = height - 1;
				y_step = - 1;
				y_end = - 1;
				break;

			case TGA_ORIGIN_UR:
				x_start = width - 1;
				x_step = - 1;
				x_end = - 1;
				y_start = 0;
				y_step = 1;
				y_end = height;
				break;

			case TGA_ORIGIN_BR:
				x_start = width - 1;
				x_step = - 1;
				x_end = - 1;
				y_start = height - 1;
				y_step = - 1;
				y_end = - 1;
				break;

		}

		if ( use_grey ) {

			switch ( header.pixel_size ) {
				case 8:
					tgaGetImageDataGrey8bits( data, y_start, y_step, y_end, x_start, x_step, x_end, image );
					break;
				case 16:
					tgaGetImageDataGrey16bits( data, y_start, y_step, y_end, x_start, x_step, x_end, image );
					break;
				default:
					console.error( 'THREE.TGALoader.parse.getTgaRGBA: not support this format' );
					break;
			}

		} else {

			switch ( header.pixel_size ) {
				case 8:
					tgaGetImageData8bits( data, y_start, y_step, y_end, x_start, x_step, x_end, image, palette );
					break;

				case 16:
					tgaGetImageData16bits( data, y_start, y_step, y_end, x_start, x_step, x_end, image );
					break;

				case 24:
					tgaGetImageData24bits( data, y_start, y_step, y_end, x_start, x_step, x_end, image );
					break;

				case 32:
					tgaGetImageData32bits( data, y_start, y_step, y_end, x_start, x_step, x_end, image );
					break;

				default:
					console.error( 'THREE.TGALoader.parse.getTgaRGBA: not support this format' );
					break;
			}

		}

		// Load image data according to specific method
		// var func = 'tgaGetImageData' + (use_grey ? 'Grey' : '') + (header.pixel_size) + 'bits';
		// func(data, y_start, y_step, y_end, x_start, x_step, x_end, width, image, palette );
		return data;

	}

	var canvas = document.createElement( 'canvas' );
	canvas.width = header.width;
	canvas.height = header.height;

	var context = canvas.getContext( '2d' );
	var imageData = context.createImageData( header.width, header.height );

	var result = tgaParse( use_rle, use_pal, header, offset, content );
	var rgbaData = getTgaRGBA( imageData.data, header.width, header.height, result.pixel_data, result.palettes );

	context.putImageData( imageData, 0, 0 );

	return canvas;

};
