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

THREE.TGALoader = function ( manager ) {

	THREE.Loader.call( this, manager );

};

THREE.TGALoader.prototype = Object.assign( Object.create( THREE.Loader.prototype ), {

	constructor: THREE.TGALoader,

	load: function ( url, onLoad, onProgress, onError ) {

		var scope = this;

		var texture = new THREE.Texture();

		var loader = new THREE.FileLoader( this.manager );
		loader.setResponseType( 'arraybuffer' );
		loader.setPath( this.path );

		loader.load( url, function ( buffer ) {

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

			if ( onLoad !== undefined ) {

				onLoad( texture );

			}

		}, onProgress, onError );

		return texture;

	},

	parse: function ( buffer ) {

		// reference from vthibault, https://github.com/vthibault/roBrowser/blob/master/src/Loaders/Targa.js

		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: 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: 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: No data.' );

					// Invalid type ?

				default:
					console.error( 'THREE.TGALoader: Invalid type "%s".', header.image_type );

			}

			// check image width and height

			if ( header.width <= 0 || header.height <= 0 ) {

				console.error( 'THREE.TGALoader: 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: Invalid pixel size "%s".', header.pixel_size );

			}

		}

		// 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: Format not supported.' );
						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: Format not supported.' );
						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;

		}

		// 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: 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 ++ ]
			};

		// check tga if it is valid format

		tgaCheckHeader( header );

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

			console.error( 'THREE.TGALoader: 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;

		}

		//

		var useOffscreen = typeof OffscreenCanvas !== 'undefined';

		var canvas = useOffscreen ? new OffscreenCanvas( header.width, header.height ) : 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 useOffscreen ? canvas.transferToImageBitmap() : canvas;

	}

} );
