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

THREE.TGALoader = function ( manager ) {

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

};

// extend THREE.BinaryTextureLoader
THREE.TGALoader.prototype = Object.create( THREE.BinaryTextureLoader.prototype );

// reference from vthibault, https://github.com/vthibault/roBrowser/blob/master/src/Loaders/Targa.js
THREE.TGALoader.prototype._parser = 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( width, height, image, palette ) {

		var x_start,
			y_start,
			x_step,
			y_step,
			x_end,
			y_end,
			data = new Uint8Array(width * height * 4);

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

	return {
		width: header.width,
		height: header.height,
		data: rgbaData
	};

};