/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

 // Based off ffmpeg's msvideo.cpp

#include "image/codecs/msvideo1.h"
#include "common/stream.h"
#include "common/textconsole.h"

namespace Image {

#define CHECK_STREAM_PTR(n) \
  if ((stream.pos() + n) > stream.size() ) { \
	warning ("MS Video-1: Stream out of bounds (%d >= %d) d%d", (int)stream.pos() + n, (int)stream.size(), n); \
	return; \
  }

MSVideo1Decoder::MSVideo1Decoder(uint16 width, uint16 height, byte bitsPerPixel) : Codec() {
	_surface = new Graphics::Surface();
	_surface->create(width, height, (bitsPerPixel == 8) ? Graphics::PixelFormat::createFormatCLUT8() :
														  Graphics::PixelFormat(2, 5, 5, 5, 0, 10, 5, 0, 0));

	_bitsPerPixel = bitsPerPixel;
}

MSVideo1Decoder::~MSVideo1Decoder() {
	_surface->free();
	delete _surface;
}

void MSVideo1Decoder::decode8(Common::SeekableReadStream &stream) {
	byte colors[8];
	byte *pixels = (byte *)_surface->getPixels();
	uint16 stride = _surface->w;

	int skipBlocks = 0;
	uint16 blocks_wide = _surface->w / 4;
	uint16 blocks_high = _surface->h / 4;
	uint32 totalBlocks = blocks_wide * blocks_high;
	uint32 blockInc = 4;
	uint16 rowDec = stride + 4;

	for (uint16 block_y = blocks_high; block_y > 0; block_y--) {
		uint32 blockPtr = (block_y * 4 - 1) * stride;
		for (uint16 block_x = blocks_wide; block_x > 0; block_x--) {
			// check if this block should be skipped
			if (skipBlocks > 0) {
				blockPtr += blockInc;
				skipBlocks--;
				totalBlocks--;
				continue;
			}

			uint32 pixelPtr = blockPtr;

			/* get the next two bytes in the encoded data stream */
			CHECK_STREAM_PTR(2);
			byte byte_a = stream.readByte();
			byte byte_b = stream.readByte();

			/* check if the decode is finished */
			if (byte_a == 0 && byte_b == 0 && totalBlocks == 0) {
				return;
			} else if ((byte_b & 0xFC) == 0x84) {
				// skip code, but don't count the current block
				skipBlocks = ((byte_b - 0x84) << 8) + byte_a - 1;
			} else if (byte_b < 0x80) {
				// 2-color encoding
				uint16 flags = (byte_b << 8) | byte_a;

				CHECK_STREAM_PTR(2);
				colors[0] = stream.readByte();
				colors[1] = stream.readByte();

				for (byte pixel_y = 0; pixel_y < 4; pixel_y++) {
					for (byte pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
						pixels[pixelPtr++] = colors[(flags & 0x1) ^ 1];
					pixelPtr -= rowDec;
				}
			} else if (byte_b >= 0x90) {
				// 8-color encoding
				uint16 flags = (byte_b << 8) | byte_a;

				CHECK_STREAM_PTR(8);
				for (byte i = 0; i < 8; i++)
					colors[i] = stream.readByte();

				for (byte pixel_y = 0; pixel_y < 4; pixel_y++) {
					for (byte pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
						pixels[pixelPtr++] = colors[((pixel_y & 0x2) << 1) + (pixel_x & 0x2) + ((flags & 0x1) ^ 1)];
					pixelPtr -= rowDec;
				}
			} else {
				// 1-color encoding
				colors[0] = byte_a;

				for (byte pixel_y = 0; pixel_y < 4; pixel_y++) {
					for (byte pixel_x = 0; pixel_x < 4; pixel_x++)
						pixels[pixelPtr++] = colors[0];
					pixelPtr -= rowDec;
				}
			}

			blockPtr += blockInc;
			totalBlocks--;
		}
	}
}

void MSVideo1Decoder::decode16(Common::SeekableReadStream &stream) {
	/* decoding parameters */
	uint16 colors[8];
	uint16 *pixels = (uint16 *)_surface->getPixels();
	int32 stride = _surface->w;

	int32 skip_blocks = 0;
	int32 blocks_wide = _surface->w / 4;
	int32 blocks_high = _surface->h / 4;
	int32 total_blocks = blocks_wide * blocks_high;
	int32 block_inc = 4;
	int32 row_dec = stride + 4;

	for (int32 block_y = blocks_high; block_y > 0; block_y--) {
		int32 block_ptr = ((block_y * 4) - 1) * stride;
		for (int32 block_x = blocks_wide; block_x > 0; block_x--) {
			/* check if this block should be skipped */
			if (skip_blocks) {
				block_ptr += block_inc;
				skip_blocks--;
				total_blocks--;
				continue;
			}

			int32 pixel_ptr = block_ptr;

			/* get the next two bytes in the encoded data stream */
			CHECK_STREAM_PTR(2);
			byte byte_a = stream.readByte();
			byte byte_b = stream.readByte();

			/* check if the decode is finished */
			if ((byte_a == 0) && (byte_b == 0) && (total_blocks == 0)) {
				return;
			} else if ((byte_b & 0xFC) == 0x84) {
				/* skip code, but don't count the current block */
				skip_blocks = ((byte_b - 0x84) << 8) + byte_a - 1;
			} else if (byte_b < 0x80) {
				/* 2- or 8-color encoding modes */
				uint16 flags = (byte_b << 8) | byte_a;

				CHECK_STREAM_PTR(4);
				colors[0] = stream.readUint16LE();
				colors[1] = stream.readUint16LE();

				if (colors[0] & 0x8000) {
					/* 8-color encoding */
					CHECK_STREAM_PTR(12);
					colors[2] = stream.readUint16LE();
					colors[3] = stream.readUint16LE();
					colors[4] = stream.readUint16LE();
					colors[5] = stream.readUint16LE();
					colors[6] = stream.readUint16LE();
					colors[7] = stream.readUint16LE();

					for (int pixel_y = 0; pixel_y < 4; pixel_y++) {
						for (int pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
							pixels[pixel_ptr++] =
								colors[((pixel_y & 0x2) << 1) +
									(pixel_x & 0x2) + ((flags & 0x1) ^ 1)];
						pixel_ptr -= row_dec;
					}
				} else {
					/* 2-color encoding */
					for (int pixel_y = 0; pixel_y < 4; pixel_y++) {
						for (int pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
							pixels[pixel_ptr++] = colors[(flags & 0x1) ^ 1];
						pixel_ptr -= row_dec;
					}
				}
			} else {
				/* otherwise, it's a 1-color block */
				colors[0] = (byte_b << 8) | byte_a;

				for (int pixel_y = 0; pixel_y < 4; pixel_y++) {
					for (int pixel_x = 0; pixel_x < 4; pixel_x++)
						pixels[pixel_ptr++] = colors[0];
					pixel_ptr -= row_dec;
				}
			}

			block_ptr += block_inc;
			total_blocks--;
		}
	}
}

const Graphics::Surface *MSVideo1Decoder::decodeFrame(Common::SeekableReadStream &stream) {
	if (_bitsPerPixel == 8)
		decode8(stream);
	else
		decode16(stream);

	return _surface;
}

} // End of namespace Image
