/* $Id$ */

/*

 * This file is part of OpenTTD.

 * OpenTTD 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, version 2.

 * OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.

 */

/** @file grf.cpp Reading graphics data from (New)GRF files. */

#include "../stdafx.h"

#include "../gfx_func.h"

#include "../fileio_func.h"

#include "../debug.h"

#include "../strings_func.h"

#include "table/strings.h"

#include "../gui.h"

#include "grf.hpp"

/**

 * We found a corrupted sprite. This means that the sprite itself

 * contains invalid data or is too small for the given dimensions.

 * @param file_slot the file the errored sprite is in

 * @param file_pos the location in the file of the errored sprite

 * @param line the line where the error occurs.

 * @return always false (to tell loading the sprite failed)

 */

static bool WarnCorruptSprite(uint8 file_slot, size_t file_pos, int line)

{

	static byte warning_level = 0;

	if (warning_level == 0) {

		SetDParamStr(0, FioGetFilename(file_slot));

		ShowErrorMessage(STR_NEWGRF_ERROR_CORRUPT_SPRITE, INVALID_STRING_ID, 0, 0);

	}

	DEBUG(sprite, warning_level, "[%i] Loading corrupted sprite from %s at position %i", line, FioGetFilename(file_slot), (int)file_pos);

	warning_level = 6;

	return false;

}

bool SpriteLoaderGrf::LoadSprite(SpriteLoader::Sprite *sprite, uint8 file_slot, size_t file_pos, SpriteType sprite_type)

{

	/* Open the right file and go to the correct position */

	FioSeekToFile(file_slot, file_pos);

	/* Read the size and type */

	int num = FioReadWord();

	byte type = FioReadByte();

	/* Type 0xFF indicates either a colourmap or some other non-sprite info; we do not handle them here */

	if (type == 0xFF) return false;

	sprite->height = FioReadByte();

	sprite->width  = FioReadWord();

	sprite->x_offs = FioReadWord();

	sprite->y_offs = FioReadWord();

	/* 0x02 indicates it is a compressed sprite, so we can't rely on 'num' to be valid.

	 *  In case it is uncompressed, the size is 'num' - 8 (header-size). */

	num = (type & 0x02) ? sprite->width * sprite->height : num - 8;

	byte *dest_orig = AllocaM(byte, num);

	byte *dest = dest_orig;

	const int dest_size = num;

	/* Read the file, which has some kind of compression */

	while (num > 0) {

		int8 code = FioReadByte();

		if (code >= 0) {

			/* Plain bytes to read */

			int size = (code == 0) ? 0x80 : code;

			num -= size;

			if (num < 0) return WarnCorruptSprite(file_slot, file_pos, __LINE__);

			for (; size > 0; size--) {

				*dest = FioReadByte();

				dest++;

			}

		} else {

			/* Copy bytes from earlier in the sprite */

			const uint data_offset = ((code & 7) << 8) | FioReadByte();

			if (dest - data_offset < dest_orig) return WarnCorruptSprite(file_slot, file_pos, __LINE__);

			int size = -(code >> 3);

			num -= size;

			if (num < 0) return WarnCorruptSprite(file_slot, file_pos, __LINE__);

			for (; size > 0; size--) {

				*dest = *(dest - data_offset);

				dest++;

			}

		}

	}

	if (num != 0) return WarnCorruptSprite(file_slot, file_pos, __LINE__);

	sprite->AllocateData(sprite->width * sprite->height);

	if (type & 0x08) {

		for (int y = 0; y < sprite->height; y++) {

			bool last_item = false;

			/* Look up in the header-table where the real data is stored for this row */

			int offset = (dest_orig[y * 2 + 1] << 8) | dest_orig[y * 2];

			/* Go to that row */

			dest = dest_orig + offset;

			do {

				if (dest + 2 > dest_orig + dest_size) {

					free(sprite->data);

					return WarnCorruptSprite(file_slot, file_pos, __LINE__);

				}

				SpriteLoader::CommonPixel *data;

				/* Read the header:

				 *  0 .. 14  - length

				 *  15       - last_item

				 *  16 .. 31 - transparency bytes */

				last_item  = ((*dest) & 0x80) != 0;

				int length =  (*dest++) & 0x7F;

				int skip   =   *dest++;

				data = &sprite->data[y * sprite->width + skip];

				if (skip + length > sprite->width || dest + length > dest_orig + dest_size) {

					free(sprite->data);

					return WarnCorruptSprite(file_slot, file_pos, __LINE__);

				}

				for (int x = 0; x < length; x++) {

					switch (sprite_type) {

						case ST_NORMAL: data->m = _palette_remap_grf[file_slot] ? _palette_remap[*dest] : *dest; break;

						case ST_FONT:   data->m = min(*dest, 2u); break;

						default:        data->m = *dest; break;

					}

					dest++;

					data++;

				}

			} while (!last_item);

		}

	} else {

		if (dest_size < sprite->width * sprite->height) {

			free(sprite->data);

			return WarnCorruptSprite(file_slot, file_pos, __LINE__);

		}

		if (dest_size > sprite->width * sprite->height) {

			static byte warning_level = 0;

			DEBUG(sprite, warning_level, "Ignoring %i unused extra bytes from the sprite from %s at position %i", dest_size - sprite->width * sprite->height, FioGetFilename(file_slot), (int)file_pos);

			warning_level = 6;

		}

		dest = dest_orig;

		for (int i = 0; i < sprite->width * sprite->height; i++) {

			switch (sprite_type) {

				case ST_NORMAL: sprite->data[i].m = _palette_remap_grf[file_slot] ? _palette_remap[dest[i]] : dest[i]; break;

				case ST_FONT:   sprite->data[i].m = min(dest[i], 2u); break;

				default:        sprite->data[i].m = dest[i]; break;

			}

		}

	}

	/* Make sure to mark all transparent pixels transparent on the alpha channel too */

	for (int i = 0; i < sprite->width * sprite->height; i++)

		if (sprite->data[i].m != 0) sprite->data[i].a = 0xFF;

	return true;

}