/* ResidualVM - A 3D game interpreter
 *
 * ResidualVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the AUTHORS
 * 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 2
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */

#include "engines/myst3/archive.h"
#include "common/debug.h"
#include "common/memstream.h"

namespace Myst3 {

void Archive::_decryptHeader(Common::SeekableReadStream &inStream, Common::WriteStream &outStream) {
	static const uint32 addKey = 0x3C6EF35F;
	static const uint32 multKey = 0x0019660D;

	inStream.seek(0);
	uint32 size = inStream.readUint32LE();

	bool encrypted = size > 1000000;
	
	inStream.seek(0);

	if (encrypted) {
		uint32 decryptedSize = size ^ addKey;

		uint32 currentKey = 0;
		for (uint i = 0; i < decryptedSize; i++) {
			currentKey += addKey;
			outStream.writeUint32LE(inStream.readUint32LE() ^ currentKey);
			currentKey *= multKey;
		}
	} else {
		for (uint i = 0; i < size; i++) {
			outStream.writeUint32LE(inStream.readUint32LE());
		}
	}
}

void Archive::_readDirectory() {
	Common::MemoryWriteStreamDynamic buf(DisposeAfterUse::YES);
	_decryptHeader(_file, buf);

	Common::MemoryReadStream directory(buf.getData(), buf.size());
	directory.skip(sizeof(uint32));

	while (directory.pos() + 4 < directory.size()) {
		DirectoryEntry entry(this);
		
		if (_multipleRoom)
			entry.readFromStream(directory, 0);
		else
			entry.readFromStream(directory, _roomName);

		_directory.push_back(entry);
	}
}

void Archive::dumpToFiles() {
	for (uint i = 0; i < _directory.size(); i++) {
		_directory[i].dumpToFiles(_file);
	}
}

Common::MemoryReadStream *Archive::dumpToMemory(uint32 offset, uint32 size) {
	_file.seek(offset);
	return static_cast<Common::MemoryReadStream *>(_file.readStream(size));
}

const DirectorySubEntry *Archive::getDescription(const char *room, uint32 index, uint16 face, DirectorySubEntry::ResourceType type) {
	for (uint i = 0; i < _directory.size(); i++) {
		if (_directory[i].getIndex() == index
				&& !strcmp(_directory[i].getRoom(), room)) {
			return _directory[i].getItemDescription(face, type);
		}
	}

	return 0;
}

bool Archive::open(const char *fileName, const char *room) {
	// Copy the room name if provided
	// If the room name is not provided, it is assumed that
	// we are opening a multi-room archive
	_multipleRoom = room == 0;
	if (!_multipleRoom)
		Common::strlcpy(_roomName, room, sizeof(_roomName));

	if (_file.open(fileName)) {
		_readDirectory();
		return true;
	}
	
	return false;
}

void Archive::close() {
	_directory.clear();
	_file.close();
}

} // End of namespace Myst3
