/* 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/>.
 *
 */

#include "common/file.h"
#include "common/memstream.h"
#include "common/zlib.h"
#include "titanic/support/files_manager.h"
#include "titanic/game_manager.h"
#include "titanic/titanic.h"

namespace Titanic {

CFilesManager::CFilesManager(TitanicEngine *vm) : _vm(vm), _gameManager(nullptr),
		_assetsPath("Assets"), _drive(-1), _version(0) {
}

CFilesManager::~CFilesManager() {
	_datFile.close();
}

bool CFilesManager::loadResourceIndex() {
	if (!_datFile.open("titanic.dat")) {
		GUIErrorMessage("Could not find titanic.dat data file");
		return false;
	}

	uint headerId = _datFile.readUint32BE();
	_version = _datFile.readUint16LE();
	if (headerId != MKTAG('S', 'V', 'T', 'N')) {
		GUIErrorMessage("titanic.dat has invalid contents");
		return false;
	}

	if (_version != 5) {
		GUIErrorMessage("titanic.dat is out of date");
		return false;
	}

	// Read in entries
	uint offset, size, flags;
	char c;
	Common::String resourceName;
	for (;;) {
		offset = _datFile.readUint32LE();
		size = _datFile.readUint32LE();
		flags = (_version == 1) ? 0 : _datFile.readUint16LE();

		if (offset == 0 && size == 0)
			break;

		Common::String resName;
		while ((c = _datFile.readByte()) != '\0')
			resName += c;

		_resources[resName] = ResourceEntry(offset, size, flags);
	}

	return true;
}

bool CFilesManager::fileExists(const CString &name) {
	Common::File f;
	return f.exists(name);
}

bool CFilesManager::scanForFile(const CString &name) {
	if (name.empty())
		return false;

	CString filename = name;
	filename.toLowercase();

	if (filename[0] == 'y' || filename[0] == 'z')
		return true;
	else if (filename[0] < 'a' || filename[0] > 'c')
		return false;

	CString fname = filename;
	int idx = fname.indexOf('#');
	if (idx >= 0) {
		fname = fname.left(idx);
		fname += ".st";
	}

	// Return true if the file exists
	if (fileExists(fname))
		return true;

	// Couldn't find file. Start by calling the game manager's roomChange
	// method, which handles all active scene objects freeing their resources
	if (_gameManager)
		_gameManager->roomChange();

	return false;
}

void CFilesManager::loadDrive() {
	assert(_drive == -1);
	resetView();
}

void CFilesManager::insertCD(CScreenManager *screenManager) {
	// We don't support running the game directly from the original CDs,
	// so this method can remain stubbed
}

void CFilesManager::resetView() {
	if (_gameManager) {
		_gameManager->_gameState.setMode(GSMODE_INTERACTIVE);
		_gameManager->markAllDirty();
	}
}

void CFilesManager::preload(const CString &name) {
	// We don't currently do any preloading of resources
}

Common::SeekableReadStream *CFilesManager::getResource(const CString &str) {
	ResourceEntry resEntry = _resources[str];

	// If we're running the German version, check for the existance of
	// a German specific version of the given resource
	if (_vm->isGerman() && _resources.contains(str + "/DE"))
		resEntry = _resources[str + "/DE"];

	_datFile.seek(resEntry._offset);

	Common::SeekableReadStream *stream = (resEntry._size > 0) ?
		_datFile.readStream(resEntry._size) :
		new Common::MemoryReadStream(nullptr, 0);
	if (resEntry._flags & FLAG_COMPRESSED)
		stream = Common::wrapCompressedReadStream(stream);

	return stream;
}

} // End of namespace Titanic
