/* 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 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.
 *
 * $URL$
 * $Id$
 *
 */

#include "common/archive.h"
#include "common/file.h"
#include "common/str.h"
#include "common/savefile.h"

#include "sci/sci.h"
#include "sci/engine/state.h"
#include "sci/engine/kernel.h"
#include "sci/engine/savegame.h"
#include "sci/console.h"

namespace Sci {

struct SavegameDesc {
	uint id;
	int virtualId; // straight numbered, according to id but w/o gaps
	int date;
	int time;
	int version;
	char name[SCI_MAX_SAVENAME_LENGTH];
};

/*
 * Note on how file I/O is implemented: In ScummVM, one can not create/write
 * arbitrary data files, simply because many of our target platforms do not
 * support this. The only files one can create are savestates. But SCI has an
 * opcode to create and write to seemingly 'arbitrary' files. This is mainly
 * used in LSL3 for LARRY3.DRV (which is a game data file, not a driver) and
 * in LSL5 for MEMORY.DRV (which is again a game data file and contains the
 * game's password).
 * To implement that opcode, we combine the SaveFileManager with regular file
 * code, similarly to how the SCUMM HE engine does it.
 *
 * To handle opening a file called "foobar", what we do is this: First, we
 * create an 'augmented file name', by prepending the game target and a dash,
 * so if we running game target sq1sci, the name becomes "sq1sci-foobar".
 * Next, we check if such a file is known to the SaveFileManager. If so, we
 * we use that for reading/writing, delete it, whatever.
 *
 * If no such file is present but we were only asked to *read* the file,
 * we fallback to looking for a regular file called "foobar", and open that
 * for reading only.
 */



FileHandle::FileHandle() : _in(0), _out(0) {
}

FileHandle::~FileHandle() {
	close();
}

void FileHandle::close() {
	delete _in;
	delete _out;
	_in = 0;
	_out = 0;
	_name.clear();
}

bool FileHandle::isOpen() const {
	return _in || _out;
}



enum {
	_K_FILE_MODE_OPEN_OR_CREATE = 0,
	_K_FILE_MODE_OPEN_OR_FAIL = 1,
	_K_FILE_MODE_CREATE = 2
};



reg_t file_open(EngineState *s, const char *filename, int mode) {
	// QfG3 character import prepends /\ to the filenames.
	if (filename[0] == '/' && filename[1] == '\\')
		filename += 2;

	Common::String englishName = g_sci->getSciLanguageString(filename, K_LANG_ENGLISH);
	const Common::String wrappedName = g_sci->wrapFilename(englishName);
	Common::SeekableReadStream *inFile = 0;
	Common::WriteStream *outFile = 0;
	Common::SaveFileManager *saveFileMan = g_engine->getSaveFileManager();

	if (mode == _K_FILE_MODE_OPEN_OR_FAIL) {
		// Try to open file, abort if not possible
		inFile = saveFileMan->openForLoading(wrappedName);
		// If no matching savestate exists: fall back to reading from a regular
		// file
		if (!inFile)
			inFile = SearchMan.createReadStreamForMember(englishName);

		// Special case for LSL3: It tries to create a new dummy file,
		// LARRY3.DRV. Apparently, if the file doesn't exist here, it should be
		// created. The game scripts then go ahead and fill its contents with
		// data. It seems to be a similar case as the dummy MEMORY.DRV file in
		// LSL5, but LSL5 creates the file if it can't find it with a separate
		// call to file_open().
		if (!inFile && englishName == "LARRY3.DRV") {
			outFile = saveFileMan->openForSaving(wrappedName);
			outFile->finalize();
			delete outFile;
			outFile = 0;
			inFile = SearchMan.createReadStreamForMember(wrappedName);
		}

		if (!inFile)
			warning("  -> file_open(_K_FILE_MODE_OPEN_OR_FAIL): failed to open file '%s'", englishName.c_str());
	} else if (mode == _K_FILE_MODE_CREATE) {
		// Create the file, destroying any content it might have had
		outFile = saveFileMan->openForSaving(wrappedName);
		if (!outFile)
			warning("  -> file_open(_K_FILE_MODE_CREATE): failed to create file '%s'", englishName.c_str());
	} else if (mode == _K_FILE_MODE_OPEN_OR_CREATE) {
		// Try to open file, create it if it doesn't exist
		outFile = saveFileMan->openForSaving(wrappedName);
		if (!outFile)
			warning("  -> file_open(_K_FILE_MODE_CREATE): failed to create file '%s'", englishName.c_str());
		// QfG1 opens the character export file with _K_FILE_MODE_CREATE first,
		// closes it immediately and opens it again with this here. Perhaps
		// other games use this for read access as well. I guess changing this
		// whole code into using virtual files and writing them after close
		// would be more appropriate.
	} else {
		error("file_open: unsupported mode %d (filename '%s')", mode, englishName.c_str());
	}

	if (!inFile && !outFile) { // Failed
		debugC(2, kDebugLevelFile, "  -> file_open() failed");
		return SIGNAL_REG;
	}

	// Find a free file handle
	uint handle = 1; // Ignore _fileHandles[0]
	while ((handle < s->_fileHandles.size()) && s->_fileHandles[handle].isOpen())
		handle++;

	if (handle == s->_fileHandles.size()) {
		// Hit size limit => Allocate more space
		s->_fileHandles.resize(s->_fileHandles.size() + 1);
	}

	s->_fileHandles[handle]._in = inFile;
	s->_fileHandles[handle]._out = outFile;
	s->_fileHandles[handle]._name = englishName;

	debugC(2, kDebugLevelFile, "  -> opened file '%s' with handle %d", englishName.c_str(), handle);
	return make_reg(0, handle);
}

reg_t kFOpen(EngineState *s, int argc, reg_t *argv) {
	Common::String name = s->_segMan->getString(argv[0]);
	int mode = argv[1].toUint16();

	debugC(2, kDebugLevelFile, "kFOpen(%s,0x%x)", name.c_str(), mode);
	return file_open(s, name.c_str(), mode);
}

static FileHandle *getFileFromHandle(EngineState *s, uint handle) {
	if (handle == 0) {
		error("Attempt to use file handle 0");
		return 0;
	}

	if ((handle >= s->_fileHandles.size()) || !s->_fileHandles[handle].isOpen()) {
		warning("Attempt to use invalid/unused file handle %d", handle);
		return 0;
	}

	return &s->_fileHandles[handle];
}

reg_t kFClose(EngineState *s, int argc, reg_t *argv) {
	debugC(2, kDebugLevelFile, "kFClose(%d)", argv[0].toUint16());
	if (argv[0] != SIGNAL_REG) {
		FileHandle *f = getFileFromHandle(s, argv[0].toUint16());
		if (f)
			f->close();
	}
	return s->r_acc;
}

reg_t kFPuts(EngineState *s, int argc, reg_t *argv) {
	int handle = argv[0].toUint16();
	Common::String data = s->_segMan->getString(argv[1]);
	
	FileHandle *f = getFileFromHandle(s, handle);
	if (f)
		f->_out->write(data.c_str(), data.size());

	return s->r_acc;
}

static void fgets_wrapper(EngineState *s, char *dest, int maxsize, int handle) {
	FileHandle *f = getFileFromHandle(s, handle);
	if (!f)
		return;

	if (!f->_in) {
		error("fgets_wrapper: Trying to read from file '%s' opened for writing", f->_name.c_str());
		return;
	}
	if (maxsize > 1) {
		memset(dest, 0, maxsize);
		f->_in->readLine(dest, maxsize);
		// The returned string must not have an ending LF
		int strSize = strlen(dest);
		if (strSize > 0) {
			if (dest[strSize - 1] == 0x0A)
				dest[strSize - 1] = 0;
		}
	} else {
		*dest = f->_in->readByte();
	}

	debugC(2, kDebugLevelFile, "  -> FGets'ed \"%s\"", dest);
}

reg_t kFGets(EngineState *s, int argc, reg_t *argv) {
	int maxsize = argv[1].toUint16();
	char *buf = new char[maxsize];
	int handle = argv[2].toUint16();

	debugC(2, kDebugLevelFile, "kFGets(%d, %d)", handle, maxsize);
	fgets_wrapper(s, buf, maxsize, handle);
	s->_segMan->memcpy(argv[0], (const byte*)buf, maxsize);
	return argv[0];
}

/**
 * Writes the cwd to the supplied address and returns the address in acc.
 */
reg_t kGetCWD(EngineState *s, int argc, reg_t *argv) {
	// We do not let the scripts see the file system, instead pretending
	// we are always in the same directory.
	// TODO/FIXME: Is "/" a good value? Maybe "" or "." or "C:\" are better?
	s->_segMan->strcpy(argv[0], "/");

	debugC(2, kDebugLevelFile, "kGetCWD() -> %s", "/");

	return argv[0];
}

static void listSavegames(Common::Array<SavegameDesc> &saves);
static int findSavegame(Common::Array<SavegameDesc> &saves, uint saveId);

enum {
	K_DEVICE_INFO_GET_DEVICE = 0,
	K_DEVICE_INFO_GET_CURRENT_DEVICE = 1,
	K_DEVICE_INFO_PATHS_EQUAL = 2,
	K_DEVICE_INFO_IS_FLOPPY = 3,
	K_DEVICE_INFO_GET_CONFIG_PATH = 5,
	K_DEVICE_INFO_GET_SAVECAT_NAME = 7,
	K_DEVICE_INFO_GET_SAVEFILE_NAME = 8
};

reg_t kDeviceInfo(EngineState *s, int argc, reg_t *argv) {
	int mode = argv[0].toUint16();

	switch (mode) {
	case K_DEVICE_INFO_GET_DEVICE: {
		Common::String input_str = s->_segMan->getString(argv[1]);

		s->_segMan->strcpy(argv[2], "/");
		debug(3, "K_DEVICE_INFO_GET_DEVICE(%s) -> %s", input_str.c_str(), "/");
		break;
	}
	case K_DEVICE_INFO_GET_CURRENT_DEVICE:
		s->_segMan->strcpy(argv[1], "/");
		debug(3, "K_DEVICE_INFO_GET_CURRENT_DEVICE() -> %s", "/");
		break;

	case K_DEVICE_INFO_PATHS_EQUAL: {
		Common::String path1_s = s->_segMan->getString(argv[1]);
		Common::String path2_s = s->_segMan->getString(argv[2]);
		debug(3, "K_DEVICE_INFO_PATHS_EQUAL(%s,%s)", path1_s.c_str(), path2_s.c_str());

		return make_reg(0, Common::matchString(path2_s.c_str(), path1_s.c_str(), false, true));
		}
		break;

	case K_DEVICE_INFO_IS_FLOPPY: {
		Common::String input_str = s->_segMan->getString(argv[1]);
		debug(3, "K_DEVICE_INFO_IS_FLOPPY(%s)", input_str.c_str());
		return NULL_REG; /* Never */
	}
	case K_DEVICE_INFO_GET_CONFIG_PATH: {
		// Early versions return drive letter, later versions a path string
		// FIXME: Implement if needed, for now return NULL_REG
		return NULL_REG;
	}
	/* SCI uses these in a less-than-portable way to delete savegames.
	** Read http://www-plan.cs.colorado.edu/creichen/freesci-logs/2005.10/log20051019.html
	** for more information on our workaround for this.
	*/
	case K_DEVICE_INFO_GET_SAVECAT_NAME: {
		Common::String game_prefix = s->_segMan->getString(argv[2]);
		s->_segMan->strcpy(argv[1], "__throwaway");
		debug(3, "K_DEVICE_INFO_GET_SAVECAT_NAME(%s) -> %s", game_prefix.c_str(), "__throwaway");
		}

	break;
	case K_DEVICE_INFO_GET_SAVEFILE_NAME: {
		Common::String game_prefix = s->_segMan->getString(argv[2]);
		uint virtualId = argv[3].toUint16();
		s->_segMan->strcpy(argv[1], "__throwaway");
		debug(3, "K_DEVICE_INFO_GET_SAVEFILE_NAME(%s,%d) -> %s", game_prefix.c_str(), virtualId, "__throwaway");
		if ((virtualId < SAVEGAMEID_OFFICIALRANGE_START) || (virtualId > SAVEGAMEID_OFFICIALRANGE_END))
			error("kDeviceInfo(deleteSave): invalid savegame-id specified");
		uint savegameId = virtualId - SAVEGAMEID_OFFICIALRANGE_START;
		Common::Array<SavegameDesc> saves;
		listSavegames(saves);
		if (findSavegame(saves, savegameId) != -1) {
			// Confirmed that this id still lives...
			Common::String filename = g_sci->getSavegameName(savegameId);
			Common::SaveFileManager *saveFileMan = g_engine->getSaveFileManager();
			saveFileMan->removeSavefile(filename);
		}
		break;
	}

	default:
		error("Unknown DeviceInfo() sub-command: %d", mode);
		break;
	}

	return s->r_acc;
}

reg_t kGetSaveDir(EngineState *s, int argc, reg_t *argv) {
#ifdef ENABLE_SCI32
	// TODO: SCI32 uses a parameter here.
	if (argc > 0)
		warning("kGetSaveDir called with %d parameter(s): %04x:%04x", argc, PRINT_REG(argv[0]));
#endif

	return make_reg(s->_segMan->getSysStringsSegment(), SYS_STRING_SAVEDIR);
}

reg_t kCheckFreeSpace(EngineState *s, int argc, reg_t *argv) {
	if (argc > 1) {
		// SCI1.1/SCI32
		// TODO: don't know if those are right for SCI32 as well
		// Please note that sierra sci supported both calls either w/ or w/o opcode in SCI1.1
		switch (argv[1].toUint16()) {
		case 0: // return saved game size
			return make_reg(0, 0); // we return 0

		case 1: // return free harddisc space (shifted right somehow)
			return make_reg(0, 0x7fff); // we return maximum

		case 2: // same as call w/o opcode
			break;
			return make_reg(0, 1);

		default:
			error("kCheckFreeSpace: called with unknown sub-op %d", argv[1].toUint16());
		}
	}

	Common::String path = s->_segMan->getString(argv[0]);

	debug(3, "kCheckFreeSpace(%s)", path.c_str());
	// We simply always pretend that there is enough space. The alternative
	// would be to write a big test file, which is not nice on systems where
	// doing so is very slow.
	return make_reg(0, 1);
}

static bool _savegame_sort_byDate(const SavegameDesc &l, const SavegameDesc &r) {
	if (l.date != r.date)
		return (l.date > r.date);
	return (l.time > r.time);
}

// Create a sorted array containing all found savedgames
static void listSavegames(Common::Array<SavegameDesc> &saves) {
	Common::SaveFileManager *saveFileMan = g_engine->getSaveFileManager();

	// Load all saves
	Common::StringArray saveNames = saveFileMan->listSavefiles(g_sci->getSavegamePattern());

	for (Common::StringArray::const_iterator iter = saveNames.begin(); iter != saveNames.end(); ++iter) {
		Common::String filename = *iter;
		Common::SeekableReadStream *in;
		if ((in = saveFileMan->openForLoading(filename))) {
			SavegameMetadata meta;
			if (!get_savegame_metadata(in, &meta) || meta.savegame_name.empty()) {
				// invalid
				delete in;
				continue;
			}
			delete in;

			SavegameDesc desc;
			desc.id = strtol(filename.end() - 3, NULL, 10);
			desc.date = meta.savegame_date;
			// We need to fix date in here, because we save DDMMYYYY instead of
			// YYYYMMDD, so sorting wouldn't work
			desc.date = ((desc.date & 0xFFFF) << 16) | ((desc.date & 0xFF0000) >> 8) | ((desc.date & 0xFF000000) >> 24);
			desc.time = meta.savegame_time;
			desc.version = meta.savegame_version;

			if (meta.savegame_name.lastChar() == '\n')
				meta.savegame_name.deleteLastChar();

			Common::strlcpy(desc.name, meta.savegame_name.c_str(), SCI_MAX_SAVENAME_LENGTH);

			debug(3, "Savegame in file %s ok, id %d", filename.c_str(), desc.id);

			saves.push_back(desc);
		}
	}

	// Sort the list by creation date of the saves
	Common::sort(saves.begin(), saves.end(), _savegame_sort_byDate);
}

// Find a savedgame according to virtualId and return the position within our array
static int findSavegame(Common::Array<SavegameDesc> &saves, uint savegameId) {
	for (uint saveNr = 0; saveNr < saves.size(); saveNr++) {
		if (saves[saveNr].id == savegameId)
			return saveNr;
	}
	return -1;
}

// The scripts get IDs ranging from 1000->1999, because the scripts require us to assign unique ids THAT EVEN STAY BETWEEN
//  SAVES and the scripts also use "saves-count + 1" to create a new savedgame slot.
//  SCI1.1 actually recycles ids, in that case we will currently get "0".
// This behaviour is required especially for LSL6. In this game, it's possible to quick save. The scripts will use
//  the last-used id for that feature. If we don't assign sticky ids, the feature will overwrite different saves all the
//  time. And sadly we can't just use the actual filename ids directly, because of the creation method for new slots.

bool Console::cmdListSaves(int argc, const char **argv) {
	Common::Array<SavegameDesc> saves;
	listSavegames(saves);

	for (uint i = 0; i < saves.size(); i++) {
		Common::String filename = g_sci->getSavegameName(saves[i].id);
		DebugPrintf("%s: '%s'\n", filename.c_str(), saves[i].name);
	}

	return true;
}

reg_t kCheckSaveGame(EngineState *s, int argc, reg_t *argv) {
	Common::String game_id = s->_segMan->getString(argv[0]);
	uint16 virtualId = argv[1].toUint16();

	debug(3, "kCheckSaveGame(%s, %d)", game_id.c_str(), virtualId);

	Common::Array<SavegameDesc> saves;
	listSavegames(saves);

	// Find saved-game
	if ((virtualId < SAVEGAMEID_OFFICIALRANGE_START) || (virtualId > SAVEGAMEID_OFFICIALRANGE_END))
		error("kCheckSaveGame: called with invalid savegameId!");
	uint savegameId = virtualId - SAVEGAMEID_OFFICIALRANGE_START;
	int savegameNr = findSavegame(saves, savegameId);
	if (savegameNr == -1)
		return NULL_REG;

	// Check for compatible savegame version
	int ver = saves[savegameNr].version;
	if (ver < MINIMUM_SAVEGAME_VERSION || ver > CURRENT_SAVEGAME_VERSION)
		return NULL_REG;

	// Otherwise we assume the savegame is OK
	return make_reg(0, 1);
}

reg_t kGetSaveFiles(EngineState *s, int argc, reg_t *argv) {
	Common::String game_id = s->_segMan->getString(argv[0]);

	debug(3, "kGetSaveFiles(%s)", game_id.c_str());

	// Scripts ask for current save files, we can assume that if afterwards they ask us to create a new slot they really
	//  mean new slot instead of overwriting the old one
	s->_lastSaveVirtualId = SAVEGAMEID_OFFICIALRANGE_START;

	Common::Array<SavegameDesc> saves;
	listSavegames(saves);
	uint totalSaves = MIN<uint>(saves.size(), MAX_SAVEGAME_NR);

	reg_t *slot = s->_segMan->derefRegPtr(argv[2], totalSaves);

	if (!slot) {
		warning("kGetSaveFiles: %04X:%04X invalid or too small to hold slot data", PRINT_REG(argv[2]));
		totalSaves = 0;
	}

	const uint bufSize = (totalSaves * SCI_MAX_SAVENAME_LENGTH) + 1;
	char *saveNames = new char[bufSize];
	char *saveNamePtr = saveNames;

	for (uint i = 0; i < totalSaves; i++) {
		*slot++ = make_reg(0, saves[i].id + SAVEGAMEID_OFFICIALRANGE_START); // Store the virtual savegame-id ffs. see above
		strcpy(saveNamePtr, saves[i].name);
		saveNamePtr += SCI_MAX_SAVENAME_LENGTH;
	}

	*saveNamePtr = 0; // Terminate list

	s->_segMan->memcpy(argv[1], (byte *)saveNames, bufSize);
	delete[] saveNames;

	return make_reg(0, totalSaves);
}

reg_t kSaveGame(EngineState *s, int argc, reg_t *argv) {
	Common::String game_id = s->_segMan->getString(argv[0]);
	uint virtualId = argv[1].toUint16();
	Common::String game_description = s->_segMan->getString(argv[2]);
	Common::String version;
	if (argc > 3)
		version = s->_segMan->getString(argv[3]);

	debug(3, "kSaveGame(%s,%d,%s,%s)", game_id.c_str(), virtualId, game_description.c_str(), version.c_str());

	// We check here, we don't want to delete a users save in case we are within a kernel function
	if (s->executionStackBase) {
		warning("kSaveGame - won't save from within kernel function");
		return NULL_REG;
	}

	Common::Array<SavegameDesc> saves;
	listSavegames(saves);

	uint savegameId;
	if ((virtualId >= SAVEGAMEID_OFFICIALRANGE_START) && (virtualId <= SAVEGAMEID_OFFICIALRANGE_END)) {
		// savegameId is an actual Id, so search for it just to make sure
		savegameId = virtualId - SAVEGAMEID_OFFICIALRANGE_START;
		if (findSavegame(saves, savegameId) == -1)
			return NULL_REG;
	} else if (virtualId < SAVEGAMEID_OFFICIALRANGE_START) {
		// virtualId is low, we assume that scripts expect us to create new slot
		if (virtualId == s->_lastSaveVirtualId) {
			// if last virtual id is the same as this one, we assume that caller wants to overwrite last save
			savegameId = s->_lastSaveNewId;
		} else {
			uint savegameNr;
			// savegameId is in lower range, scripts expect us to create a new slot
			for (savegameId = 0; savegameId < SAVEGAMEID_OFFICIALRANGE_START; savegameId++) {
				for (savegameNr = 0; savegameNr < saves.size(); savegameNr++) {
					if (savegameId == saves[savegameNr].id)
						break;
				}
				if (savegameNr == saves.size())
					break;
			}
			if (savegameId == SAVEGAMEID_OFFICIALRANGE_START)
				error("kSavegame: no more savegame slots available");
		}
	} else {
		error("kSaveGame: invalid savegameId used");
	}

	// Save in case caller wants to overwrite last newly created save
	s->_lastSaveVirtualId = virtualId;
	s->_lastSaveNewId = savegameId;

	Common::String filename = g_sci->getSavegameName(savegameId);
	Common::SaveFileManager *saveFileMan = g_engine->getSaveFileManager();
	Common::OutSaveFile *out;
	if (!(out = saveFileMan->openForSaving(filename))) {
		warning("Error opening savegame \"%s\" for writing", filename.c_str());
		s->r_acc = NULL_REG;
		return NULL_REG;
	}

	if (!gamestate_save(s, out, game_description.c_str(), version.c_str())) {
		warning("Saving the game failed.");
		s->r_acc = NULL_REG;
	} else {
		out->finalize();
		if (out->err()) {
			delete out;
			warning("Writing the savegame failed.");
			s->r_acc = NULL_REG;
		} else {
			delete out;
			s->r_acc = make_reg(0, 1);
		}
	}

	return s->r_acc;
}

reg_t kRestoreGame(EngineState *s, int argc, reg_t *argv) {
	Common::String game_id = !argv[0].isNull() ? s->_segMan->getString(argv[0]) : "";
	uint savegameId = argv[1].toUint16();

	debug(3, "kRestoreGame(%s,%d)", game_id.c_str(), savegameId);

	if (argv[0].isNull()) {
		// Loading from the launcher, don't adjust the ID of the saved game
	} else {
		if ((savegameId < 1000) || (savegameId > 1999)) {
			warning("Savegame ID %d is not allowed", savegameId);
			return TRUE_REG;
		}
		savegameId -= 1000;
	}

	Common::Array<SavegameDesc> saves;
	listSavegames(saves);
	if (findSavegame(saves, savegameId) == -1) {
		warning("Savegame ID %d not found", savegameId);
		return TRUE_REG;
	}

	Common::SaveFileManager *saveFileMan = g_engine->getSaveFileManager();
	Common::String filename = g_sci->getSavegameName(savegameId);
	Common::SeekableReadStream *in;
	if ((in = saveFileMan->openForLoading(filename))) {
		// found a savegame file

		gamestate_restore(s, in);
		delete in;

		return s->r_acc;
	}

	s->r_acc = TRUE_REG;
	warning("Savegame #%d not found", savegameId);

	return s->r_acc;
}

reg_t kValidPath(EngineState *s, int argc, reg_t *argv) {
	Common::String path = s->_segMan->getString(argv[0]);

	debug(3, "kValidPath(%s) -> %d", path.c_str(), s->r_acc.offset);

	// Always return true
	return make_reg(0, 1);
}

reg_t DirSeeker::firstFile(const Common::String &mask, reg_t buffer, SegManager *segMan) {
	// Verify that we are given a valid buffer
	if (!buffer.segment) {
		error("DirSeeker::firstFile('%s') invoked with invalid buffer", mask.c_str());
		return NULL_REG;
	}
	_outbuffer = buffer;

	// Prefix the mask
	const Common::String wrappedMask = g_sci->wrapFilename(mask);

	// Obtain a list of all savefiles matching the given mask
	Common::SaveFileManager *saveFileMan = g_engine->getSaveFileManager();
	_savefiles = saveFileMan->listSavefiles(wrappedMask);

	// Reset the list iterator and write the first match to the output buffer,
	// if any.
	_iter = _savefiles.begin();
	return nextFile(segMan);
}

reg_t DirSeeker::nextFile(SegManager *segMan) {
	if (_iter == _savefiles.end()) {
		return NULL_REG;
	}

	const Common::String wrappedString = *_iter;

	// Strip the prefix
	Common::String string = g_sci->unwrapFilename(wrappedString);
	if (string.size() > 12)
		string = Common::String(string.c_str(), 12);
	segMan->strcpy(_outbuffer, string.c_str());

	// Return the result and advance the list iterator :)
	++_iter;
	return _outbuffer;
}

reg_t kFileIO(EngineState *s, int argc, reg_t *argv) {
	if (!s)
		return make_reg(0, getSciVersion());
	error("not supposed to call this");
}

reg_t kFileIOOpen(EngineState *s, int argc, reg_t *argv) {
	Common::String name = s->_segMan->getString(argv[0]);

	// SCI32 can call K_FILEIO_OPEN with only one argument. It seems to
	// just be checking if it exists.
	int mode = (argc < 2) ? (int)_K_FILE_MODE_OPEN_OR_FAIL : argv[1].toUint16();

	// SQ4 floppy prepends /\ to the filenames
	if (name.hasPrefix("/\\")) {
		name.deleteChar(0);
		name.deleteChar(0);
	}

	// SQ4 floppy attempts to update the savegame index file sq4sg.dir when
	// deleting saved games. We don't use an index file for saving or
	// loading, so just stop the game from modifying the file here in order
	// to avoid having it saved in the ScummVM save directory.
	if (name == "sq4sg.dir") {
		debugC(2, kDebugLevelFile, "Not opening unused file sq4sg.dir");
		return SIGNAL_REG;
	}

	if (name.empty()) {
		warning("Attempted to open a file with an empty filename");
		return SIGNAL_REG;
	}
	debugC(2, kDebugLevelFile, "kFileIO(open): %s, 0x%x", name.c_str(), mode);
	return file_open(s, name.c_str(), mode);
}

reg_t kFileIOClose(EngineState *s, int argc, reg_t *argv) {
	debugC(2, kDebugLevelFile, "kFileIO(close): %d", argv[0].toUint16());

	FileHandle *f = getFileFromHandle(s, argv[0].toUint16());
	if (f) {
		f->close();
		return SIGNAL_REG;
	}
	return NULL_REG;
}

reg_t kFileIOReadRaw(EngineState *s, int argc, reg_t *argv) {
	int handle = argv[0].toUint16();
	int size = argv[2].toUint16();
	int bytesRead = 0;
	char *buf = new char[size];
	debugC(2, kDebugLevelFile, "kFileIO(readRaw): %d, %d", handle, size);
		
	FileHandle *f = getFileFromHandle(s, handle);
	if (f) {
		bytesRead = f->_in->read(buf, size);
		s->_segMan->memcpy(argv[1], (const byte*)buf, size);
	}

	delete[] buf;
	return make_reg(0, bytesRead);
}

reg_t kFileIOWriteRaw(EngineState *s, int argc, reg_t *argv) {
	int handle = argv[0].toUint16();
	int size = argv[2].toUint16();
	char *buf = new char[size];
	bool success = false;
	s->_segMan->memcpy((byte*)buf, argv[1], size);
	debugC(2, kDebugLevelFile, "kFileIO(writeRaw): %d, %d", handle, size);

	FileHandle *f = getFileFromHandle(s, handle);
	if (f) {
		f->_out->write(buf, size);
		success = true;
	}

	delete[] buf;
	if (success)
		return NULL_REG;
	return make_reg(0, 6); // DOS - invalid handle
}

reg_t kFileIOUnlink(EngineState *s, int argc, reg_t *argv) {
	Common::String name = s->_segMan->getString(argv[0]);
	Common::SaveFileManager *saveFileMan = g_engine->getSaveFileManager();
	bool result;

	// SQ4 floppy prepends /\ to the filenames
	if (name.hasPrefix("/\\")) {
		name.deleteChar(0);
		name.deleteChar(0);
	}

	// Special case for SQ4 floppy: This game has hardcoded names for all of
	// its savegames, and they are all named "sq4sg.xxx", where xxx is the
	// slot. We just take the slot number here, and delete the appropriate
	// save game.
	if (name.hasPrefix("sq4sg.")) {
		// Special handling for SQ4... get the slot number and construct the
		// save game name.
		int slotNum = atoi(name.c_str() + name.size() - 3);
		Common::Array<SavegameDesc> saves;
		listSavegames(saves);
		int savedir_nr = saves[slotNum].id;
		name = g_sci->getSavegameName(savedir_nr);
		result = saveFileMan->removeSavefile(name);
	} else {
		const Common::String wrappedName = g_sci->wrapFilename(name);
		result = saveFileMan->removeSavefile(wrappedName);
	}

	debugC(2, kDebugLevelFile, "kFileIO(unlink): %s", name.c_str());
	if (result)
		return NULL_REG;
	return make_reg(0, 2); // DOS - file not found error code
}

reg_t kFileIOReadString(EngineState *s, int argc, reg_t *argv) {
	int size = argv[1].toUint16();
	char *buf = new char[size];
	int handle = argv[2].toUint16();
	debugC(2, kDebugLevelFile, "kFileIO(readString): %d, %d", handle, size);

	fgets_wrapper(s, buf, size, handle);
	s->_segMan->memcpy(argv[0], (const byte*)buf, size);
	delete[] buf;
	return argv[0];
}

reg_t kFileIOWriteString(EngineState *s, int argc, reg_t *argv) {
	int handle = argv[0].toUint16();
	Common::String str = s->_segMan->getString(argv[1]);
	debugC(2, kDebugLevelFile, "kFileIO(writeString): %d", handle);

	FileHandle *f = getFileFromHandle(s, handle);
	if (f)
		f->_out->write(str.c_str(), str.size());
		return NULL_REG;
	return make_reg(0, 6); // DOS - invalid handle
}

reg_t kFileIOSeek(EngineState *s, int argc, reg_t *argv) {
	int handle = argv[0].toUint16();
	int offset = argv[1].toUint16();
	int whence = argv[2].toUint16();
	debugC(2, kDebugLevelFile, "kFileIO(seek): %d, %d, %d", handle, offset, whence);
		
	FileHandle *f = getFileFromHandle(s, handle);
	if (f)
		s->r_acc = make_reg(0, f->_in->seek(offset, whence));
	return SIGNAL_REG;
}

reg_t kFileIOFindFirst(EngineState *s, int argc, reg_t *argv) {
	Common::String mask = s->_segMan->getString(argv[0]);
	reg_t buf = argv[1];
	int attr = argv[2].toUint16(); // We won't use this, Win32 might, though...
	debugC(2, kDebugLevelFile, "kFileIO(findFirst): %s, 0x%x", mask.c_str(), attr);

	// QfG3 uses "/\*.*" for the character import, QfG4 uses "/\*"
	if (mask.hasPrefix("/\\")) {
		mask.deleteChar(0);
		mask.deleteChar(0);
	}

	// We remove ".*". mask will get prefixed, so we will return all additional files for that gameid
	if (mask == "*.*")
		mask = "*";
	return s->_dirseeker.firstFile(mask, buf, s->_segMan);
}

reg_t kFileIOFindNext(EngineState *s, int argc, reg_t *argv) {
	debugC(2, kDebugLevelFile, "kFileIO(findNext)");
	return s->_dirseeker.nextFile(s->_segMan);
}

reg_t kFileIOExists(EngineState *s, int argc, reg_t *argv) {
	Common::String name = s->_segMan->getString(argv[0]);

	// Check for regular file
	bool exists = Common::File::exists(name);
	Common::SaveFileManager *saveFileMan = g_engine->getSaveFileManager();
	const Common::String wrappedName = g_sci->wrapFilename(name);

	if (!exists)
		exists = !saveFileMan->listSavefiles(name).empty();

	if (!exists) {
		// Try searching for the file prepending target-
		Common::SeekableReadStream *inFile = saveFileMan->openForLoading(wrappedName);
		exists = (inFile != 0);
		delete inFile;
	}

	// Special case for non-English versions of LSL5: The English version of
	// LSL5 calls kFileIO(), case K_FILEIO_OPEN for reading to check if
	// memory.drv exists (which is where the game's password is stored). If
	// it's not found, it calls kFileIO() again, case K_FILEIO_OPEN for
	// writing and creates a new file. Non-English versions call kFileIO(),
	// case K_FILEIO_FILE_EXISTS instead, and fail if memory.drv can't be
	// found. We create a default memory.drv file with no password, so that
	// the game can continue.
	if (!exists && name == "memory.drv") {
		// Create a new file, and write the bytes for the empty password
		// string inside
		byte defaultContent[] = { 0xE9, 0xE9, 0xEB, 0xE1, 0x0D, 0x0A, 0x31, 0x30, 0x30, 0x30 };
		Common::WriteStream *outFile = saveFileMan->openForSaving(wrappedName);
		for (int i = 0; i < 10; i++)
			outFile->writeByte(defaultContent[i]);
		outFile->finalize();
		delete outFile;
		exists = true;
	}

	debugC(2, kDebugLevelFile, "kFileIO(fileExists) %s -> %d", name.c_str(), exists);
	return make_reg(0, exists);
}

reg_t kFileIORename(EngineState *s, int argc, reg_t *argv) {
	Common::String oldName = s->_segMan->getString(argv[0]);
	Common::String newName = s->_segMan->getString(argv[1]);

	// SCI1.1 returns 0 on success and a DOS error code on fail. SCI32
	// returns -1 on fail. We just return -1 for all versions.
	if (g_engine->getSaveFileManager()->renameSavefile(oldName, newName))
		return NULL_REG;
	else
		return SIGNAL_REG;
}

#ifdef ENABLE_SCI32
reg_t kFileIOReadByte(EngineState *s, int argc, reg_t *argv) {
	// Read the byte into the low byte of the accumulator
	FileHandle *f = getFileFromHandle(s, argv[0].toUint16());
	if (!f)
		return NULL_REG;
	return make_reg(0, (s->r_acc.toUint16() & 0xff00) | f->_in->readByte());
}

reg_t kFileIOWriteByte(EngineState *s, int argc, reg_t *argv) {
	FileHandle *f = getFileFromHandle(s, argv[0].toUint16());
	if (f)
		f->_out->writeByte(argv[1].toUint16() & 0xff);
	return s->r_acc; // FIXME: does this really doesn't return anything?
}

reg_t kFileIOReadWord(EngineState *s, int argc, reg_t *argv) {
	FileHandle *f = getFileFromHandle(s, argv[0].toUint16());
	if (!f)
		return NULL_REG;
	return make_reg(0, f->_in->readUint16LE());
}

reg_t kFileIOWriteWord(EngineState *s, int argc, reg_t *argv) {
	FileHandle *f = getFileFromHandle(s, argv[0].toUint16());
	if (f)
		f->_out->writeUint16LE(argv[1].toUint16());
	return s->r_acc; // FIXME: does this really doesn't return anything?
}

reg_t kCD(EngineState *s, int argc, reg_t *argv) {
	// TODO: Stub
	switch (argv[0].toUint16()) {
	case 0:
		// Return whether the contents of disc argv[1] is available.
		return TRUE_REG;
	default:
		warning("CD(%d)", argv[0].toUint16());
	}

	return NULL_REG;
}

reg_t kSave(EngineState *s, int argc, reg_t *argv) {
	switch (argv[0].toUint16()) {
	case 0: // Called by kq7 when starting chapters
		return SIGNAL_REG;
	case 2: // GetSaveDir
		// Yay! Reusing the old kernel function!
		return kGetSaveDir(s, argc - 1, argv + 1);
	case 8:
		// TODO
		// This function has to return something other than 0 to proceed
		return s->r_acc;
	default:
		warning("Unknown/unhandled kSave subop %d", argv[0].toUint16());
	}

	return NULL_REG;
}

#endif

} // End of namespace Sci