/* 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 "agi/agi.h"
#include "agi/lzw.h"
#include "agi/words.h"

#include "common/config-manager.h"
#include "common/fs.h"
#include "common/textconsole.h"

namespace Agi {

int AgiLoader_v3::detectGame() {
	int ec = errUnk;
	bool found = false;

	Common::FSList fslist;
	Common::FSNode dir(ConfMan.getPath("path"));

	if (!dir.getChildren(fslist, Common::FSNode::kListFilesOnly)) {
		warning("AgiLoader_v3: invalid game path '%s'", dir.getPath().toString(Common::Path::kNativeSeparator).c_str());
		return errInvalidAGIFile;
	}

	for (Common::FSList::const_iterator file = fslist.begin(); file != fslist.end() && !found; ++file) {
		Common::String f = file->getName();
		f.toLowercase();

		if (f.hasSuffix("dir")) {
			memset(_vm->_game.name, 0, 8);
			strncpy(_vm->_game.name, f.c_str(), MIN((uint)6, f.size() > 3 ? f.size() - 3 : f.size()));
			debugC(3, kDebugLevelMain, "game.name = %s", _vm->_game.name);

			ec = errOK;

			found = true;
		}
	}

	if (!found) {
		debugC(3, kDebugLevelMain, "directory file not found");
		ec = errInvalidAGIFile;
	}

	return ec;
}

int AgiLoader_v3::loadDir(AgiDir *agid, Common::File *fp, uint32 offs, uint32 len) {
	fp->seek(offs, SEEK_SET);
	uint8 *mem = (uint8 *)malloc(len);
	if (mem == nullptr) {
		return errNotEnoughMemory;
	}

	fp->read(mem, len);

	// initialize directory entries to empty
	for (int i = 0; i < MAX_DIRECTORY_ENTRIES; i++) {
		agid[i].volume = 0xff;
		agid[i].offset = _EMPTY;
	}

	// read directory entries
	for (uint32 i = 0; i + 2 < len; i += 3) {
		agid[i / 3].volume = *(mem + i) >> 4;
		agid[i / 3].offset = READ_BE_UINT24(mem + i) & (uint32) _EMPTY;
		debugC(3, kDebugLevelResources, "%d: volume %d, offset 0x%05x", i / 3, agid[i / 3].volume, agid[i / 3].offset);
	}	

	free(mem);
	return errOK;
}

int AgiLoader_v3::init() {
	int ec = errOK;
	uint8 fileHeader[8];
	Common::File fp;
	Common::Path path;

	if (_vm->getPlatform() == Common::kPlatformAmiga) {
		path = Common::Path("dirs");
		_vm->_game.name[0] = 0; // Empty prefix
	} else {
		path = Common::Path(Common::String(_vm->_game.name) + DIR_);
	}

	if (!fp.open(path)) {
		warning("Failed to open '%s'", path.toString().c_str());
		return errBadFileOpen;
	}
	// build offset table for v3 directory format
	fp.read(&fileHeader, 8);
	fp.seek(0, SEEK_END);

	uint16 dirOffsets[4];
	for (int i = 0; i < 4; i++)
		dirOffsets[i] = READ_LE_UINT16(&fileHeader[i * 2]);

	uint32 dirLengths[4];
	dirLengths[0] = dirOffsets[1] - dirOffsets[0];
	dirLengths[1] = dirOffsets[2] - dirOffsets[1];
	dirLengths[2] = dirOffsets[3] - dirOffsets[2];
	dirLengths[3] = fp.pos() - dirOffsets[3];

	if (dirLengths[3] > 256 * 3)
		dirLengths[3] = 256 * 3;

	fp.seek(0, SEEK_SET);

	// read in directory files
	ec = loadDir(_vm->_game.dirLogic, &fp, dirOffsets[0], dirLengths[0]);
	if (ec == errOK)
		ec = loadDir(_vm->_game.dirPic, &fp, dirOffsets[1], dirLengths[1]);
	if (ec == errOK)
		ec = loadDir(_vm->_game.dirView, &fp, dirOffsets[2], dirLengths[2]);
	if (ec == errOK)
		ec = loadDir(_vm->_game.dirSound, &fp, dirOffsets[3], dirLengths[3]);

	return ec;
}

void AgiLoader_v3::unloadResource(int16 resourceType, int16 resourceNr) {
	switch (resourceType) {
	case RESOURCETYPE_LOGIC:
		_vm->unloadLogic(resourceNr);
		break;
	case RESOURCETYPE_PICTURE:
		_vm->_picture->unloadPicture(resourceNr);
		break;
	case RESOURCETYPE_VIEW:
		_vm->unloadView(resourceNr);
		break;
	case RESOURCETYPE_SOUND:
		_vm->_sound->unloadSound(resourceNr);
		break;
	default:
		break;
	}
}

/**
 * This function loads a raw resource into memory.
 * If further decoding is required, it must be done by another
 * routine.
 *
 * NULL is returned if unsuccessful.
 */
uint8 *AgiLoader_v3::loadVolRes(AgiDir *agid) {
	uint8 volumeHeader[7];
	uint8 *data = nullptr;
	Common::File fp;
	Common::Path path;

	debugC(3, kDebugLevelResources, "(%p)", (void *)agid);
	if (_vm->getPlatform() == Common::kPlatformMacintosh) {
		path = Common::String::format("vol.%i", agid->volume);
	} else {
		path = Common::String::format("%svol.%i", _vm->_game.name, agid->volume);
	}

	if (agid->offset != _EMPTY && fp.open(path)) {
		fp.seek(agid->offset, SEEK_SET);
		fp.read(&volumeHeader, 7);

		uint16 signature = READ_BE_UINT16(volumeHeader);
		if (signature != 0x1234) {
			warning("AgiLoader_v3::loadVolRes: bad signature %04x", signature);
			return nullptr;
		}

		agid->len = READ_LE_UINT16(volumeHeader + 3);    // uncompressed size
		agid->clen = READ_LE_UINT16(volumeHeader + 5);   // compressed len

		uint8 *compBuffer = (uint8 *)calloc(1, agid->clen + 32); // why the extra 32 bytes?
		fp.read(compBuffer, agid->clen);

		if (volumeHeader[2] & 0x80) { // compressed pic
			// effectively uncompressed, but having only 4-bit parameters for F0 / F2 commands
			// Manhunter 2 uses such pictures
			data = compBuffer;
			agid->flags |= RES_PICTURE_V3_NIBBLE_PARM;
		} else if (agid->len == agid->clen) {
			// do not decompress
			data = compBuffer;
		} else {
			// it is compressed
			data = (uint8 *)calloc(1, agid->len + 32); // why the extra 32 bytes?
			lzwExpand(compBuffer, data, agid->len);
			free(compBuffer);
			agid->flags |= RES_COMPRESSED;
		}
	} else {
		// we have a bad volume resource
		// set that resource to NA
		agid->offset = _EMPTY;
	}

	return data;
}

/**
 * Loads a resource into memory, a raw resource is loaded in
 * with above routine, then further decoded here.
 */
int AgiLoader_v3::loadResource(int16 resourceType, int16 resourceNr) {
	int ec = errOK;
	uint8 *data = nullptr;

	if (resourceNr >= MAX_DIRECTORY_ENTRIES)
		return errBadResource;

	switch (resourceType) {
	case RESOURCETYPE_LOGIC:
		// load resource into memory, decrypt messages at the end
		// and build the message list (if logic is in memory)
		if (~_vm->_game.dirLogic[resourceNr].flags & RES_LOADED) {
			// if logic is already in memory, unload it
			unloadResource(RESOURCETYPE_LOGIC, resourceNr);

			// load raw resource into data
			data = loadVolRes(&_vm->_game.dirLogic[resourceNr]);
			_vm->_game.logics[resourceNr].data = data;

			// uncompressed logic files need to be decrypted
			if (data != nullptr) {
				// RES_LOADED flag gets set by decode logic
				// needed to build string table
				ec = _vm->decodeLogic(resourceNr);
				_vm->_game.logics[resourceNr].sIP = 2;
			} else {
				ec = errBadResource;
			}
		}

		// reset code pointers in case logic was cached
		_vm->_game.logics[resourceNr].cIP = _vm->_game.logics[resourceNr].sIP;
		break;
	case RESOURCETYPE_PICTURE:
		// if picture is currently NOT loaded *OR* cacheing is off,
		// unload the resource (caching==off) and reload it
		if (~_vm->_game.dirPic[resourceNr].flags & RES_LOADED) {
			unloadResource(RESOURCETYPE_PICTURE, resourceNr);
			data = loadVolRes(&_vm->_game.dirPic[resourceNr]);
			if (data != nullptr) {
				_vm->_game.pictures[resourceNr].rdata = data;
				_vm->_game.dirPic[resourceNr].flags |= RES_LOADED;
			} else {
				ec = errBadResource;
			}
		}
		break;
	case RESOURCETYPE_SOUND:
		if (_vm->_game.dirSound[resourceNr].flags & RES_LOADED)
			break;

		data = loadVolRes(&_vm->_game.dirSound[resourceNr]);

		// "data" is freed by objects created by createFromRawResource on success
		_vm->_game.sounds[resourceNr] = AgiSound::createFromRawResource(data, _vm->_game.dirSound[resourceNr].len, resourceNr, _vm->_soundemu);
		if (_vm->_game.sounds[resourceNr] != nullptr) {
			_vm->_game.dirSound[resourceNr].flags |= RES_LOADED;
		} else {
			free(data);
			ec = errBadResource;
		}
		break;
	case RESOURCETYPE_VIEW:
		// Load a VIEW resource into memory...
		// Since VIEWS alter the view table ALL the time can we
		// cache the view? or must we reload it all the time?
		//
		// load a raw view from a VOL file into data
		if (_vm->_game.dirView[resourceNr].flags & RES_LOADED)
			break;

		unloadResource(RESOURCETYPE_VIEW, resourceNr);
		data = loadVolRes(&_vm->_game.dirView[resourceNr]);
		if (data != nullptr) {
			_vm->_game.dirView[resourceNr].flags |= RES_LOADED;
			ec = _vm->decodeView(data, _vm->_game.dirView[resourceNr].len, resourceNr);
			free(data);
		} else {
			ec = errBadResource;
		}
		break;
	default:
		ec = errBadResource;
		break;
	}

	return ec;
}

int AgiLoader_v3::loadObjects(const char *fname) {
	return _vm->loadObjects(fname);
}

int AgiLoader_v3::loadWords(const char *fname) {
	return _vm->_words->loadDictionary(fname);
}

} // End of namespace Agi