/* 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 "sci/engine/message.h"
#include "sci/tools.h"

namespace Sci {

void MessageState::parse(IndexRecordCursor *cursor, MessageTuple *t) {
	t->noun = *(cursor->index_record + 0);
	t->verb = *(cursor->index_record + 1);
	if (_version == 2101) {
		t->cond = 0;
		t->seq = 1;
	} else {
		t->cond = *(cursor->index_record + 2);
		t->seq = *(cursor->index_record + 3);
	}
}

void MessageState::parseRef(IndexRecordCursor *cursor, MessageTuple *t) {
	if (_version == 2101) {
		t->noun = 0;
		t->verb = 0;
		t->cond = 0;
	} else {
		t->noun = *(cursor->index_record + 7);
		t->verb = *(cursor->index_record + 8);
		t->cond = *(cursor->index_record + 9);
	}
	t->seq = 1;
}

void MessageState::initCursor() {
	_engineCursor.index_record = _indexRecords;
	_engineCursor.index = 0;
	_engineCursor.nextSeq = 0;
}

void MessageState::advanceCursor(bool increaseSeq) {
	_engineCursor.index_record += ((_version == 2101) ? 4 : 11);
	_engineCursor.index++;

	if (increaseSeq)
		_engineCursor.nextSeq++;
}

int MessageState::getMessage(MessageTuple *t) {
	// Reset the cursor
	initCursor();
	_engineCursor.nextSeq = t->seq;

	// Do a linear search for the message
	while (1) {
		MessageTuple looking_at;
		parse(&_engineCursor, &looking_at);

		if (t->noun == looking_at.noun && 
			t->verb == looking_at.verb && 
			t->cond == looking_at.cond && 
			t->seq == looking_at.seq)
			break;

		advanceCursor(false);

		// Message tuple is not present
		if (_engineCursor.index == _recordCount)
			return 0;
	}

	return getNext();
}

int MessageState::getNext() {
	if (_engineCursor.index != _recordCount) {
		MessageTuple mesg;
		parse(&_engineCursor, &mesg);
		MessageTuple ref;
		parseRef(&_engineCursor, &ref);

		if (_engineCursor.nextSeq == mesg.seq) {
			// We found the right sequence number, check for recursion

			if (ref.noun != 0) {
				// Recursion, advance the current cursor and load the reference
				advanceCursor(true);

				if (getMessage(&ref))
					return getNext();
				else {
					// Reference not found
					return 0;
				}
			} else {
				// No recursion, we are done
				return 1;
			}
		}
	}

	// We either ran out of records, or found an incorrect sequence number. Go to previous stack frame.
	if (!_cursorStack.empty()) {
		_engineCursor = _cursorStack.pop();
		return getNext();
	}

	// Stack is empty, no message available
	return 0;
}

int MessageState::getTalker() {
	return (_version == 2101) ? -1 : *(_engineCursor.index_record + 4);
}

void MessageState::getText(char *buffer) {
	int offset = READ_LE_UINT16(_engineCursor.index_record + ((_version == 2101) ? 2 : 5));
	char *stringptr = (char *)_currentResource->data + offset;
	strcpy(buffer, stringptr);
	advanceCursor(true);
}

int MessageState::getLength() {
	int offset = READ_LE_UINT16(_engineCursor.index_record + ((_version == 2101) ? 2 : 5));
	char *stringptr = (char *)_currentResource->data + offset;
	return strlen(stringptr);
}

int MessageState::loadRes(ResourceManager *resmgr, int module, bool lock) {
	if (_module == module)
		return 1;

	// Unlock old resource
	if (_module != -1) {
		resmgr->unlockResource(_currentResource, _module, kResourceTypeMessage);
		_module = -1;
	}

	_currentResource = resmgr->findResource(kResourceTypeMessage, module, lock);

	if (_currentResource == NULL || _currentResource->data == NULL) {
		warning("Message subsystem: failed to load %d.msg", module);
		return 0;
	}

	if (lock)
		_module = module;

	_version = READ_LE_UINT16(_currentResource->data);

	int offs = (_version == 2101) ? 0 : 4;
	_recordCount = READ_LE_UINT16(_currentResource->data + 4 + offs);
	_indexRecords = _currentResource->data + 6 + offs;

	_cursorStack.clear();
	initCursor();

	return 1;
}

} // End of namespace Sci