/* 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/>.
 *
 */

/*
 * This file is based on Wintermute Engine
 * http://dead-code.org/redir.php?target=wme
 * Copyright (c) 2011 Jan Nedoma
 */

#include "engines/wintermute/video/video_subtitler.h"
#include "engines/wintermute/base/base_file_manager.h"
#include "engines/wintermute/utils/path_util.h"
#include "engines/wintermute/base/font/base_font.h"
#include "engines/wintermute/base/base_game.h"
#include "engines/wintermute/base/gfx/base_renderer.h"

namespace Wintermute {

VideoSubtitler::VideoSubtitler(BaseGame *inGame): BaseClass(inGame) {
	_lastSample = -1;
	_currentSubtitle = 0;
	_showSubtitle = false;
}

VideoSubtitler::~VideoSubtitler(void) {
	_subtitles.clear();
}

bool VideoSubtitler::loadSubtitles(const Common::String &filename, const Common::String &subtitleFile) {
	if (filename.size() == 0) {
		return false;
	}

	_subtitles.clear();

	_lastSample = -1;
	_currentSubtitle = 0;
	_showSubtitle = false;

	Common::String newFile;

	/*
	 * Okay, the expected behaviour is this: either we are
	 * provided with a subtitle file to use by the script when
	 * calling PlayTheora(), or we try to autodetect a suitable
	 * one which, for /some/path/movie/ogg is to be called
	 * /some/path/movie.sub
	 */
	if (subtitleFile.size() != 0) {
		newFile = subtitleFile;
	} else {
		Common::String path = PathUtil::getDirectoryName(filename);
		Common::String name = PathUtil::getFileNameWithoutExtension(filename);
		Common::String ext = ".SUB";
		newFile = PathUtil::combine(path, name + ext);
	}

	Common::SeekableReadStream *file = BaseFileManager::getEngineInstance()->openFile(newFile, true, false);

	if (file == nullptr) {
		return false; // no subtitles
	}

	int fileSize = file->size();
	char *buffer = new char[fileSize];

	file->read(buffer, fileSize);

	/* This is where we parse .sub files.
	 * Subtitles cards are in the form
	 * {StartFrame}{EndFrame} FirstLine | SecondLine \n
	 */
	int pos = 0;

	while (pos < fileSize) {
		char *tokenStart = 0;
		int tokenLength = 0;
		int tokenPos = -1;
		int lineLength = 0;
		int start = -1;
		int end = -1;
		bool inToken = false;

		while (pos + lineLength < fileSize &&
				buffer[pos + lineLength] != '\n' &&
				buffer[pos + lineLength] != '\0') {
			// Measure the line until we hit EOL, EOS or just hit the boundary
			lineLength++;
		}

		int realLength;

		if (pos + lineLength >= fileSize) {
			realLength = lineLength - 0;
		} else {
			// If we got here the above loop exited after hitting "\0" "\n"
			realLength = lineLength - 1;
		}

		Common::String cardText;
		char *fileLine = (char *)&buffer[pos];

		for (int i = 0; i < realLength; i++) {
			if (fileLine[i] == '{') {
				if (!inToken) {
					// We've hit the start of a Start/EndFrame token
					inToken = true;
					tokenStart = fileLine + i + 1;
					tokenLength = 0;
					tokenPos++;
				} else {
					// Actually, we were already inside an (invalid) one.
					tokenLength++;
				}
			} else if (fileLine[i] == '}') {
				if (inToken) {
					// we were /inside/ a {.*} token, so this is the end of the block
					inToken = false;
					char *token = new char[tokenLength + 1];
					strncpy(token, tokenStart, tokenLength);
					token[tokenLength] = '\0';
					if (tokenPos == 0) {
						// Was this StartFrame...
						start = atoi(token);
					} else if (tokenPos == 1) {
						// Or the EndFrame?
						end = atoi(token);
					}
					delete[] token;
				} else {
					// This char is part of the plain text, just append it
					cardText += fileLine[i];
				}
			} else {
				if (inToken) {
					tokenLength++;
				} else {
					if (fileLine[i] == '|') {
						// The pipe character signals a linebreak in the text
						cardText += '\n';
					} else {
						// This char is part of the plain text, just append it
						cardText += fileLine[i];
					}
				}
			}
		}

		if (start != -1 && cardText.size() > 0 && (start != 1 || end != 1)){
			// Add a subtitlecard based on the line we have just parsed
			_subtitles.push_back(SubtitleCard(_gameRef, cardText, start, end));
		}

		pos += lineLength + 1;
	}

	delete[] buffer;
	// Succeeded loading subtitles!

	return true;
}

void VideoSubtitler::display() {
	if (_showSubtitle) {

		BaseFont *font;

		if (_gameRef->getVideoFont() == nullptr) {
			font = _gameRef->getSystemFont();
		} else {
			font = _gameRef->getVideoFont();
		}

		int textHeight = font->getTextHeight(
		                     (const byte *)_subtitles[_currentSubtitle].getText().c_str(),
		                     _gameRef->_renderer->getWidth());

		font->drawText(
		    (const byte *)_subtitles[_currentSubtitle].getText().c_str(),
		    0,
		    (_gameRef->_renderer->getHeight() - textHeight - 5),
		    (_gameRef->_renderer->getWidth()),
		    TAL_CENTER);
	}
}

void VideoSubtitler::update(uint32 frame) {
	if (_subtitles.size() == 0) {
		// Edge case: we have loaded subtitles early on... from a blank file.
		return;
	}

	if ((int32)frame != _lastSample) {
		/*
		 * If the frame count hasn't advanced the previous state still matches
		 * the current frame (obviously).
		 */

		_lastSample = frame;
		// Otherwise, we update _lastSample; see above.

		_showSubtitle = false;

		bool overdue = (frame > _subtitles[_currentSubtitle].getEndFrame());
		bool hasNext = (_currentSubtitle + 1 < _subtitles.size());
		bool nextStarted = false;
		if (hasNext) {
			nextStarted = (_subtitles[_currentSubtitle + 1].getStartFrame() <= frame);
		}

		while (_currentSubtitle < _subtitles.size() &&
		        overdue && hasNext && nextStarted) {
			/*
			 *  We advance until we get past all overdue subtitles.
			 *  We should exit the cycle when we either reach the first
			 *  subtitle which is not overdue whose subsequent subtitle
			 *  has not started yet (aka the one we must display now or
			 *  the one which WILL be displayed when its time comes)
			 *  and / or when we reach the last one.
			 */

			_currentSubtitle++;

			overdue = (frame > _subtitles[_currentSubtitle].getEndFrame());
			hasNext = (_currentSubtitle + 1 < _subtitles.size());
			if (hasNext) {
				nextStarted = (_subtitles[_currentSubtitle + 1].getStartFrame() <= frame);
			} else {
				nextStarted = false;
			}
		}

		bool currentValid = (_subtitles[_currentSubtitle].getEndFrame() != 0);
		/*
		 * No idea why we do this check, carried over from Mnemonic's code.
		 * Possibly a workaround for buggy subtitles or some kind of sentinel? :-\
		 */

		bool currentStarted = frame >= _subtitles[_currentSubtitle].getStartFrame();

		if (currentStarted && !overdue && currentValid) {
			_showSubtitle = true;
		}
	}
}

} // End of namespace Wintermute
