/*
 * Copyright (C) 2013 Emeric Poupon
 *
 * This file is part of LMS.
 *
 * LMS 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.
 *
 * LMS 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 LMS.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "MediaScanner.hpp"

#include <stdexcept>

#include <boost/filesystem.hpp>
#include <boost/asio/placeholders.hpp>

#include <Wt/WLocalDateTime.h>

#include "cover/CoverArtGrabber.hpp"

#include "database/Artist.hpp"
#include "database/Cluster.hpp"
#include "database/Release.hpp"
#include "database/ScanSettings.hpp"
#include "database/Track.hpp"

#include "utils/Logger.hpp"
#include "utils/Path.hpp"
#include "utils/Utils.hpp"

using namespace Database;

namespace {

Wt::WDate
getNextMonday(Wt::WDate current)
{
	do
	{
		current = current.addDays(1);
	} while (current.dayOfWeek() != 1);

	return current;
}

Wt::WDate
getNextFirstOfMonth(Wt::WDate current)
{
	do
	{
		current = current.addDays(1);
	} while (current.day() != 1);

	return current;
}

bool
isFileSupported(const boost::filesystem::path& file, const std::set<boost::filesystem::path>& extensions)
{
	return (extensions.find(file.extension()) != extensions.end());
}

bool
isPathInParentPath(const boost::filesystem::path& path, const boost::filesystem::path& parentPath)
{
	boost::filesystem::path curPath = path;

	while (curPath.has_parent_path())
	{
		curPath = curPath.parent_path();

		if (curPath == parentPath)
			return true;
	}

	return false;
}

Artist::pointer
getArtist(Wt::Dbo::Session& session, const std::string& name, const std::string& mbid)
{
	Artist::pointer artist;

	// First try to get by MBID
	if (!mbid.empty())
	{
		artist = Artist::getByMBID(session, mbid);
		if (!artist)
			artist = Artist::create(session, name, mbid);

		return artist;
	}

	// Fall back on artist name (collisions may occur)
	if (!name.empty())
	{
		for (Artist::pointer sameNamedArtist : Artist::getByName(session, name))
		{
			if (sameNamedArtist->getMBID().empty())
			{
				artist = sameNamedArtist;
				break;
			}
		}

		// No Artist found with the same name and without MBID -> creating
		if (!artist)
			artist = Artist::create(session, name);

		return artist;
	}

	return Artist::pointer();
}

Release::pointer
getRelease(Wt::Dbo::Session& session, const std::string& name, const std::string& mbid)
{
	Release::pointer release;

	// First try to get by MBID
	if (!mbid.empty())
	{
		release = Release::getByMBID(session, mbid );
		if (!release)
			release = Release::create(session, name, mbid);

		return release;
	}

	// Fall back on release name (collisions may occur)
	if (!name.empty())
	{
		for (Release::pointer sameNamedRelease : Release::getByName(session, name))
		{
			if (sameNamedRelease->getMBID().empty())
			{
				release = sameNamedRelease;
				break;
			}
		}

		// No release found with the same name and without MBID -> creating
		if (!release)
			release = Release::create(session, name);

		return release;
	}

	return Release::pointer();
}

std::vector<Cluster::pointer>
getClusters(Wt::Dbo::Session& session, const MetaData::Clusters& clustersNames)
{
	std::vector< Cluster::pointer > clusters;

	for (auto clusterNames : clustersNames)
	{
		auto clusterType = ClusterType::getByName(session, clusterNames.first);
		if (!clusterType)
			continue;

		for (auto clusterName : clusterNames.second)
		{
			auto cluster = clusterType->getCluster(clusterName);
			if (!cluster)
				cluster = Cluster::create(session, clusterType, clusterName);

			clusters.push_back(cluster);
		}
	}

	return clusters;
}

} // namespace

namespace Scanner {

MediaScanner::MediaScanner(Wt::Dbo::SqlConnectionPool& connectionPool)
 : _running(false),
_scheduleTimer(_ioService),
_db(connectionPool)
{
	_ioService.setThreadCount(1);

	refreshScanSettings();
}

void
MediaScanner::restart(void)
{
	stop();
	start();
}

void
MediaScanner::start(void)
{
	_running = true;

	// post some jobs in the io_service
	scheduleScan();

	_ioService.start();
}

void
MediaScanner::stop(void)
{
	_running = false;

	_scheduleTimer.cancel();

	_ioService.stop();
}

void
MediaScanner::scheduleImmediateScan()
{
	_ioService.post([=]()
	{
		LMS_LOG(DBUPDATER, INFO) << "Schedule immediate scan";
		scheduleScan(std::chrono::seconds(0));
	});
}

void
MediaScanner::reschedule()
{
	_ioService.post([=]()
	{
		LMS_LOG(DBUPDATER, INFO) << "Rescheduling scan";
		scheduleScan();
	});
}

void
MediaScanner::scheduleScan()
{
	refreshScanSettings();

	Wt::WDateTime now = Wt::WLocalDateTime::currentServerDateTime().toUTC();

	Wt::WDate nextScanDate;
	switch (_updatePeriod)
	{
		case ScanSettings::UpdatePeriod::Daily:
			if (now.time() < _startTime)
				nextScanDate = now.date();
			else
				nextScanDate = now.date().addDays(1);
			break;

		case ScanSettings::UpdatePeriod::Weekly:
			if (now.time() < _startTime && now.date().dayOfWeek() == 1)
				nextScanDate = now.date();
			else
				nextScanDate = getNextMonday(now.date());
			break;

		case ScanSettings::UpdatePeriod::Monthly:
			if (now.time() < _startTime && now.date().day() == 1)
				nextScanDate = now.date();
			else
				nextScanDate = getNextFirstOfMonth(now.date());
			break;

		case ScanSettings::UpdatePeriod::Never:
			LMS_LOG(DBUPDATER, INFO) << "Auto scan disabled!";
			break;
	}

	if (nextScanDate.isValid())
		scheduleScan( Wt::WDateTime(nextScanDate, _startTime).toTimePoint() );
}

void
MediaScanner::scheduleScan(std::chrono::seconds duration)
{
	LMS_LOG(DBUPDATER, INFO) << "Scheduling next scan in " << duration.count() << " seconds";
	_scheduleTimer.expires_from_now(duration);
	_scheduleTimer.async_wait( std::bind( &MediaScanner::scan, this, std::placeholders::_1) );
}

void
MediaScanner::scheduleScan(std::chrono::system_clock::time_point timePoint)
{
	std::time_t t = std::chrono::system_clock::to_time_t(timePoint);
	LMS_LOG(DBUPDATER, INFO) << "Scheduling next scan at " << std::string(std::ctime(&t));
	_scheduleTimer.expires_at(timePoint);
	_scheduleTimer.async_wait(std::bind(&MediaScanner::scan, this, std::placeholders::_1));
}

void
MediaScanner::scan(boost::system::error_code err)
{
	if (err)
		return;

	LMS_LOG(UI, INFO) << "New scan started!";

	refreshScanSettings();

	bool forceScan = false;
	Stats stats;

	removeMissingTracks(stats);

	LMS_LOG(UI, INFO) << "Checks complete, force scan = " << forceScan;

	LMS_LOG(DBUPDATER, INFO) << "scaning media directory '" << _mediaDirectory.string() << "'...";
	scanMediaDirectory(_mediaDirectory, forceScan, stats);
	LMS_LOG(DBUPDATER, INFO) << "scaning media directory '" << _mediaDirectory.string() << "' DONE";

	if (_running)
	{
		removeOrphanEntries();
		checkDuplicatedAudioFiles(stats);
	}

	LMS_LOG(DBUPDATER, INFO) << "Scan " << (_running ? "complete" : "aborted") << ". Changes = " << stats.nbChanges() << " (added = " << stats.additions << ", removed = " << stats.deletions << ", updated = " << stats.updates << "), Not changed = " << stats.skips << ", Scanned = " << stats.scans << " (errors = " << stats.scanErrors << ", not imported = " << stats.incompleteScans << "), duplicates = " << stats.nbDuplicates() << " (hash = " << stats.duplicateHashes << ", mbid = " << stats.duplicateMBID << ")";

	// Save the last scan only if it has been completed
	if (_running)
	{
		scheduleScan();

		scanComplete().emit(stats);
	}
}

void
MediaScanner::refreshScanSettings()
{
	Wt::Dbo::Transaction transaction(_db.getSession());

	auto scanSettings = ScanSettings::get(_db.getSession());

	LMS_LOG(DBUPDATER, INFO) << "Using scan settings version " << scanSettings->getScanVersion();

	_scanVersion = scanSettings->getScanVersion();
	_startTime = scanSettings->getUpdateStartTime();
	_updatePeriod = scanSettings->getUpdatePeriod();

	_fileExtensions = scanSettings->getAudioFileExtensions();
	_mediaDirectory = scanSettings->getMediaDirectory();

	auto clusterTypes = scanSettings->getClusterTypes();
	std::set<std::string> clusterTypeNames;

	std::transform(clusterTypes.begin(), clusterTypes.end(),
			std::inserter(clusterTypeNames, clusterTypeNames.begin()),
			[](ClusterType::pointer clusterType) -> std::string { return clusterType->getName(); });

	_metadataParser.setClusterTypeNames(clusterTypeNames);
}

void
MediaScanner::scanAudioFile(const boost::filesystem::path& file, bool forceScan, Stats& stats)
{
	auto lastWriteTime = Wt::WDateTime::fromTime_t(boost::filesystem::last_write_time(file));

	if (!forceScan)
	{
		// Skip file if last write is the same
		Wt::Dbo::Transaction transaction(_db.getSession());

		Wt::Dbo::ptr<Track> track = Track::getByPath(_db.getSession(), file);

		if (track && track->getLastWriteTime() == lastWriteTime && track->getScanVersion() == _scanVersion)
		{
			stats.skips++;
			return;
		}
	}

	boost::optional<MetaData::Items> items = _metadataParser.parse(file);
	if (!items)
	{
		stats.scanErrors++;
		return;
	}

	stats.scans++;

	std::vector<unsigned char> checksum ;
	computeCrc(file, checksum);

	Wt::Dbo::Transaction transaction(_db.getSession());

	Wt::Dbo::ptr<Track> track = Track::getByPath(_db.getSession(), file);

	// We estimate this is a audio file if:
	// - we found a least one audio stream
	// - the duration is not null
	if ((*items).find(MetaData::Type::AudioStreams) == (*items).end()
			|| boost::any_cast<std::vector<MetaData::AudioStream>> ((*items)[MetaData::Type::AudioStreams]).empty())
	{
		LMS_LOG(DBUPDATER, INFO) << "Skipped '" << file.string() << "' (no audio stream found)";

		// If Track exists here, delete it!
		if (track)
		{
			track.remove();
			stats.deletions++;
		}
		stats.incompleteScans++;
		return;
	}
	if ((*items).find(MetaData::Type::Duration) == (*items).end()
			|| boost::any_cast<std::chrono::milliseconds>((*items)[MetaData::Type::Duration]).count() <= 0)
	{
		LMS_LOG(DBUPDATER, INFO) << "Skipped '" << file.string() << "' (no duration or duration <= 0)";

		// If Track exists here, delete it!
		if (track)
		{
			track.remove();
			stats.deletions++;
		}
		stats.incompleteScans++;
		return;
	}

	// ***** Title
	std::string title;
	if ((*items).find(MetaData::Type::Title) != (*items).end())
	{
		title = boost::any_cast<std::string>((*items)[MetaData::Type::Title]);
	}
	else
	{
		// TODO parse file name guess track etc.
		// For now juste use file name as title
		title = file.filename().string();
	}

	// ***** Clusters
	std::vector< Cluster::pointer > genres;
	{
		MetaData::Clusters clusterNames;

		if ((*items).find(MetaData::Type::Clusters) != (*items).end())
		{
			clusterNames = boost::any_cast<MetaData::Clusters> ((*items)[MetaData::Type::Clusters]);
		}

		genres = getClusters(_db.getSession(), clusterNames);
	}

	//  ***** Artist
	Artist::pointer artist;
	{
		std::string artistName;
		std::string artistMusicBrainzID;

		if ((*items).find(MetaData::Type::MusicBrainzArtistID) != (*items).end())
			artistMusicBrainzID = boost::any_cast<std::string>((*items)[MetaData::Type::MusicBrainzArtistID] );

		if ((*items).find(MetaData::Type::Artist) != (*items).end())
			artistName = boost::any_cast<std::string>((*items)[MetaData::Type::Artist]);

		artist = getArtist(_db.getSession(), artistName, artistMusicBrainzID);
	}

	//  ***** Release
	Release::pointer release;
	{
		std::string releaseName;
		std::string releaseMusicBrainzID;

		if ((*items).find(MetaData::Type::MusicBrainzAlbumID) != (*items).end())
			releaseMusicBrainzID = boost::any_cast<std::string>((*items)[MetaData::Type::MusicBrainzAlbumID] );

		if ((*items).find(MetaData::Type::Album) != (*items).end())
			releaseName = boost::any_cast<std::string>((*items)[MetaData::Type::Album]);

		release = getRelease(_db.getSession(), releaseName, releaseMusicBrainzID);
	}

	// If file already exist, update data
	// Otherwise, create it
	if (!track)
	{
		// Create a new song
		track = Track::create(_db.getSession(), file);
		LMS_LOG(DBUPDATER, INFO) << "Adding '" << file.string() << "'";
		stats.additions++;
	}
	else
	{
		LMS_LOG(DBUPDATER, INFO) << "Updating '" << file.string() << "'";

		// Remove the songs from its clusters
		for (auto cluster : track->getClusters())
			cluster.remove();

		stats.updates++;
	}

	assert(track);

	track.modify()->setScanVersion(_scanVersion);
	track.modify()->setChecksum(checksum);
	track.modify()->setArtist(artist);
	track.modify()->setRelease(release);
	track.modify()->setLastWriteTime(lastWriteTime);
	track.modify()->setName(title);
	track.modify()->setDuration( boost::any_cast<std::chrono::milliseconds>((*items)[MetaData::Type::Duration]) );
	track.modify()->setAddedTime( Wt::WLocalDateTime::currentServerDateTime().toUTC() );

	{
		std::string trackClusterList;
		// Product genre list
		for (Cluster::pointer genre : genres)
		{
			if (!trackClusterList.empty())
				trackClusterList += ", ";
			trackClusterList += genre->getName();

			genre.modify()->addTrack(track);
		}

		track.modify()->setGenres( trackClusterList );
	}

	if ((*items).find(MetaData::Type::TrackNumber) != (*items).end())
		track.modify()->setTrackNumber( boost::any_cast<std::size_t>((*items)[MetaData::Type::TrackNumber]) );

	if ((*items).find(MetaData::Type::TotalTrack) != (*items).end())
		track.modify()->setTotalTrackNumber( boost::any_cast<std::size_t>((*items)[MetaData::Type::TotalTrack]) );

	if ((*items).find(MetaData::Type::DiscNumber) != (*items).end())
		track.modify()->setDiscNumber( boost::any_cast<std::size_t>((*items)[MetaData::Type::DiscNumber]) );

	if ((*items).find(MetaData::Type::TotalDisc) != (*items).end())
		track.modify()->setTotalDiscNumber( boost::any_cast<std::size_t>((*items)[MetaData::Type::TotalDisc]) );

	if ((*items).find(MetaData::Type::Year) != (*items).end())
		track.modify()->setYear( boost::any_cast<int>((*items)[MetaData::Type::Year]) );

	if ((*items).find(MetaData::Type::OriginalYear) != (*items).end())
	{
		track.modify()->setOriginalYear( boost::any_cast<int>((*items)[MetaData::Type::OriginalYear]) );

		// If a file has an OriginalYear but no Year, set it o ease filtering
		if ((*items).find(MetaData::Type::Year) == (*items).end())
			track.modify()->setYear( boost::any_cast<int>((*items)[MetaData::Type::OriginalYear]) );
	}

	if ((*items).find(MetaData::Type::MusicBrainzRecordingID) != (*items).end())
	{
		track.modify()->setMBID( boost::any_cast<std::string>((*items)[MetaData::Type::MusicBrainzRecordingID]) );
	}

	if ((*items).find(MetaData::Type::HasCover) != (*items).end())
	{
		bool hasCover = boost::any_cast<bool>((*items)[MetaData::Type::HasCover]);

		track.modify()->setHasCover(hasCover);
	}

	if ((*items).find(MetaData::Type::Copyright) != (*items).end())
	{

		track.modify()->setCopyright( boost::any_cast<std::string>((*items)[MetaData::Type::Copyright]) );
	}

	if ((*items).find(MetaData::Type::CopyrightURL) != (*items).end())
	{
		track.modify()->setCopyrightURL( boost::any_cast<std::string>((*items)[MetaData::Type::CopyrightURL]) );
	}

	transaction.commit();
}

void
MediaScanner::scanMediaDirectory(boost::filesystem::path mediaDirectory, bool forceScan, Stats& stats)
{
	boost::system::error_code ec;

	boost::filesystem::recursive_directory_iterator itPath(mediaDirectory, ec);
	if (ec)
	{
		LMS_LOG(DBUPDATER, ERROR) << "Cannot iterate over '" << mediaDirectory.string() << "': " << ec.message();
		return;
	}

	boost::filesystem::recursive_directory_iterator itEnd;
	while (itPath != itEnd)
	{
		boost::filesystem::path path = *itPath;

		if (!_running)
			return;

		if (ec)
		{
			LMS_LOG(DBUPDATER, ERROR) << "Cannot process entry: " << ec.message();
		}
		else if (boost::filesystem::is_regular(path))
		{
			if (isFileSupported(path, _fileExtensions))
				scanAudioFile(path, forceScan, stats );
		}

		itPath.increment(ec);
	}
}

// Check if a file exists and is still in a media directory
static bool
checkFile(const boost::filesystem::path& p, boost::filesystem::path mediaDirectory, const std::set<boost::filesystem::path>& extensions)
{
	try
	{
		bool status = true;

		// For each track, make sure the the file still exists
		// and still belongs to a media directory
		if (!boost::filesystem::exists( p )
			|| !boost::filesystem::is_regular( p ) )
		{
			LMS_LOG(DBUPDATER, INFO) << "Removing '" << p.string() << "': missing";
			status = false;
		}
		else if (!isPathInParentPath(p, mediaDirectory))
		{
			LMS_LOG(DBUPDATER, INFO) << "Removing '" << p.string() << "': out of media directory";
			status = false;
		}
		else if (!isFileSupported(p, extensions))
		{
			LMS_LOG(DBUPDATER, INFO) << "Removing '" << p.string() << "': file format no longer handled";
			status = false;
		}

		return status;

	}
	catch (boost::filesystem::filesystem_error& e)
	{
		LMS_LOG(DBUPDATER, ERROR) << "Caught exception while checking file '" << p.string() << "': " << e.what();
		return false;
	}
}

void
MediaScanner::removeMissingTracks(Stats& stats)
{
	std::vector<boost::filesystem::path> trackPaths = Track::getAllPaths(_db.getSession());;

	LMS_LOG(DBUPDATER, DEBUG) << "Checking tracks...";
	for (auto& trackPath : trackPaths)
	{
		if (!_running)
			return;

		if (!checkFile(trackPath, _mediaDirectory, _fileExtensions))
		{
			Wt::Dbo::Transaction transaction(_db.getSession());

			Track::pointer track = Track::getByPath(_db.getSession(), trackPath);
			if (track)
			{
				track.remove();
				stats.deletions++;
			}
		}
	}
}

void
MediaScanner::removeOrphanEntries()
{
	LMS_LOG(DBUPDATER, DEBUG) << "Checking orphan clusters...";
	{
		Wt::Dbo::Transaction transaction(_db.getSession());

		// TODO better query for this
		// Now process orphan Cluster (no track)
		auto clusters = Cluster::getAll(_db.getSession());
		for (auto cluster : clusters)
		{
			if (cluster->getCount() == 0)
			{
				LMS_LOG(DBUPDATER, DEBUG) << "Removing orphan cluster '" << cluster->getName() << "'";
				cluster.remove();
			}
		}
	}

	LMS_LOG(DBUPDATER, DEBUG) << "Checking orphan artists...";
	{
		Wt::Dbo::Transaction transaction(_db.getSession());

		auto artists = Artist::getAllOrphans(_db.getSession());
		for (auto artist : artists)
		{
			LMS_LOG(DBUPDATER, DEBUG) << "Removing orphan artist '" << artist->getName() << "'";
			artist.remove();
		}
	}

	LMS_LOG(DBUPDATER, DEBUG) << "Checking orphan releases...";
	{
		Wt::Dbo::Transaction transaction(_db.getSession());

		auto releases = Release::getAllOrphans(_db.getSession());
		for (auto release : releases)
		{
			LMS_LOG(DBUPDATER, DEBUG) << "Removing orphan release '" << release->getName() << "'";
			release.remove();
		}
	}

	LMS_LOG(DBUPDATER, INFO) << "Check audio files done!";
}

void
MediaScanner::checkDuplicatedAudioFiles(Stats& stats)
{
	LMS_LOG(DBUPDATER, INFO) << "Checking duplicated audio files";

	Wt::Dbo::Transaction transaction(_db.getSession());

	std::vector<Track::pointer> tracks = Database::Track::getMBIDDuplicates(_db.getSession());
	for (Track::pointer track : tracks)
	{
		LMS_LOG(DBUPDATER, INFO) << "Found duplicated MBID [" << track->getMBID() << "], file: " << track->getPath().string() << " - " << track->getName();
		stats.duplicateMBID++;
	}

	tracks = Database::Track::getChecksumDuplicates(_db.getSession());
	for (Track::pointer track : tracks)
	{
		LMS_LOG(DBUPDATER, INFO) << "Found duplicated checksum [" << bufferToString(track->getChecksum()) << "], file: " << track->getPath().string() << " - " << track->getName();
		stats.duplicateHashes++;
	}


	LMS_LOG(DBUPDATER, INFO) << "Checking duplicated audio files done!";
}


} // namespace Scanner