/*
 * 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/>.
 */

#pragma once

#include <chrono>
#include <shared_mutex>
#include <optional>
#include <unordered_set>

#include <Wt/WDateTime.h>
#include <Wt/WIOService.h>
#include <Wt/WSignal.h>

#include <boost/asio/system_timer.hpp>

#include "database/Types.hpp"
#include "database/ScanSettings.hpp"
#include "database/Session.hpp"
#include "metadata/IParser.hpp"
#include "scanner/IScanner.hpp"
#include "utils/Path.hpp"

class UUID;

namespace Recommendation
{
	class IEngine;
}

namespace Scanner {

class Scanner : public IScanner
{
	public:
		Scanner(Database::Db& db, Recommendation::IEngine& recommendationEngine);
		~Scanner();

		Scanner(const Scanner&) = delete;
		Scanner(Scanner&&) = delete;
		Scanner& operator=(const Scanner&) = delete;
		Scanner& operator=(Scanner&&) = delete;

		void requestReload() override;
		void requestImmediateScan(bool force) override;

		Status	getStatus() const override;
		Events&	getEvents() override { return _events; }

	private:
		void start();
		void stop();

		// Job handling
		void scheduleNextScan();
		void scheduleScan(bool force, const Wt::WDateTime& dateTime = {});

		void abortScan();

		// Update database (scheduled callback)
		void scan(bool force);

		void scanMediaDirectory( const std::filesystem::path& mediaDirectory, bool forceScan, ScanStats& stats);
		bool fetchTrackFeatures(Database::TrackId trackId, const UUID& MBID);
		void fetchTrackFeatures(ScanStats& stats);

		// Helpers
		void refreshScanSettings();

		void countAllFiles(ScanStats& stats);
		void removeMissingTracks(ScanStats& stats);
		void removeOrphanEntries();
		void checkDuplicatedAudioFiles(ScanStats& stats);
		void scanAudioFile(const std::filesystem::path& file, bool forceScan, ScanStats& stats);
		void notifyInProgressIfNeeded(const ScanStepStats& stats);
		void notifyInProgress(const ScanStepStats& stats);
		void reloadSimilarityEngine(ScanStats& stats);

		Recommendation::IEngine&				_recommendationEngine;

		std::mutex								_controlMutex;
		std::atomic<bool>						_abortScan {};
		Wt::WIOService							_ioService;
		boost::asio::system_timer				_scheduleTimer {_ioService};
		Events									_events;
		std::chrono::system_clock::time_point	_lastScanInProgressEmit {};
		Database::Session						_dbSession;
		std::unique_ptr<MetaData::IParser>		_metadataParser;

		mutable std::shared_mutex			_statusMutex;
		State								_curState {State::NotScheduled};
		std::optional<ScanStats> 			_lastCompleteScanStats;
		std::optional<ScanStepStats> 		_currentScanStepStats;
		Wt::WDateTime						_nextScheduledScan;

		// Current scan settings
		std::size_t				_scanVersion {};
		Wt::WTime				_startTime;
		Database::ScanSettings::UpdatePeriod 	_updatePeriod {Database::ScanSettings::UpdatePeriod::Never};
		std::unordered_set<std::filesystem::path>		_fileExtensions;
		std::filesystem::path					_mediaDirectory;
		Database::ScanSettings::RecommendationEngineType _recommendationEngineType;
};

} // Scanner