/*
 Copyright (C) 2018 Erik Ogenvik

 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#ifndef CYPHESIS_FILESYSTEMOBSERVER_H
#define CYPHESIS_FILESYSTEMOBSERVER_H

#include "external/dir_monitor/include/dir_monitor/dir_monitor.hpp"

#include <boost/asio/io_service.hpp>
#include <boost/filesystem/path.hpp>

class FileSystemObserver
{
    public:
        /**
         * A file system event.
         */
        struct FileSystemEvent {
            /**
             * The directory monitoring event.
             */
            const boost::asio::dir_monitor_event& ev;

            /**
             * The path relative to the watched directory.
             */
            const boost::filesystem::path& relativePath;
        };

        explicit FileSystemObserver(boost::asio::io_service& ioService);

        ~FileSystemObserver();

        /**
         * Adds a directory recursively.
         * @param dirname The path.
         * @param callback A callback, called whenever a change is detected.
         */
        void add_directory(const boost::filesystem::path& dirname, std::function<void(const FileSystemEvent&)> callback);

        /**
         * Removes a previously watched directory.
         * @param dirname
         */
        void remove_directory(const boost::filesystem::path& dirname);

    private:
        std::unique_ptr<boost::asio::dir_monitor> mDirectoryMonitor;

        std::map<boost::filesystem::path, std::function<void(const FileSystemEvent&)>> mCallBacks;

        boost::asio::io_service& m_ioService;

        std::map<boost::filesystem::path, std::pair<std::chrono::steady_clock::time_point, boost::asio::dir_monitor_event>> m_changedPaths;

        void observe();

        void processChangedPaths();
};


#endif //CYPHESIS_FILESYSTEMOBSERVER_H