// *****************************************************************************
// * This file is part of the FreeFileSync project. It is distributed under    *
// * GNU General Public License: http://www.gnu.org/licenses/gpl-3.0           *
// * Copyright (C) Zenju (zenju AT freefilesync DOT org) - All Rights Reserved *
// *****************************************************************************

#ifndef DIR_WATCHER_348577025748023458
#define DIR_WATCHER_348577025748023458

#include <vector>
#include <memory>
#include <functional>
#include "file_error.h"


namespace zen
{
//Windows: ReadDirectoryChangesW https://msdn.microsoft.com/en-us/library/aa365465
//Linux:   inotify               http://linux.die.net/man/7/inotify
//OS X:    kqueue                http://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man2/kqueue.2.html

//watch directory including subdirectories
/*
!Note handling of directories!:
    Windows: removal of top watched directory is NOT notified when watching the dir handle, e.g. brute force usb stick removal,
             (watchting for GUID_DEVINTERFACE_WPD OTOH works fine!)
             however manual unmount IS notified (e.g. usb stick removal, then re-insert), but watching is stopped!
             Renaming of top watched directory handled incorrectly: Not notified(!) + additional changes in subfolders
             now do report FILE_ACTION_MODIFIED for directory (check that should prevent this fails!)

    Linux: newly added subdirectories are reported but not automatically added for watching! -> reset Dirwatcher!
           removal of top watched directory is NOT notified!

    OS X: everything works as expected; renaming of top level folder is also detected

    Overcome all issues portably: check existence of top watched directory externally + reinstall watch after changes in directory structure (added directories) are detected
*/
class DirWatcher
{
public:
    DirWatcher(const Zstring& dirPath); //throw FileError
    ~DirWatcher();

    enum ActionType
    {
        ACTION_CREATE, //informal only!
        ACTION_UPDATE, //use for debugging/logging only!
        ACTION_DELETE, //
    };

    struct Entry
    {
        Entry() {}
        Entry(ActionType action, const Zstring& filepath) : action_(action), filepath_(filepath) {}

        ActionType action_ = ACTION_CREATE;
        Zstring filepath_;
    };

    //extract accumulated changes since last call
    std::vector<Entry> getChanges(const std::function<void()>& processGuiMessages); //throw FileError

private:
    DirWatcher           (const DirWatcher&) = delete;
    DirWatcher& operator=(const DirWatcher&) = delete;

    const Zstring baseDirPath;

    struct Impl;
    const std::unique_ptr<Impl> pimpl_;
};

}

#endif