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

#ifndef DIR_LOCK_H_81740832174954356
#define DIR_LOCK_H_81740832174954356

#include <memory>
#include <chrono>
#include <functional>
#include <zen/file_error.h>


namespace fff
{
/* RAII structure to place a directory lock against other FFS processes:
    - recursive locking supported, even with alternate lockfile names, e.g. via symlinks, network mounts, case-differences etc.
    - ownership shared between all object instances refering to a specific lock location(= GUID)
    - can be copied safely and efficiently! (ref-counting)
    - detects and resolves abandoned locks (instantly if lock is associated with local pc, else after 30 seconds)
    - temporary locks created during abandoned lock resolution keep "lockFilePath"'s extension
    - race-free (Windows, almost on Linux(NFS))
    - NOT thread-safe! (1. global LockAdmin 2. locks for directory aliases should be created sequentially to detect duplicate locks!)         */

//intermediate locks created by DirLock use this extension, too:
constexpr ZstringView LOCK_FILE_ENDING = Zstr(".ffs_lock"); //don't use Zstring as global constant: avoid static initialization order problem in global namespace!

//while waiting for the lock
using DirLockCallback = std::function<void(std::wstring&& msg)>; //throw X

class DirLock
{
public:
    DirLock(const Zstring& folderPath,
            const DirLockCallback& notifyStatus, //callback only used during construction
            std::chrono::milliseconds cbInterval) :
        DirLock(folderPath, Zstring(Zstr("sync")) + LOCK_FILE_ENDING, notifyStatus, cbInterval) {} //throw FileError

    DirLock(const Zstring& folderPath,
            const Zstring& fileName,
            const DirLockCallback& notifyStatus,
            std::chrono::milliseconds cbInterval); //throw FileError

private:
    class LockAdmin;
    class SharedDirLock;
    std::shared_ptr<SharedDirLock> sharedLock_;
};


namespace impl //declare for unit tests:
{
Zstring getAbandonedLockFileName(const Zstring& lockFilePath); //throw FileError
}
}

#endif //DIR_LOCK_H_81740832174954356