// TortoiseSVN - a Windows shell extension for easy version control

// External Cache Copyright (C) 2007-2008, 2012, 2021 - TortoiseSVN

// 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,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
#pragma once
#include "TSVNPath.h"
#include "SmartHandle.h"

#define READ_DIR_CHANGE_BUFFER_SIZE 4096
#define MAX_CHANGED_PATHS           4000

using AutoLocker = CComCritSecLock<CComCriticalSection>;

/**
 * \ingroup Utils
 * Watches the file system for changes.
 *
 * When a CPathWatcher object is created, a new thread is started which
 * waits for file system change notifications.
 * To add folders to the list of watched folders, call \c AddPath().
 *
 * The folders are watched recursively. To prevent having too many folders watched,
 * children of already watched folders are automatically removed from watching.
 */
class CPathWatcher
{
public:
    CPathWatcher();
    ~CPathWatcher();

    /**
     * Adds a new path to be watched. The path \b must point to a directory.
     * If the path is already watched because a parent of that path is already
     * watched recursively, then the new path is just ignored and the method
     * returns false.
     */
    bool AddPath(const CTSVNPath& path);
    /**
     * Removes a path and all its children from the watched list.
     */
    bool RemovePathAndChildren(const CTSVNPath& path);

    /**
     * Returns the number of recursively watched paths.
     */
    int GetNumberOfWatchedPaths() const { return watchedPaths.GetCount(); }

    /**
     * Stops the watching thread.
     */
    void Stop();

    /**
     * Returns the number of changed paths up to now.
     */
    int GetNumberOfChangedPaths()
    {
        AutoLocker lock(m_critSec);
        return m_changedPaths.GetCount();
    }

    /**
     * Returns the list of paths which maybe got changed, i.e., for which
     * a change notification was received.
     */
    CTSVNPathList GetChangedPaths()
    {
        AutoLocker lock(m_critSec);
        return m_changedPaths;
    }

    /**
     * Clears the list of changed paths
     */
    void ClearChangedPaths()
    {
        AutoLocker lock(m_critSec);
        m_changedPaths.Clear();
    }

    /**
     * If the limit of changed paths has been reached, returns true.
     * \remark the limit is necessary to avoid memory problems.
     */
    bool LimitReached() const { return m_bLimitReached; }

private:
    static unsigned int __stdcall ThreadEntry(void* pContext);
    void WorkerThread();

    void ClearInfoMap();

private:
    CComAutoCriticalSection m_critSec;
    CAutoGeneralHandle      m_hThread;
    CAutoGeneralHandle      m_hCompPort;
    volatile LONG           m_bRunning;

    CTSVNPathList watchedPaths;   ///< list of watched paths.
    CTSVNPathList m_changedPaths; ///< list of paths which got changed
    bool          m_bLimitReached;

    /**
     * Helper class: provides information about watched directories.
     */
    class CDirWatchInfo
    {
    private:
        CDirWatchInfo()        = delete;
        CDirWatchInfo& operator=(const CDirWatchInfo& rhs) = delete; //so that they're aren't accidentally used. -- you'll get a linker error
    public:
        CDirWatchInfo(CAutoFile&& hDir, const CTSVNPath& directoryName);
        ~CDirWatchInfo();

    protected:
    public:
        bool CloseDirectoryHandle();

        CAutoFile  m_hDir;                                ///< handle to the directory that we're watching
        CTSVNPath  m_dirName;                             ///< the directory that we're watching
        CHAR       m_buffer[READ_DIR_CHANGE_BUFFER_SIZE]; ///< buffer for ReadDirectoryChangesW
        OVERLAPPED m_overlapped;
        CString    m_dirPath; ///< the directory name we're watching with a backslash at the end
        //HDEVNOTIFY    m_hDevNotify;   ///< Notification handle
    };

    std::map<HANDLE, CDirWatchInfo*> watchInfoMap;

    HDEVNOTIFY m_hDev;
};