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

#ifndef LONGPATHPREFIX_H_INCLUDED
#define LONGPATHPREFIX_H_INCLUDED

#include "win.h"
#include "zstring.h"

namespace zen
{
//handle filenames longer-equal 260 (== MAX_PATH) characters by applying \\?\-prefix; see: http://msdn.microsoft.com/en-us/library/aa365247(VS.85).aspx#maxpath
/*
1. path must be absolute
2. if path is smaller than MAX_PATH nothing is changed! caveat: FindFirstFile() "Prepending the string "\\?\" does not allow access to the root directory."
3. path may already contain \\?\-prefix
*/
Zstring applyLongPathPrefix(const Zstring& path); //throw()
Zstring applyLongPathPrefixCreateDir(const Zstring& path); //throw() -> special rule for ::CreateDirectory()/::CreateDirectoryEx(): MAX_PATH - 12(=^ 8.3 filename) is threshold

Zstring removeLongPathPrefix(const Zstring& path); //throw()
}






















//################## implementation ##################

//there are two flavors of long path prefix: one for UNC paths, one for regular paths
const wchar_t LONG_PATH_PREFIX    [] = L"\\\\?\\";    //don't use Zstring as global constant: avoid static initialization order problem in global namespace!
const wchar_t LONG_PATH_PREFIX_UNC[] = L"\\\\?\\UNC"; //

template <size_t maxPath> inline
Zstring applyLongPathPrefixImpl(const Zstring& path)
{
    assert(!path.empty()); //nicely check almost all WinAPI accesses!
    assert(!zen::isWhiteSpace(path[0]));

    //http://msdn.microsoft.com/en-us/library/windows/desktop/aa365247%28v=vs.85%29.aspx#naming_conventions))
    /*
      - special names like ".NUL" create all kinds of trouble (e.g. CreateDirectory() reports success, but does nothing)
        unless prefix is supplied => accept as limitation
    */
    if (path.length() >= maxPath || //maximum allowed path length without prefix is (MAX_PATH - 1)
        endsWith(path, L' ') || //by default all Win32 APIs trim trailing spaces and period, unless long path prefix is supplied!
        endsWith(path, L'.'))   //note: adding long path prefix might screw up relative paths "." and ".."!
        if (!startsWith(path, LONG_PATH_PREFIX))
        {
            if (startsWith(path, L"\\\\")) //UNC-name, e.g. \\zenju-pc\Users
                return LONG_PATH_PREFIX_UNC + afterFirst(path, L'\\'); //convert to \\?\UNC\zenju-pc\Users
            else
                return LONG_PATH_PREFIX + path; //prepend \\?\ prefix
        }
    return path; //fallback
}


inline
Zstring zen::applyLongPathPrefix(const Zstring& path)
{
    return applyLongPathPrefixImpl<MAX_PATH>(path);
}


inline
Zstring zen::applyLongPathPrefixCreateDir(const Zstring& path) //throw()
{
    //special rule for ::CreateDirectoryEx(): MAX_PATH - 12(=^ 8.3 filename) is threshold
    return applyLongPathPrefixImpl<MAX_PATH - 12> (path);
}


inline
Zstring zen::removeLongPathPrefix(const Zstring& path) //throw()
{
    if (zen::startsWith(path, LONG_PATH_PREFIX))
    {
        if (zen::startsWith(path, LONG_PATH_PREFIX_UNC)) //UNC-name
            return replaceCpy(path, LONG_PATH_PREFIX_UNC, Zstr("\\"), false);
        else
            return replaceCpy(path, LONG_PATH_PREFIX, Zstr(""), false);
    }
    return path; //fallback
}

#endif //LONGPATHPREFIX_H_INCLUDED