// *****************************************************************************
// * 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 *
// *****************************************************************************

#include "file_traverser.h"
#include "file_error.h"
#include "file_access.h"


    #include <sys/stat.h>
    #include <dirent.h>

using namespace zen;


void zen::traverseFolder(const Zstring& dirPath,
                         const std::function<void(const FileInfo&    fi)>& onFile,
                         const std::function<void(const FolderInfo&  fi)>& onFolder,
                         const std::function<void(const SymlinkInfo& si)>& onSymlink) //throw FileError
{
    DIR* folder = ::opendir(dirPath.c_str()); //directory must NOT end with path separator, except "/"
    if (!folder)
        THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot open directory %x."), L"%x", fmtPath(dirPath)), "opendir");
    ZEN_ON_SCOPE_EXIT(::closedir(folder)); //never close nullptr handles! -> crash

    for (;;)
    {
        errno = 0;
        const dirent* dirEntry = ::readdir(folder); //don't use readdir_r(), see comment in native.cpp
        if (!dirEntry)
        {
            if (errno == 0) //errno left unchanged => no more items
                return;

            THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot read directory %x."), L"%x", fmtPath(dirPath)), "readdir");
            //don't retry but restart dir traversal on error! https://devblogs.microsoft.com/oldnewthing/20140612-00/?p=753/
        }

        //don't return "." and ".."
        const char* itemNameRaw = dirEntry->d_name;

        if (itemNameRaw[0] == '.' &&
            (itemNameRaw[1] == 0 || (itemNameRaw[1] == '.' && itemNameRaw[2] == 0)))
            continue;

        const Zstring& itemName = itemNameRaw;
        if (itemName.empty()) //checks result of normalizeUtfForPosix, too!
            throw FileError(replaceCpy(_("Cannot read directory %x."), L"%x", fmtPath(dirPath)), formatSystemError("readdir", L"", L"Folder contains an item without name."));

        const Zstring& itemPath = appendPath(dirPath, itemName);

        struct stat statData = {};
        if (::lstat(itemPath.c_str(), &statData) != 0) //lstat() does not resolve symlinks
            THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot read file attributes of %x."), L"%x", fmtPath(itemPath)), "lstat");

        if (S_ISLNK(statData.st_mode)) //on Linux there is no distinction between file and directory symlinks!
        {
            if (onSymlink)
                onSymlink({ itemName, itemPath, statData.st_mtime});
        }
        else if (S_ISDIR(statData.st_mode)) //a directory
        {
            if (onFolder)
                onFolder({itemName, itemPath});
        }
        else //a file or named pipe, etc. S_ISREG, S_ISCHR, S_ISBLK, S_ISFIFO, S_ISSOCK
        {
            if (onFile)
                onFile({itemName, itemPath, makeUnsigned(statData.st_size), statData.st_mtime});
            /* It may be a good idea to not check "S_ISREG(statData.st_mode)" explicitly and to not issue an error message on other types to support these scenarios:
                - RTS setup watch (essentially wants to read directories only)
                - removeDirectory (wants to delete everything; pipes can be deleted just like files via "unlink")

                However an "open" on a pipe will block (https://sourceforge.net/p/freefilesync/bugs/221/), so the copy routines better be smart!          */
        }
    }
}
