/**
 * @file filesystem.h
 * @brief Simulate local file system operations.
 * @Note The initial implementation does actually use standard C++
 *       file operations but eventually, there will be another
 *       layer that caches and manages file meta data too.
 *
 * $LicenseInfo:firstyear=2002&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#ifndef LL_FILESYSTEM_H
#define LL_FILESYSTEM_H

#include "lluuid.h"
#include "llassettype.h"
#include "lldiskcache.h"

class LLFileSystem
{
    public:
        LLFileSystem(const LLUUID& file_id, const LLAssetType::EType file_type, S32 mode = LLFileSystem::READ);
        ~LLFileSystem() = default;

        bool read(U8* buffer, S32 bytes);
        S32  getLastBytesRead() const;
        bool eof() const;

        bool write(const U8* buffer, S32 bytes);
        bool seek(S32 offset, S32 origin = -1);
        S32  tell() const;

        S32 getSize() const;
        S32 getMaxSize() const;
        bool rename(const LLUUID& new_id, const LLAssetType::EType new_type);
        bool remove() const;

        /**
         * Update the "last write time" of a file to "now". This must be called whenever a
         * file in the cache is read (not written) so that the last time the file was
         * accessed is up to date (This is used in the mechanism for purging the cache)
         */
        void updateFileAccessTime(const std::string& file_path);

        static bool getExists(const LLUUID& file_id, const LLAssetType::EType file_type);
        static bool removeFile(const LLUUID& file_id, const LLAssetType::EType file_type, int suppress_error = 0);
        static bool renameFile(const LLUUID& old_file_id, const LLAssetType::EType old_file_type,
                               const LLUUID& new_file_id, const LLAssetType::EType new_file_type);
        static S32 getFileSize(const LLUUID& file_id, const LLAssetType::EType file_type);

    public:
        static const S32 READ;
        static const S32 WRITE;
        static const S32 READ_WRITE;
        static const S32 APPEND;

    protected:
        LLAssetType::EType mFileType;
        LLUUID  mFileID;
        S32     mPosition;
        S32     mMode;
        S32     mBytesRead;
};

#endif  // LL_FILESYSTEM_H