/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
/*
 * This file is part of the LibreOffice project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

#include <config.h>

#include "FileUtil.hpp"

#include <ftw.h>
#include <sys/stat.h>
#ifdef __linux
#include <sys/vfs.h>
#elif defined IOS
#import <Foundation/Foundation.h>
#endif

#include <chrono>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <mutex>
#include <string>

#if HAVE_STD_FILESYSTEM
# if HAVE_STD_FILESYSTEM_EXPERIMENTAL
#  include <experimental/filesystem>
namespace filesystem = ::std::experimental::filesystem;
# else
#  include <filesystem>
namespace filesystem = ::std::filesystem;
# endif
#else
# include <Poco/TemporaryFile.h>
#endif

#include "Log.hpp"
#include "Util.hpp"
#include "Unit.hpp"

namespace
{
    void alertAllUsersAndLog(const std::string& message, const std::string& cmd, const std::string& kind)
    {
        LOG_ERR(message);
        Util::alertAllUsers(cmd, kind);
    }

#if HAVE_STD_FILESYSTEM
/// Class to delete files when the process ends.
class FileDeleter
{
    std::vector<std::string> _filesToDelete;
    std::mutex _lock;
public:
    FileDeleter() {}
    ~FileDeleter()
    {
        std::unique_lock<std::mutex> guard(_lock);
        for (const std::string& file: _filesToDelete)
            filesystem::remove(file);
    }

    void registerForDeletion(const std::string& file)
    {
        std::unique_lock<std::mutex> guard(_lock);
        _filesToDelete.push_back(file);
    }
};
#endif
}

namespace FileUtil
{
    std::string createRandomDir(const std::string& path)
    {
        const std::string name = Util::rng::getFilename(64);
#if HAVE_STD_FILESYSTEM
        filesystem::create_directory(path + '/' + name);
#else
        Poco::File(Poco::Path(path, name)).createDirectories();
#endif
        return name;
    }

    std::string getTempFilePath(const std::string& srcDir, const std::string& srcFilename, const std::string& dstFilenamePrefix)
    {
        const std::string srcPath = srcDir + '/' + srcFilename;
        const std::string dstFilename = dstFilenamePrefix + Util::encodeId(Util::rng::getNext()) + '_' + srcFilename;
#if HAVE_STD_FILESYSTEM
        const std::string dstPath = filesystem::temp_directory_path() / dstFilename;
        filesystem::copy(srcPath, dstPath);

        static FileDeleter fileDeleter;
        fileDeleter.registerForDeletion(dstPath);
#else
        const std::string dstPath = Poco::Path(Poco::Path::temp(), dstFilename).toString();
        Poco::File(srcPath).copyTo(dstPath);
        Poco::TemporaryFile::registerForDeletion(dstPath);
#endif

        return dstPath;
    }

    bool saveDataToFileSafely(const std::string& fileName, const char *data, size_t size)
    {
        const auto tempFileName = fileName + ".temp";
        std::fstream outStream(tempFileName, std::ios::out);

        // If we can't create the file properly, just remove it
        if (!outStream.good())
        {
            alertAllUsersAndLog("Creating " + tempFileName + " failed, disk full?", "internal", "diskfull");
            // Try removing both just in case
            std::remove(tempFileName.c_str());
            std::remove(fileName.c_str());
            return false;
        }
        else
        {
            outStream.write(data, size);
            if (!outStream.good())
            {
                alertAllUsersAndLog("Writing to " + tempFileName + " failed, disk full?", "internal", "diskfull");
                outStream.close();
                std::remove(tempFileName.c_str());
                std::remove(fileName.c_str());
                return false;
            }
            else
            {
                outStream.close();
                if (!outStream.good())
                {
                    alertAllUsersAndLog("Closing " + tempFileName + " failed, disk full?", "internal", "diskfull");
                    std::remove(tempFileName.c_str());
                    std::remove(fileName.c_str());
                    return false;
                }
                else
                {
                    // Everything OK, rename the file to its proper name
                    if (std::rename(tempFileName.c_str(), fileName.c_str()) == 0)
                    {
                        LOG_DBG("Renaming " << tempFileName << " to " << fileName << " OK.");
                        return true;
                    }
                    else
                    {
                        alertAllUsersAndLog("Renaming " + tempFileName + " to " + fileName + " failed, disk full?", "internal", "diskfull");
                        std::remove(tempFileName.c_str());
                        std::remove(fileName.c_str());
                        return false;
                    }
                }
            }
        }
    }

#if !HAVE_STD_FILESYSTEM
    static int nftw_cb(const char *fpath, const struct stat*, int type, struct FTW*)
    {
        if (type == FTW_DP)
        {
            rmdir(fpath);
        }
        else if (type == FTW_F || type == FTW_SL)
        {
            unlink(fpath);
        }

        // Always continue even when things go wrong.
        return 0;
    }
#endif

    void removeFile(const std::string& path, const bool recursive)
    {
#if HAVE_STD_FILESYSTEM
        std::error_code ec;
        if (recursive)
            filesystem::remove_all(path, ec);
        else
            filesystem::remove(path, ec);

        // Already removed or we don't care about failures.
        (void) ec;
#else
        try
        {
            struct stat sb;
            if (!recursive || stat(path.c_str(), &sb) == -1 || S_ISREG(sb.st_mode))
            {
                // Non-recursive directories, and files.
                Poco::File(path).remove(recursive);
            }
            else
            {
                // Directories only.
                nftw(path.c_str(), nftw_cb, 128, FTW_DEPTH | FTW_PHYS);
            }
        }
        catch (const std::exception&)
        {
            // Already removed or we don't care about failures.
        }
#endif
    }


} // namespace FileUtil

namespace
{

    struct fs
    {
        fs(const std::string& path, dev_t dev)
            : _path(path), _dev(dev)
        {
        }

        const std::string& getPath() const { return _path; }

        dev_t getDev() const { return _dev; }

    private:
        std::string _path;
        dev_t _dev;
    };

    struct fsComparator
    {
        bool operator() (const fs& lhs, const fs& rhs) const
        {
            return (lhs.getDev() < rhs.getDev());
        }
    };

    static std::mutex fsmutex;
    static std::set<fs, fsComparator> filesystems;

} // anonymous namespace

namespace FileUtil
{
#if !MOBILEAPP
    void registerFileSystemForDiskSpaceChecks(const std::string& path)
    {
        const std::string::size_type lastSlash = path.rfind('/');
        assert(path.empty() || lastSlash != std::string::npos);
        if (lastSlash != std::string::npos)
        {
            const std::string dirPath = path.substr(0, lastSlash + 1) + '.';
            LOG_INF("Registering filesystem for space checks: [" << dirPath << "]");

            std::lock_guard<std::mutex> lock(fsmutex);

            struct stat s;
            if (stat(dirPath.c_str(), &s) == 0)
            {
                filesystems.insert(fs(dirPath, s.st_dev));
            }
        }
    }

    std::string checkDiskSpaceOnRegisteredFileSystems(const bool cacheLastCheck)
    {
        static std::chrono::steady_clock::time_point lastCheck;
        std::chrono::steady_clock::time_point now(std::chrono::steady_clock::now());

        std::lock_guard<std::mutex> lock(fsmutex);

        // Don't check more often than once a minute
        if (std::chrono::duration_cast<std::chrono::seconds>(now - lastCheck).count() < 60)
            return std::string();

        if (cacheLastCheck)
            lastCheck = now;

        for (const auto& i: filesystems)
        {
            if (!checkDiskSpace(i.getPath()))
            {
                return i.getPath();
            }
        }

        return std::string();
    }
#endif

    bool checkDiskSpace(const std::string& path)
    {
        assert(!path.empty());

#if !MOBILEAPP
        bool hookResult;
        if (UnitBase::get().filterCheckDiskSpace(path, hookResult))
            return hookResult;
#endif

        // we should be able to run just OK with 5GB for production or 1GB for development
#if ENABLE_DEBUG
        const int64_t gb(1);
#else
        const int64_t gb(5);
#endif
        constexpr int64_t ENOUGH_SPACE = gb*1024*1024*1024;

#ifdef __linux
        struct statfs sfs;
        if (statfs(path.c_str(), &sfs) == -1)
            return true;

        const int64_t freeBytes = static_cast<int64_t>(sfs.f_bavail) * sfs.f_bsize;

        LOG_INF("Filesystem [" << path << "] has " << (freeBytes / 1024 / 1024) <<
                " MB free (" << (sfs.f_bavail * 100. / sfs.f_blocks) << "%).");

        if (freeBytes > ENOUGH_SPACE)
            return true;

        if (static_cast<double>(sfs.f_bavail) / sfs.f_blocks <= 0.05)
            return false;
#elif defined IOS
        NSDictionary *atDict = [[NSFileManager defaultManager] attributesOfFileSystemForPath:@"/" error:NULL];
        long long freeSpace = [[atDict objectForKey:NSFileSystemFreeSize] longLongValue];
        long long totalSpace = [[atDict objectForKey:NSFileSystemSize] longLongValue];

        if (freeSpace > ENOUGH_SPACE)
            return true;

        if (static_cast<double>(freeSpace) / totalSpace <= 0.05)
            return false;
#endif

        return true;
    }

} // namespace FileUtil

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