/*
 * Copyright (C) 2007, 2009 Holger Hans Peter Freyther
 * Copyright (C) 2008 Collabora, Ltd.
 * Copyright (C) 2008 Apple Inc. All rights reserved.
 * Portions Copyright (c) 2010 Motorola Mobility, Inc.  All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "config.h"
#include <wtf/FileSystem.h>

#include <gio/gfiledescriptorbased.h>
#include <gio/gio.h>
#include <glib.h>
#include <glib/gstdio.h>
#include <sys/file.h>
#include <wtf/EnumTraits.h>
#include <wtf/UUID.h>
#include <wtf/glib/GRefPtr.h>
#include <wtf/glib/GUniquePtr.h>
#include <wtf/text/ASCIIFastPath.h>
#include <wtf/text/CString.h>
#include <wtf/text/StringBuilder.h>
#include <wtf/text/WTFString.h>

#if OS(WINDOWS)
#include <windows.h>
#else
#include <limits.h>
#include <unistd.h>
#endif

namespace WTF {

namespace FileSystemImpl {

String stringFromFileSystemRepresentation(const char* representation)
{
    if (!representation)
        return { };

    // Short-cut to String creation when only ASCII characters are used.
    size_t representationLength = strlen(representation);
    if (charactersAreAllASCII(reinterpret_cast<const LChar*>(representation), representationLength))
        return String(representation, representationLength);

    // If the returned charset is UTF-8 (i.e. g_get_filename_charsets() returns true),
    // go directly to String creation.
    const gchar** filenameCharsets = nullptr;
    if (g_get_filename_charsets(&filenameCharsets))
        return String::fromUTF8(representation, representationLength);

    ASSERT(filenameCharsets);
    // FIXME: If possible, we'd want to convert directly to UTF-16 and construct
    // WTF::String object with resulting data.
    size_t utf8Length = 0;
    GUniquePtr<gchar> utf8(g_convert(representation, representationLength,
        "UTF-8", filenameCharsets[0], nullptr, &utf8Length, nullptr));
    if (!utf8)
        return { };

    return String::fromUTF8(utf8.get(), utf8Length);
}

CString fileSystemRepresentation(const String& path)
{
    if (path.isNull())
        return { };
    if (path.isEmpty())
        return CString("");

    CString utf8 = path.utf8();

    // If the returned charset is UTF-8 (i.e. g_get_filename_charsets() returns true),
    // simply return the CString object.
    const gchar** filenameCharsets = nullptr;
    if (g_get_filename_charsets(&filenameCharsets))
        return utf8;

    ASSERT(filenameCharsets);
    // FIXME: If possible, we'd want to convert directly from WTF::String's UTF-16 data.
    size_t representationLength = 0;
    GUniquePtr<gchar> representation(g_convert(utf8.data(), utf8.length(),
        filenameCharsets[0], "UTF-8", nullptr, &representationLength, nullptr));
    if (!representation)
        return { };

    return CString(representation.get(), representationLength);
}

bool validRepresentation(const CString& representation)
{
    auto* data = representation.data();
    return !!data && data[0] != '\0';
}

// Converts a string to something suitable to be displayed to the user.
String filenameForDisplay(const String& string)
{
#if OS(WINDOWS)
    return string;
#else
    auto filename = fileSystemRepresentation(string);
    if (!validRepresentation(filename))
        return string;

    GUniquePtr<gchar> display(g_filename_display_name(filename.data()));
    if (!display)
        return string;
    return String::fromUTF8(display.get());
#endif
}

std::optional<uint64_t> fileSize(PlatformFileHandle handle)
{
    GRefPtr<GFileInfo> info = adoptGRef(g_file_io_stream_query_info(handle, G_FILE_ATTRIBUTE_STANDARD_SIZE, nullptr, nullptr));
    if (!info)
        return std::nullopt;

    return g_file_info_get_size(info.get());
}

std::optional<WallTime> fileCreationTime(const String&)
{
    // FIXME: Is there a way to retrieve file creation time with Gtk on platforms that support it?
    return std::nullopt;
}

String openTemporaryFile(StringView prefix, PlatformFileHandle& handle, StringView suffix)
{
    // FIXME: Suffix is not supported, but OK for now since the code using it is macOS-port-only.
    ASSERT_UNUSED(suffix, suffix.isEmpty());

    GUniquePtr<gchar> filename(g_strdup_printf("%s%s", prefix.utf8().data(), createVersion4UUIDString().utf8().data()));
    GUniquePtr<gchar> tempPath(g_build_filename(g_get_tmp_dir(), filename.get(), nullptr));
    GRefPtr<GFile> file = adoptGRef(g_file_new_for_path(tempPath.get()));

    handle = g_file_create_readwrite(file.get(), G_FILE_CREATE_NONE, nullptr, nullptr);
    if (!isHandleValid(handle))
        return String();
    return String::fromUTF8(tempPath.get());
}

PlatformFileHandle openFile(const String& path, FileOpenMode mode, FileAccessPermission permission, bool failIfFileExists)
{
    auto filename = fileSystemRepresentation(path);
    if (!validRepresentation(filename))
        return invalidPlatformFileHandle;

    GRefPtr<GFile> file = adoptGRef(g_file_new_for_path(filename.data()));
    GRefPtr<GFileIOStream> ioStream;
    GFileCreateFlags permissionFlag = (permission == FileAccessPermission::All) ? G_FILE_CREATE_NONE : G_FILE_CREATE_PRIVATE;

    if (failIfFileExists) {
        ioStream = adoptGRef(g_file_create_readwrite(file.get(), permissionFlag, nullptr, nullptr));
        return ioStream.leakRef();
    }

    if (mode == FileOpenMode::Read)
        ioStream = adoptGRef(g_file_open_readwrite(file.get(), nullptr, nullptr));
    else if (mode == FileOpenMode::Write || mode == FileOpenMode::ReadWrite) {
        if (g_file_test(filename.data(), static_cast<GFileTest>(G_FILE_TEST_EXISTS | G_FILE_TEST_IS_REGULAR)))
            ioStream = adoptGRef(g_file_open_readwrite(file.get(), nullptr, nullptr));
        else
            ioStream = adoptGRef(g_file_create_readwrite(file.get(), permissionFlag, nullptr, nullptr));
    }

    return ioStream.leakRef();
}

void closeFile(PlatformFileHandle& handle)
{
    if (!isHandleValid(handle))
        return;

    g_io_stream_close(G_IO_STREAM(handle), 0, 0);
    g_object_unref(handle);
    handle = invalidPlatformFileHandle;
}

long long seekFile(PlatformFileHandle handle, long long offset, FileSeekOrigin origin)
{
    GSeekType seekType = G_SEEK_SET;
    switch (origin) {
    case FileSeekOrigin::Beginning:
        seekType = G_SEEK_SET;
        break;
    case FileSeekOrigin::Current:
        seekType = G_SEEK_CUR;
        break;
    case FileSeekOrigin::End:
        seekType = G_SEEK_END;
        break;
    default:
        ASSERT_NOT_REACHED();
    }

    if (!g_seekable_seek(G_SEEKABLE(g_io_stream_get_input_stream(G_IO_STREAM(handle))), offset, seekType, nullptr, nullptr))
        return -1;
    return g_seekable_tell(G_SEEKABLE(g_io_stream_get_input_stream(G_IO_STREAM(handle))));
}

bool truncateFile(PlatformFileHandle handle, long long offset)
{
    return g_seekable_truncate(G_SEEKABLE(g_io_stream_get_output_stream(G_IO_STREAM(handle))), offset, nullptr, nullptr);
}

bool flushFile(PlatformFileHandle handle)
{
    return g_output_stream_flush(g_io_stream_get_output_stream(G_IO_STREAM(handle)), nullptr, nullptr);
}

int writeToFile(PlatformFileHandle handle, const void* data, int length)
{
    if (!length)
        return 0;

    gsize bytesWritten;
    g_output_stream_write_all(g_io_stream_get_output_stream(G_IO_STREAM(handle)),
        data, length, &bytesWritten, nullptr, nullptr);
    return bytesWritten;
}

int readFromFile(PlatformFileHandle handle, void* data, int length)
{
    GUniqueOutPtr<GError> error;
    do {
        gssize bytesRead = g_input_stream_read(g_io_stream_get_input_stream(G_IO_STREAM(handle)),
            data, length, nullptr, &error.outPtr());
        if (bytesRead >= 0)
            return bytesRead;
    } while (error && error->code == G_FILE_ERROR_INTR);
    return -1;
}

std::optional<int32_t> getFileDeviceId(const String& path)
{
    auto fsFile = fileSystemRepresentation(path);
    if (fsFile.isNull())
        return std::nullopt;

    GRefPtr<GFile> file = adoptGRef(g_file_new_for_path(fsFile.data()));
    GRefPtr<GFileInfo> fileInfo = adoptGRef(g_file_query_filesystem_info(file.get(), G_FILE_ATTRIBUTE_UNIX_DEVICE, nullptr, nullptr));
    if (!fileInfo)
        return std::nullopt;

    return g_file_info_get_attribute_uint32(fileInfo.get(), G_FILE_ATTRIBUTE_UNIX_DEVICE);
}

std::optional<uint32_t> volumeFileBlockSize(const String&)
{
    return std::nullopt;
}

#if USE(FILE_LOCK)
bool lockFile(PlatformFileHandle handle, OptionSet<FileLockMode> lockMode)
{
    static_assert(LOCK_SH == WTF::enumToUnderlyingType(FileLockMode::Shared), "LockSharedEncoding is as expected");
    static_assert(LOCK_EX == WTF::enumToUnderlyingType(FileLockMode::Exclusive), "LockExclusiveEncoding is as expected");
    static_assert(LOCK_NB == WTF::enumToUnderlyingType(FileLockMode::Nonblocking), "LockNonblockingEncoding is as expected");
    auto* inputStream = g_io_stream_get_input_stream(G_IO_STREAM(handle));
    int result = flock(g_file_descriptor_based_get_fd(G_FILE_DESCRIPTOR_BASED(inputStream)), lockMode.toRaw());
    return result != -1;
}

bool unlockFile(PlatformFileHandle handle)
{
    auto* inputStream = g_io_stream_get_input_stream(G_IO_STREAM(handle));
    int result = flock(g_file_descriptor_based_get_fd(G_FILE_DESCRIPTOR_BASED(inputStream)), LOCK_UN);
    return result != -1;
}
#endif // USE(FILE_LOCK)

#if OS(LINUX)
CString currentExecutablePath()
{
    static char readLinkBuffer[PATH_MAX];
    ssize_t result = readlink("/proc/self/exe", readLinkBuffer, PATH_MAX);
    if (result == -1)
        return { };
    return CString(readLinkBuffer, result);
}
#elif OS(HURD)
CString currentExecutablePath()
{
    return { };
}
#elif OS(UNIX)
CString currentExecutablePath()
{
    static char readLinkBuffer[PATH_MAX];
    ssize_t result = readlink("/proc/curproc/file", readLinkBuffer, PATH_MAX);
    if (result == -1)
        return { };
    return CString(readLinkBuffer, result);
}
#elif OS(WINDOWS)
CString currentExecutablePath()
{
    static WCHAR buffer[MAX_PATH];
    DWORD length = GetModuleFileNameW(0, buffer, MAX_PATH);
    if (!length || (length == MAX_PATH && GetLastError() == ERROR_INSUFFICIENT_BUFFER))
        return { };

    String path(buffer, length);
    return path.utf8();
}
#endif

CString currentExecutableName()
{
    auto executablePath = currentExecutablePath();
    if (!executablePath.isNull()) {
        GUniquePtr<char> basename(g_path_get_basename(executablePath.data()));
        return basename.get();
    }

    return g_get_prgname();
}

String userCacheDirectory()
{
    return stringFromFileSystemRepresentation(g_get_user_cache_dir());
}

String userDataDirectory()
{
    return stringFromFileSystemRepresentation(g_get_user_data_dir());
}

} // namespace FileSystemImpl
} // namespace WTF