/* vim:set ts=2 sw=2 et cindent: */
/* 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/. */

/*
 * This code is based on original Mozilla gnome-vfs extension. It implements
 * input stream provided by GVFS/GIO.
 */
#include "nsGIOProtocolHandler.h"
#include "GIOChannelChild.h"
#include "mozilla/Components.h"
#include "mozilla/ClearOnShutdown.h"
#include "mozilla/Logging.h"
#include "mozilla/net/NeckoChild.h"
#include "mozilla/NullPrincipal.h"
#include "nsIPrefBranch.h"
#include "nsIPrefService.h"
#include "nsIObserver.h"
#include "nsCRT.h"
#include "nsThreadUtils.h"
#include "nsProxyRelease.h"
#include "nsIStringBundle.h"
#include "nsMimeTypes.h"
#include "nsNetCID.h"
#include "nsNetUtil.h"
#include "nsServiceManagerUtils.h"
#include "nsIURI.h"
#include "nsIAuthPrompt.h"
#include "nsIChannel.h"
#include "nsIInputStream.h"
#include "nsIProtocolHandler.h"
#include "mozilla/Monitor.h"
#include "plstr.h"
#include "prtime.h"
#include <gio/gio.h>
#include <algorithm>

using namespace mozilla;

#define MOZ_GIO_SCHEME "moz-gio"
#define MOZ_GIO_SUPPORTED_PROTOCOLS "network.gio.supported-protocols"

//-----------------------------------------------------------------------------

// NSPR_LOG_MODULES=gio:5
LazyLogModule gGIOLog("gio");
#undef LOG
#define LOG(args) MOZ_LOG(gGIOLog, mozilla::LogLevel::Debug, args)

//-----------------------------------------------------------------------------
static nsresult MapGIOResult(gint code) {
  switch (code) {
    case G_IO_ERROR_NOT_FOUND:
      return NS_ERROR_FILE_NOT_FOUND;  // shows error
    case G_IO_ERROR_INVALID_ARGUMENT:
      return NS_ERROR_INVALID_ARG;
    case G_IO_ERROR_NOT_SUPPORTED:
      return NS_ERROR_NOT_AVAILABLE;
    case G_IO_ERROR_NO_SPACE:
      return NS_ERROR_FILE_NO_DEVICE_SPACE;
    case G_IO_ERROR_READ_ONLY:
      return NS_ERROR_FILE_READ_ONLY;
    case G_IO_ERROR_PERMISSION_DENIED:
      return NS_ERROR_FILE_ACCESS_DENIED;  // wrong password/login
    case G_IO_ERROR_CLOSED:
      return NS_BASE_STREAM_CLOSED;  // was EOF
    case G_IO_ERROR_NOT_DIRECTORY:
      return NS_ERROR_FILE_NOT_DIRECTORY;
    case G_IO_ERROR_PENDING:
      return NS_ERROR_IN_PROGRESS;
    case G_IO_ERROR_EXISTS:
      return NS_ERROR_FILE_ALREADY_EXISTS;
    case G_IO_ERROR_IS_DIRECTORY:
      return NS_ERROR_FILE_IS_DIRECTORY;
    case G_IO_ERROR_NOT_MOUNTED:
      return NS_ERROR_NOT_CONNECTED;  // shows error
    case G_IO_ERROR_HOST_NOT_FOUND:
      return NS_ERROR_UNKNOWN_HOST;  // shows error
    case G_IO_ERROR_CANCELLED:
      return NS_ERROR_ABORT;
    case G_IO_ERROR_NOT_EMPTY:
      return NS_ERROR_FILE_DIR_NOT_EMPTY;
    case G_IO_ERROR_FILENAME_TOO_LONG:
      return NS_ERROR_FILE_NAME_TOO_LONG;
    case G_IO_ERROR_INVALID_FILENAME:
      return NS_ERROR_FILE_INVALID_PATH;
    case G_IO_ERROR_TIMED_OUT:
      return NS_ERROR_NET_TIMEOUT;  // shows error
    case G_IO_ERROR_WOULD_BLOCK:
      return NS_BASE_STREAM_WOULD_BLOCK;
    case G_IO_ERROR_FAILED_HANDLED:
      return NS_ERROR_ABORT;  // Cancel on login dialog

      /* unhandled:
        G_IO_ERROR_NOT_REGULAR_FILE,
        G_IO_ERROR_NOT_SYMBOLIC_LINK,
        G_IO_ERROR_NOT_MOUNTABLE_FILE,
        G_IO_ERROR_TOO_MANY_LINKS,
        G_IO_ERROR_ALREADY_MOUNTED,
        G_IO_ERROR_CANT_CREATE_BACKUP,
        G_IO_ERROR_WRONG_ETAG,
        G_IO_ERROR_WOULD_RECURSE,
        G_IO_ERROR_BUSY,
        G_IO_ERROR_WOULD_MERGE,
        G_IO_ERROR_TOO_MANY_OPEN_FILES
      */
    // Make GCC happy
    default:
      return NS_ERROR_FAILURE;
  }
}

static nsresult MapGIOResult(GError* result) {
  if (!result) {
    return NS_OK;
  }
  return MapGIOResult(result->code);
}

/** Return values for mount operation.
 * These enums are used as mount operation return values.
 */
enum class MountOperationResult {
  MOUNT_OPERATION_IN_PROGRESS, /** \enum operation in progress */
  MOUNT_OPERATION_SUCCESS,     /** \enum operation successful */
  MOUNT_OPERATION_FAILED       /** \enum operation not successful */
};

//-----------------------------------------------------------------------------
/**
 * Sort function compares according to file type (directory/file)
 * and alphabethical order
 * @param a pointer to GFileInfo object to compare
 * @param b pointer to GFileInfo object to compare
 * @return -1 when first object should be before the second, 0 when equal,
 * +1 when second object should be before the first
 */
static gint FileInfoComparator(gconstpointer a, gconstpointer b) {
  GFileInfo* ia = (GFileInfo*)a;
  GFileInfo* ib = (GFileInfo*)b;
  if (g_file_info_get_file_type(ia) == G_FILE_TYPE_DIRECTORY &&
      g_file_info_get_file_type(ib) != G_FILE_TYPE_DIRECTORY) {
    return -1;
  }
  if (g_file_info_get_file_type(ib) == G_FILE_TYPE_DIRECTORY &&
      g_file_info_get_file_type(ia) != G_FILE_TYPE_DIRECTORY) {
    return 1;
  }

  return nsCRT::strcasecmp(g_file_info_get_name(ia), g_file_info_get_name(ib));
}

/* Declaration of mount callback functions */
static void mount_enclosing_volume_finished(GObject* source_object,
                                            GAsyncResult* res,
                                            gpointer user_data);
static void mount_operation_ask_password(
    GMountOperation* mount_op, const char* message, const char* default_user,
    const char* default_domain, GAskPasswordFlags flags, gpointer user_data);
//-----------------------------------------------------------------------------
class nsGIOInputStream final : public nsIInputStream {
 public:
  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSIINPUTSTREAM

  explicit nsGIOInputStream(const nsCString& uriSpec) : mSpec(uriSpec) {}

  void SetChannel(nsIChannel* channel) {
    // We need to hold an owning reference to our channel.  This is done
    // so we can access the channel's notification callbacks to acquire
    // a reference to a nsIAuthPrompt if we need to handle an interactive
    // mount operation.
    //
    // However, the channel can only be accessed on the main thread, so
    // we have to be very careful with ownership.  Moreover, it doesn't
    // support threadsafe addref/release, so proxying is the answer.
    //
    // Also, it's important to note that this likely creates a reference
    // cycle since the channel likely owns this stream.  This reference
    // cycle is broken in our Close method.

    mChannel = do_AddRef(channel).take();
  }
  void SetMountResult(MountOperationResult result, gint error_code);

 private:
  ~nsGIOInputStream() { Close(); }
  nsresult DoOpen();
  nsresult DoRead(char* aBuf, uint32_t aCount, uint32_t* aCountRead);
  nsresult SetContentTypeOfChannel(const char* contentType);
  nsresult MountVolume();
  nsresult DoOpenDirectory();
  nsresult DoOpenFile(GFileInfo* info);
  nsCString mSpec;
  nsIChannel* mChannel{nullptr};  // manually refcounted
  GFile* mHandle{nullptr};
  GFileInputStream* mStream{nullptr};
  uint64_t mBytesRemaining{UINT64_MAX};
  nsresult mStatus{NS_OK};
  GList* mDirList{nullptr};
  GList* mDirListPtr{nullptr};
  nsCString mDirBuf;
  uint32_t mDirBufCursor{0};
  bool mDirOpen{false};
  MountOperationResult mMountRes =
      MountOperationResult::MOUNT_OPERATION_SUCCESS;
  mozilla::Monitor mMonitorMountInProgress MOZ_UNANNOTATED{
      "GIOInputStream::MountFinished"};
  gint mMountErrorCode{};
};

/**
 * Set result of mount operation and notify monitor waiting for results.
 * This method is called in main thread as long as it is used only
 * in mount_enclosing_volume_finished function.
 * @param result Result of mount operation
 */
void nsGIOInputStream::SetMountResult(MountOperationResult result,
                                      gint error_code) {
  mozilla::MonitorAutoLock mon(mMonitorMountInProgress);
  mMountRes = result;
  mMountErrorCode = error_code;
  mon.Notify();
}

/**
 * Start mount operation and wait in loop until it is finished. This method is
 * called from thread which is trying to read from location.
 */
nsresult nsGIOInputStream::MountVolume() {
  GMountOperation* mount_op = g_mount_operation_new();
  g_signal_connect(mount_op, "ask-password",
                   G_CALLBACK(mount_operation_ask_password), mChannel);
  mMountRes = MountOperationResult::MOUNT_OPERATION_IN_PROGRESS;
  /* g_file_mount_enclosing_volume uses a dbus request to mount the volume.
     Callback mount_enclosing_volume_finished is called in main thread
     (not this thread on which this method is called). */
  g_file_mount_enclosing_volume(mHandle, G_MOUNT_MOUNT_NONE, mount_op, nullptr,
                                mount_enclosing_volume_finished, this);
  mozilla::MonitorAutoLock mon(mMonitorMountInProgress);
  /* Waiting for finish of mount operation thread */
  while (mMountRes == MountOperationResult::MOUNT_OPERATION_IN_PROGRESS) {
    mon.Wait();
  }

  g_object_unref(mount_op);

  if (mMountRes == MountOperationResult::MOUNT_OPERATION_FAILED) {
    return MapGIOResult(mMountErrorCode);
  }
  return NS_OK;
}

/**
 * Create list of infos about objects in opened directory
 * Return: NS_OK when list obtained, otherwise error code according
 * to failed operation.
 */
nsresult nsGIOInputStream::DoOpenDirectory() {
  GError* error = nullptr;

  GFileEnumerator* f_enum = g_file_enumerate_children(
      mHandle, "standard::*,time::*", G_FILE_QUERY_INFO_NONE, nullptr, &error);
  if (!f_enum) {
    nsresult rv = MapGIOResult(error);
    g_warning("Cannot read from directory: %s", error->message);
    g_error_free(error);
    return rv;
  }
  // fill list of file infos
  GFileInfo* info = g_file_enumerator_next_file(f_enum, nullptr, &error);
  while (info) {
    mDirList = g_list_append(mDirList, info);
    info = g_file_enumerator_next_file(f_enum, nullptr, &error);
  }
  g_object_unref(f_enum);
  if (error) {
    g_warning("Error reading directory content: %s", error->message);
    nsresult rv = MapGIOResult(error);
    g_error_free(error);
    return rv;
  }
  mDirOpen = true;

  // Sort list of file infos by using FileInfoComparator function
  mDirList = g_list_sort(mDirList, FileInfoComparator);
  mDirListPtr = mDirList;

  // Write base URL (make sure it ends with a '/')
  mDirBuf.AppendLiteral("300: ");
  mDirBuf.Append(mSpec);
  if (mSpec.get()[mSpec.Length() - 1] != '/') {
    mDirBuf.Append('/');
  }
  mDirBuf.Append('\n');

  // Write column names
  mDirBuf.AppendLiteral(
      "200: filename content-length last-modified file-type\n");

  // Write charset (assume UTF-8)
  // XXX is this correct?
  mDirBuf.AppendLiteral("301: UTF-8\n");
  SetContentTypeOfChannel(APPLICATION_HTTP_INDEX_FORMAT);
  return NS_OK;
}

/**
 * Create file stream and set mime type for channel
 * @param info file info used to determine mime type
 * @return NS_OK when file stream created successfuly, error code otherwise
 */
nsresult nsGIOInputStream::DoOpenFile(GFileInfo* info) {
  GError* error = nullptr;

  mStream = g_file_read(mHandle, nullptr, &error);
  if (!mStream) {
    nsresult rv = MapGIOResult(error);
    g_warning("Cannot read from file: %s", error->message);
    g_error_free(error);
    return rv;
  }

  const char* content_type = g_file_info_get_content_type(info);
  if (content_type) {
    char* mime_type = g_content_type_get_mime_type(content_type);
    if (mime_type) {
      if (strcmp(mime_type, APPLICATION_OCTET_STREAM) != 0) {
        SetContentTypeOfChannel(mime_type);
      }
      g_free(mime_type);
    }
  } else {
    g_warning("Missing content type.");
  }

  mBytesRemaining = g_file_info_get_size(info);
  // Update the content length attribute on the channel.  We do this
  // synchronously without proxying.  This hack is not as bad as it looks!
  mChannel->SetContentLength(mBytesRemaining);

  return NS_OK;
}

/**
 * Start file open operation, mount volume when needed and according to file
 * type create file output stream or read directory content.
 * @return NS_OK when file or directory opened successfully, error code
 * otherwise
 */
nsresult nsGIOInputStream::DoOpen() {
  nsresult rv;
  GError* error = nullptr;

  NS_ASSERTION(mHandle == nullptr, "already open");

  mHandle = g_file_new_for_uri(mSpec.get());

  GFileInfo* info = g_file_query_info(mHandle, "standard::*",
                                      G_FILE_QUERY_INFO_NONE, nullptr, &error);

  if (error) {
    if (error->domain == G_IO_ERROR && error->code == G_IO_ERROR_NOT_MOUNTED) {
      // location is not yet mounted, try to mount
      g_error_free(error);
      if (NS_IsMainThread()) {
        return NS_ERROR_NOT_CONNECTED;
      }
      error = nullptr;
      rv = MountVolume();
      if (rv != NS_OK) {
        return rv;
      }
      // get info again
      info = g_file_query_info(mHandle, "standard::*", G_FILE_QUERY_INFO_NONE,
                               nullptr, &error);
      // second try to get file info from remote files after media mount
      if (!info) {
        g_warning("Unable to get file info: %s", error->message);
        rv = MapGIOResult(error);
        g_error_free(error);
        return rv;
      }
    } else {
      g_warning("Unable to get file info: %s", error->message);
      rv = MapGIOResult(error);
      g_error_free(error);
      return rv;
    }
  }
  // Get file type to handle directories and file differently
  GFileType f_type = g_file_info_get_file_type(info);
  if (f_type == G_FILE_TYPE_DIRECTORY) {
    // directory
    rv = DoOpenDirectory();
  } else if (f_type != G_FILE_TYPE_UNKNOWN) {
    // file
    rv = DoOpenFile(info);
  } else {
    g_warning("Unable to get file type.");
    rv = NS_ERROR_FILE_NOT_FOUND;
  }
  if (info) {
    g_object_unref(info);
  }
  return rv;
}

/**
 * Read content of file or create file list from directory
 * @param aBuf read destination buffer
 * @param aCount length of destination buffer
 * @param aCountRead number of read characters
 * @return NS_OK when read successfully, NS_BASE_STREAM_CLOSED when end of file,
 *         error code otherwise
 */
nsresult nsGIOInputStream::DoRead(char* aBuf, uint32_t aCount,
                                  uint32_t* aCountRead) {
  nsresult rv = NS_ERROR_NOT_AVAILABLE;
  if (mStream) {
    // file read
    GError* error = nullptr;
    uint32_t bytes_read = g_input_stream_read(G_INPUT_STREAM(mStream), aBuf,
                                              aCount, nullptr, &error);
    if (error) {
      rv = MapGIOResult(error);
      *aCountRead = 0;
      g_warning("Cannot read from file: %s", error->message);
      g_error_free(error);
      return rv;
    }
    *aCountRead = bytes_read;
    mBytesRemaining -= *aCountRead;
    return NS_OK;
  }
  if (mDirOpen) {
    // directory read
    while (aCount && rv != NS_BASE_STREAM_CLOSED) {
      // Copy data out of our buffer
      uint32_t bufLen = mDirBuf.Length() - mDirBufCursor;
      if (bufLen) {
        uint32_t n = std::min(bufLen, aCount);
        memcpy(aBuf, mDirBuf.get() + mDirBufCursor, n);
        *aCountRead += n;
        aBuf += n;
        aCount -= n;
        mDirBufCursor += n;
      }

      if (!mDirListPtr)  // Are we at the end of the directory list?
      {
        rv = NS_BASE_STREAM_CLOSED;
      } else if (aCount)  // Do we need more data?
      {
        GFileInfo* info = (GFileInfo*)mDirListPtr->data;

        // Prune '.' and '..' from directory listing.
        const char* fname = g_file_info_get_name(info);
        if (fname && fname[0] == '.' &&
            (fname[1] == '\0' || (fname[1] == '.' && fname[2] == '\0'))) {
          mDirListPtr = mDirListPtr->next;
          continue;
        }

        mDirBuf.AssignLiteral("201: ");

        // The "filename" field
        nsCString escName;
        nsCOMPtr<nsINetUtil> nu = do_GetService(NS_NETUTIL_CONTRACTID);
        if (nu && fname) {
          nu->EscapeString(nsDependentCString(fname),
                           nsINetUtil::ESCAPE_URL_PATH, escName);

          mDirBuf.Append(escName);
          mDirBuf.Append(' ');
        }

        // The "content-length" field
        // XXX truncates size from 64-bit to 32-bit
        mDirBuf.AppendInt(int32_t(g_file_info_get_size(info)));
        mDirBuf.Append(' ');

        // The "last-modified" field
        //
        // NSPR promises: PRTime is compatible with time_t
        // we just need to convert from seconds to microseconds
        GTimeVal gtime;
        g_file_info_get_modification_time(info, &gtime);

        PRExplodedTime tm;
        PRTime pt = ((PRTime)gtime.tv_sec) * 1000000;
        PR_ExplodeTime(pt, PR_GMTParameters, &tm);
        {
          char buf[64];
          PR_FormatTimeUSEnglish(buf, sizeof(buf),
                                 "%a,%%20%d%%20%b%%20%Y%%20%H:%M:%S%%20GMT ",
                                 &tm);
          mDirBuf.Append(buf);
        }

        // The "file-type" field
        switch (g_file_info_get_file_type(info)) {
          case G_FILE_TYPE_REGULAR:
            mDirBuf.AppendLiteral("FILE ");
            break;
          case G_FILE_TYPE_DIRECTORY:
            mDirBuf.AppendLiteral("DIRECTORY ");
            break;
          case G_FILE_TYPE_SYMBOLIC_LINK:
            mDirBuf.AppendLiteral("SYMBOLIC-LINK ");
            break;
          default:
            break;
        }
        mDirBuf.Append('\n');

        mDirBufCursor = 0;
        mDirListPtr = mDirListPtr->next;
      }
    }
  }
  return rv;
}

/**
 * This class is used to implement SetContentTypeOfChannel.
 */
class nsGIOSetContentTypeEvent : public mozilla::Runnable {
 public:
  nsGIOSetContentTypeEvent(nsIChannel* channel, const char* contentType)
      : mozilla::Runnable("nsGIOSetContentTypeEvent"),
        mChannel(channel),
        mContentType(contentType) {
    // stash channel reference in mChannel.  no AddRef here!  see note
    // in SetContentTypeOfchannel.
  }

  NS_IMETHOD Run() override {
    mChannel->SetContentType(mContentType);
    return NS_OK;
  }

 private:
  nsIChannel* mChannel;
  nsCString mContentType;
};

nsresult nsGIOInputStream::SetContentTypeOfChannel(const char* contentType) {
  // We need to proxy this call over to the main thread.  We post an
  // asynchronous event in this case so that we don't delay reading data, and
  // we know that this is safe to do since the channel's reference will be
  // released asynchronously as well.  We trust the ordering of the main
  // thread's event queue to protect us against memory corruption.

  nsresult rv;
  nsCOMPtr<nsIRunnable> ev =
      new nsGIOSetContentTypeEvent(mChannel, contentType);
  if (!ev) {
    rv = NS_ERROR_OUT_OF_MEMORY;
  } else {
    rv = NS_DispatchToMainThread(ev);
  }
  return rv;
}

NS_IMPL_ISUPPORTS(nsGIOInputStream, nsIInputStream)

/**
 * Free all used memory and close stream.
 */
NS_IMETHODIMP
nsGIOInputStream::Close() {
  if (mStream) {
    g_object_unref(mStream);
    mStream = nullptr;
  }

  if (mHandle) {
    g_object_unref(mHandle);
    mHandle = nullptr;
  }

  if (mDirList) {
    // Destroy the list of GIOFileInfo objects...
    g_list_foreach(mDirList, (GFunc)g_object_unref, nullptr);
    g_list_free(mDirList);
    mDirList = nullptr;
    mDirListPtr = nullptr;
  }

  if (mChannel) {
    NS_ReleaseOnMainThread("nsGIOInputStream::mChannel", dont_AddRef(mChannel));

    mChannel = nullptr;
  }

  mSpec.Truncate();  // free memory

  // Prevent future reads from re-opening the handle.
  if (NS_SUCCEEDED(mStatus)) {
    mStatus = NS_BASE_STREAM_CLOSED;
  }

  return NS_OK;
}

/**
 * Return number of remaining bytes available on input
 * @param aResult remaining bytes
 */
NS_IMETHODIMP
nsGIOInputStream::Available(uint64_t* aResult) {
  if (NS_FAILED(mStatus)) {
    return mStatus;
  }

  *aResult = mBytesRemaining;

  return NS_OK;
}

/**
 * Trying to read from stream. When location is not available it tries to mount
 * it.
 * @param aBuf buffer to put read data
 * @param aCount length of aBuf
 * @param aCountRead number of bytes actually read
 */
NS_IMETHODIMP
nsGIOInputStream::Read(char* aBuf, uint32_t aCount, uint32_t* aCountRead) {
  *aCountRead = 0;
  // Check if file is already opened, otherwise open it
  if (!mStream && !mDirOpen && mStatus == NS_OK) {
    mStatus = DoOpen();
    if (NS_FAILED(mStatus)) {
      return mStatus;
    }
  }

  mStatus = DoRead(aBuf, aCount, aCountRead);
  // Check if all data has been read
  if (mStatus == NS_BASE_STREAM_CLOSED) {
    return NS_OK;
  }

  // Check whenever any error appears while reading
  return mStatus;
}

NS_IMETHODIMP
nsGIOInputStream::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
                               uint32_t aCount, uint32_t* aResult) {
  // There is no way to implement this using GnomeVFS, but fortunately
  // that doesn't matter.  Because we are a blocking input stream, Necko
  // isn't going to call our ReadSegments method.
  MOZ_ASSERT_UNREACHABLE("nsGIOInputStream::ReadSegments");
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsGIOInputStream::IsNonBlocking(bool* aResult) {
  *aResult = false;
  return NS_OK;
}

//-----------------------------------------------------------------------------

/**
 * Called when finishing mount operation. Result of operation is set in
 * nsGIOInputStream. This function is called in main thread as an async request
 * typically from dbus.
 * @param source_object GFile object which requested the mount
 * @param res result object
 * @param user_data pointer to nsGIOInputStream
 */
static void mount_enclosing_volume_finished(GObject* source_object,
                                            GAsyncResult* res,
                                            gpointer user_data) {
  GError* error = nullptr;

  nsGIOInputStream* istream = static_cast<nsGIOInputStream*>(user_data);

  g_file_mount_enclosing_volume_finish(G_FILE(source_object), res, &error);

  if (error) {
    g_warning("Mount failed: %s %d", error->message, error->code);
    istream->SetMountResult(MountOperationResult::MOUNT_OPERATION_FAILED,
                            error->code);
    g_error_free(error);
  } else {
    istream->SetMountResult(MountOperationResult::MOUNT_OPERATION_SUCCESS, 0);
  }
}

/**
 * This function is called when username or password are requested from user.
 * This function is called in main thread as async request from dbus.
 * @param mount_op mount operation
 * @param message message to show to user
 * @param default_user preffered user
 * @param default_domain domain name
 * @param flags what type of information is required
 * @param user_data nsIChannel
 */
static void mount_operation_ask_password(
    GMountOperation* mount_op, const char* message, const char* default_user,
    const char* default_domain, GAskPasswordFlags flags, gpointer user_data) {
  nsIChannel* channel = (nsIChannel*)user_data;
  if (!channel) {
    g_mount_operation_reply(mount_op, G_MOUNT_OPERATION_ABORTED);
    return;
  }
  // We can't handle request for domain
  if (flags & G_ASK_PASSWORD_NEED_DOMAIN) {
    g_mount_operation_reply(mount_op, G_MOUNT_OPERATION_ABORTED);
    return;
  }

  nsCOMPtr<nsIAuthPrompt> prompt;
  NS_QueryNotificationCallbacks(channel, prompt);

  // If no auth prompt, then give up.  We could failover to using the
  // WindowWatcher service, but that might defeat a consumer's purposeful
  // attempt to disable authentication (for whatever reason).
  if (!prompt) {
    g_mount_operation_reply(mount_op, G_MOUNT_OPERATION_ABORTED);
    return;
  }
  // Parse out the host and port...
  nsCOMPtr<nsIURI> uri;
  channel->GetURI(getter_AddRefs(uri));
  if (!uri) {
    g_mount_operation_reply(mount_op, G_MOUNT_OPERATION_ABORTED);
    return;
  }

  nsAutoCString scheme, hostPort;
  uri->GetScheme(scheme);
  uri->GetHostPort(hostPort);

  // It doesn't make sense for either of these strings to be empty.  What kind
  // of funky URI is this?
  if (scheme.IsEmpty() || hostPort.IsEmpty()) {
    g_mount_operation_reply(mount_op, G_MOUNT_OPERATION_ABORTED);
    return;
  }
  // Construct the single signon key.  Altering the value of this key will
  // cause people's remembered passwords to be forgotten.  Think carefully
  // before changing the way this key is constructed.
  nsAutoString key, realm;

  NS_ConvertUTF8toUTF16 dispHost(scheme);
  dispHost.AppendLiteral("://");
  dispHost.Append(NS_ConvertUTF8toUTF16(hostPort));

  key = dispHost;
  if (*default_domain != '\0') {
    // We assume the realm string is ASCII.  That might be a bogus assumption,
    // but we have no idea what encoding GnomeVFS is using, so for now we'll
    // limit ourselves to ISO-Latin-1.  XXX What is a better solution?
    realm.Append('"');
    realm.Append(NS_ConvertASCIItoUTF16(default_domain));
    realm.Append('"');
    key.Append(' ');
    key.Append(realm);
  }
  // Construct the message string...
  //
  // We use Necko's string bundle here.  This code really should be encapsulated
  // behind some Necko API, after all this code is based closely on the code in
  // nsHttpChannel.cpp.
  nsCOMPtr<nsIStringBundleService> bundleSvc =
      do_GetService(NS_STRINGBUNDLE_CONTRACTID);
  if (!bundleSvc) {
    g_mount_operation_reply(mount_op, G_MOUNT_OPERATION_ABORTED);
    return;
  }
  nsCOMPtr<nsIStringBundle> bundle;
  bundleSvc->CreateBundle("chrome://global/locale/commonDialogs.properties",
                          getter_AddRefs(bundle));
  if (!bundle) {
    g_mount_operation_reply(mount_op, G_MOUNT_OPERATION_ABORTED);
    return;
  }
  nsAutoString nsmessage;

  if (flags & G_ASK_PASSWORD_NEED_PASSWORD) {
    if (flags & G_ASK_PASSWORD_NEED_USERNAME) {
      if (!realm.IsEmpty()) {
        AutoTArray<nsString, 2> strings = {realm, dispHost};
        bundle->FormatStringFromName("EnterLoginForRealm3", strings, nsmessage);
      } else {
        AutoTArray<nsString, 1> strings = {dispHost};
        bundle->FormatStringFromName("EnterUserPasswordFor2", strings,
                                     nsmessage);
      }
    } else {
      NS_ConvertUTF8toUTF16 userName(default_user);
      AutoTArray<nsString, 2> strings = {userName, dispHost};
      bundle->FormatStringFromName("EnterPasswordFor", strings, nsmessage);
    }
  } else {
    g_warning("Unknown mount operation request (flags: %x)", flags);
  }

  if (nsmessage.IsEmpty()) {
    g_mount_operation_reply(mount_op, G_MOUNT_OPERATION_ABORTED);
    return;
  }
  // Prompt the user...
  nsresult rv;
  bool retval = false;
  char16_t *user = nullptr, *pass = nullptr;
  if (default_user) {
    // user will be freed by PromptUsernameAndPassword
    user = ToNewUnicode(NS_ConvertUTF8toUTF16(default_user));
  }
  if (flags & G_ASK_PASSWORD_NEED_USERNAME) {
    rv = prompt->PromptUsernameAndPassword(
        nullptr, nsmessage.get(), key.get(),
        nsIAuthPrompt::SAVE_PASSWORD_PERMANENTLY, &user, &pass, &retval);
  } else {
    rv = prompt->PromptPassword(nullptr, nsmessage.get(), key.get(),
                                nsIAuthPrompt::SAVE_PASSWORD_PERMANENTLY, &pass,
                                &retval);
  }
  if (NS_FAILED(rv) || !retval) {  //  was || user == '\0' || pass == '\0'
    g_mount_operation_reply(mount_op, G_MOUNT_OPERATION_ABORTED);
    free(user);
    free(pass);
    return;
  }
  /* GIO should accept UTF8 */
  g_mount_operation_set_username(mount_op, NS_ConvertUTF16toUTF8(user).get());
  g_mount_operation_set_password(mount_op, NS_ConvertUTF16toUTF8(pass).get());
  free(user);
  free(pass);
  g_mount_operation_reply(mount_op, G_MOUNT_OPERATION_HANDLED);
}

//-----------------------------------------------------------------------------

mozilla::StaticRefPtr<nsGIOProtocolHandler> nsGIOProtocolHandler::sSingleton;

already_AddRefed<nsGIOProtocolHandler> nsGIOProtocolHandler::GetSingleton() {
  if (!sSingleton) {
    sSingleton = new nsGIOProtocolHandler();
    sSingleton->Init();
    ClearOnShutdown(&sSingleton);
  }
  return do_AddRef(sSingleton);
}

NS_IMPL_ISUPPORTS(nsGIOProtocolHandler, nsIProtocolHandler, nsIObserver)

nsresult nsGIOProtocolHandler::Init() {
  if (net::IsNeckoChild()) {
    net::NeckoChild::InitNeckoChild();
  }
  nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
  if (prefs) {
    InitSupportedProtocolsPref(prefs);
    prefs->AddObserver(MOZ_GIO_SUPPORTED_PROTOCOLS, this, false);
  }

  return NS_OK;
}

void nsGIOProtocolHandler::InitSupportedProtocolsPref(nsIPrefBranch* prefs) {
  nsCOMPtr<nsIIOService> ioService = components::IO::Service();
  if (NS_WARN_IF(!ioService)) {
    LOG(("gio: ioservice not available\n"));
    return;
  }

  // Get user preferences to determine which protocol is supported.
  // Gvfs/GIO has a set of supported protocols like obex, network, archive,
  // computer, dav, cdda, gphoto2, trash, etc. Some of these seems to be
  // irrelevant to process by browser. By default accept only sftp protocol so
  // far.
  nsAutoCString prefValue;
  nsresult rv = prefs->GetCharPref(MOZ_GIO_SUPPORTED_PROTOCOLS, prefValue);
  if (NS_SUCCEEDED(rv)) {
    prefValue.StripWhitespace();
    ToLowerCase(prefValue);
  } else {
    prefValue.AssignLiteral(
#ifdef MOZ_PROXY_BYPASS_PROTECTION
        ""  // use none
#else
        "sftp:"  // use defaults (comma separated list)
#endif
    );
  }
  LOG(("gio: supported protocols \"%s\"\n", prefValue.get()));

  // Unregister any previously registered dynamic protocols.
  for (const nsCString& scheme : mSupportedProtocols) {
    LOG(("gio: unregistering handler for \"%s\"", scheme.get()));
    ioService->UnregisterProtocolHandler(scheme);
  }
  mSupportedProtocols.Clear();

  // Register each protocol from the pref branch to reference
  // nsGIOProtocolHandler.
  for (const nsDependentCSubstring& protocol : prefValue.Split(',')) {
    if (NS_WARN_IF(!StringEndsWith(protocol, ":"_ns))) {
      continue;  // each protocol must end with a `:` character to be recognized
    }

    nsCString scheme(Substring(protocol, 0, protocol.Length() - 1));
    if (NS_SUCCEEDED(ioService->RegisterProtocolHandler(
            scheme, this,
            nsIProtocolHandler::URI_STD |
                nsIProtocolHandler::URI_DANGEROUS_TO_LOAD,
            /* aDefaultPort */ -1))) {
      LOG(("gio: successfully registered handler for \"%s\"", scheme.get()));
      mSupportedProtocols.AppendElement(scheme);
    } else {
      LOG(("gio: failed to register handler for \"%s\"", scheme.get()));
    }
  }
}

bool nsGIOProtocolHandler::IsSupportedProtocol(const nsCString& aScheme) {
  for (const auto& protocol : mSupportedProtocols) {
    if (aScheme.EqualsIgnoreCase(protocol)) {
      return true;
    }
  }
  return false;
}

NS_IMETHODIMP
nsGIOProtocolHandler::GetScheme(nsACString& aScheme) {
  aScheme.AssignLiteral(MOZ_GIO_SCHEME);
  return NS_OK;
}

static bool IsValidGIOScheme(const nsACString& aScheme) {
  // Verify that GIO supports this URI scheme.
  GVfs* gvfs = g_vfs_get_default();

  if (!gvfs) {
    g_warning("Cannot get GVfs object.");
    return false;
  }

  const gchar* const* uri_schemes = g_vfs_get_supported_uri_schemes(gvfs);

  while (*uri_schemes != nullptr) {
    // While flatSpec ends with ':' the uri_scheme does not. Therefore do not
    // compare last character.
    if (aScheme.Equals(*uri_schemes)) {
      return true;
    }
    uri_schemes++;
  }

  return false;
}

NS_IMETHODIMP
nsGIOProtocolHandler::NewChannel(nsIURI* aURI, nsILoadInfo* aLoadInfo,
                                 nsIChannel** aResult) {
  NS_ENSURE_ARG_POINTER(aURI);
  nsresult rv;

  nsAutoCString spec;
  rv = aURI->GetSpec(spec);
  if (NS_FAILED(rv)) {
    return rv;
  }

  nsAutoCString scheme;
  rv = aURI->GetScheme(scheme);
  if (NS_FAILED(rv)) {
    return rv;
  }

  if (!IsSupportedProtocol(scheme)) {
    return NS_ERROR_UNKNOWN_PROTOCOL;
  }

  // g_vfs_get_supported_uri_schemes() returns a very limited list in the
  // child due to the sandbox, so we only check if its valid for the parent.
  if (XRE_IsParentProcess() && !IsValidGIOScheme(scheme)) {
    return NS_ERROR_UNKNOWN_PROTOCOL;
  }

  RefPtr<nsBaseChannel> channel;
  if (net::IsNeckoChild()) {
    channel = new mozilla::net::GIOChannelChild(aURI);
    // set the loadInfo on the new channel
    channel->SetLoadInfo(aLoadInfo);

    rv = channel->SetContentType(nsLiteralCString(UNKNOWN_CONTENT_TYPE));
    NS_ENSURE_SUCCESS(rv, rv);

    channel.forget(aResult);
    return NS_OK;
  }

  RefPtr<nsGIOInputStream> stream = new nsGIOInputStream(spec);
  if (!stream) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  RefPtr<nsGIOInputStream> tmpStream = stream;
  rv = NS_NewInputStreamChannelInternal(aResult, aURI, tmpStream.forget(),
                                        nsLiteralCString(UNKNOWN_CONTENT_TYPE),
                                        ""_ns,  // aContentCharset
                                        aLoadInfo);
  if (NS_SUCCEEDED(rv)) {
    stream->SetChannel(*aResult);
  }

  return rv;
}

NS_IMETHODIMP
nsGIOProtocolHandler::AllowPort(int32_t aPort, const char* aScheme,
                                bool* aResult) {
  // Don't override anything.
  *aResult = false;
  return NS_OK;
}

NS_IMETHODIMP
nsGIOProtocolHandler::Observe(nsISupports* aSubject, const char* aTopic,
                              const char16_t* aData) {
  if (strcmp(aTopic, NS_PREFBRANCH_PREFCHANGE_TOPIC_ID) == 0) {
    nsCOMPtr<nsIPrefBranch> prefs = do_QueryInterface(aSubject);
    InitSupportedProtocolsPref(prefs);
  }
  return NS_OK;
}