// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef FLUTTER_SHELL_PLATFORM_LINUX_FL_BINARY_MESSENGER_H_
#define FLUTTER_SHELL_PLATFORM_LINUX_FL_BINARY_MESSENGER_H_

#if !defined(__FLUTTER_LINUX_INSIDE__) && !defined(FLUTTER_LINUX_COMPILATION)
#error "Only <flutter_linux/flutter_linux.h> can be included directly."
#endif

#include <gio/gio.h>
#include <glib-object.h>
#include <gmodule.h>

G_BEGIN_DECLS

/**
 * FlBinaryMessengerError:
 * @FL_BINARY_MESSENGER_ERROR_ALREADY_RESPONDED: unable to send response, this
 * message has already been responded to.
 *
 * Errors for #FlBinaryMessenger objects to set on failures.
 */
#define FL_BINARY_MESSENGER_ERROR fl_binary_messenger_codec_error_quark()

typedef enum {
  FL_BINARY_MESSENGER_ERROR_ALREADY_RESPONDED,
} FlBinaryMessengerError;

GQuark fl_binary_messenger_codec_error_quark(void) G_GNUC_CONST;

G_MODULE_EXPORT
G_DECLARE_INTERFACE(FlBinaryMessenger,
                    fl_binary_messenger,
                    FL,
                    BINARY_MESSENGER,
                    GObject)

G_MODULE_EXPORT
G_DECLARE_DERIVABLE_TYPE(FlBinaryMessengerResponseHandle,
                         fl_binary_messenger_response_handle,
                         FL,
                         BINARY_MESSENGER_RESPONSE_HANDLE,
                         GObject)

/**
 * FlBinaryMessengerMessageHandler:
 * @messenger: an #FlBinaryMessenger.
 * @channel: channel message received on.
 * @message: message content received from Dart.
 * @response_handle: a handle to respond to the message with.
 * @user_data: (closure): data provided when registering this handler.
 *
 * Function called when platform messages are received. Call
 * fl_binary_messenger_send_response() to respond to this message. If the
 * response is not occurring in this callback take a reference to
 * @response_handle and release that once it has been responded to. Failing to
 * respond before the last reference to @response_handle is dropped is a
 * programming error.
 */
typedef void (*FlBinaryMessengerMessageHandler)(
    FlBinaryMessenger* messenger,
    const gchar* channel,
    GBytes* message,
    FlBinaryMessengerResponseHandle* response_handle,
    gpointer user_data);

struct _FlBinaryMessengerInterface {
  GTypeInterface parent_iface;

  void (*set_message_handler_on_channel)(
      FlBinaryMessenger* messenger,
      const gchar* channel,
      FlBinaryMessengerMessageHandler handler,
      gpointer user_data,
      GDestroyNotify destroy_notify);

  gboolean (*send_response)(FlBinaryMessenger* messenger,
                            FlBinaryMessengerResponseHandle* response_handle,
                            GBytes* response,
                            GError** error);

  void (*send_on_channel)(FlBinaryMessenger* messenger,
                          const gchar* channel,
                          GBytes* message,
                          GCancellable* cancellable,
                          GAsyncReadyCallback callback,
                          gpointer user_data);

  GBytes* (*send_on_channel_finish)(FlBinaryMessenger* messenger,
                                    GAsyncResult* result,
                                    GError** error);
};

struct _FlBinaryMessengerResponseHandleClass {
  GObjectClass parent_class;
};

/**
 * FlBinaryMessenger:
 *
 * #FlBinaryMessenger is an object that allows sending and receiving of platform
 * messages with an #FlEngine.
 */

/**
 * FlBinaryMessengerResponseHandle:
 *
 * #FlBinaryMessengerResponseHandle is an object used to send responses with.
 */

/**
 * fl_binary_messenger_set_platform_message_handler:
 * @binary_messenger: an #FlBinaryMessenger.
 * @channel: channel to listen on.
 * @handler: (allow-none): function to call when a message is received on this
 * channel or %NULL to disable a handler
 * @user_data: (closure): user data to pass to @handler.
 * @destroy_notify: (allow-none): a function which gets called to free
 * @user_data, or %NULL.
 *
 * Sets the function called when a platform message is received on the given
 * channel. See #FlBinaryMessengerMessageHandler for details on how to respond
 * to messages.
 *
 * The handler is removed if the channel is closed or is replaced by another
 * handler, set @destroy_notify if you want to detect this.
 */
void fl_binary_messenger_set_message_handler_on_channel(
    FlBinaryMessenger* messenger,
    const gchar* channel,
    FlBinaryMessengerMessageHandler handler,
    gpointer user_data,
    GDestroyNotify destroy_notify);

/**
 * fl_binary_messenger_send_response:
 * @binary_messenger: an #FlBinaryMessenger.
 * @response_handle: handle that was provided in a
 * #FlBinaryMessengerMessageHandler.
 * @response: (allow-none): response to send or %NULL for an empty response.
 * @error: (allow-none): #GError location to store the error occurring, or %NULL
 * to ignore.
 *
 * Responds to a platform message. This function is thread-safe.
 *
 * Returns: %TRUE on success.
 */
gboolean fl_binary_messenger_send_response(
    FlBinaryMessenger* messenger,
    FlBinaryMessengerResponseHandle* response_handle,
    GBytes* response,
    GError** error);

/**
 * fl_binary_messenger_send_on_channel:
 * @binary_messenger: an #FlBinaryMessenger.
 * @channel: channel to send to.
 * @message: (allow-none): message buffer to send or %NULL for an empty message.
 * @cancellable: (allow-none): a #GCancellable or %NULL.
 * @callback: (scope async): a #GAsyncReadyCallback to call when the request is
 * satisfied.
 * @user_data: (closure): user data to pass to @callback.
 *
 * Asynchronously sends a platform message.
 */
void fl_binary_messenger_send_on_channel(FlBinaryMessenger* messenger,
                                         const gchar* channel,
                                         GBytes* message,
                                         GCancellable* cancellable,
                                         GAsyncReadyCallback callback,
                                         gpointer user_data);

/**
 * fl_binary_messenger_send_on_channel_finish:
 * @binary_messenger: an #FlBinaryMessenger.
 * @result: a #GAsyncResult.
 * @error: (allow-none): #GError location to store the error occurring, or %NULL
 * to ignore.
 *
 * Completes request started with fl_binary_messenger_send_on_channel().
 *
 * Returns: (transfer full): message response on success or %NULL on error.
 */
GBytes* fl_binary_messenger_send_on_channel_finish(FlBinaryMessenger* messenger,
                                                   GAsyncResult* result,
                                                   GError** error);

G_END_DECLS

#endif  // FLUTTER_SHELL_PLATFORM_LINUX_FL_BINARY_MESSENGER_H_