/*
 * GStreamer
 * Copyright (C) 2010  Intel Corporation.
 * Copyright (C) 2012 Matthew Waters <ystreet00@gmail.com>
 *
 * 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; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 * Authors:
 *  Matthew Allum
 *  Robert Bragg
 *  Kristian Høgsberg
 */

/* code originally from clutter's wayland backend found here
 * http://git.gnome.org/browse/clutter/tree/clutter/wayland/clutter-event-wayland.c
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdint.h>
#include <stdlib.h>
#include <wayland-client.h>
#include <gst/gst.h>

#include "wayland_event_source.h"

#define GST_CAT_DEFAULT gst_gl_wayland_event_source_debug
GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);

static void
init_debug (void)
{
  static volatile gsize _debug;

  if (g_once_init_enter (&_debug)) {
    GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT, "glwaylandeventsource", 0,
        "OpenGL Wayland event source");
    g_once_init_leave (&_debug, 1);
  }
}

typedef struct _WaylandEventSource
{
  GSource source;
  GPollFD pfd;
  uint32_t mask;
  struct wl_display *display;
  struct wl_event_queue *queue;
  gboolean reading;
} WaylandEventSource;

static gboolean
wayland_event_source_prepare (GSource * base, gint * timeout)
{
  WaylandEventSource *source = (WaylandEventSource *) base;

  *timeout = -1;

  /* we may be called multiple times for prepare */
  if (source->reading)
    wl_display_cancel_read (source->display);

  if (source->queue) {
    if (wl_display_prepare_read_queue (source->display, source->queue) != 0)
      return TRUE;
  } else {
    if (wl_display_prepare_read (source->display) != 0)
      return TRUE;
  }

  source->reading = TRUE;

  /* FIXME: this may return EAGAIN if the fd is full */
  if (wl_display_flush (source->display) < 0)
    g_critical ("Failed to flush Wayland connection\n");

  return FALSE;
}

static gboolean
wayland_event_source_check (GSource * base)
{
  WaylandEventSource *source = (WaylandEventSource *) base;

  source->reading = FALSE;

  if (source->pfd.revents & G_IO_IN) {
    if (wl_display_read_events (source->display) == 0)
      return TRUE;
  } else {
    wl_display_cancel_read (source->display);
  }

  return FALSE;
}

static gboolean
wayland_event_source_dispatch (GSource * base,
    GSourceFunc callback, gpointer data)
{
  WaylandEventSource *source = (WaylandEventSource *) base;

  if (source->queue) {
    wl_display_dispatch_queue_pending (source->display, source->queue);
  } else {
    wl_display_dispatch_pending (source->display);
  }
  source->pfd.revents = 0;

  if (callback)
    callback (data);

  return TRUE;
}

static void
wayland_event_source_finalize (GSource * base)
{
  WaylandEventSource *source = (WaylandEventSource *) base;

  if (source->reading) {
    wl_display_cancel_read (source->display);
  }
  source->reading = FALSE;
}

static GSourceFuncs wayland_event_source_funcs = {
  wayland_event_source_prepare,
  wayland_event_source_check,
  wayland_event_source_dispatch,
  wayland_event_source_finalize
};

GSource *
wayland_event_source_new (struct wl_display *display,
    struct wl_event_queue *queue)
{
  WaylandEventSource *source;

  init_debug ();

  source = (WaylandEventSource *)
      g_source_new (&wayland_event_source_funcs, sizeof (WaylandEventSource));
  source->display = display;
  source->queue = queue;
  source->pfd.fd = wl_display_get_fd (display);
  source->pfd.events = G_IO_IN | G_IO_ERR;
  g_source_add_poll (&source->source, &source->pfd);

  return &source->source;
}
