/* Pinos
 * Copyright (C) 2016 Wim Taymans <wim.taymans@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.
 */

#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/eventfd.h>

#include <gio/gio.h>

#include "spa/include/spa/list.h"
#include "spa/include/spa/ringbuffer.h"
#include "pinos/client/log.h"
#include "pinos/client/object.h"
#include "pinos/server/main-loop.h"

typedef struct _WorkItem WorkItem;

struct _WorkItem {
  uint32_t        id;
  void           *obj;
  uint32_t        seq;
  SpaResult       res;
  PinosDeferFunc  func;
  void           *data;
  SpaList         link;
};

typedef struct
{
  PinosMainLoop this;

  PinosLoop *loop;

  GMainContext *context;
  GMainLoop *main_loop;

  uint32_t counter;

  SpaList  work_list;
  SpaList  free_list;

  gulong work_id;
} PinosMainLoopImpl;

typedef struct {
  PinosMainLoopImpl *impl;
  SpaSource         *source;
  guint              id;
} LoopData;

static bool
poll_event (GIOChannel   *source,
            GIOCondition  condition,
            void         *user_data)
{
  LoopData *data = user_data;
  SpaSource *s = data->source;

  s->rmask = 0;
  if (condition & G_IO_IN)
    s->rmask |= SPA_IO_IN;
  if (condition & G_IO_OUT)
    s->rmask |= SPA_IO_OUT;
  if (condition & G_IO_ERR)
    s->rmask |= SPA_IO_ERR;
  if (condition & G_IO_HUP)
    s->rmask |= SPA_IO_HUP;
  s->func (s);

  return TRUE;
}

static SpaResult
do_add_source (SpaLoop   *loop,
               SpaSource *source)
{
  PinosMainLoopImpl *impl = SPA_CONTAINER_OF (loop, PinosMainLoopImpl, loop);
  GIOChannel *channel;
  GSource *s;
  LoopData *data;

  channel = g_io_channel_unix_new (source->fd);
  s = g_io_create_watch (channel, G_IO_IN);
  g_io_channel_unref (channel);

  data = g_new0 (LoopData, 1);
  data->impl = impl;
  data->source = source;

  g_source_set_callback (s, (GSourceFunc) poll_event, data, g_free);
  data->id = g_source_attach (s, g_main_context_get_thread_default ());
  g_source_unref (s);

  source->loop_private = data;
  source->loop = loop;

  pinos_log_debug ("added main poll %d", data->id);

  return SPA_RESULT_OK;
}

static SpaResult
do_update_source (SpaSource *source)
{
  LoopData *data = source->loop_private;
  pinos_log_debug ("update main poll %d", data->id);
  return SPA_RESULT_OK;
}

static void
do_remove_source (SpaSource *source)
{
  GSource *gsource;
  LoopData *data = source->loop_private;

  pinos_log_debug ("remove main poll %d", data->id);
  gsource = g_main_context_find_source_by_id (g_main_context_get_thread_default (), data->id);
  g_source_destroy (gsource);
}

static bool
process_work_queue (PinosMainLoop *this)
{
  PinosMainLoopImpl *impl = SPA_CONTAINER_OF (this, PinosMainLoopImpl, this);
  WorkItem *item, *tmp;

  impl->work_id = 0;

  spa_list_for_each_safe (item, tmp, &impl->work_list, link) {
    if (item->seq != SPA_ID_INVALID)
      continue;

    spa_list_remove (&item->link);

    if (item->func) {
      pinos_log_debug ("main-loop %p: process work item %p %d", this, item->obj, item->seq);
      item->func (item->obj, item->data, item->res, item->id);
    }
    spa_list_insert (impl->free_list.prev, &item->link);
  }
  return false;
}

static uint32_t
do_add_work (PinosMainLoop  *loop,
             void           *obj,
             SpaResult       res,
             PinosDeferFunc  func,
             void           *data)
{
  PinosMainLoopImpl *impl = SPA_CONTAINER_OF (loop, PinosMainLoopImpl, this);
  WorkItem *item;
  bool have_work = false;

  if (!spa_list_is_empty (&impl->free_list)) {
    item = spa_list_first (&impl->free_list, WorkItem, link);
    spa_list_remove (&item->link);
  } else {
    item = malloc (sizeof (WorkItem));
  }
  item->id = ++impl->counter;
  item->obj = obj;
  item->func = func;
  item->data = data;

  if (SPA_RESULT_IS_ASYNC (res)) {
    item->seq = SPA_RESULT_ASYNC_SEQ (res);
    item->res = res;
    pinos_log_debug ("main-loop %p: defer async %d for object %p", loop, item->seq, obj);
  } else {
    item->seq = SPA_ID_INVALID;
    item->res = res;
    have_work = TRUE;
    pinos_log_debug ("main-loop %p: defer object %p", loop, obj);
  }
  spa_list_insert (impl->work_list.prev, &item->link);

  if (impl->work_id == 0 && have_work)
    impl->work_id = g_idle_add ((GSourceFunc) process_work_queue, loop);

  return item->id;
}

static uint32_t
main_loop_defer (PinosMainLoop  *loop,
                 void           *obj,
                 SpaResult       res,
                 PinosDeferFunc  func,
                 void           *data)
{
  return do_add_work (loop, obj, res, func, data);
}

static void
main_loop_defer_cancel (PinosMainLoop  *loop,
                        void           *obj,
                        uint32_t        id)
{
  PinosMainLoopImpl *impl = SPA_CONTAINER_OF (loop, PinosMainLoopImpl, this);
  bool have_work = false;
  WorkItem *item;

  spa_list_for_each (item, &impl->work_list, link) {
    if ((id == 0 || item->id == id) && (obj == NULL || item->obj == obj)) {
      pinos_log_debug ("main-loop %p: cancel defer %d for object %p", loop, item->seq, item->obj);
      item->seq = SPA_ID_INVALID;
      item->func = NULL;
      have_work = true;
    }
  }
  if (impl->work_id == 0 && have_work)
    impl->work_id = g_idle_add ((GSourceFunc) process_work_queue, loop);
}

static bool
main_loop_defer_complete (PinosMainLoop  *loop,
                          void           *obj,
                          uint32_t        seq,
                          SpaResult       res)
{
  WorkItem *item;
  PinosMainLoopImpl *impl = SPA_CONTAINER_OF (loop, PinosMainLoopImpl, this);
  bool have_work = false;

  spa_list_for_each (item, &impl->work_list, link) {
    if (item->obj == obj && item->seq == seq) {
      pinos_log_debug ("main-loop %p: found defered %d for object %p", loop, seq, obj);
      item->seq = SPA_ID_INVALID;
      item->res = res;
      have_work = TRUE;
    }
  }
  if (!have_work)
    pinos_log_debug ("main-loop %p: no defered %d found for object %p", loop, seq, obj);

  if (impl->work_id == 0 && have_work)
    impl->work_id = g_idle_add ((GSourceFunc) process_work_queue, loop);

  return have_work;
}

static void
main_loop_quit (PinosMainLoop *loop)
{
  PinosMainLoopImpl *impl = SPA_CONTAINER_OF (loop, PinosMainLoopImpl, this);
  pinos_log_debug ("main-loop %p: quit", impl);
  g_main_loop_quit (impl->main_loop);
}

static void
main_loop_run (PinosMainLoop *loop)
{
  PinosMainLoopImpl *impl = SPA_CONTAINER_OF (loop, PinosMainLoopImpl, this);
  pinos_log_debug ("main-loop %p: run", impl);
  pinos_loop_enter (loop->loop);
  g_main_loop_run (impl->main_loop);
  pinos_loop_leave (loop->loop);
}

/**
 * pinos_main_loop_new:
 *
 * Create a new #PinosMainLoop.
 *
 * Returns: a new #PinosMainLoop
 */
PinosMainLoop *
pinos_main_loop_new (void)
{
  PinosMainLoopImpl *impl;
  PinosMainLoop *this;

  impl = calloc (1, sizeof (PinosMainLoopImpl));
  pinos_log_debug ("main-loop %p: new", impl);
  this = &impl->this;

  this->loop = pinos_loop_new ();
  this->loop->loop->add_source = do_add_source;
  this->loop->loop->update_source = do_update_source;
  this->loop->loop->remove_source = do_remove_source;

  impl->context = g_main_context_default ();
  impl->main_loop = g_main_loop_new (impl->context, false);

  this->run = main_loop_run;
  this->quit = main_loop_quit;
  this->defer = main_loop_defer;
  this->defer_cancel = main_loop_defer_cancel;
  this->defer_complete = main_loop_defer_complete;

  spa_list_init (&impl->work_list);
  spa_list_init (&impl->free_list);

  return this;
}

void
pinos_main_loop_destroy (PinosMainLoop *loop)
{
  PinosMainLoopImpl *impl = SPA_CONTAINER_OF (loop, PinosMainLoopImpl, this);
  WorkItem *item, *tmp;

  pinos_log_debug ("main-loop %p: destroy", impl);

  g_main_loop_unref (impl->main_loop);

  pinos_loop_destroy (loop->loop);

  spa_list_for_each_safe (item, tmp, &impl->free_list, link)
    free (item);
  free (impl);
}