/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 * Copyright (C) 2006 Imendio AB
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, see <https://www.gnu.org/licenses>
 */

#include <config.h>

#include "lm-message-queue.h"

struct _LmMessageQueue {
    GQueue                  *messages;

    GMainContext            *context;
    GSource                 *source;

    LmMessageQueueCallback  callback;
    gpointer                user_data;

    gint                    ref_count;
};

typedef struct {
    GSource         source;
    LmMessageQueue *queue;
} MessageQueueSource;

static void        message_queue_free            (LmMessageQueue *queue);
static gboolean    message_queue_prepare_func    (GSource         *source,
                                                  gint            *timeout);
static gboolean    message_queue_check_func      (GSource         *source);
static gboolean    message_queue_dispatch_func   (GSource         *source,
                                                  GSourceFunc      callback,
                                                  gpointer         user_data);

static GSourceFuncs source_funcs = {
    message_queue_prepare_func,
    message_queue_check_func,
    message_queue_dispatch_func,
    NULL
};

static void
foreach_free_message (LmMessage *m, gpointer user_data)
{
    lm_message_unref (m);
}

static void
message_queue_free (LmMessageQueue *queue)
{
    lm_message_queue_detach (queue);

    g_queue_foreach (queue->messages, (GFunc) foreach_free_message, NULL);
    g_queue_free (queue->messages);

    g_free (queue);
}

static gboolean
message_queue_prepare_func (GSource *source, gint *timeout)
{
    LmMessageQueue *queue;

    queue = ((MessageQueueSource *)source)->queue;

    return !g_queue_is_empty (queue->messages);
}

static gboolean
message_queue_check_func (GSource *source)
{
    return FALSE;
}

static gboolean
message_queue_dispatch_func (GSource     *source,
                             GSourceFunc  callback,
                             gpointer     user_data)
{
    LmMessageQueue *queue;

    queue = ((MessageQueueSource *)source)->queue;

    if (queue->callback) {
        (queue->callback) (queue, queue->user_data);
    }

    return TRUE;
}

LmMessageQueue *
lm_message_queue_new (LmMessageQueueCallback  callback,
                      gpointer                user_data)
{
    LmMessageQueue *queue;

    queue = g_new0 (LmMessageQueue, 1);

    queue->messages = g_queue_new ();
    queue->context = NULL;
    queue->source = NULL;
    queue->ref_count = 1;

    queue->callback = callback;
    queue->user_data = user_data;

    return queue;
}

void
lm_message_queue_attach (LmMessageQueue *queue, GMainContext *context)
{
    GSource *source;

    if (queue->source) {
        if (queue->context == context) {
            /* Already attached */
            return;
        }
        lm_message_queue_detach (queue);
    }

    if (context)  {
        queue->context = g_main_context_ref (context);
    }

    source = g_source_new (&source_funcs, sizeof (MessageQueueSource));
    ((MessageQueueSource *)source)->queue = queue;
    queue->source = source;

    g_source_attach (source, queue->context);
}

void
lm_message_queue_detach (LmMessageQueue *queue)
{
    if (queue->source) {
        g_source_destroy (queue->source);
        g_source_unref (queue->source);
    }

    if (queue->context) {
        g_main_context_unref (queue->context);
    }

    queue->source = NULL;
    queue->context = NULL;
}

void
lm_message_queue_push_tail (LmMessageQueue *queue, LmMessage *m)
{
    g_return_if_fail (queue != NULL);
    g_return_if_fail (m != NULL);

    g_queue_push_tail (queue->messages, m);
}

LmMessage *
lm_message_queue_peek_nth (LmMessageQueue *queue, guint n)
{
    g_return_val_if_fail (queue != NULL, NULL);

    return (LmMessage *) g_queue_peek_nth (queue->messages, n);
}

LmMessage *
lm_message_queue_pop_nth (LmMessageQueue *queue, guint n)
{
    g_return_val_if_fail (queue != NULL, NULL);

    return (LmMessage *) g_queue_pop_nth (queue->messages, n);
}

guint
lm_message_queue_get_length (LmMessageQueue *queue)
{
    g_return_val_if_fail (queue != NULL, 0);

    return g_queue_get_length (queue->messages);
}

gboolean
lm_message_queue_is_empty (LmMessageQueue *queue)
{
    g_return_val_if_fail (queue != NULL, TRUE);

    return g_queue_is_empty (queue->messages);
}

LmMessageQueue *
lm_message_queue_ref (LmMessageQueue *queue)
{
    g_return_val_if_fail (queue != NULL, NULL);

    queue->ref_count++;

    return queue;
}

void
lm_message_queue_unref (LmMessageQueue *queue)
{
    g_return_if_fail (queue != NULL);

    queue->ref_count--;

    if (queue->ref_count <= 0) {
        message_queue_free (queue);
    }
}