/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- */

/*  Libnul - Another Utility Library
 *  Copyright (C) 2002-2008  Søren Sandmann
 *
 *  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., 59 Temple Place - Suite 330,
 *  Boston, MA  02111-1307, USA.
 */

#include <glib.h>
#include "libnul.h"

typedef struct Watch Watch;

struct Watch
{
    GSource source;
    GPollFD poll_fd;
    gboolean removed;

    WatchCallback read_callback;
    WatchCallback write_callback;
    WatchCallback hangup_callback;
    WatchCallback error_callback;
    WatchCallback priority_callback;
    WatchCallback poll_callback; /* Called before going back to poll */

    gpointer data;
};

static GHashTable *watched_fds;

static void
init (void)
{
    if (!watched_fds)
        watched_fds = g_hash_table_new (g_int_hash, g_int_equal);
}

static Watch *
lookup_watch (gint fd)
{
    init ();

    return g_hash_table_lookup (watched_fds, &fd);
}

static void
internal_add_watch (Watch *watch)
{
    gpointer fd = &(watch->poll_fd.fd);

    init ();

    g_hash_table_insert (watched_fds, fd, watch);
    g_source_add_poll ((GSource *)watch, &(watch->poll_fd));
}

static void
internal_remove_watch (Watch *watch)
{
    gpointer fd = &(watch->poll_fd.fd);

    init ();

    watch->removed = TRUE;
    g_source_remove_poll ((GSource *)watch, &(watch->poll_fd));
    g_hash_table_remove (watched_fds, fd);
}

static gboolean
watch_prepare (GSource *source,
               gint    *timeout)
{
    Watch *watch = (Watch *)source;

    *timeout = -1;

    if (watch->poll_callback)
        watch->poll_callback (watch->data);

    return FALSE;
}

static gboolean
watch_check (GSource *source)
{
    Watch *watch = (Watch *)source;
    gint revents = watch->poll_fd.revents;

    if (revents & (G_IO_NVAL))
    {
        /* This can happen if the user closes the file descriptor
         * without first removing the watch. We silently ignore it
         */
        internal_remove_watch (watch);
        g_source_unref (source);
        return FALSE;
    }

    if ((revents & G_IO_HUP) && watch->hangup_callback)
        return TRUE;

    if ((revents & G_IO_IN) && watch->read_callback)
        return TRUE;

    if ((revents & G_IO_PRI) && watch->priority_callback)
        return TRUE;

    if ((revents & G_IO_ERR) && watch->error_callback)
        return TRUE;

    if ((revents & G_IO_OUT) && watch->write_callback)
        return TRUE;

    return FALSE;
}

static gboolean
watch_dispatch (GSource     *source,
                GSourceFunc  callback,
                gpointer     user_data)
{
    Watch *watch = (Watch *)source;
    gint revents = watch->poll_fd.revents;
    gboolean removed;

    g_source_ref (source);

    if (!watch->removed && (revents & G_IO_IN)  && watch->read_callback)
        watch->read_callback (watch->data);

    if (!watch->removed && (revents & G_IO_PRI) && watch->priority_callback)
        watch->priority_callback (watch->data);

    if (!watch->removed && (revents & G_IO_OUT) && watch->write_callback)
        watch->write_callback (watch->data);

    if (!watch->removed && (revents & G_IO_ERR) && watch->error_callback)
        watch->error_callback (watch->data);

    if (!watch->removed && (revents & G_IO_HUP) && watch->hangup_callback)
        watch->hangup_callback (watch->data);

    removed = watch->removed;

    g_source_unref (source);

    if (removed)
        return FALSE;

    return TRUE;
}

static void
watch_finalize (GSource *source)
{
}

static void
update_poll_mask (Watch *watch)
{
    gint events = 0;

    g_source_remove_poll ((GSource *)watch, &(watch->poll_fd));

    if (watch->read_callback)
        events |= G_IO_IN;

    if (watch->write_callback)
        events |= G_IO_OUT;

    if (watch->priority_callback)
        events |= G_IO_PRI;

    if (watch->hangup_callback)
        events |= G_IO_HUP;

    if (watch->error_callback)
        events |= G_IO_ERR;

    watch->poll_fd.events = events;

    g_source_add_poll ((GSource *)watch, &(watch->poll_fd));
}

void
nul_fd_add_watch (gint     fd,
                  gpointer data)
{
    static GSourceFuncs watch_funcs = {
        watch_prepare,
        watch_check,
        watch_dispatch,
        watch_finalize,
        NULL,
    };
    Watch *watch = lookup_watch (fd);

    g_return_if_fail (fd > 0);
    g_return_if_fail (watch == NULL);

    watch = (Watch *)g_source_new (&watch_funcs, sizeof (Watch));
    g_source_set_can_recurse ((GSource *)watch, TRUE);
    g_source_attach ((GSource *)watch, NULL);

    watch->poll_fd.fd = fd;
    watch->poll_fd.events = 0;
    watch->removed = FALSE;

    watch->read_callback = NULL;
    watch->write_callback = NULL;
    watch->hangup_callback = NULL;
    watch->error_callback = NULL;
    watch->priority_callback = NULL;

    watch->data = data;

    internal_add_watch (watch);
}

gpointer
nul_fd_get_data (gint fd)
{
    Watch *watch = lookup_watch (fd);

    g_return_val_if_fail (fd > 0, NULL);
    g_return_val_if_fail (watch != NULL, NULL);

    return watch->data;
}

void
nul_fd_set_data (gint     fd,
                 gpointer data)
{
    Watch *watch = lookup_watch (fd);

    g_return_if_fail (fd > 0);
    g_return_if_fail (watch != NULL);

    watch->data = data;
}

void
nul_fd_set_read_callback (gint             fd,
                          WatchCallback read_cb)
{
    Watch *watch = lookup_watch (fd);

    g_return_if_fail (fd > 0);
    g_return_if_fail (watch != NULL);

    if (watch->read_callback != read_cb)
    {
        watch->read_callback = read_cb;
        update_poll_mask (watch);
    }
}

void
nul_fd_set_write_callback (gint             fd,
                           WatchCallback write_cb)
{
    Watch *watch = lookup_watch (fd);

    g_return_if_fail (fd > 0);
    g_return_if_fail (watch != NULL);

    if (watch->write_callback != write_cb)
    {
        watch->write_callback = write_cb;
        update_poll_mask (watch);
    }
}

void
nul_fd_set_hangup_callback (gint             fd,
                            WatchCallback hangup_cb)
{
    Watch *watch = lookup_watch (fd);

    g_return_if_fail (fd > 0);
    g_return_if_fail (watch != NULL);

    if (watch->hangup_callback != hangup_cb)
    {
        watch->hangup_callback = hangup_cb;
        update_poll_mask (watch);
    }
}

void
nul_fd_set_error_callback (gint             fd,
                           WatchCallback error_cb)
{
    Watch *watch = lookup_watch (fd);

    g_return_if_fail (fd > 0);
    g_return_if_fail (watch != NULL);

    if (watch->error_callback != error_cb)
    {
        watch->error_callback = error_cb;
        update_poll_mask (watch);
    }
}

void
nul_fd_set_priority_callback (gint             fd,
                              WatchCallback priority_cb)
{
    Watch *watch = lookup_watch (fd);

    g_return_if_fail (fd > 0);
    g_return_if_fail (watch != NULL);

    if (watch->priority_callback != priority_cb)
    {
        watch->priority_callback = priority_cb;
        update_poll_mask (watch);
    }
}

void
nul_fd_set_poll_handler (gint	   fd,
                         WatchCallback poll_cb)
{
    Watch *watch = lookup_watch (fd);

    g_return_if_fail (fd > 0);
    g_return_if_fail (watch != NULL);

    if (watch->poll_callback != poll_cb)
    {
        watch->poll_callback = poll_cb;
        update_poll_mask (watch);
    }
}

void
nul_fd_remove_watch (gint fd)
{
    Watch *watch = lookup_watch (fd);

    g_return_if_fail (fd > 0);

    if (!watch)
        return;

    internal_remove_watch (watch);
    g_source_unref ((GSource *)watch);
}

gboolean
nul_fd_is_watched (gint fd)
{
    g_return_val_if_fail (fd > 0, FALSE);

    if (lookup_watch (fd))
        return TRUE;
    else
        return FALSE;
}