/*
 * CsNotificationWatcher: An introspectable C class that eavesdrops on the
 * session bus, watching for calls to our notification handler (usually Cinnamon.)
 * 
 * Any notifications received are checked for transiency (and ignored if they are)
 * and passed on to be handled by Cinnamon.
 *
 * Any non-transient notifications cause a signal to be sent to our notification
 * widget, along with the sender name (in order to filter our mpris player notifications.)
 */


#include "cs-notification-watcher.h"

enum {
        NOTIFICATION_RECEIVED,
        LAST_SIGNAL
};

static guint signals [LAST_SIGNAL] = { 0, };

G_DEFINE_TYPE (CsNotificationWatcher, cs_notification_watcher, G_TYPE_OBJECT);

#define DBUS_SERVICE "org.freedesktop.DBus"
#define DBUS_PATH "/org/freedesktop/DBus"
#define DBUS_INTERFACE "org.freedesktop.DBus"
#define MATCH_RULE "type='method_call', interface='org.freedesktop.Notifications', member='Notify', eavesdrop=true"

#define NOTIFICATIONS_INTERFACE "org.freedesktop.Notifications"
#define NOTIFY_METHOD "Notify"

static gboolean debug_mode = FALSE;

typedef struct
{
    CsNotificationWatcher *watcher;
    gchar *sender;
} NotificationIdleData;

static gboolean
idle_notify_received (gpointer user_data)
{
    NotificationIdleData *data = (NotificationIdleData *) user_data;

    g_return_val_if_fail (CS_IS_NOTIFICATION_WATCHER (data->watcher), FALSE);
    g_signal_emit (data->watcher, signals[NOTIFICATION_RECEIVED], 0, data->sender);

    g_clear_pointer (&data->sender, g_free);
    g_slice_free (NotificationIdleData, data);

    return FALSE;
}

static GDBusMessage *
notification_filter_func (GDBusConnection *connection,
                          GDBusMessage    *message,
                          gboolean        *incoming,
                          gpointer         user_data)
{
    GDBusMessage *ret = NULL;
    gboolean transient = FALSE;
    gboolean replaces_existing = FALSE;
    gchar *sender_str = NULL;

    CsNotificationWatcher *watcher = CS_NOTIFICATION_WATCHER (user_data);

    if (incoming &&
        g_dbus_message_get_message_type (message) == G_DBUS_MESSAGE_TYPE_METHOD_CALL &&
        g_strcmp0 (g_dbus_message_get_interface (message), NOTIFICATIONS_INTERFACE) == 0 &&
        g_strcmp0 (g_dbus_message_get_member (message), NOTIFY_METHOD) == 0)
    {
        GVariant *body = g_dbus_message_get_body (message);

        if (body != NULL &&
            g_variant_is_of_type (body, G_VARIANT_TYPE_TUPLE) &&
            g_variant_n_children (body) >= 7)
        {
            GVariant *hints, *sender, *replaces_id;

            if (debug_mode)
            {
                GVariant *dbg_var = NULL;
                const gchar *dbg_str;

                g_printerr ("Notification received...\n");

                dbg_var = g_variant_get_child_value (body, 0);

                if (dbg_var != NULL && g_variant_is_of_type (dbg_var, G_VARIANT_TYPE_STRING))
                {
                    dbg_str = g_variant_get_string (dbg_var, NULL);

                    if (dbg_str != NULL)
                    {
                        g_printerr ("Sender: %s\n", dbg_str);
                    }
                }

                g_clear_pointer (&dbg_var, g_variant_unref);

                dbg_var = g_variant_get_child_value (body, 3);

                if (dbg_var != NULL && g_variant_is_of_type (dbg_var, G_VARIANT_TYPE_STRING))
                {
                    dbg_str = g_variant_get_string (dbg_var, NULL);

                    if (dbg_str != NULL)
                    {
                        g_printerr ("Summary: %s\n", dbg_str);
                    }
                }

                g_clear_pointer (&dbg_var, g_variant_unref);

                dbg_var = g_variant_get_child_value (body, 4);

                if (dbg_var != NULL && g_variant_is_of_type (dbg_var, G_VARIANT_TYPE_STRING))
                {
                    dbg_str = g_variant_get_string (dbg_var, NULL);

                    if (dbg_str != NULL)
                    {
                        g_printerr ("Body: %s\n", dbg_str);
                    }
                }

                g_clear_pointer (&dbg_var, g_variant_unref);
            }

            hints = g_variant_get_child_value (body, 6);

            if (hints != NULL && g_variant_is_of_type (hints, G_VARIANT_TYPE_DICTIONARY))
            {
                GVariant *transient_hint;

                transient_hint = g_variant_lookup_value (hints, "transient", NULL);

                if (transient_hint)
                {
                    transient = g_variant_get_boolean (transient_hint);
                }

                g_clear_pointer (&transient_hint, g_variant_unref);
            }

            g_clear_pointer (&hints, g_variant_unref);

            sender = g_variant_get_child_value (body, 0);

            if (sender)
            {
                sender_str = g_variant_dup_string (sender, NULL);
            }

            g_clear_pointer (&sender, g_variant_unref);

            replaces_id = g_variant_get_child_value (body, 1);

            if (replaces_id)
            {
                /* The replaces_id will be 0 if the notification is not replacing
                 * another - if it's not zero, we can ignore it, so we don't accumulate
                 * notifications from spammy programs (like dropbox can be)
                 */

                replaces_existing = g_variant_get_uint32 (replaces_id) > 0;
            }

            g_clear_pointer (&replaces_id, g_variant_unref);
        }
    }
    else
    {
        ret = message;
    }

    if (ret == NULL && !transient && !replaces_existing)
    {
        NotificationIdleData *data = g_slice_new0 (NotificationIdleData);

        data->watcher = watcher;
        data->sender = sender_str;

        g_idle_add (idle_notify_received, data);
    }

    return ret;
}

static void
cs_notification_watcher_init (CsNotificationWatcher *watcher)
{
    GError *error = NULL;
    GVariant *rulev;
    GVariant *result;

    watcher->connection = g_bus_get_sync (G_BUS_TYPE_SESSION, NULL, &error);

    if (!watcher->connection)
    {
        g_printerr ("CsNotificationWatcher: Could not connect to session bus - %s\n", error->message);
        g_clear_error (&error);
        return;
    }

    rulev = g_variant_new("(s)", MATCH_RULE);

    result = g_dbus_connection_call_sync (watcher->connection,
                                          DBUS_SERVICE,
                                          DBUS_PATH,
                                          DBUS_INTERFACE,
                                          "AddMatch",
                                          rulev,
                                          G_VARIANT_TYPE ("()"),
                                          G_DBUS_CALL_FLAGS_NONE,
                                          -1,
                                          NULL,
                                          &error);

    if (!result)
    {
        g_printerr ("CsNotificationWatcher: Could not add match rule to bus - %s\n", error->message);
        g_clear_error (&error);
        return;
    }

    watcher->filter_id = g_dbus_connection_add_filter (watcher->connection,
                                                       (GDBusMessageFilterFunction) notification_filter_func,
                                                       watcher,
                                                       NULL);
}

static void
cs_notification_watcher_dispose (GObject *object)
{
    CsNotificationWatcher *watcher;

    g_return_if_fail (object != NULL);
    g_return_if_fail (CS_IS_NOTIFICATION_WATCHER (object));

    watcher = CS_NOTIFICATION_WATCHER (object);

    if (watcher->filter_id > 0)
    {
        g_dbus_connection_remove_filter (watcher->connection, watcher->filter_id);
        watcher->filter_id = 0;
    }

    g_clear_object (&watcher->connection);

    G_OBJECT_CLASS (cs_notification_watcher_parent_class)->dispose (object);
}

static void
cs_notification_watcher_class_init (CsNotificationWatcherClass *klass)
{
    GObjectClass   *object_class = G_OBJECT_CLASS (klass);

    object_class->dispose     = cs_notification_watcher_dispose;

    signals [NOTIFICATION_RECEIVED] =
        g_signal_new ("notification-received",
        G_TYPE_FROM_CLASS (object_class),
        G_SIGNAL_RUN_LAST,
        G_STRUCT_OFFSET (CsNotificationWatcherClass, notification_received),
        NULL, NULL,
        g_cclosure_marshal_VOID__VOID,
        G_TYPE_NONE, 1, G_TYPE_STRING);
}

CsNotificationWatcher *
cs_notification_watcher_new (gboolean debug)
{
    GObject     *result;

    debug_mode = debug;

    result = g_object_new (CS_TYPE_NOTIFICATION_WATCHER,
                           NULL);

    return CS_NOTIFICATION_WATCHER (result);
}
