path: root/calendar/gui/alarm-notify/alarm-queue.c

/* Evolution calendar - Alarm queueing engine
 *
 * Copyright (C) 2001 Ximian, Inc.
 *
 * Authors: Federico Mena-Quintero <federico@ximian.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <string.h>
#include <glib.h>
#include <bonobo-activation/bonobo-activation.h>
#include <bonobo/bonobo-object.h>
#include <gtk/gtksignal.h>
#include <gtk/gtkbox.h>
#include <gtk/gtkdialog.h>
#include <gtk/gtklabel.h>
#include <gtk/gtkcheckbutton.h>
#include <gtk/gtkstock.h>
#include <libgnome/gnome-i18n.h>
#include <libgnome/gnome-exec.h>
#include <libgnome/gnome-sound.h>
#include <libgnomeui/gnome-dialog-util.h>
#include <libgnomeui/gnome-uidefs.h>
#include <cal-util/timeutil.h>
#include "alarm.h"
#include "alarm-notify-dialog.h"
#include "alarm-queue.h"
#include "config-data.h"
#include "save.h"



/* Whether the queueing system has been initialized */
static gboolean alarm_queue_inited;

/* When the alarm queue system is inited, this gets set to the last time an
 * alarm notification was issued.  This lets us present any notifications that
 * should have happened while the alarm daemon was not running.
 */
static time_t saved_notification_time;

/* Clients we are monitoring for alarms */
static GHashTable *client_alarms_hash = NULL;

/* Structure that stores a client we are monitoring */
typedef struct {
    /* Monitored client */
    CalClient *client;

    /* Number of times this client has been registered */
    int refcount;

    /* Hash table of component UID -> CompQueuedAlarms.  If an element is
     * present here, then it means its cqa->queued_alarms contains at least
     * one queued alarm.  When all the alarms for a component have been
     * dequeued, the CompQueuedAlarms structure is removed from the hash
     * table.  Thus a CQA exists <=> it has queued alarms.
     */
    GHashTable *uid_alarms_hash;
} ClientAlarms;

/* Pair of a CalComponentAlarms and the mapping from queued alarm IDs to the
 * actual alarm instance structures.
 */
typedef struct {
    /* The parent client alarms structure */
    ClientAlarms *parent_client;

    /* The component's UID */
    char *uid;

    /* The actual component and its alarm instances */
    CalComponentAlarms *alarms;

    /* List of QueuedAlarm structures */
    GSList *queued_alarms;

    /* Flags */
    gboolean expecting_update;
} CompQueuedAlarms;

/* Pair of a queued alarm ID and the alarm trigger instance it refers to */
typedef struct {
    /* Alarm ID from alarm.h */
    gpointer alarm_id;

    /* Instance from our parent CompQueuedAlarms->alarms->alarms list */
    CalAlarmInstance *instance;

    /* Whether this is a snoozed queued alarm or a normal one */
    guint snooze : 1;
} QueuedAlarm;

/* Alarm ID for the midnight refresh function */
static gpointer midnight_refresh_id = NULL;

static void display_notification (time_t trigger, CompQueuedAlarms *cqa,
                  gpointer alarm_id, gboolean use_description);
static void audio_notification (time_t trigger, CompQueuedAlarms *cqa, gpointer alarm_id);
static void mail_notification (time_t trigger, CompQueuedAlarms *cqa, gpointer alarm_id);
static void procedure_notification (time_t trigger, CompQueuedAlarms *cqa, gpointer alarm_id);



/* Alarm queue engine */

static void load_alarms_for_today (ClientAlarms *ca);
static void midnight_refresh_cb (gpointer alarm_id, time_t trigger, gpointer data);

/* Queues an alarm trigger for midnight so that we can load the next day's worth
 * of alarms.
 */
static void
queue_midnight_refresh (void)
{
    time_t midnight;
    icaltimezone *zone;

    g_assert (midnight_refresh_id == NULL);

    zone = config_data_get_timezone ();

    midnight = time_day_end_with_zone (time (NULL), zone);

    midnight_refresh_id = alarm_add (midnight, midnight_refresh_cb, NULL, NULL);
    if (!midnight_refresh_id) {
        g_message ("queue_midnight_refresh(): Could not set up the midnight refresh alarm!");
        /* FIXME: what to do? */
    }
}

/* Loads a client's alarms; called from g_hash_table_foreach() */
static void
add_client_alarms_cb (gpointer key, gpointer value, gpointer data)
{
    ClientAlarms *ca;

    ca = value;
    load_alarms_for_today (ca);
}

/* Loads the alarms for the new day every midnight */
static void
midnight_refresh_cb (gpointer alarm_id, time_t trigger, gpointer data)
{
    /* Re-load the alarms for all clients */

    g_hash_table_foreach (client_alarms_hash, add_client_alarms_cb, NULL);

    /* Re-schedule the midnight update */

    midnight_refresh_id = NULL;
    queue_midnight_refresh ();
}

/* Looks up a client in the client alarms hash table */
static ClientAlarms *
lookup_client (CalClient *client)
{
    return g_hash_table_lookup (client_alarms_hash, client);
}

/* Looks up a queued alarm based on its alarm ID */
static QueuedAlarm *
lookup_queued_alarm (CompQueuedAlarms *cqa, gpointer alarm_id)
{
    GSList *l;
    QueuedAlarm *qa;

    qa = NULL;

    for (l = cqa->queued_alarms; l; l = l->next) {
        qa = l->data;
        if (qa->alarm_id == alarm_id)
            return qa;
    }

    /* not found, might have been updated/removed */
    return NULL;
}

/* Removes an alarm from the list of alarms of a component.  If the alarm was
 * the last one listed for the component, it removes the component itself.
 */
static void
remove_queued_alarm (CompQueuedAlarms *cqa, gpointer alarm_id,
             gboolean free_object, gboolean remove_alarm)
{
    QueuedAlarm *qa;
    GSList *l;

    qa = NULL;

    for (l = cqa->queued_alarms; l; l = l->next) {
        qa = l->data;
        if (qa->alarm_id == alarm_id)
            break;
    }

    if (!l)
        return;

    cqa->queued_alarms = g_slist_remove_link (cqa->queued_alarms, l);
    g_slist_free_1 (l);

    if (remove_alarm &&
        cal_client_get_static_capability (cqa->parent_client->client,
                          CAL_STATIC_CAPABILITY_REMOVE_ALARMS)) {
        cal_component_remove_alarm (cqa->alarms->comp, qa->instance->auid);
        cqa->expecting_update = TRUE;
        cal_client_update_object (cqa->parent_client->client, cqa->alarms->comp);
        cqa->expecting_update = FALSE;
    }

    g_free (qa);

    /* If this was the last queued alarm for this component, remove the
     * component itself.
     */

    if (cqa->queued_alarms != NULL)
        return;

    if (free_object) {
        g_hash_table_remove (cqa->parent_client->uid_alarms_hash, cqa->uid);
        g_free (cqa->uid);
        cqa->uid = NULL;
        cqa->parent_client = NULL;
        cal_component_alarms_free (cqa->alarms);
        g_free (cqa);
    } else {
        cal_component_alarms_free (cqa->alarms);
        cqa->alarms = NULL;
    }
}

/* Callback used when an alarm triggers */
static void
alarm_trigger_cb (gpointer alarm_id, time_t trigger, gpointer data)
{
    CompQueuedAlarms *cqa;
    CalComponent *comp;
    QueuedAlarm *qa;
    CalComponentAlarm *alarm;
    CalAlarmAction action;

    cqa = data;
    comp = cqa->alarms->comp;

    save_notification_time (trigger);
    saved_notification_time = trigger;

    qa = lookup_queued_alarm (cqa, alarm_id);
    if (!qa)
        return;

    /* Decide what to do based on the alarm action.  We use the trigger that
     * is passed to us instead of the one from the instance structure
     * because this may be a snoozed alarm instead of an original
     * occurrence.
     */

    alarm = cal_component_get_alarm (comp, qa->instance->auid);
    g_assert (alarm != NULL);

    cal_component_alarm_get_action (alarm, &action);
    cal_component_alarm_free (alarm);

    switch (action) {
    case CAL_ALARM_AUDIO:
        audio_notification (trigger, cqa, alarm_id);
        break;

    case CAL_ALARM_DISPLAY:
        display_notification (trigger, cqa, alarm_id, TRUE);
        break;

    case CAL_ALARM_EMAIL:
        mail_notification (trigger, cqa, alarm_id);
        break;

    case CAL_ALARM_PROCEDURE:
        procedure_notification (trigger, cqa, alarm_id);
        break;

    default:
        g_assert_not_reached ();
        break;
    }
}

/* Adds the alarms in a CalComponentAlarms structure to the alarms queued for a
 * particular client.  Also puts the triggers in the alarm timer queue.
 */
static void
add_component_alarms (ClientAlarms *ca, CalComponentAlarms *alarms)
{
    const char *uid;
    CompQueuedAlarms *cqa;
    GSList *l;

    /* No alarms? */
    if (alarms->alarms == NULL) {
        cal_component_alarms_free (alarms);
        return;
    }

    cqa = g_new (CompQueuedAlarms, 1);
    cqa->parent_client = ca;
    cqa->alarms = alarms;
    cqa->expecting_update = FALSE;

    cqa->queued_alarms = NULL;

    for (l = alarms->alarms; l; l = l->next) {
        CalAlarmInstance *instance;
        gpointer alarm_id;
        QueuedAlarm *qa;

        instance = l->data;

        alarm_id = alarm_add (instance->trigger, alarm_trigger_cb, cqa, NULL);
        if (!alarm_id) {
            g_message ("add_component_alarms(): Could not schedule a trigger for "
                   "%ld, discarding...", (long) instance->trigger);
            continue;
        }

        qa = g_new (QueuedAlarm, 1);
        qa->alarm_id = alarm_id;
        qa->instance = instance;
        qa->snooze = FALSE;

        cqa->queued_alarms = g_slist_prepend (cqa->queued_alarms, qa);
    }

    cal_component_get_uid (alarms->comp, &uid);

    /* If we failed to add all the alarms, then we should get rid of the cqa */
    if (cqa->queued_alarms == NULL) {
        g_message ("add_component_alarms(): Could not add any of the alarms "
               "for the component `%s'; discarding it...", uid);

        cal_component_alarms_free (cqa->alarms);
        cqa->alarms = NULL;

        g_free (cqa);
        return;
    }

    cqa->queued_alarms = g_slist_reverse (cqa->queued_alarms);
    cqa->uid = g_strdup (uid);
    g_hash_table_insert (ca->uid_alarms_hash, cqa->uid, cqa);
}

/* Loads the alarms of a client for a given range of time */
static void
load_alarms (ClientAlarms *ca, time_t start, time_t end)
{
    GSList *comp_alarms;
    GSList *l;

    comp_alarms = cal_client_get_alarms_in_range (ca->client, start, end);

    for (l = comp_alarms; l; l = l->next) {
        CalComponentAlarms *alarms;

        alarms = l->data;
        add_component_alarms (ca, alarms);
    }

    g_slist_free (comp_alarms);
}

/* Loads today's remaining alarms for a client */
static void
load_alarms_for_today (ClientAlarms *ca)
{
    time_t now, day_end;
    icaltimezone *zone;

    now = time (NULL);

    zone = config_data_get_timezone ();

    day_end = time_day_end_with_zone (now, zone);
    load_alarms (ca, now, day_end);
}

/* Adds any alarms that should have occurred while the alarm daemon was not
 * running.
 */
static void
load_missed_alarms (ClientAlarms *ca)
{
    time_t now;

    now = time (NULL);

    g_assert (saved_notification_time != -1);

    /* We add 1 to the saved_notification_time to make the time ranges
     * half-open; we do not want to display the "last" displayed alarm
     * twice, once when it occurs and once when the alarm daemon restarts.
     */
    load_alarms (ca, saved_notification_time + 1, now);
}

/* Called when a calendar client finished loading; we load its alarms */
static void
cal_opened_cb (CalClient *client, CalClientOpenStatus status, gpointer data)
{
    ClientAlarms *ca;

    ca = data;

    if (status != CAL_CLIENT_OPEN_SUCCESS)
        return;

    load_alarms_for_today (ca);
    load_missed_alarms (ca);
}

/* Looks up a component's queued alarm structure in a client alarms structure */
static CompQueuedAlarms *
lookup_comp_queued_alarms (ClientAlarms *ca, const char *uid)
{
    return g_hash_table_lookup (ca->uid_alarms_hash, uid);
}

static void
remove_alarms (CompQueuedAlarms *cqa, gboolean free_object)
{
    GSList *l;

    for (l = cqa->queued_alarms; l;) {
        QueuedAlarm *qa;

        qa = l->data;

        /* Get the next element here because the list element will go
         * away in remove_queued_alarm().  The qa will be freed there as
         * well.
         */
        l = l->next;

        alarm_remove (qa->alarm_id);
        remove_queued_alarm (cqa, qa->alarm_id, free_object, FALSE);
    }

}

/* Removes a component an its alarms */
static void
remove_comp (ClientAlarms *ca, const char *uid)
{
    CompQueuedAlarms *cqa;

    cqa = lookup_comp_queued_alarms (ca, uid);
    if (!cqa)
        return;

    /* If a component is present, then it means we must have alarms queued
     * for it.
     */
    g_assert (cqa->queued_alarms != NULL);

    remove_alarms (cqa, TRUE);

    /* The list should be empty now, and thus the queued component alarms
     * structure should have been freed and removed from the hash table.
     */
    g_assert (lookup_comp_queued_alarms (ca, uid) == NULL);
}

/* Called when a calendar component changes; we must reload its corresponding
 * alarms.
 */
static void
obj_updated_cb (CalClient *client, const char *uid, gpointer data)
{
    ClientAlarms *ca;
    time_t now, day_end;
    CalComponentAlarms *alarms;
    gboolean found;
    icaltimezone *zone;
    CompQueuedAlarms *cqa;

    ca = data;

    now = time (NULL);

    zone = config_data_get_timezone ();

    day_end = time_day_end_with_zone (now, zone);

    found = cal_client_get_alarms_for_object (ca->client, uid, now, day_end, &alarms);

    if (!found) {
        remove_comp (ca, uid);
        return;
    }

    cqa = lookup_comp_queued_alarms (ca, uid);
    if (!cqa)
        add_component_alarms (ca, alarms);
    else {
        GSList *l;

        /* if already in the list, just update it */
        remove_alarms (cqa, FALSE);
        cqa->alarms = alarms;
        cqa->queued_alarms = NULL;

        /* add the new alarms */
        for (l = cqa->alarms->alarms; l; l = l->next) {
            CalAlarmInstance *instance;
            gpointer alarm_id;
            QueuedAlarm *qa;

            instance = l->data;

            alarm_id = alarm_add (instance->trigger, alarm_trigger_cb, cqa, NULL);
            if (!alarm_id) {
                g_message ("obj_updated_cb(): Could not schedule a trigger for "
                       "%ld, discarding...", (long) instance->trigger);
                continue;
            }

            qa = g_new (QueuedAlarm, 1);
            qa->alarm_id = alarm_id;
            qa->instance = instance;
            qa->snooze = FALSE;

            cqa->queued_alarms = g_slist_prepend (cqa->queued_alarms, qa);
        }

        if (cqa->queued_alarms == NULL) {
            if (!cqa->expecting_update)
                remove_comp (ca, uid);
        } else
            cqa->queued_alarms = g_slist_reverse (cqa->queued_alarms);
    }
}

/* Called when a calendar component is removed; we must delete its corresponding
 * alarms.
 */
static void
obj_removed_cb (CalClient *client, const char *uid, gpointer data)
{
    ClientAlarms *ca;

    ca = data;

    remove_comp (ca, uid);
}



/* Notification functions */

/* Creates a snooze alarm based on an existing one.  The snooze offset is
 * compued with respect to the current time.
 */
static void
create_snooze (CompQueuedAlarms *cqa, gpointer alarm_id, int snooze_mins)
{
    QueuedAlarm *orig_qa, *qa;
    CalAlarmInstance *instance;
    time_t t;
    gpointer new_id;

    orig_qa = lookup_queued_alarm (cqa, alarm_id);
    if (!orig_qa)
        return;

    t = time (NULL);
    t += snooze_mins * 60;

    new_id = alarm_add (t, alarm_trigger_cb, cqa, NULL);
    if (!new_id) {
        g_message ("create_snooze(): Could not schedule a trigger for "
               "%ld, discarding...", (long) t);
        return;
    }

    instance = g_new (CalAlarmInstance, 1);
    instance->auid = orig_qa->instance->auid;
    instance->trigger = t;
    instance->occur_start = orig_qa->instance->occur_start;
    instance->occur_end = orig_qa->instance->occur_end;

    cqa->alarms->alarms = g_slist_prepend (cqa->alarms->alarms, instance);

    qa = g_new (QueuedAlarm, 1);
    qa->alarm_id = new_id;
    qa->instance = instance;
    qa->snooze = TRUE;

    cqa->queued_alarms = g_slist_prepend (cqa->queued_alarms, qa);
}

/* Launches a component editor for a component */
static void
edit_component (CalClient *client, CalComponent *comp)
{
    const char *uid;
    const char *uri;
    CORBA_Environment ev;
    GNOME_Evolution_Calendar_CompEditorFactory factory;

    cal_component_get_uid (comp, &uid);

    uri = cal_client_get_uri (client);

    /* Get the factory */

    CORBA_exception_init (&ev);
    factory = bonobo_activation_activate_from_id ("OAFIID:GNOME_Evolution_Calendar_CompEditorFactory",
                              0, NULL, &ev);

    if (ev._major != CORBA_NO_EXCEPTION) {
        g_message ("edit_component(): Could not activate the component editor factory");
        CORBA_exception_free (&ev);
        return;
    }
    CORBA_exception_free (&ev);

    /* Edit the component */

    CORBA_exception_init (&ev);
    GNOME_Evolution_Calendar_CompEditorFactory_editExisting (factory, uri, (char *) uid, &ev);

    if (ev._major != CORBA_NO_EXCEPTION)
        g_message ("edit_component(): Exception while editing the component");

    CORBA_exception_free (&ev);

    /* Get rid of the factory */

    CORBA_exception_init (&ev);
    bonobo_object_release_unref (factory, &ev);
    if (ev._major != CORBA_NO_EXCEPTION)
        g_message ("edit_component(): Could not unref the calendar component factory");

    CORBA_exception_free (&ev);
}

struct notify_dialog_closure {
    CompQueuedAlarms *cqa;
    gpointer alarm_id;
    CalClient *client;
    CalComponent *comp;
    gpointer dialog;
};

static void
on_dialog_obj_updated_cb (CalClient *client, const char *uid, gpointer data)
{
    struct notify_dialog_closure *c = data;
}

static void
on_dialog_obj_removed_cb (CalClient *client, const char *uid, gpointer data)
{
    const char *our_uid;
    struct notify_dialog_closure *c = data;

    cal_component_get_uid (c->comp, &our_uid);
    g_return_if_fail (our_uid && *our_uid);

    if (!strcmp (uid, our_uid)) {
        alarm_notify_dialog_disable_buttons (c->dialog);
        c->cqa = NULL;
        c->alarm_id = NULL;
    }
}

/* Callback used from the alarm notify dialog */
static void
notify_dialog_cb (AlarmNotifyResult result, int snooze_mins, gpointer data)
{
    struct notify_dialog_closure *c;

    c = data;

    g_signal_handlers_disconnect_matched (c->client, G_SIGNAL_MATCH_FUNC,
                          0, 0, NULL, on_dialog_obj_updated_cb, NULL);
    g_signal_handlers_disconnect_matched (c->client, G_SIGNAL_MATCH_FUNC,
                          0, 0, NULL, on_dialog_obj_removed_cb, NULL);

    switch (result) {
    case ALARM_NOTIFY_SNOOZE:
        create_snooze (c->cqa, c->alarm_id, snooze_mins);
        break;

    case ALARM_NOTIFY_EDIT:
        edit_component (c->client, c->comp);
        break;

    case ALARM_NOTIFY_CLOSE:
        /* Do nothing */
        break;

    default:
        g_assert_not_reached ();
    }

    if (c->cqa != NULL)
        remove_queued_alarm (c->cqa, c->alarm_id, TRUE, TRUE);
    g_object_unref (c->comp);
    g_object_unref (c->client);
    g_free (c);
}

/* Performs notification of a display alarm */
static void
display_notification (time_t trigger, CompQueuedAlarms *cqa,
              gpointer alarm_id, gboolean use_description)
{
    CalComponent *comp;
    CalComponentVType vtype;
    CalComponentText text;
    QueuedAlarm *qa;
    const char *message;
    struct notify_dialog_closure *c;
    gboolean use_summary;

    comp = cqa->alarms->comp;
    qa = lookup_queued_alarm (cqa, alarm_id);
    if (!qa)
        return;

    vtype = cal_component_get_vtype (comp);

    /* Pick a sensible notification message.  First we try the DESCRIPTION
     * from the alarm, then the SUMMARY of the component.
     */

    use_summary = TRUE;
    message = NULL;

    if (use_description) {
        CalComponentAlarm *alarm;

        alarm = cal_component_get_alarm (comp, qa->instance->auid);
        g_assert (alarm != NULL);

        cal_component_alarm_get_description (alarm, &text);
        cal_component_alarm_free (alarm);

        if (text.value) {
            message = text.value;
            use_summary = FALSE;
        }
    }

    if (use_summary) {
        cal_component_get_summary (comp, &text);
        if (text.value)
            message = text.value;
        else
            message = _("No description available.");
    }

    c = g_new (struct notify_dialog_closure, 1);
    c->cqa = cqa;
    c->alarm_id = alarm_id;
    c->comp = cal_component_clone (comp);
    c->client = c->cqa->parent_client->client;
    g_object_ref (c->client);

    if (!(c->dialog = alarm_notify_dialog (trigger,
                           qa->instance->occur_start, qa->instance->occur_end,
                           vtype, message,
                           notify_dialog_cb, c)))
        g_message ("display_notification(): Could not create the alarm notify dialog");
    else {
        g_signal_connect (c->client, "obj_updated",
                  G_CALLBACK (on_dialog_obj_updated_cb), c);
        g_signal_connect (c->client, "obj_removed",
                  G_CALLBACK (on_dialog_obj_removed_cb), c);
    }
}

/* Performs notification of an audio alarm */
static void
audio_notification (time_t trigger, CompQueuedAlarms *cqa,
            gpointer alarm_id)
{
    QueuedAlarm *qa;
    CalComponent *comp;
    CalComponentAlarm *alarm;
    icalattach *attach;

    comp = cqa->alarms->comp;
    qa = lookup_queued_alarm (cqa, alarm_id);
    if (!qa)
        return;

    alarm = cal_component_get_alarm (comp, qa->instance->auid);
    g_assert (alarm != NULL);

    cal_component_alarm_get_attach (alarm, &attach);
    cal_component_alarm_free (alarm);

    if (attach && icalattach_get_is_url (attach)) {
        const char *url;

        url = icalattach_get_url (attach);
        g_assert (url != NULL);

        gnome_sound_play (url); /* this sucks */
    }

    if (attach)
        icalattach_unref (attach);

    /* We present a notification message in addition to playing the sound */
    display_notification (trigger, cqa, alarm_id, FALSE);
}

/* Performs notification of a mail alarm */
static void
mail_notification (time_t trigger, CompQueuedAlarms *cqa, gpointer alarm_id)
{
    GtkWidget *dialog;
    GtkWidget *label;

    /* FIXME */

    display_notification (trigger, cqa, alarm_id, FALSE);

    dialog = gtk_dialog_new_with_buttons (_("Warning"),
                          NULL, 0,
                          GTK_STOCK_OK, GTK_RESPONSE_CANCEL,
                          NULL);
    label = gtk_label_new (_("Evolution does not support calendar reminders with\n"
                 "email notifications yet, but this reminder was\n"
                 "configured to send an email.  Evolution will display\n"
                 "a normal reminder dialog box instead."));
    gtk_box_pack_start (GTK_BOX (GTK_DIALOG (dialog)->vbox), label, TRUE, TRUE, 4);

    gtk_dialog_run (GTK_DIALOG (dialog));
}

/* Performs notification of a procedure alarm */
static gboolean
procedure_notification_dialog (const char *cmd, const char *url) 
{
    GtkWidget *dialog, *label, *checkbox;
    char *str;
    int btn;
    
    if (is_blessed_program (url))
        return TRUE;
    
    dialog = gtk_dialog_new_with_buttons (_("Warning"),
                          NULL, 0,
                          GTK_STOCK_NO, GTK_RESPONSE_CANCEL,
                          GTK_STOCK_YES, GTK_RESPONSE_OK,
                          NULL);

    str = g_strdup_printf (_("An Evolution Calendar reminder is about to trigger. "
                 "This reminder is configured to run the following program:\n\n"
                 "        %s\n\n"
                 "Are you sure you want to run this program?"),
                   cmd);
    label = gtk_label_new (str);
    gtk_label_set_line_wrap (GTK_LABEL (label), TRUE);
    gtk_label_set_justify (GTK_LABEL (label), GTK_JUSTIFY_LEFT);
    gtk_widget_show (label);
    gtk_box_pack_start (GTK_BOX (GTK_DIALOG (dialog)->vbox),
                label, TRUE, TRUE, 4);
    g_free (str);

    checkbox = gtk_check_button_new_with_label
        (_("Do not ask me about this program again."));
    gtk_widget_show (checkbox);
    gtk_box_pack_start (GTK_BOX (GTK_DIALOG (dialog)->vbox), 
                checkbox, TRUE, TRUE, 4);

    /* Run the dialog */
    btn = gtk_dialog_run (GTK_DIALOG (dialog));
    if (btn == GTK_RESPONSE_OK && gtk_toggle_button_get_active (GTK_TOGGLE_BUTTON (checkbox)))
        save_blessed_program (url);
    gtk_widget_destroy (dialog);

    return (btn == GTK_RESPONSE_OK);
}

static void
procedure_notification (time_t trigger, CompQueuedAlarms *cqa, gpointer alarm_id)
{
    QueuedAlarm *qa;
    CalComponent *comp;
    CalComponentAlarm *alarm;
    CalComponentText description;
    icalattach *attach;
    const char *url;
    char *cmd;
    int result;

    comp = cqa->alarms->comp;
    qa = lookup_queued_alarm (cqa, alarm_id);
    if (!qa)
        return;

    alarm = cal_component_get_alarm (comp, qa->instance->auid);
    g_assert (alarm != NULL);

    cal_component_alarm_get_attach (alarm, &attach);
    cal_component_alarm_get_description (alarm, &description);
    cal_component_alarm_free (alarm);

    /* If the alarm has no attachment, simply display a notification dialog. */
    if (!attach)
        goto fallback;

    if (!icalattach_get_is_url (attach)) {
        icalattach_unref (attach);
        goto fallback;
    }

    url = icalattach_get_url (attach);
    g_assert (url != NULL);

    /* Ask for confirmation before executing the stuff */
    if (description.value)
        cmd = g_strconcat (url, " ", description.value, NULL);
    else
        cmd = (char *) url;

    result = 0;
    if (procedure_notification_dialog (cmd, url))
        result = gnome_execute_shell (NULL, cmd);
    
    if (cmd != (char *) url)
        g_free (cmd);

    icalattach_unref (attach);

    /* Fall back to display notification if we got an error */
    if (result < 0)
        goto fallback;

    remove_queued_alarm (cqa, alarm_id, TRUE, TRUE);
    return;

 fallback:

    display_notification (trigger, cqa, alarm_id, FALSE);
}



/**
 * alarm_queue_init:
 *
 * Initializes the alarm queueing system.  This should be called near the
 * beginning of the program.
 **/
void
alarm_queue_init (void)
{
    g_return_if_fail (alarm_queue_inited == FALSE);

    client_alarms_hash = g_hash_table_new (g_direct_hash, g_direct_equal);
    queue_midnight_refresh ();

    saved_notification_time = get_saved_notification_time ();
    if (saved_notification_time == -1) {
        saved_notification_time = time (NULL);
        save_notification_time (saved_notification_time);
    }

    alarm_queue_inited = TRUE;
}

/**
 * alarm_queue_done:
 *
 * Shuts down the alarm queueing system.  This should be called near the end
 * of the program.  All the monitored calendar clients should already have been
 * unregistered with alarm_queue_remove_client().
 **/
void
alarm_queue_done (void)
{
    g_return_if_fail (alarm_queue_inited);

    /* All clients must be unregistered by now */
    g_return_if_fail (g_hash_table_size (client_alarms_hash) == 0);

    g_hash_table_destroy (client_alarms_hash);
    client_alarms_hash = NULL;

    g_assert (midnight_refresh_id != NULL);
    alarm_remove (midnight_refresh_id);
    midnight_refresh_id = NULL;

    alarm_queue_inited = FALSE;
}

/**
 * alarm_queue_add_client:
 * @client: A calendar client.
 *
 * Adds a calendar client to the alarm queueing system.  Alarm trigger
 * notifications will be presented at the appropriate times.  The client should
 * be removed with alarm_queue_remove_client() when receiving notifications
 * from it is no longer desired.
 *
 * A client can be added any number of times to the alarm queueing system,
 * but any single alarm trigger will only be presented once for a particular
 * client.  The client must still be removed the same number of times from the
 * queueing system when it is no longer wanted.
 **/
void
alarm_queue_add_client (CalClient *client)
{
    ClientAlarms *ca;

    g_return_if_fail (alarm_queue_inited);
    g_return_if_fail (client != NULL);
    g_return_if_fail (IS_CAL_CLIENT (client));

    ca = lookup_client (client);
    if (ca) {
        ca->refcount++;
        return;
    }

    ca = g_new (ClientAlarms, 1);

    ca->client = client;
    g_object_ref (ca->client);

    ca->refcount = 1;
    g_hash_table_insert (client_alarms_hash, client, ca);

    ca->uid_alarms_hash = g_hash_table_new (g_str_hash, g_str_equal);

    if (cal_client_get_load_state (client) != CAL_CLIENT_LOAD_LOADED)
        g_signal_connect (client, "cal_opened",
                  G_CALLBACK (cal_opened_cb),
                  ca);

    g_signal_connect (client, "obj_updated",
              G_CALLBACK (obj_updated_cb),
              ca);
    g_signal_connect (client, "obj_removed",
              G_CALLBACK (obj_removed_cb),
              ca);

    if (cal_client_get_load_state (client) == CAL_CLIENT_LOAD_LOADED) {
        load_alarms_for_today (ca);
        load_missed_alarms (ca);
    }
}

/* Called from g_hash_table_foreach(); adds a component UID to a list */
static void
add_uid_cb (gpointer key, gpointer value, gpointer data)
{
    GSList **uids;
    const char *uid;

    uids = data;
    uid = key;

    *uids = g_slist_prepend (*uids, (char *) uid);
}

/* Removes all the alarms queued for a particular calendar client */
static void
remove_client_alarms (ClientAlarms *ca)
{
    GSList *uids;
    GSList *l;

    /* First we build a list of UIDs so that we can remove them one by one */

    uids = NULL;
    g_hash_table_foreach (ca->uid_alarms_hash, add_uid_cb, &uids);

    for (l = uids; l; l = l->next) {
        const char *uid;

        uid = l->data;

        remove_comp (ca, uid);
    }

    g_slist_free (uids);

    /* The hash table should be empty now */

    g_assert (g_hash_table_size (ca->uid_alarms_hash) == 0);
}

/**
 * alarm_queue_remove_client:
 * @client: A calendar client.
 *
 * Removes a calendar client from the alarm queueing system.
 **/
void
alarm_queue_remove_client (CalClient *client)
{
    ClientAlarms *ca;

    g_return_if_fail (alarm_queue_inited);
    g_return_if_fail (client != NULL);
    g_return_if_fail (IS_CAL_CLIENT (client));

    ca = lookup_client (client);
    g_return_if_fail (ca != NULL);

    g_assert (ca->refcount > 0);
    ca->refcount--;

    if (ca->refcount > 0)
        return;

    remove_client_alarms (ca);

    /* Clean up */

    g_signal_handlers_disconnect_matched (ca->client, G_SIGNAL_MATCH_DATA,
                          0, 0, NULL, NULL, ca);

    g_object_unref (ca->client);
    ca->client = NULL;

    g_hash_table_destroy (ca->uid_alarms_hash);
    ca->uid_alarms_hash = NULL;

    g_free (ca);

    g_hash_table_remove (client_alarms_hash, client);
}