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/* Evolution calendar - iCalendar file backend
 *
 * Copyright (C) 2000 Helix Code, Inc.
 *
 * Author: Federico Mena-Quintero <federico@helixcode.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU 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 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.
 */

#include <config.h>
#include <gtk/gtksignal.h>
#include "cal-util/cal-recur.h"
#include "cal-backend-file.h"



/* Private part of the CalBackendFile structure */
struct _CalBackendFilePrivate {
    /* URI where the calendar data is stored */
    GnomeVFSURI *uri;

    /* List of Cal objects with their listeners */
    GList *clients;

    /* Toplevel VCALENDAR component */
    icalcomponent *icalcomp;

    /* All the CalComponent objects in the calendar, hashed by UID.  The
     * hash key *is* the uid returned by cal_component_get_uid(); it is not
     * copied, so don't free it when you remove an object from the hash
     * table.
     */
    GHashTable *comp_uid_hash;

    /* All event, to-do, and journal components in the calendar; they are
     * here just for easy access (i.e. so that you don't have to iterate
     * over the comp_uid_hash).  If you need *all* the components in the
     * calendar, iterate over the hash instead.
     */
    GList *events;
    GList *todos;
    GList *journals;

    /* Idle handler for saving the calendar when it is dirty */
    guint idle_id;
};



static void cal_backend_file_class_init (CalBackendFileClass *class);
static void cal_backend_file_init (CalBackendFile *cbfile);
static void cal_backend_file_destroy (GtkObject *object);

static GnomeVFSURI *cal_backend_file_get_uri (CalBackend *backend);
static void cal_backend_file_add_cal (CalBackend *backend, Cal *cal);
static CalBackendLoadStatus cal_backend_file_load (CalBackend *backend, GnomeVFSURI *uri);
static void cal_backend_file_create (CalBackend *backend, GnomeVFSURI *uri);

static int cal_backend_file_get_n_objects (CalBackend *backend, CalObjType type);
static char *cal_backend_file_get_object (CalBackend *backend, const char *uid);
static CalObjType cal_backend_file_get_type_by_uid (CalBackend *backend, const char *uid);
static GList *cal_backend_file_get_uids (CalBackend *backend, CalObjType type);
static GList *cal_backend_file_get_objects_in_range (CalBackend *backend, CalObjType type,
                             time_t start, time_t end);
static GList *cal_backend_file_get_alarms_in_range (CalBackend *backend, time_t start, time_t end);
static gboolean cal_backend_file_get_alarms_for_object (CalBackend *backend, const char *uid,
                            time_t start, time_t end,
                            GList **alarms);
static gboolean cal_backend_file_update_object (CalBackend *backend, const char *uid,
                           const char *calobj);
static gboolean cal_backend_file_remove_object (CalBackend *backend, const char *uid);

static CalBackendClass *parent_class;



/**
 * cal_backend_file_get_type:
 * @void: 
 * 
 * Registers the #CalBackendFile class if necessary, and returns the type ID
 * associated to it.
 * 
 * Return value: The type ID of the #CalBackendFile class.
 **/
GtkType
cal_backend_file_get_type (void)
{
    static GtkType cal_backend_file_type = 0;

    if (!cal_backend_file_type) {
        static const GtkTypeInfo cal_backend_file_info = {
            "CalBackendFile",
            sizeof (CalBackendFile),
            sizeof (CalBackendFileClass),
            (GtkClassInitFunc) cal_backend_file_class_init,
            (GtkObjectInitFunc) cal_backend_file_init,
            NULL, /* reserved_1 */
            NULL, /* reserved_2 */
            (GtkClassInitFunc) NULL
        };

        cal_backend_file_type = gtk_type_unique (CAL_BACKEND_TYPE, &cal_backend_file_info);
    }

    return cal_backend_file_type;
}

/* Class initialization function for the file backend */
static void
cal_backend_file_class_init (CalBackendFileClass *class)
{
    GtkObjectClass *object_class;
    CalBackendClass *backend_class;

    object_class = (GtkObjectClass *) class;
    backend_class = (CalBackendClass *) class;

    parent_class = gtk_type_class (CAL_BACKEND_TYPE);

    object_class->destroy = cal_backend_file_destroy;

    backend_class->get_uri = cal_backend_file_get_uri;
    backend_class->add_cal = cal_backend_file_add_cal;
    backend_class->load = cal_backend_file_load;
    backend_class->create = cal_backend_file_create;
    backend_class->get_n_objects = cal_backend_file_get_n_objects;
    backend_class->get_object = cal_backend_file_get_object;
    backend_class->get_type_by_uid = cal_backend_file_get_type_by_uid;
    backend_class->get_uids = cal_backend_file_get_uids;
    backend_class->get_objects_in_range = cal_backend_file_get_objects_in_range;
    backend_class->get_alarms_in_range = cal_backend_file_get_alarms_in_range;
    backend_class->get_alarms_for_object = cal_backend_file_get_alarms_for_object;
    backend_class->update_object = cal_backend_file_update_object;
    backend_class->remove_object = cal_backend_file_remove_object;
}

/* Object initialization function for the file backend */
static void
cal_backend_file_init (CalBackendFile *cbfile)
{
    CalBackendFilePrivate *priv;

    priv = g_new0 (CalBackendFilePrivate, 1);
    cbfile->priv = priv;
}

/* g_hash_table_foreach() callback to destroy a CalComponent */
static void
free_cal_component (gpointer key, gpointer value, gpointer data)
{
    CalComponent *comp;

    comp = CAL_COMPONENT (value);
    gtk_object_unref (GTK_OBJECT (comp));
}

/* Saves the calendar data */
static void
save (CalBackendFile *cbfile)
{
    CalBackendFilePrivate *priv;
    GnomeVFSHandle *handle = NULL;
    GnomeVFSResult result;
    GnomeVFSFileSize out;
    gchar *tmp;
    char *buf;
    
    priv = cbfile->priv;
    g_assert (priv->uri != NULL);
    g_assert (priv->icalcomp != NULL);

    /* Make a backup copy of the file if it exists */
    tmp = gnome_vfs_uri_to_string (priv->uri, GNOME_VFS_URI_HIDE_NONE);
    if (tmp) {
        GnomeVFSURI *backup_uri;
        gchar *backup_uristr;
        
        backup_uristr = g_strconcat (tmp, "~", NULL);
        backup_uri = gnome_vfs_uri_new (backup_uristr);
        
        result = gnome_vfs_move_uri (priv->uri, backup_uri, TRUE);
        gnome_vfs_uri_unref (backup_uri);
        
        g_free (tmp);
        g_free (backup_uristr);
    }
    
    /* Now write the new file out */
    result = gnome_vfs_create_uri (&handle, priv->uri, 
                       GNOME_VFS_OPEN_WRITE,
                       FALSE, 0666);
    
    if (result != GNOME_VFS_OK)
        goto error;
    
    buf = icalcomponent_as_ical_string (priv->icalcomp);
    result = gnome_vfs_write (handle, buf, strlen (buf) * sizeof (char), &out);

    if (result != GNOME_VFS_OK)
        goto error;

    gnome_vfs_close (handle);

    return;
    
 error:
    g_warning ("Error writing calendar file.");
    return;
}

/* Destroy handler for the file backend */
static void
cal_backend_file_destroy (GtkObject *object)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;

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

    cbfile = CAL_BACKEND_FILE (object);
    priv = cbfile->priv;

    g_assert (priv->clients == NULL);

    /* Save if necessary */

    if (priv->idle_id != 0) {
        save (cbfile);
        g_source_remove (priv->idle_id);
        priv->idle_id = 0;
    }

    /* Clean up */

    if (priv->uri) {
        gnome_vfs_uri_unref (priv->uri);
        priv->uri = NULL;
    }

    if (priv->comp_uid_hash) {
        g_hash_table_foreach (priv->comp_uid_hash, 
                      free_cal_component, NULL);
        g_hash_table_destroy (priv->comp_uid_hash);
        priv->comp_uid_hash = NULL;
    }

    g_list_free (priv->events);
    g_list_free (priv->todos);
    g_list_free (priv->journals);

    priv->events = NULL;
    priv->todos = NULL;
    priv->journals = NULL;

    if (priv->icalcomp) {
        icalcomponent_free (priv->icalcomp);
        priv->icalcomp = NULL;
    }

    g_free (priv);
    cbfile->priv = NULL;

    if (GTK_OBJECT_CLASS (parent_class)->destroy)
        (* GTK_OBJECT_CLASS (parent_class)->destroy) (object);
}



/* Looks up a component by its UID on the backend's component hash table */
static CalComponent *
lookup_component (CalBackendFile *cbfile, const char *uid)
{
    CalBackendFilePrivate *priv;
    CalComponent *comp;

    priv = cbfile->priv;

    comp = g_hash_table_lookup (priv->comp_uid_hash, uid);

    return comp;
}



/* Calendar backend methods */

/* Get_uri handler for the file backend */
static GnomeVFSURI *
cal_backend_file_get_uri (CalBackend *backend)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;

    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    g_return_val_if_fail (priv->icalcomp != NULL, NULL);
    g_assert (priv->uri != NULL);

    return priv->uri;
}

/* Callback used when a Cal is destroyed */
static void
cal_destroy_cb (GtkObject *object, gpointer data)
{
    Cal *cal;
    Cal *lcal;
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;
    GList *l;

    cal = CAL (object);

    cbfile = CAL_BACKEND_FILE (data);
    priv = cbfile->priv;

    /* Find the cal in the list of clients */

    for (l = priv->clients; l; l = l->next) {
        lcal = CAL (l->data);

        if (lcal == cal)
            break;
    }

    g_assert (l != NULL);

    /* Disconnect */

    priv->clients = g_list_remove_link (priv->clients, l);
    g_list_free_1 (l);

    /* When all clients go away, notify the parent factory about it so that
     * it may decide whether to kill the backend or not.
     */
    if (!priv->clients)
        cal_backend_last_client_gone (CAL_BACKEND (cbfile));
}

/* Add_cal handler for the file backend */
static void
cal_backend_file_add_cal (CalBackend *backend, Cal *cal)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;

    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    g_return_if_fail (priv->icalcomp != NULL);
    g_return_if_fail (cal != NULL);
    g_return_if_fail (IS_CAL (cal));

    /* We do not keep a reference to the Cal since the calendar user agent
     * owns it.
     */

    gtk_signal_connect (GTK_OBJECT (cal), "destroy",
                GTK_SIGNAL_FUNC (cal_destroy_cb),
                backend);

    priv->clients = g_list_prepend (priv->clients, cal);
}

/* Idle handler; we save the calendar since it is dirty */
static gboolean
save_idle (gpointer data)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;

    cbfile = CAL_BACKEND_FILE (data);
    priv = cbfile->priv;

    g_assert (priv->icalcomp != NULL);

    save (cbfile);

    priv->idle_id = 0;
    return FALSE;
}

/* Marks the file backend as dirty and queues a save operation */
static void
mark_dirty (CalBackendFile *cbfile)
{
    CalBackendFilePrivate *priv;

    priv = cbfile->priv;

    if (priv->idle_id != 0)
        return;

    priv->idle_id = g_idle_add (save_idle, cbfile);
}

/* Checks if the specified component has a duplicated UID and if so changes it */
static void
check_dup_uid (CalBackendFile *cbfile, CalComponent *comp)
{
    CalBackendFilePrivate *priv;
    CalComponent *old_comp;
    const char *uid;
    char *new_uid;

    priv = cbfile->priv;

    cal_component_get_uid (comp, &uid);

    old_comp = g_hash_table_lookup (priv->comp_uid_hash, uid);
    if (!old_comp)
        return; /* Everything is fine */

    g_message ("check_dup_uid(): Got object with duplicated UID `%s', changing it...", uid);

    new_uid = cal_component_gen_uid ();
    cal_component_set_uid (comp, new_uid);
    g_free (new_uid);

    /* FIXME: I think we need to reset the SEQUENCE property and reset the
     * CREATED/DTSTAMP/LAST-MODIFIED.
     */

    mark_dirty (cbfile);
}

/* Tries to add an icalcomponent to the file backend.  We only store the objects
 * of the types we support; all others just remain in the toplevel component so
 * that we don't lose them.
 */
static void
add_component (CalBackendFile *cbfile, CalComponent *comp, gboolean add_to_toplevel)
{
    CalBackendFilePrivate *priv;
    GList **list;
    const char *uid;
    
    priv = cbfile->priv;

    switch (cal_component_get_vtype (comp)) {
    case CAL_COMPONENT_EVENT:
        list = &priv->events;
        break;

    case CAL_COMPONENT_TODO:
        list = &priv->todos;
        break;

    case CAL_COMPONENT_JOURNAL:
        list = &priv->journals;
        break;

    default:
        g_assert_not_reached ();
        return;
    }

    /* Ensure that the UID is unique; some broken implementations spit
     * components with duplicated UIDs.
     */
    check_dup_uid (cbfile, comp);
    cal_component_get_uid (comp, &uid);
    g_hash_table_insert (priv->comp_uid_hash, (char *)uid, comp);

    *list = g_list_prepend (*list, comp);

    /* Put the object in the toplevel component if required */

    if (add_to_toplevel) {
        icalcomponent *icalcomp;

        icalcomp = cal_component_get_icalcomponent (comp);
        g_assert (icalcomp != NULL);

        icalcomponent_add_component (priv->icalcomp, icalcomp);
    }
}

/* Removes a component from the backend's hash and lists.  Does not perform
 * notification on the clients.  Also removes the component from the toplevel
 * icalcomponent.
 */
static void
remove_component (CalBackendFile *cbfile, CalComponent *comp)
{
    CalBackendFilePrivate *priv;
    icalcomponent *icalcomp;
    const char *uid;
    GList **list, *l;

    priv = cbfile->priv;

    /* Remove the icalcomp from the toplevel */

    icalcomp = cal_component_get_icalcomponent (comp);
    g_assert (icalcomp != NULL);

    icalcomponent_remove_component (priv->icalcomp, icalcomp);

    /* Remove it from our mapping */

    cal_component_get_uid (comp, &uid);
    g_hash_table_remove (priv->comp_uid_hash, uid);
    
    switch (cal_component_get_vtype (comp)) {
    case CAL_COMPONENT_EVENT:
        list = &priv->events;
        break;

    case CAL_COMPONENT_TODO:
        list = &priv->todos;
        break;

    case CAL_COMPONENT_JOURNAL:
        list = &priv->journals;
        break;

    default:
                /* Make the compiler shut up. */
            list = NULL;
        g_assert_not_reached ();
    }

    l = g_list_find (*list, comp);
    g_assert (l != NULL);

    *list = g_list_remove_link (*list, l);
    g_list_free_1 (l);

    gtk_object_unref (GTK_OBJECT (comp));
}

/* Scans the toplevel VCALENDAR component and stores the objects it finds */
static void
scan_vcalendar (CalBackendFile *cbfile)
{
    CalBackendFilePrivate *priv;
    icalcomponent *icalcomp;

    priv = cbfile->priv;
    g_assert (priv->icalcomp != NULL);
    g_assert (priv->comp_uid_hash != NULL);

    for (icalcomp = icalcomponent_get_first_component (priv->icalcomp, ICAL_ANY_COMPONENT);
         icalcomp;
         icalcomp = icalcomponent_get_next_component (priv->icalcomp, ICAL_ANY_COMPONENT)) {
        icalcomponent_kind kind;
        CalComponent *comp;

        kind = icalcomponent_isa (icalcomp);

        if (!(kind == ICAL_VEVENT_COMPONENT
              || kind == ICAL_VTODO_COMPONENT
              || kind == ICAL_VJOURNAL_COMPONENT))
            continue;

        comp = cal_component_new ();

        if (!cal_component_set_icalcomponent (comp, icalcomp))
            continue;

        add_component (cbfile, comp, FALSE);
    }
}

/* Callback used from icalparser_parse() */
static char *
get_line (char *s, size_t size, void *data)
{
    FILE *file;

    file = data;
    return fgets (s, size, file);
}

/* Load handler for the file backend */
static CalBackendLoadStatus
cal_backend_file_load (CalBackend *backend, GnomeVFSURI *uri)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;
    char *str_uri;
    FILE *file;
    icalparser *parser;
    icalcomponent *icalcomp;

    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    g_return_val_if_fail (priv->icalcomp == NULL, CAL_BACKEND_LOAD_ERROR);
    g_return_val_if_fail (uri != NULL, CAL_BACKEND_LOAD_ERROR);

    if (!gnome_vfs_uri_is_local (uri))
        return CAL_BACKEND_LOAD_ERROR;

    str_uri = gnome_vfs_uri_to_string (uri,
                       (GNOME_VFS_URI_HIDE_USER_NAME
                        | GNOME_VFS_URI_HIDE_PASSWORD
                        | GNOME_VFS_URI_HIDE_HOST_NAME
                        | GNOME_VFS_URI_HIDE_HOST_PORT
                        | GNOME_VFS_URI_HIDE_TOPLEVEL_METHOD));

    /* Load! */
    file = fopen (str_uri, "r");
    g_free (str_uri);

    if (!file)
        return CAL_BACKEND_LOAD_ERROR;

    parser = icalparser_new ();
    icalparser_set_gen_data (parser, file);

    icalcomp = icalparser_parse (parser, get_line);
    icalparser_free (parser);

    if (fclose (file) != 0)
        return CAL_BACKEND_LOAD_ERROR;

    if (!icalcomp)
        return CAL_BACKEND_LOAD_ERROR;

    /* FIXME: should we try to demangle XROOT components and individual
         * components as well?
     */

    if (icalcomponent_isa (icalcomp) != ICAL_VCALENDAR_COMPONENT)
        return CAL_BACKEND_LOAD_ERROR;

    priv->icalcomp = icalcomp;

    priv->comp_uid_hash = g_hash_table_new (g_str_hash, g_str_equal);
    scan_vcalendar (cbfile);

    /* Clean up */
    if (priv->uri)
        gnome_vfs_uri_unref (priv->uri);
    
    gnome_vfs_uri_ref (uri);
    priv->uri = uri;

    return CAL_BACKEND_LOAD_SUCCESS;
}

/* Create handler for the file backend */
static void
cal_backend_file_create (CalBackend *backend, GnomeVFSURI *uri)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;
    icalproperty *prop;

    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    g_return_if_fail (priv->icalcomp == NULL);
    g_return_if_fail (uri != NULL);

    /* Create the new calendar information */

    g_assert (priv->icalcomp == NULL);
    priv->icalcomp = icalcomponent_new (ICAL_VCALENDAR_COMPONENT);

    /* RFC 2445, section 4.7.1 */
    prop = icalproperty_new_calscale ("GREGORIAN");
    icalcomponent_add_property (priv->icalcomp, prop);

    /* RFC 2445, section 4.7.3 */
    prop = icalproperty_new_prodid ("-//Helix Code//NONSGML Evolution Calendar//EN");
    icalcomponent_add_property (priv->icalcomp, prop);

    /* RFC 2445, section 4.7.4 */
    prop = icalproperty_new_version ("2.0");
    icalcomponent_add_property (priv->icalcomp, prop);

    /* Create our internal data */

    g_assert (priv->comp_uid_hash == NULL);
    priv->comp_uid_hash = g_hash_table_new (g_str_hash, g_str_equal);

    /* Clean up */
    if (priv->uri)
        gnome_vfs_uri_unref (priv->uri);
    
    gnome_vfs_uri_ref (uri);
    priv->uri = uri;

    mark_dirty (cbfile);
}

/* Get_n_objects handler for the file backend */
static int
cal_backend_file_get_n_objects (CalBackend *backend, CalObjType type)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;
    int n;

    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    g_return_val_if_fail (priv->icalcomp != NULL, -1);

    n = 0;

    if (type & CALOBJ_TYPE_EVENT)
        n += g_list_length (priv->events);

    if (type & CALOBJ_TYPE_TODO)
        n += g_list_length (priv->todos);

    if (type & CALOBJ_TYPE_JOURNAL)
        n += g_list_length (priv->journals);

    return n;
}

/* Get_object handler for the file backend */
static char *
cal_backend_file_get_object (CalBackend *backend, const char *uid)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;
    CalComponent *comp;

    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    g_return_val_if_fail (uid != NULL, NULL);

    g_return_val_if_fail (priv->icalcomp != NULL, NULL);
    g_assert (priv->comp_uid_hash != NULL);

    comp = lookup_component (cbfile, uid);

    if (!comp)
        return NULL;

    return cal_component_get_as_string (comp);
}

static CalObjType
cal_backend_file_get_type_by_uid (CalBackend *backend, const char *uid)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;
    CalComponent *comp;
    CalComponentVType type;
    
    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    comp = lookup_component (cbfile, uid);
    if (!comp)
        return CAL_COMPONENT_NO_TYPE;
    
    type = cal_component_get_vtype (comp);
    switch (type) {
    case CAL_COMPONENT_EVENT:
        return CALOBJ_TYPE_EVENT;
    case CAL_COMPONENT_TODO:
        return CALOBJ_TYPE_TODO;
    case CAL_COMPONENT_JOURNAL:
        return CALOBJ_TYPE_JOURNAL;
    default:
        return CAL_COMPONENT_NO_TYPE;
    }
}

/* Builds a list of UIDs from a list of CalComponent objects */
static void
build_uids_list (GList **list, GList *components)
{
    GList *l;

    for (l = components; l; l = l->next) {
        CalComponent *comp;
        const char *uid;

        comp = CAL_COMPONENT (l->data);
        cal_component_get_uid (comp, &uid);
        *list = g_list_prepend (*list, g_strdup (uid));
    }
}

/* Get_uids handler for the file backend */
static GList *
cal_backend_file_get_uids (CalBackend *backend, CalObjType type)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;
    GList *list;

    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    g_return_val_if_fail (priv->icalcomp != NULL, NULL);

    list = NULL;

    if (type & CALOBJ_TYPE_EVENT)
        build_uids_list (&list, priv->events);

    if (type & CALOBJ_TYPE_TODO)
        build_uids_list (&list, priv->todos);

    if (type & CALOBJ_TYPE_JOURNAL)
        build_uids_list (&list, priv->journals);

    return list;
}

/* Callback used from cal_recur_generate_instances(); adds the component's UID
 * to our hash table.
 */
static gboolean
add_instance (CalComponent *comp, time_t start, time_t end, gpointer data)
{
    GHashTable *uid_hash;
    const char *uid;
    const char *old_uid;

    uid_hash = data;

    /* We only care that the component's UID is listed in the hash table;
     * that's why we only allow generation of one instance (i.e. return
     * FALSE every time).
     */

    cal_component_get_uid (comp, &uid);

    old_uid = g_hash_table_lookup (uid_hash, uid);
    if (old_uid)
        return FALSE;

    g_hash_table_insert (uid_hash, (char *) uid, NULL);
    return FALSE;
}

/* Populates a hash table with the UIDs of the components that occur or recur
 * within a specific time range.
 */
static void
get_instances_in_range (GHashTable *uid_hash, GList *components, time_t start, time_t end)
{
    GList *l;

    for (l = components; l; l = l->next) {
        CalComponent *comp;

        comp = CAL_COMPONENT (l->data);
        cal_recur_generate_instances (comp, start, end, add_instance, uid_hash);
    }
}

/* Used from g_hash_table_foreach(), adds a UID from the hash table to our list */
static void
add_uid_to_list (gpointer key, gpointer value, gpointer data)
{
    GList **list;
    const char *uid;
    char *uid_copy;

    list = data;

    uid = key;
    uid_copy = g_strdup (uid);

    *list = g_list_prepend (*list, uid_copy);
}

/* Get_objects_in_range handler for the file backend */
static GList *
cal_backend_file_get_objects_in_range (CalBackend *backend, CalObjType type,
                       time_t start, time_t end)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;
    GList *event_list;
    GHashTable *uid_hash;

    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    g_return_val_if_fail (priv->icalcomp != NULL, NULL);

    g_return_val_if_fail (start != -1 && end != -1, NULL);
    g_return_val_if_fail (start <= end, NULL);

    uid_hash = g_hash_table_new (g_str_hash, g_str_equal);

    if (type & CALOBJ_TYPE_EVENT)
        get_instances_in_range (uid_hash, priv->events, start, end);

    if (type & CALOBJ_TYPE_TODO)
        get_instances_in_range (uid_hash, priv->todos, start, end);

    if (type & CALOBJ_TYPE_JOURNAL)
        get_instances_in_range (uid_hash, priv->journals, start, end);

    event_list = NULL;
    g_hash_table_foreach (uid_hash, add_uid_to_list, &event_list);
    g_hash_table_destroy (uid_hash);

    return event_list;
}

/* Get_alarms_in_range handler for the file backend */
static GList *
cal_backend_file_get_alarms_in_range (CalBackend *backend, time_t start, time_t end)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;

    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    g_return_val_if_fail (priv->icalcomp != NULL, NULL);

    g_return_val_if_fail (start != -1 && end != -1, NULL);
    g_return_val_if_fail (start <= end, NULL);

    /* FIXME: have to deal with an unknown number of alarms; we can't just
     * do the same thing as in cal-backend-imc.
     */
    return NULL;
}

/* Get_alarms_for_object handler for the file backend */
static gboolean
cal_backend_file_get_alarms_for_object (CalBackend *backend, const char *uid,
                    time_t start, time_t end,
                    GList **alarms)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;

    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    g_return_val_if_fail (priv->icalcomp != NULL, FALSE);

    g_return_val_if_fail (uid != NULL, FALSE);
    g_return_val_if_fail (start != -1 && end != -1, FALSE);
    g_return_val_if_fail (start <= end, FALSE);
    g_return_val_if_fail (alarms != NULL, FALSE);

    /* FIXME */

    *alarms = NULL;
    return FALSE;
}

/* Notifies a backend's clients that an object was updated */
static void
notify_update (CalBackendFile *cbfile, const char *uid)
{
    CalBackendFilePrivate *priv;
    GList *l;

    priv = cbfile->priv;

    for (l = priv->clients; l; l = l->next) {
        Cal *cal;

        cal = CAL (l->data);
        cal_notify_update (cal, uid);
    }
}

/* Notifies a backend's clients that an object was removed */
static void
notify_remove (CalBackendFile *cbfile, const char *uid)
{
    CalBackendFilePrivate *priv;
    GList *l;

    priv = cbfile->priv;

    for (l = priv->clients; l; l = l->next) {
        Cal *cal;

        cal = CAL (l->data);
        cal_notify_remove (cal, uid);
    }
}

/* Update_object handler for the file backend */
static gboolean
cal_backend_file_update_object (CalBackend *backend, const char *uid, const char *calobj)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;
    icalcomponent *icalcomp;
    icalcomponent_kind kind;
    CalComponent *old_comp;
    CalComponent *comp;
    const char *comp_uid;

    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    g_return_val_if_fail (priv->icalcomp != NULL, FALSE);

    g_return_val_if_fail (uid != NULL, FALSE);
    g_return_val_if_fail (calobj != NULL, FALSE);

    /* Pull the component from the string and ensure that it is sane */

    icalcomp = icalparser_parse_string ((char *) calobj);

    if (!icalcomp)
        return FALSE;

    kind = icalcomponent_isa (icalcomp);

    if (!(kind == ICAL_VEVENT_COMPONENT
          || kind == ICAL_VTODO_COMPONENT
          || kind == ICAL_VJOURNAL_COMPONENT)) {
        /* We don't support this type of component */
        icalcomponent_free (icalcomp);
        return FALSE;
    }

    comp = cal_component_new ();
    if (!cal_component_set_icalcomponent (comp, icalcomp)) {
        gtk_object_unref (GTK_OBJECT (comp));
        icalcomponent_free (icalcomp);
        return FALSE;
    }

    /* Check the UID for sanity's sake */

    cal_component_get_uid (comp, &comp_uid);

    if (strcmp (uid, comp_uid) != 0) {
        gtk_object_unref (GTK_OBJECT (comp));
        return FALSE;
    }

    /* Update the component */

    old_comp = lookup_component (cbfile, uid);

    if (old_comp)
        remove_component (cbfile, old_comp);

    add_component (cbfile, comp, TRUE);

    mark_dirty (cbfile);

    /* FIXME: do the notification asynchronously */
    notify_update (cbfile, comp_uid);

    return TRUE;
}

/* Remove_object handler for the file backend */
static gboolean
cal_backend_file_remove_object (CalBackend *backend, const char *uid)
{
    CalBackendFile *cbfile;
    CalBackendFilePrivate *priv;
    CalComponent *comp;

    cbfile = CAL_BACKEND_FILE (backend);
    priv = cbfile->priv;

    g_return_val_if_fail (priv->icalcomp != NULL, FALSE);

    g_return_val_if_fail (uid != NULL, FALSE);

    comp = lookup_component (cbfile, uid);
    if (!comp)
        return FALSE;

    remove_component (cbfile, comp);
    mark_dirty (cbfile);

    /* FIXME: do the notification asynchronously */
    notify_remove (cbfile, uid);

    return TRUE;
}