New files for the iCalendar file backend.

2000-08-02  Federico Mena Quintero  <federico@helixcode.com>

	* pcs/cal-backend-file.[ch]: New files for the iCalendar file
	backend.

	* pcs/Makefile.am (libpcs_a_SOURCES): Added cal-backend-file.[ch].

	* cal-util/cal-component.c (cal_component_set_icalcomponent):
	Return an operation success code for if we are passed a component
	of a type we don't support.

svn path=/trunk/; revision=4479

7 files changed, 1108 insertions, 9 deletions

diff --git a/calendar/ChangeLog b/calendar/ChangeLog
index 280f75e57d..0e156caa66 100644
--- a/calendar/ChangeLog
+++ b/calendar/ChangeLog
@@ -1,3 +1,14 @@
+2000-08-02  Federico Mena Quintero  <federico@helixcode.com>
+
+	* pcs/cal-backend-file.[ch]: New files for the iCalendar file
+	backend.
+
+	* pcs/Makefile.am (libpcs_a_SOURCES): Added cal-backend-file.[ch].
+
+	* cal-util/cal-component.c (cal_component_set_icalcomponent):
+	Return an operation success code for if we are passed a component
+	of a type we don't support.
+
 2000-07-31  Federico Mena Quintero  <federico@helixcode.com>
 
 	* cal-util/cal-recur.c (*): Use CalComponent and the new property
diff --git a/calendar/cal-util/cal-component.c b/calendar/cal-util/cal-component.c
index e8b1adb96c..b697b60389 100644
--- a/calendar/cal-util/cal-component.c
+++ b/calendar/cal-util/cal-component.c
@@ -652,29 +652,48 @@ cal_component_set_new_vtype (CalComponent *comp, CalComponentVType type)
  * structure.  If the @comp already had an #icalcomponent set into it, it will
  * will be freed automatically if the #icalcomponent does not have a parent
  * component itself.
+ *
+ * Supported component types are VEVENT, VTODO, VJOURNAL, VFREEBUSY, and VTIMEZONE.
+ *
+ * Return value: TRUE on success, FALSE if @icalcomp is an unsupported component
+ * type.
  **/
-void
+gboolean
 cal_component_set_icalcomponent (CalComponent *comp, icalcomponent *icalcomp)
 {
 	CalComponentPrivate *priv;
+	icalcomponent_kind kind;
 
-	g_return_if_fail (comp != NULL);
-	g_return_if_fail (IS_CAL_COMPONENT (comp));
+	g_return_val_if_fail (comp != NULL, FALSE);
+	g_return_val_if_fail (IS_CAL_COMPONENT (comp), FALSE);
 
 	priv = comp->priv;
 
 	if (priv->icalcomp == icalcomp)
-		return;
+		return TRUE;
 
 	free_icalcomponent (comp);
 
-	priv->icalcomp = icalcomp;
+	if (!icalcomp) {
+		priv->icalcomp = NULL;
+		return TRUE;
+	}
 
-	if (!icalcomp)
-		return;
+	kind = icalcomponent_isa (icalcomp);
+
+	if (!(kind == ICAL_VEVENT_COMPONENT
+	      || kind == ICAL_VTODO_COMPONENT
+	      || kind == ICAL_VJOURNAL_COMPONENT
+	      || kind == ICAL_VFREEBUSY_COMPONENT
+	      || kind == ICAL_VTIMEZONE_COMPONENT))
+		return FALSE;
+
+	priv->icalcomp = icalcomp;
 
 	scan_icalcomponent (comp);
 	ensure_mandatory_properties (comp);
+
+	return TRUE;
 }
 
 /**
diff --git a/calendar/cal-util/cal-component.h b/calendar/cal-util/cal-component.h
index c09c73d5bb..38b9e60aed 100644
--- a/calendar/cal-util/cal-component.h
+++ b/calendar/cal-util/cal-component.h
@@ -128,7 +128,7 @@ CalComponent *cal_component_new (void);
 
 void cal_component_set_new_vtype (CalComponent *comp, CalComponentVType type);
 
-void cal_component_set_icalcomponent (CalComponent *comp, icalcomponent *icalcomp);
+gboolean cal_component_set_icalcomponent (CalComponent *comp, icalcomponent *icalcomp);
 icalcomponent *cal_component_get_icalcomponent (CalComponent *comp);
 
 CalComponentVType cal_component_get_vtype (CalComponent *comp);
diff --git a/calendar/pcs/Makefile.am b/calendar/pcs/Makefile.am
index 64aef701c9..320e3f0a14 100644
--- a/calendar/pcs/Makefile.am
+++ b/calendar/pcs/Makefile.am
@@ -29,6 +29,8 @@ libpcs_a_SOURCES =		\
 	cal.h			\
 	cal-backend.c		\
 	cal-backend.h		\
+	cal-backend-file.c	\
+	cal-backend-file.h	\
 	cal-backend-imc.c	\
 	cal-backend-imc.h	\
 	cal-common.h		\
diff --git a/calendar/pcs/cal-backend-file.c b/calendar/pcs/cal-backend-file.c
new file mode 100644
index 0000000000..8c12e38e3b
--- /dev/null
+++ b/calendar/pcs/cal-backend-file.c
@@ -0,0 +1,1004 @@
+/* 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 GList *cal_backend_file_get_uids (CalBackend *backend, CalObjType type);
+static GList *cal_backend_file_get_events_in_range (CalBackend *backend, 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 char *cal_backend_file_get_uid_by_pilot_id (CalBackend *backend, unsigned long int pilot_id);
+static void cal_backend_file_update_pilot_id (CalBackend *backend,
+					      const char *uid,
+					      unsigned long int pilot_id,
+					      unsigned long int pilot_status);
+
+
+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_uids = cal_backend_file_get_uids;
+	backend_class->get_events_in_range = cal_backend_file_get_events_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;
+	backend_class->get_uid_by_pilot_id = cal_backend_file_get_uid_by_pilot_id;
+	backend_class->update_pilot_id = cal_backend_file_update_pilot_id;
+}
+
+/* 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;
+
+	priv = cbfile->priv;
+	g_assert (priv->uri != NULL);
+	g_assert (priv->icalcomp != NULL);
+
+	/* FIXME */
+
+	/* FIXME: ensure we have the mandatory PRODID and VERSION properties, and throw
+	 * in CALSCALE for good measure.
+	 */
+}
+
+/* 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)
+{
+	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);
+}
+
+/* Removes a component from the backend's hash and lists.  Does not perform
+ * notification on the clients.
+ */
+static void
+remove_component (CalBackendFile *cbfile, CalComponent *comp)
+{
+	CalBackendFilePrivate *priv;
+	const char *uid;
+	GList **list, *l;
+
+	priv = cbfile->priv;
+
+	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);
+	}
+}
+
+/* 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);
+
+	/* FIXME: this looks rather bad; maybe we should check for local files
+	 * and fail if they are remote.
+	 */
+
+	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 */
+
+	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);
+
+	/* Done */
+
+	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);
+}
+
+/* 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;
+}
+
+/* Allocates and fills in a new CalComponentInstance structure */
+static CalObjInstance *
+build_cal_obj_instance (CalComponent *comp, time_t start, time_t end)
+{
+	CalObjInstance *icoi;
+	const char *uid;
+
+	cal_component_get_uid (comp, &uid);
+
+	icoi = g_new (CalObjInstance, 1);
+	icoi->uid = g_strdup (uid);
+	icoi->start = start;
+	icoi->end = end;
+
+	return icoi;
+}
+
+/* Builds a list of event component instances.  Used as a callback from
+ * cal_recur_generate_instances().
+ */
+static gboolean
+build_event_list (CalComponent *comp, time_t start, time_t end, gpointer data)
+{
+	CalObjInstance *icoi;
+	GList **l;
+
+	l = data;
+
+	icoi = build_cal_obj_instance (comp, start, end);
+	*l = g_list_prepend (*l, icoi);
+
+	return TRUE;
+}
+
+/* Compares two CalObjInstance structures by their start times.  Called from
+ * g_list_sort().
+ */
+static gint
+compare_instance_func (gconstpointer a, gconstpointer b)
+{
+	const CalObjInstance *ca, *cb;
+	time_t diff;
+
+	ca = a;
+	cb = b;
+
+	diff = ca->start - cb->start;
+	return (diff < 0) ? -1 : (diff > 0) ? 1 : 0;
+}
+
+/* Get_events_in_range handler for the file backend */
+static GList *
+cal_backend_file_get_events_in_range (CalBackend *backend, time_t start, time_t end)
+{
+	CalBackendFile *cbfile;
+	CalBackendFilePrivate *priv;
+	GList *l;
+	GList *event_list;
+
+	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);
+
+	event_list = NULL;
+
+	for (l = priv->events; l; l = l->next) {
+		CalComponent *comp;
+
+		comp = l->data;
+		cal_recur_generate_instances (comp, start, end, build_event_list, &event_list);
+	}
+
+	event_list = g_list_sort (event_list, compare_instance_func);
+	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);
+#if 0
+	/* FIXME */
+	new_ico->pilot_status = ICAL_PILOT_SYNC_MOD;
+#endif
+
+	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;
+}
diff --git a/calendar/pcs/cal-backend-file.h b/calendar/pcs/cal-backend-file.h
new file mode 100644
index 0000000000..376790751c
--- /dev/null
+++ b/calendar/pcs/cal-backend-file.h
@@ -0,0 +1,62 @@
+/* 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.
+ */
+
+#ifndef CAL_BACKEND_FILE_H
+#define CAL_BACKEND_FILE_H
+
+#include <libgnome/gnome-defs.h>
+#include "cal-backend.h"
+
+BEGIN_GNOME_DECLS
+
+
+
+#define CAL_BACKEND_FILE_TYPE            (cal_backend_file_get_type ())
+#define CAL_BACKEND_FILE(obj)            (GTK_CHECK_CAST ((obj), CAL_BACKEND_FILE_TYPE,		\
+					  CalBackendFile))
+#define CAL_BACKEND_FILE_CLASS(klass)    (GTK_CHECK_CLASS_CAST ((klass), CAL_BACKEND_FILE_TYPE,	\
+					  CalBackendFileClass))
+#define IS_CAL_BACKEND_FILE(obj)         (GTK_CHECK_TYPE ((obj), CAL_BACKEND_FILE_TYPE))
+#define IS_CAL_BACKEND_FILE_CLASS(klass) (GTK_CHECK_CLASS_TYPE ((klass), CAL_BACKEND_FILE_TYPE))
+
+typedef struct _CalBackendFile CalBackendFile;
+typedef struct _CalBackendFileClass CalBackendFileClass;
+
+typedef struct _CalBackendFilePrivate CalBackendFilePrivate;
+
+struct _CalBackendFile {
+	CalBackend backend;
+
+	/* Private data */
+	CalBackendFilePrivate *priv;
+};
+
+struct _CalBackendFileClass {
+	CalBackendClass parent_class;
+};
+
+GtkType cal_backend_file_get_type (void);
+
+
+
+END_GNOME_DECLS
+
+#endif
diff --git a/calendar/pcs/cal-backend.c b/calendar/pcs/cal-backend.c
index 658f55012b..97d09fac24 100644
--- a/calendar/pcs/cal-backend.c
+++ b/calendar/pcs/cal-backend.c
@@ -347,7 +347,8 @@ void cal_backend_update_pilot_id (CalBackend *backend, const char *uid,
  * object that has the same UID as the specified one.  The backend will in
  * turn notify all of its clients about the change.
  * 
- * Return value: TRUE on success, FALSE on being passed an invalid object.
+ * Return value: TRUE on success, FALSE on being passed an invalid object or one
+ * with an unsupported type.
  **/
 gboolean
 cal_backend_update_object (CalBackend *backend, const char *uid, const char *calobj)