CalBackendClass now is just an interface for calendar backends; this is an

2000-05-08  Federico Mena Quintero  <federico@helixcode.com>

	* pcs/cal-backend.h (CalBackendClass): CalBackendClass now is just
	an interface for calendar backends; this is an abstract class.
	Put in the vtable for the backend methods.

	* pcs/cal-backend.c (cal_backend_new): Removed function, since
	CalBackend is not just an abstract class.
	Removed implementation-specific functions and made public
	functions call the virtual methods instead.

	* pcs/cal-backend-imc.[ch]: New files with the CalBackendIMC
	implementation; this implements a backend for iCalendar and
	vCalendar files.  Moved the implementation-specific stuff from
	cal-backend.[ch] to here.

	* pcs/cal-backend-imc.c (CalendarFormat): Moved enumeration to
	here.  Added a CAL_UNKNOWN value for when the backend is not
	loaded yet.
	(cal_backend_imc_init): Initialize priv->format as CAL_UNKNOWN.
	(save_to_vcal): Use the same VCProdIdProp value as in
	cal-util/calobj.c.  Use "1.0" as the VCVersionProp as per the
	vCalendar spec.
	(ensure_uid): Return nothing, since the result value need not be
	used anymore.
	(add_object): Since we mark the calendar as dirty anyways, we do
	not need to check the result value of ensure_uid() anymore.
	(remove_object): Asssert that we know how to handle the object's
	type.  We do this in add_object() anyways.

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

	* gui/gnome-cal.c: Replaced debugging printf()s with g_message()
	so that we can see the line number where they occur.

	* gui/gnome-cal.c (gnome_calendar_load_cb): Sort of handle the
	LOAD_METHOD_NOT_SUPPORTED result code, and added a default for the
	switch.

	* cal-client/cal-listener.h (CalListenerLoadStatus): Removed
	enumeration; it is stupid to translate all values for the
	CalClient when it is going to translate them again.
	(CalListenerClass::cal_loaded): This signal now passes the
	LoadStatus directly from the CORBA side.

	* cal-client/cal-listener.c (Listener_cal_loaded): Do not
	translate the status value.

	* cal-client/cal-client.h (CalClientLoadStatus): Added the
	CAL_CLIENT_LOAD_METHOD_NOT_SUPPORTED error code.

	* cal-client/cal-client.c (cal_loaded_cb): Translate the CORBA
	version of the LoadStatus result code.

	* pcs/cal-factory.c (CalFactoryPrivate): New methods field for the
	hash table from method strings to the GtkTypes for backend class
	types.
	(cal_factory_init): Create the priv->methods hash table.
	(cal_factory_destroy): Free the priv->methods hash table.
	(cal_factory_register_method): New function to register a backend
	class for a particular URI method.
	(launch_backend_for_uri): New function to launch a backend for a
	particular URI's method.
	(load_backend): Use launch_backend_for_uri().  Move the error
	notification code from load_fn() to here.
	(create_backend): Use launch_backend_for_uri().  Move the error
	notification code form create_fn() to here; it is #ifdefed out
	since currently cal_backend_create() does not have any error
	reporting capabilities.

	* idl/evolution-calendar.idl (Listener::LoadStatus): Added a
	PROTOCOL_NOT_SUPPORTED error code.

	* pcs/cal-factory.c (cal_factory_load cal_factory_create): Removed
	functions, since they were supposed to be internal only.
	(CalFactory_load): Call queue_load_create_job() directly.
	(CalFactory_create): Likewise.

svn path=/trunk/; revision=2921

7 files changed, 1443 insertions, 1068 deletions

diff --git a/calendar/pcs/Makefile.am b/calendar/pcs/Makefile.am
index b9ea5fecd0..b496659f03 100644
--- a/calendar/pcs/Makefile.am
+++ b/calendar/pcs/Makefile.am
@@ -28,6 +28,8 @@ libpcs_a_SOURCES =		\
 	cal.h			\
 	cal-backend.c		\
 	cal-backend.h		\
+	cal-backend-imc.c	\
+	cal-backend-imc.h	\
 	cal-common.h		\
 	cal-factory.c		\
 	cal-factory.h		\
diff --git a/calendar/pcs/cal-backend-imc.c b/calendar/pcs/cal-backend-imc.c
new file mode 100644
index 0000000000..29c806a89f
--- /dev/null
+++ b/calendar/pcs/cal-backend-imc.c
@@ -0,0 +1,1068 @@
+/* Evolution calendar - Internet Mail Consortium formats backend
+ *
+ * Copyright (C) 2000 Helix Code, Inc.
+ *
+ * Authors: Federico Mena-Quintero <federico@helixcode.com>
+ *          Seth Alves <alves@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-backend-imc.h"
+#include "icalendar.h"
+
+
+
+/* Supported calendar formats from the IMC */
+typedef enum {
+	CAL_FORMAT_UNKNOWN,
+	CAL_FORMAT_VCALENDAR,
+	CAL_FORMAT_ICALENDAR
+} CalendarFormat;
+
+/* Private part of the CalBackendIMC structure */
+typedef struct {
+	/* URI where the calendar data is stored */
+	GnomeVFSURI *uri;
+
+        /* Format of this calendar (iCalendar or vCalendar) */
+	CalendarFormat format;
+
+	/* List of Cal objects with their listeners */
+	GList *clients;
+
+	/* All the iCalObject structures in the calendar, hashed by UID.  The
+	 * hash key *is* icalobj->uid; it is not copied, so don't free it when
+	 * you remove an object from the hash table.
+	 */
+	GHashTable *object_hash;
+
+	/* All events, TODOs, and journals in the calendar */
+	GList *events;
+	GList *todos;
+	GList *journals;
+
+	/* Whether a calendar has been loaded */
+	guint loaded : 1;
+
+	/* Do we need to sync to permanent storage? */
+	gboolean dirty : 1;
+} IMCPrivate;
+
+
+
+static void cal_backend_imc_class_init (CalBackendIMCClass *class);
+static void cal_backend_imc_init (CalBackendIMC *bimc);
+static void cal_backend_imc_destroy (GtkObject *object);
+
+static GnomeVFSURI *cal_backend_imc_get_uri (CalBackend *backend);
+static void cal_backend_imc_add_cal (CalBackend *backend, Cal *cal);
+static CalBackendLoadStatus cal_backend_imc_load (CalBackend *backend, GnomeVFSURI *uri);
+static void cal_backend_imc_create (CalBackend *backend, GnomeVFSURI *uri);
+static char *cal_backend_imc_get_object (CalBackend *backend, const char *uid);
+static GList *cal_backend_imc_get_uids (CalBackend *backend, CalObjType type);
+static GList *cal_backend_imc_get_events_in_range (CalBackend *backend, time_t start, time_t end);
+static gboolean cal_backend_imc_update_object (CalBackend *backend, const char *uid,
+					       const char *calobj);
+static gboolean cal_backend_imc_remove_object (CalBackend *backend, const char *uid);
+
+static CalBackendClass *parent_class;
+
+
+
+/**
+ * cal_backend_imc_get_type:
+ * @void:
+ *
+ * Registers the #CalBackendIMC class if necessary, and returns the type ID
+ * associated to it.
+ *
+ * Return value: The type ID of the #CalBackendIMC class.
+ **/
+GtkType
+cal_backend_imc_get_type (void)
+{
+	static GtkType cal_backend_imc_type = 0;
+
+	if (!cal_backend_imc_type) {
+		static const GtkTypeInfo cal_backend_imc_info = {
+			"CalBackendIMC",
+			sizeof (CalBackendIMC),
+			sizeof (CalBackendIMCClass),
+			(GtkClassInitFunc) cal_backend_imc_class_init,
+			(GtkObjectInitFunc) cal_backend_imc_init,
+			NULL, /* reserved_1 */
+			NULL, /* reserved_2 */
+			(GtkClassInitFunc) NULL
+		};
+
+		cal_backend_imc_type = gtk_type_unique (CAL_BACKEND_TYPE, &cal_backend_imc_info);
+	}
+
+	return cal_backend_imc_type;
+}
+
+/* Class initialization function for the IMC backend */
+static void
+cal_backend_imc_class_init (CalBackendIMCClass *class)
+{
+	GtkObjectClass *object_class;
+	CalBackendClass *backend_class;
+
+	object_class = (GtkObjectClass *) class;
+	backend_class = (CalBackendClass *) class;
+
+	parent_class = gtk_type_class (CAL_BACKEND_TYPE);
+
+	backend_class->get_uri = cal_backend_imc_get_uri;
+	backend_class->add_cal = cal_backend_imc_add_cal;
+	backend_class->load = cal_backend_imc_load;
+	backend_class->create = cal_backend_imc_create;
+	backend_class->get_object = cal_backend_imc_get_object;
+	backend_class->get_uids = cal_backend_imc_get_uids;
+	backend_class->get_events_in_range = cal_backend_imc_get_events_in_range;
+	backend_class->update_object = cal_backend_imc_update_object;
+	backend_class->remove_object = cal_backend_imc_remove_object;
+
+	object_class->destroy = cal_backend_imc_destroy;
+}
+
+/* Object initialization function for the IMC backend */
+static void
+cal_backend_imc_init (CalBackendIMC *cbimc)
+{
+	IMCPrivate *priv;
+
+	priv = g_new0 (IMCPrivate, 1);
+	cbimc->priv = priv;
+
+	priv->format = CAL_FORMAT_UNKNOWN;
+}
+
+static void
+save_to_vcal (CalBackendIMC *cbimc, char *fname)
+{
+	FILE *fp;
+	IMCPrivate *priv;
+	VObject *vcal;
+	GList *l;
+
+	priv = cbimc->priv;
+
+	if (g_file_exists (fname)) {
+		char *backup_name = g_strconcat (fname, "~", NULL);
+
+		/* FIXME: do error checking on system calls!!!! */
+
+		if (g_file_exists (backup_name))
+			unlink (backup_name);
+
+		rename (fname, backup_name);
+		g_free (backup_name);
+	}
+
+	vcal = newVObject (VCCalProp);
+	addPropValue (vcal, VCProdIdProp,
+		      "-//Helix Code//NONSGML Evolution Calendar//EN");
+
+	/* Per the vCalendar spec, this must be "1.0" */
+	addPropValue (vcal, VCVersionProp, "1.0");
+
+	/* FIXME: this should really iterate over the object hash table instead
+	 * of the lists; that way we won't lose objects if they are of a type
+	 * that we don't support but are in the calendar anyways.
+	 */
+
+	for (l = priv->events; l; l = l->next) {
+		iCalObject *ical = l->data;
+		VObject *vobject = ical_object_to_vobject (ical);
+		addVObjectProp (vcal, vobject);
+	}
+
+	for (l = priv->todos; l; l = l->next) {
+		iCalObject *ical = l->data;
+		VObject *vobject = ical_object_to_vobject (ical);
+		addVObjectProp (vcal, vobject);
+	}
+
+	for (l = priv->journals; l; l = l->next) {
+		iCalObject *ical = l->data;
+		VObject *vobject = ical_object_to_vobject (ical);
+		addVObjectProp (vcal, vobject);
+	}
+
+	fp = fopen(fname,"w");
+	if (fp) {
+		writeVObject(fp, vcal);
+		fclose(fp);
+	}
+	cleanVObject (vcal);
+	cleanStrTbl ();
+}
+
+/* Saves a calendar */
+static void
+save (CalBackendIMC *cbimc)
+{
+	char *str_uri;
+	IMCPrivate *priv = cbimc->priv;
+
+	str_uri = gnome_vfs_uri_to_string (priv->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));
+
+	if (!priv->dirty)
+		return;
+
+	switch (priv->format) {
+	case CAL_FORMAT_VCALENDAR:
+		save_to_vcal (cbimc, str_uri);
+		break;
+
+	case CAL_FORMAT_ICALENDAR:
+		/*icalendar_calendar_save (cbimc, str_uri);*/
+		/* FIX ME */
+		break;
+
+	default:
+		g_message ("save(): Attempt to save a calendar with an unknown format!");
+	        break;
+	}
+
+	printf ("cal-backend-imc: '%s' saved\n", str_uri);
+
+	g_free (str_uri);
+}
+
+/* g_hash_table_foreach() callback to destroy an iCalObject */
+static void
+free_ical_object (gpointer key, gpointer value, gpointer data)
+{
+	iCalObject *ico;
+
+	ico = value;
+	ical_object_destroy (ico);
+}
+
+/* Destroys an IMC backend's data */
+static void
+destroy (CalBackendIMC *cbimc)
+{
+	IMCPrivate *priv;
+
+	priv = cbimc->priv;
+
+	if (priv->uri) {
+		gnome_vfs_uri_unref (priv->uri);
+		priv->uri = NULL;
+	}
+
+	g_assert (priv->clients == NULL);
+
+	if (priv->object_hash) {
+		g_hash_table_foreach (priv->object_hash, free_ical_object, NULL);
+		g_hash_table_destroy (priv->object_hash);
+		priv->object_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;
+
+	priv->loaded = FALSE;
+	priv->format = CAL_FORMAT_UNKNOWN;
+}
+
+/* Destroy handler for the IMC backend */
+static void
+cal_backend_imc_destroy (GtkObject *object)
+{
+	CalBackendIMC *cbimc;
+	IMCPrivate *priv;
+
+	g_return_if_fail (object != NULL);
+	g_return_if_fail (IS_CAL_BACKEND_IMC (object));
+
+	cbimc = CAL_BACKEND_IMC (object);
+	priv = cbimc->priv;
+
+	/*
+	if (priv->loaded)
+		save (cbimc);
+	*/
+
+	destroy (cbimc);
+
+	g_free (priv);
+	cbimc->priv = NULL;
+
+	if (GTK_OBJECT_CLASS (parent_class)->destroy)
+		(* GTK_OBJECT_CLASS (parent_class)->destroy) (object);
+}
+
+
+
+/* iCalObject manipulation functions */
+
+/* Looks up an object by its UID in the backend's object hash table */
+static iCalObject *
+lookup_object (CalBackendIMC *cbimc, const char *uid)
+{
+	IMCPrivate *priv;
+	iCalObject *ico;
+
+	priv = cbimc->priv;
+	ico = g_hash_table_lookup (priv->object_hash, uid);
+
+	return ico;
+}
+
+/* Ensures that an iCalObject has a unique identifier.  If it doesn't have one,
+ * it will create one for it.
+ */
+static void
+ensure_uid (iCalObject *ico)
+{
+	char *buf;
+	gulong str_time;
+	static guint seqno = 0;
+
+	if (ico->uid)
+		return;
+
+	str_time = (gulong) time (NULL);
+
+	/* Is this good enough? */
+
+	buf = g_strdup_printf ("Evolution-Calendar-%d-%ld-%u",
+			       (int) getpid(), str_time, seqno++);
+	ico->uid = buf;
+}
+
+/* Adds an object to the calendar backend.  Does *not* perform notification to
+ * calendar clients.
+ */
+static void
+add_object (CalBackendIMC *cbimc, iCalObject *ico)
+{
+	IMCPrivate *priv;
+
+	g_assert (ico != NULL);
+
+	priv = cbimc->priv;
+
+#if 0
+	/* FIXME: gnomecal old code */
+	ico->new = 0;
+#endif
+
+	ensure_uid (ico);
+	g_hash_table_insert (priv->object_hash, ico->uid, ico);
+
+	priv->dirty = TRUE;
+
+	switch (ico->type) {
+	case ICAL_EVENT:
+		priv->events = g_list_prepend (priv->events, ico);
+#if 0
+		/* FIXME: gnomecal old code */
+		ical_object_try_alarms (ico);
+#  ifdef DEBUGGING_MAIL_ALARM
+		ico->malarm.trigger = 0;
+		calendar_notify (0, ico);
+#  endif
+#endif
+		break;
+
+	case ICAL_TODO:
+		priv->todos = g_list_prepend (priv->todos, ico);
+		break;
+
+	case ICAL_JOURNAL:
+		priv->journals = g_list_prepend (priv->journals, ico);
+		break;
+
+	default:
+		g_assert_not_reached ();
+	}
+
+#if 0
+	/* FIXME: gnomecal old code */
+	ico->last_mod = time (NULL);
+#endif
+}
+
+/* Removes an object from the backend's hash and lists.  Does not perform
+ * notification on the clients.
+ */
+static void
+remove_object (CalBackendIMC *cbimc, iCalObject *ico)
+{
+	IMCPrivate *priv;
+	GList **list, *l;
+
+	priv = cbimc->priv;
+
+	g_assert (ico->uid != NULL);
+	g_hash_table_remove (priv->object_hash, ico->uid);
+
+	priv->dirty = TRUE;
+
+	switch (ico->type) {
+	case ICAL_EVENT:
+		list = &priv->events;
+		break;
+
+	case ICAL_TODO:
+		list = &priv->todos;
+		break;
+
+	case ICAL_JOURNAL:
+		list = &priv->journals;
+		break;
+
+	default:
+		g_assert_not_reached ();
+	}
+
+	l = g_list_find (*list, ico);
+	g_assert (l != NULL);
+
+	*list = g_list_remove_link (*list, l);
+	g_list_free_1 (l);
+
+	ical_object_destroy (ico);
+}
+
+/* Load a calendar from a VObject */
+static void
+load_from_vobject (CalBackendIMC *cbimc, VObject *vobject)
+{
+	IMCPrivate *priv;
+	VObjectIterator i;
+
+	priv = cbimc->priv;
+
+	g_assert (!priv->loaded);
+	g_assert (priv->object_hash == NULL);
+	priv->object_hash = g_hash_table_new (g_str_hash, g_str_equal);
+
+	initPropIterator (&i, vobject);
+
+	while (moreIteration (&i)) {
+		VObject *this;
+		iCalObject *ical;
+		const char *object_name;
+
+		this = nextVObject (&i);
+		object_name = vObjectName (this);
+#if 0
+		/* FIXME?  What is this used for in gnomecal? */
+		if (strcmp (object_name, VCDCreatedProp) == 0) {
+			cal->created = time_from_isodate (str_val (this));
+			continue;
+		}
+#endif
+		if (strcmp (object_name, VCLocationProp) == 0)
+			continue; /* FIXME: imlement */
+
+		if (strcmp (object_name, VCProdIdProp) == 0)
+			continue; /* FIXME: implement */
+
+		if (strcmp (object_name, VCVersionProp) == 0)
+			continue; /* FIXME: implement */
+
+		if (strcmp (object_name, VCTimeZoneProp) == 0)
+			continue; /* FIXME: implement */
+
+		ical = ical_object_create_from_vobject (this, object_name);
+
+		/* FIXME: some broken files (ahem, old KOrganizer files) may
+		 * have duplicated UIDs.  This is Bad(tm).  Deal with it by
+		 * creating new UIDs for them and spitting some messages to the
+		 * console.
+		 */
+
+		if (ical)
+			add_object (cbimc, ical);
+	}
+}
+
+
+
+/* Calendar backend methods */
+
+/* Get_uri handler for the IMC backend */
+static GnomeVFSURI *
+cal_backend_imc_get_uri (CalBackend *backend)
+{
+	CalBackendIMC *cbimc;
+	IMCPrivate *priv;
+
+	cbimc = CAL_BACKEND_IMC (backend);
+	priv = cbimc->priv;
+
+	g_return_val_if_fail (priv->loaded, 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;
+	CalBackendIMC *cbimc;
+	IMCPrivate *priv;
+	GList *l;
+
+	cal = CAL (object);
+
+	cbimc = CAL_BACKEND_IMC (data);
+	priv = cbimc->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 (cbimc));
+}
+
+/* Add_cal handler for the IMC backend */
+static void
+cal_backend_imc_add_cal (CalBackend *backend, Cal *cal)
+{
+	CalBackendIMC *cbimc;
+	IMCPrivate *priv;
+
+	cbimc = CAL_BACKEND_IMC (backend);
+	priv = cbimc->priv;
+
+	g_return_if_fail (priv->loaded);
+	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);
+}
+
+static icalcomponent *
+icalendar_parse_file (char *fname)
+{
+	FILE *fp;
+	icalcomponent *comp = NULL;
+	char *str;
+	struct stat st;
+	int n;
+
+	fp = fopen (fname, "r");
+	if (!fp) {
+		/* FIXME: remove message */
+		g_message ("icalendar_parse_file(): Cannot open open calendar file.");
+		return NULL;
+	}
+
+	stat (fname, &st);
+
+	str = g_malloc (st.st_size + 2);
+
+	n = fread (str, 1, st.st_size, fp);
+	if (n != st.st_size) {
+		/* FIXME: remove message, return error code instead */
+		g_message ("icalendar_parse_file(): Read error.");
+	}
+	str[n] = '\0';
+
+	fclose (fp);
+
+	comp = icalparser_parse_string (str);
+	g_free (str);
+
+	return comp;
+}
+
+static void
+icalendar_calendar_load (CalBackendIMC *cbimc, char *fname)
+{
+	IMCPrivate *priv;
+	icalcomponent *comp;
+	icalcomponent *subcomp;
+	iCalObject    *ical;
+
+	priv = cbimc->priv;
+
+	g_assert (!priv->loaded);
+	g_assert (priv->object_hash == NULL);
+
+	priv->object_hash = g_hash_table_new (g_str_hash, g_str_equal);
+
+	comp = icalendar_parse_file (fname);
+	subcomp = icalcomponent_get_first_component (comp,
+						     ICAL_ANY_COMPONENT);
+	while (subcomp) {
+		ical = ical_object_create_from_icalcomponent (subcomp);
+		if (ical->type != ICAL_EVENT &&
+		    ical->type != ICAL_TODO  &&
+		    ical->type != ICAL_JOURNAL) {
+		       g_message ("icalendar_calendar_load(): Skipping unsupported "
+				  "iCalendar component.");
+		} else
+			add_object (cbimc, ical);
+
+		subcomp = icalcomponent_get_next_component (comp,
+							   ICAL_ANY_COMPONENT);
+	}
+}
+
+/* ics is to be used to designate a file containing (an arbitrary set of)
+ * calendaring and scheduling information.
+ *
+ * ifb is to be used to designate a file containing free or busy time
+ * information.
+ *
+ * anything else is assumed to be a vcal file.
+ *
+ * FIXME: should we return UNKNOWN at some point?
+ */
+static CalendarFormat
+cal_get_type_from_filename (char *str_uri)
+{
+	int len;
+
+	if (str_uri == NULL)
+		return CAL_FORMAT_VCALENDAR;
+
+	len = strlen (str_uri);
+	if (len < 4)
+		return CAL_FORMAT_VCALENDAR;
+
+	if (str_uri[len - 4] == '.' && str_uri[len - 3] == 'i' &&
+	    str_uri[len - 2] == 'c' && str_uri[len - 1] == 's')
+		return CAL_FORMAT_ICALENDAR;
+
+	if (str_uri[len - 4] == '.' && str_uri[len - 3] == 'i' &&
+	    str_uri[len - 2] == 'f' && str_uri[len - 1] == 'b')
+		return CAL_FORMAT_ICALENDAR;
+
+	if (str_uri[len - 4] == '.' && str_uri[len - 3] == 'i' &&
+	    str_uri[len - 2] == 'c' && str_uri[len - 1] == 's')
+		return CAL_FORMAT_ICALENDAR;
+
+	if (len < 5)
+		return CAL_FORMAT_VCALENDAR;
+
+	if (str_uri[len - 5] == '.' && str_uri[len - 4] == 'i' &&
+	    str_uri[len - 3] == 'c' && str_uri[len - 2] == 'a' &&
+	    str_uri[len - 1] == 'l')
+		return CAL_FORMAT_ICALENDAR;
+
+	return CAL_FORMAT_VCALENDAR;
+}
+
+/* Load handler for the IMC backend */
+static CalBackendLoadStatus
+cal_backend_imc_load (CalBackend *backend, GnomeVFSURI *uri)
+{
+	CalBackendIMC *cbimc;
+	IMCPrivate *priv;
+	VObject *vobject;
+	char *str_uri;
+
+	cbimc = CAL_BACKEND_IMC (backend);
+	priv = cbimc->priv;
+
+	g_return_val_if_fail (!priv->loaded, 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));
+
+	/* look at the extension on the filename and decide if this is a
+	 * iCalendar or vCalendar file.
+	 */
+	priv->format = cal_get_type_from_filename (str_uri);
+
+	/* load */
+
+	switch (priv->format) {
+	case CAL_FORMAT_VCALENDAR:
+	        vobject = Parse_MIME_FromFileName (str_uri);
+
+		if (!vobject){
+			g_free (str_uri);
+			return CAL_BACKEND_LOAD_ERROR;
+		}
+
+		load_from_vobject (cbimc, vobject);
+		cleanVObject (vobject);
+		cleanStrTbl ();
+		break;
+
+	case CAL_FORMAT_ICALENDAR:
+		icalendar_calendar_load (cbimc, str_uri);
+		break;
+
+	default:
+		g_free (str_uri);
+	        return CAL_BACKEND_LOAD_ERROR;
+	}
+
+	g_free (str_uri);
+
+	gnome_vfs_uri_ref (uri);
+
+	priv->uri = uri;
+	priv->loaded = TRUE;
+
+	return CAL_BACKEND_LOAD_SUCCESS;
+}
+
+/* Create handler for the IMC backend */
+static void
+cal_backend_imc_create (CalBackend *backend, GnomeVFSURI *uri)
+{
+	CalBackendIMC *cbimc;
+	IMCPrivate *priv;
+
+	cbimc = CAL_BACKEND_IMC (backend);
+	priv = cbimc->priv;
+
+	g_return_if_fail (!priv->loaded);
+	g_return_if_fail (uri != NULL);
+
+	/* Create the new calendar information */
+
+	g_assert (priv->object_hash == NULL);
+	priv->object_hash = g_hash_table_new (g_str_hash, g_str_equal);
+
+	priv->dirty = TRUE;
+
+	/* Done */
+
+	gnome_vfs_uri_ref (uri);
+
+	priv->uri = uri;
+	priv->loaded = TRUE;
+
+	save (cbimc);
+}
+
+/* Get_object handler for the IMC backend */
+static char *
+cal_backend_imc_get_object (CalBackend *backend, const char *uid)
+{
+	CalBackendIMC *cbimc;
+	IMCPrivate *priv;
+	iCalObject *ico;
+	char *buf;
+
+	cbimc = CAL_BACKEND_IMC (backend);
+	priv = cbimc->priv;
+
+	g_return_val_if_fail (uid != NULL, NULL);
+
+	g_return_val_if_fail (priv->loaded, NULL);
+	g_assert (priv->object_hash != NULL);
+
+	ico = lookup_object (cbimc, uid);
+
+	if (!ico)
+		return NULL;
+
+	buf = ical_object_to_string (ico);
+
+	return buf;
+}
+
+struct get_uids_closure {
+	CalObjType type;
+	GList *uid_list;
+};
+
+/* Builds a list of UIDs for objects that match the sought type.  Called from
+ * g_hash_table_foreach().
+ */
+static void
+build_uids_list (gpointer key, gpointer value, gpointer data)
+{
+	iCalObject *ico;
+	struct get_uids_closure *c;
+	gboolean store;
+
+	ico = value;
+	c = data;
+
+	store = FALSE;
+
+	if (ico->type == ICAL_EVENT)
+		store = (c->type & CALOBJ_TYPE_EVENT) ? TRUE : FALSE;
+	else if (ico->type == ICAL_TODO)
+		store = (c->type & CALOBJ_TYPE_TODO) ? TRUE : FALSE;
+	else if (ico->type == ICAL_JOURNAL)
+		store = (c->type & CALOBJ_TYPE_JOURNAL) ? TRUE : FALSE;
+	else
+		store = (c->type & CALOBJ_TYPE_OTHER) ? TRUE : FALSE;
+
+	if (store)
+		c->uid_list = g_list_prepend (c->uid_list, g_strdup (ico->uid));
+}
+
+/* Get_uids handler for the IMC backend */
+static GList *
+cal_backend_imc_get_uids (CalBackend *backend, CalObjType type)
+{
+	CalBackendIMC *cbimc;
+	IMCPrivate *priv;
+	struct get_uids_closure c;
+
+	cbimc = CAL_BACKEND_IMC (backend);
+	priv = cbimc->priv;
+
+	g_return_val_if_fail (priv->loaded, NULL);
+
+	/* We go through the hash table instead of the lists of particular
+	 * object types so that we can pick up CALOBJ_TYPE_OTHER objects.
+	 */
+	c.type = type;
+	c.uid_list = NULL;
+	g_hash_table_foreach (priv->object_hash, build_uids_list, &c);
+
+	return c.uid_list;
+}
+
+struct build_event_list_closure {
+	CalBackendIMC *cbimc;
+	GList *event_list;
+};
+
+/* Builds a sorted list of event object instances.  Used as a callback from
+ * ical_object_generate_events().
+ */
+static int
+build_event_list (iCalObject *ico, time_t start, time_t end, void *data)
+{
+	CalObjInstance *icoi;
+	struct build_event_list_closure *c;
+
+	c = data;
+
+	icoi = g_new (CalObjInstance, 1);
+
+	g_assert (ico->uid != NULL);
+	icoi->uid = g_strdup (ico->uid);
+	icoi->start = start;
+	icoi->end = end;
+
+	c->event_list = g_list_prepend (c->event_list, 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 IMC backend */
+static GList *
+cal_backend_imc_get_events_in_range (CalBackend *backend, time_t start, time_t end)
+{
+	struct build_event_list_closure c;
+	GList *l;
+
+	CalBackendIMC *cbimc;
+	IMCPrivate *priv;
+
+	cbimc = CAL_BACKEND_IMC (backend);
+	priv = cbimc->priv;
+
+	g_return_val_if_fail (priv->loaded, NULL);
+
+	g_return_val_if_fail (start != -1 && end != -1, NULL);
+	g_return_val_if_fail (start <= end, NULL);
+
+	c.cbimc = cbimc;
+	c.event_list = NULL;
+
+	for (l = priv->events; l; l = l->next) {
+		iCalObject *ico;
+
+		ico = l->data;
+		ical_object_generate_events (ico, start, end,
+					     build_event_list, &c);
+	}
+
+	c.event_list = g_list_sort (c.event_list, compare_instance_func);
+
+	return c.event_list;
+}
+
+/* Notifies a backend's clients that an object was updated */
+static void
+notify_update (CalBackendIMC *cbimc, const char *uid)
+{
+	IMCPrivate *priv;
+	GList *l;
+
+	priv = cbimc->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 (CalBackendIMC *cbimc, const char *uid)
+{
+	IMCPrivate *priv;
+	GList *l;
+
+	priv = cbimc->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 IMC backend */
+static gboolean
+cal_backend_imc_update_object (CalBackend *backend, const char *uid, const char *calobj)
+{
+	CalBackendIMC *cbimc;
+	IMCPrivate *priv;
+	iCalObject *ico, *new_ico;
+	CalObjFindStatus status;
+
+	cbimc = CAL_BACKEND_IMC (backend);
+	priv = cbimc->priv;
+
+	g_return_val_if_fail (priv->loaded, FALSE);
+
+	g_return_val_if_fail (uid != NULL, FALSE);
+	g_return_val_if_fail (calobj != NULL, FALSE);
+
+	/* Pull the object from the string */
+
+	status = ical_object_find_in_string (uid, calobj, &new_ico);
+
+	if (status != CAL_OBJ_FIND_SUCCESS)
+		return FALSE;
+
+	/* Update the object */
+
+	ico = lookup_object (cbimc, uid);
+
+	if (ico)
+		remove_object (cbimc, ico);
+
+	add_object (cbimc, new_ico);
+	save (cbimc);
+
+	/* FIXME: do the notification asynchronously */
+
+	notify_update (cbimc, new_ico->uid);
+
+	return TRUE;
+}
+
+/* Remove_object handler for the IMC backend */
+static gboolean
+cal_backend_imc_remove_object (CalBackend *backend, const char *uid)
+{
+	CalBackendIMC *cbimc;
+	IMCPrivate *priv;
+	iCalObject *ico;
+
+	cbimc = CAL_BACKEND_IMC (backend);
+	priv = cbimc->priv;
+
+	g_return_val_if_fail (priv->loaded, FALSE);
+
+	g_return_val_if_fail (uid != NULL, FALSE);
+
+	ico = lookup_object (cbimc, uid);
+	if (!ico)
+		return FALSE;
+
+	remove_object (cbimc, ico);
+
+	priv->dirty = TRUE;
+	save (cbimc);
+
+	/* FIXME: do the notification asynchronously */
+	notify_remove (cbimc, uid);
+
+	return TRUE;
+}
diff --git a/calendar/pcs/cal-backend-imc.h b/calendar/pcs/cal-backend-imc.h
new file mode 100644
index 0000000000..b0fa93611e
--- /dev/null
+++ b/calendar/pcs/cal-backend-imc.h
@@ -0,0 +1,60 @@
+/* Evolution calendar - Internet Mail Consortium formats backend
+ *
+ * Copyright (C) 2000 Helix Code, Inc.
+ *
+ * Authors: Federico Mena-Quintero <federico@helixcode.com>
+ *          Seth Alves <alves@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_IMC_H
+#define CAL_BACKEND_IMC_H
+
+#include <libgnome/gnome-defs.h>
+#include "cal-backend.h"
+
+BEGIN_GNOME_DECLS
+
+
+
+#define CAL_BACKEND_IMC_TYPE            (cal_backend_imc_get_type ())
+#define CAL_BACKEND_IMC(obj)            (GTK_CHECK_CAST ((obj), CAL_BACKEND_IMC_TYPE, CalBackendIMC))
+#define CAL_BACKEND_IMC_CLASS(klass)    (GTK_CHECK_CLASS_CAST ((klass), CAL_BACKEND_IMC_TYPE,	\
+					 CalBackendIMCClass))
+#define IS_CAL_BACKEND_IMC(obj)         (GTK_CHECK_TYPE ((obj), CAL_BACKEND_IMC_TYPE))
+#define IS_CAL_BACKEND_IMC_CLASS(klass) (GTK_CHECK_CLASS_TYPE ((klass), CAL_BACKEND_IMC_TYPE))
+
+typedef struct _CalBackendIMC CalBackendIMC;
+typedef struct _CalBackendIMCClass CalBackendIMCClass;
+
+struct _CalBackendIMC {
+	CalBackend backend;
+
+	/* Private data */
+	gpointer priv;
+};
+
+struct _CalBackendIMCClass {
+	CalBackendClass parent_class;
+};
+
+GtkType cal_backend_imc_get_type (void);
+
+
+
+END_GNOME_DECLS
+
+#endif
diff --git a/calendar/pcs/cal-backend.c b/calendar/pcs/cal-backend.c
index 3aed2a41fa..27cc3e53ce 100644
--- a/calendar/pcs/cal-backend.c
+++ b/calendar/pcs/cal-backend.c
@@ -1,5 +1,5 @@
 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
-/* Evolution calendar backend
+/* Evolution calendar - generic backend class
  *
  * Copyright (C) 2000 Helix Code, Inc.
  *
@@ -25,39 +25,6 @@
 #include <cal-util/calobj.h>
 #include "cal-backend.h"
 #include "libversit/vcc.h"
-#include "icalendar.h"
-
-
-
-
-/* Private part of the CalBackend structure */
-typedef struct {
-	/* URI where the calendar data is stored */
-	GnomeVFSURI *uri;
-
-        /* format of this calendar (ical or vcal) */
-	CalendarFormat format;
-
-	/* List of Cal objects with their listeners */
-	GList *clients;
-
-	/* All the iCalObject structures in the calendar, hashed by UID.  The
-	 * hash key *is* icalobj->uid; it is not copied, so don't free it when
-	 * you remove an object from the hash table.
-	 */
-	GHashTable *object_hash;
-
-	/* All events, TODOs, and journals in the calendar */
-	GList *events;
-	GList *todos;
-	GList *journals;
-
-	/* Whether a calendar has been loaded */
-	guint loaded : 1;
-
-	/* Do we need to sync to permanent storage? */
-	gboolean dirty : 1;
-} CalBackendPrivate;
 
 
 
@@ -68,13 +35,13 @@ enum {
 };
 
 static void cal_backend_class_init (CalBackendClass *class);
-static void cal_backend_init (CalBackend *backend);
-static void cal_backend_destroy (GtkObject *object);
 
 static GtkObjectClass *parent_class;
 
 static guint cal_backend_signals[LAST_SIGNAL];
 
+#define CLASS(backend) (CAL_BACKEND_CLASS (GTK_OBJECT (backend)->klass))
+
 
 
 /**
@@ -97,7 +64,7 @@ cal_backend_get_type (void)
 			sizeof (CalBackend),
 			sizeof (CalBackendClass),
 			(GtkClassInitFunc) cal_backend_class_init,
-			(GtkObjectInitFunc) cal_backend_init,
+			(GtkObjectInitFunc) NULL,
 			NULL, /* reserved_1 */
 			NULL, /* reserved_2 */
 			(GtkClassInitFunc) NULL
@@ -129,391 +96,11 @@ cal_backend_class_init (CalBackendClass *class)
 				GTK_TYPE_NONE, 0);
 
 	gtk_object_class_add_signals (object_class, cal_backend_signals, LAST_SIGNAL);
-
-	object_class->destroy = cal_backend_destroy;
-}
-
-/* Object initialization function for the calendar backend */
-static void
-cal_backend_init (CalBackend *backend)
-{
-	CalBackendPrivate *priv;
-
-	priv = g_new0 (CalBackendPrivate, 1);
-	backend->priv = priv;
-
-	/* FIXME can be CAL_VCAL or CAL_ICAL */
-	priv->format = CAL_VCAL;
-}
-
-static void
-save_to_vcal (CalBackend *backend, char *fname)
-{
-	FILE *fp;
-	CalBackendPrivate *priv = backend->priv;
-	VObject *vcal;
-	GList *l;
-
-	if (g_file_exists (fname)){
-		char *backup_name = g_strconcat (fname, "~", NULL);
-
-		if (g_file_exists (backup_name)){
-			unlink (backup_name);
-		}
-		rename (fname, backup_name);
-		g_free (backup_name);
-	}
-
-	vcal = newVObject (VCCalProp);
-	addPropValue (vcal, VCProdIdProp,
-		      "-//GNOME//NONSGML GnomeCalendar//EN");
-	addPropValue (vcal, VCVersionProp, VERSION);
-
-	for (l = priv->events; l; l = l->next) {
-		iCalObject *ical = l->data;
-		VObject *vobject = ical_object_to_vobject (ical);
-		addVObjectProp (vcal, vobject);
-	}
-	for (l = priv->todos; l; l = l->next) {
-		iCalObject *ical = l->data;
-		VObject *vobject = ical_object_to_vobject (ical);
-		addVObjectProp (vcal, vobject);
-	}
-	for (l = priv->journals; l; l = l->next) {
-		iCalObject *ical = l->data;
-		VObject *vobject = ical_object_to_vobject (ical);
-		addVObjectProp (vcal, vobject);
-	}
-
-	fp = fopen(fname,"w");
-	if (fp) {
-		writeVObject(fp, vcal);
-		fclose(fp);
-	}
-	cleanVObject (vcal);
-	cleanStrTbl ();
-}
-
-/* Saves a calendar */
-static void
-save (CalBackend *backend)
-{
-	char *str_uri;
-	CalBackendPrivate *priv = backend->priv;
-
-	str_uri = gnome_vfs_uri_to_string (priv->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));
-
-	if (! priv->dirty){
-		return;
-	}
-
-	switch (priv->format) {
-	case CAL_VCAL:
-		save_to_vcal (backend, str_uri);
-		break;
-	case CAL_ICAL:
-		/*icalendar_calendar_save (backend, str_uri);*/
-		/* FIX ME */
-		break;
-	default:
-		/* FIX ME log */
-	        break;
-	}
-
-	printf ("cal-backend: '%s' saved\n", str_uri);
-
-	g_free (str_uri);
-}
-
-
-/* g_hash_table_foreach() callback to destroy an iCalObject */
-static void
-free_ical_object (gpointer key, gpointer value, gpointer data)
-{
-	iCalObject *ico;
-
-	ico = value;
-	ical_object_destroy (ico);
-}
-
-/* Destroys a backend's data */
-static void
-destroy (CalBackend *backend)
-{
-	CalBackendPrivate *priv;
-
-	priv = backend->priv;
-
-	if (priv->uri) {
-		gnome_vfs_uri_unref (priv->uri);
-		priv->uri = NULL;
-	}
-
-	g_assert (priv->clients == NULL);
-
-	if (priv->object_hash) {
-		g_hash_table_foreach (priv->object_hash, free_ical_object, NULL);
-		g_hash_table_destroy (priv->object_hash);
-		priv->object_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;
-
-	priv->loaded = FALSE;
-}
-
-/* Destroy handler for the calendar backend */
-static void
-cal_backend_destroy (GtkObject *object)
-{
-	CalBackend *backend;
-	CalBackendPrivate *priv;
-
-	g_return_if_fail (object != NULL);
-	g_return_if_fail (IS_CAL_BACKEND (object));
-
-	backend = CAL_BACKEND (object);
-	priv = backend->priv;
-
-	/*
-	if (priv->loaded)
-		save (backend);
-	*/
-
-	destroy (backend);
-
-	g_free (priv);
-
-	if (GTK_OBJECT_CLASS (parent_class)->destroy)
-		(* GTK_OBJECT_CLASS (parent_class)->destroy) (object);
-}
-
-
-
-/* iCalObject manipulation functions */
-
-/* Looks up an object by its UID in the backend's object hash table */
-static iCalObject *
-lookup_object (CalBackend *backend, const char *uid)
-{
-	CalBackendPrivate *priv;
-	iCalObject *ico;
-
-	priv = backend->priv;
-	ico = g_hash_table_lookup (priv->object_hash, uid);
-
-	return ico;
-}
-
-/* Ensures that an iCalObject has a unique identifier.  If it doesn't have one,
- * it will create one for it.  Returns whether an UID was created or not.
- */
-static gboolean
-ensure_uid (iCalObject *ico)
-{
-	char *buf;
-	gulong str_time;
-	static guint seqno = 0;
-
-	if (ico->uid){
-		return FALSE;
-	}
-
-	str_time = (gulong) time (NULL);
-
-	/* Is this good enough? */
-
-	buf = g_strdup_printf ("Evolution-Tlacuache-%d-%ld-%u",
-			       (int) getpid(), str_time, seqno++);
-	ico->uid = buf;
-	return TRUE;
-}
-
-/* Adds an object to the calendar backend.  Does *not* perform notification to
- * calendar clients.
- */
-static void
-add_object (CalBackend *backend, iCalObject *ico)
-{
-	CalBackendPrivate *priv;
-
-	g_assert (ico != NULL);
-	priv = backend->priv;
-
-#if 0
-	/* FIXME: gnomecal old code */
-	ico->new = 0;
-#endif
-
-	if (ensure_uid (ico))
-		/* FIXME: mark the calendar as dirty so that we can re-save it
-		 * with the object's new UID.
-		 */
-		;
-
-	g_hash_table_insert (priv->object_hash, ico->uid, ico);
-
-	priv->dirty = TRUE;
-
-	switch (ico->type) {
-	case ICAL_EVENT:
-		priv->events = g_list_prepend (priv->events, ico);
-#if 0
-		/* FIXME: gnomecal old code */
-		ical_object_try_alarms (ico);
-#  ifdef DEBUGGING_MAIL_ALARM
-		ico->malarm.trigger = 0;
-		calendar_notify (0, ico);
-#  endif
-#endif
-		break;
-
-	case ICAL_TODO:
-		priv->todos = g_list_prepend (priv->todos, ico);
-		break;
-
-	case ICAL_JOURNAL:
-		priv->journals = g_list_prepend (priv->journals, ico);
-		break;
-
-	default:
-		g_assert_not_reached ();
-	}
-
-#if 0
-	/* FIXME: gnomecal old code */
-	ico->last_mod = time (NULL);
-#endif
-}
-
-/* Removes an object from the backend's hash and lists.  Does not perform
- * notification on the clients.
- */
-static void
-remove_object (CalBackend *backend, iCalObject *ico)
-{
-	CalBackendPrivate *priv;
-	GList **list, *l;
-
-	priv = backend->priv;
-
-	g_assert (ico->uid != NULL);
-	g_hash_table_remove (priv->object_hash, ico->uid);
-
-	priv->dirty = TRUE;
-
-	switch (ico->type) {
-	case ICAL_EVENT:
-		list = &priv->events;
-		break;
-
-	case ICAL_TODO:
-		list = &priv->todos;
-		break;
-
-	case ICAL_JOURNAL:
-		list = &priv->journals;
-		break;
-
-	default:
-		list = NULL;
-	}
-
-	if (!list){
-		return;
-	}
-
-	l = g_list_find (*list, ico);
-	g_assert (l != NULL);
-
-	*list = g_list_remove_link (*list, l);
-	g_list_free_1 (l);
-
-	ical_object_destroy (ico);
-}
-
-/* Load a calendar from a VObject */
-static void
-load_from_vobject (CalBackend *backend, VObject *vobject)
-{
-	CalBackendPrivate *priv;
-	VObjectIterator i;
-
-	priv = backend->priv;
-
-	g_assert (!priv->loaded);
-	g_assert (priv->object_hash == NULL);
-	priv->object_hash = g_hash_table_new (g_str_hash, g_str_equal);
-
-	initPropIterator (&i, vobject);
-
-	while (moreIteration (&i)) {
-		VObject *this;
-		iCalObject *ical;
-		const char *object_name;
-
-		this = nextVObject (&i);
-		object_name = vObjectName (this);
-#if 0
-		/* FIXME?  What is this used for in gnomecal? */
-		if (strcmp (object_name, VCDCreatedProp) == 0) {
-			cal->created = time_from_isodate (str_val (this));
-			continue;
-		}
-#endif
-		if (strcmp (object_name, VCLocationProp) == 0)
-			continue; /* FIXME: imlement */
-
-		if (strcmp (object_name, VCProdIdProp) == 0)
-			continue; /* FIXME: implement */
-
-		if (strcmp (object_name, VCVersionProp) == 0)
-			continue; /* FIXME: implement */
-
-		if (strcmp (object_name, VCTimeZoneProp) == 0)
-			continue; /* FIXME: implement */
-
-		ical = ical_object_create_from_vobject (this, object_name);
-
-		/* FIXME: some broken files may have duplicated UIDs.  This is
-		 * Bad(tm).  Deal with it by creating new UIDs for them and
-		 * spitting some messages to the console.
-		 */
-
-		if (ical)
-			add_object (backend, ical);
-	}
 }
 
 
 
 /**
- * cal_backend_new:
- * @void:
- *
- * Creates a new empty calendar backend.  A calendar must then be loaded or
- * created before the backend can be used.
- *
- * Return value: A newly-created calendar backend.
- **/
-CalBackend *
-cal_backend_new (void)
-{
-	return CAL_BACKEND (gtk_type_new (CAL_BACKEND_TYPE));
-}
-
-/**
  * cal_backend_get_uri:
  * @backend: A calendar backend.
  *
@@ -525,54 +112,11 @@ cal_backend_new (void)
 GnomeVFSURI *
 cal_backend_get_uri (CalBackend *backend)
 {
-	CalBackendPrivate *priv;
-
 	g_return_val_if_fail (backend != NULL, NULL);
 	g_return_val_if_fail (IS_CAL_BACKEND (backend), NULL);
 
-	priv = backend->priv;
-	g_return_val_if_fail (priv->loaded, 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;
-	CalBackend *backend;
-	CalBackendPrivate *priv;
-	GList *l;
-
-	cal = CAL (object);
-
-	backend = CAL_BACKEND (data);
-	priv = backend->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)
-		gtk_signal_emit (GTK_OBJECT (backend), cal_backend_signals[LAST_CLIENT_GONE]);
+	g_assert (CLASS (backend)->get_uri != NULL);
+	return (* CLASS (backend)->get_uri) (backend);
 }
 
 /**
@@ -586,143 +130,13 @@ cal_destroy_cb (GtkObject *object, gpointer data)
 void
 cal_backend_add_cal (CalBackend *backend, Cal *cal)
 {
-	CalBackendPrivate *priv;
-
 	g_return_if_fail (backend != NULL);
 	g_return_if_fail (IS_CAL_BACKEND (backend));
 
-	priv = backend->priv;
-	g_return_if_fail (priv->loaded);
-
-	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);
-}
-
-
-static icalcomponent* 
-icalendar_parse_file (char* fname)
-{
-	FILE* fp;
-	icalcomponent* comp = NULL;
-	gchar* str;
-	struct stat st;
-	int n;
-
-	fp = fopen (fname, "r");
-	if (!fp) {
-		g_warning ("Cannot open open calendar file.");
-		return NULL;
-	}
-	
-	stat (fname, &st);
-	
-	str = g_malloc (st.st_size + 2);
-	
-	n = fread ((gchar*) str, 1, st.st_size, fp);
-	if (n != st.st_size) {
-		g_warning ("Read error.");
-	}
-	str[n] = '\0';
-
-	fclose (fp);
-	
-	comp = icalparser_parse_string (str);
-	g_free (str);
-
-	return comp;
-}
-
-
-static void
-icalendar_calendar_load (CalBackend * cal, char* fname)
-{
-	CalBackendPrivate *priv;
-	icalcomponent *comp;
-	icalcomponent *subcomp;
-	iCalObject    *ical;
-
-	g_assert (cal);
-
-	priv = cal->priv;
-
-	g_assert (!priv->loaded);
-	g_assert (priv->object_hash == NULL);
-
-	priv->object_hash = g_hash_table_new (g_str_hash, g_str_equal);
-
-	comp = icalendar_parse_file (fname);
-	subcomp = icalcomponent_get_first_component (comp,
-						     ICAL_ANY_COMPONENT);
-	while (subcomp) {
-		ical = ical_object_create_from_icalcomponent (subcomp);
-		if (ical->type != ICAL_EVENT && 
-		    ical->type != ICAL_TODO  &&
-		    ical->type != ICAL_JOURNAL) {
-		       g_warning ("Skipping unsupported iCalendar component.");
-		} else
-			add_object (cal, ical);
-		subcomp = icalcomponent_get_next_component (comp,
-							   ICAL_ANY_COMPONENT);
-	}
+	g_assert (CLASS (backend)->add_cal != NULL);
+	return (* CLASS (backend)->add_cal) (backend, cal);
 }
 
-
-/*
-ics is to be used to designate a file containing (an arbitrary set of)
-calendaring and scheduling information.
-
-ifb is to be used to designate a file containing free or busy time
-information.
-
-anything else is assumed to be a vcal file.
-*/
-
-static CalendarFormat
-cal_get_type_from_filename (char *str_uri)
-{
-	int len;
-
-	if (str_uri == NULL)
-		return CAL_VCAL;
-
-	len = strlen (str_uri);
-	if (len < 4)
-		return CAL_VCAL;
-
-	if (str_uri[ len-4 ] == '.' && str_uri[ len-3 ] == 'i' &&
-	    str_uri[ len-2 ] == 'c' && str_uri[ len-1 ] == 's')
-		return CAL_ICAL;
-
-	if (str_uri[ len-4 ] == '.' && str_uri[ len-3 ] == 'i' &&
-	    str_uri[ len-2 ] == 'f' && str_uri[ len-1 ] == 'b')
-		return CAL_ICAL;
-
-	if (str_uri[ len-4 ] == '.' && str_uri[ len-3 ] == 'i' &&
-	    str_uri[ len-2 ] == 'c' && str_uri[ len-1 ] == 's')
-		return CAL_ICAL;
-
-	if (len < 5)
-		return CAL_VCAL;
-
-	if (str_uri[ len-5 ] == '.' && str_uri[ len-4 ] == 'i' &&
-	    str_uri[ len-3 ] == 'c' && str_uri[ len-2 ] == 'a' &&
-	    str_uri[ len-1 ] == 'l')
-		return CAL_ICAL;
-
-	return CAL_VCAL;
-}
-
-
 /**
  * cal_backend_load:
  * @backend: A calendar backend.
@@ -736,66 +150,12 @@ cal_get_type_from_filename (char *str_uri)
 CalBackendLoadStatus
 cal_backend_load (CalBackend *backend, GnomeVFSURI *uri)
 {
-	CalBackendPrivate *priv;
-	VObject *vobject;
-	char *str_uri;
-
 	g_return_val_if_fail (backend != NULL, CAL_BACKEND_LOAD_ERROR);
-	g_return_val_if_fail (IS_CAL_BACKEND (backend),CAL_BACKEND_LOAD_ERROR);
-
-	priv = backend->priv;
-	g_return_val_if_fail (!priv->loaded, CAL_BACKEND_LOAD_ERROR);
-
+	g_return_val_if_fail (IS_CAL_BACKEND (backend), 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));
-
-
-	/* look at the extension on the filename and decide
-	   if this is a ical or vcal file */
-
-	priv->format = cal_get_type_from_filename (str_uri);
-
-	/* load */
-
-	switch (priv->format) {
-	case CAL_VCAL:
-	        vobject = Parse_MIME_FromFileName (str_uri);
-	
-		if (!vobject){
-			g_free (str_uri);
-			return CAL_BACKEND_LOAD_ERROR;
-		}
-	
-		load_from_vobject (backend, vobject);
-		cleanVObject (vobject);
-		cleanStrTbl ();
-		break;
-	case CAL_ICAL:
-		icalendar_calendar_load (backend, str_uri);
-		break;
-	default:
-		g_free (str_uri);
-	        return CAL_BACKEND_LOAD_ERROR;
-	}
-
-	g_free (str_uri);
-
-	gnome_vfs_uri_ref (uri);
-
-	priv->uri = uri;
-	priv->loaded = TRUE;
-
-	return CAL_BACKEND_LOAD_SUCCESS;
+	g_assert (CLASS (backend)->load != NULL);
+	return (* CLASS (backend)->load) (backend, uri);
 }
 
 /**
@@ -808,31 +168,12 @@ cal_backend_load (CalBackend *backend, GnomeVFSURI *uri)
 void
 cal_backend_create (CalBackend *backend, GnomeVFSURI *uri)
 {
-	CalBackendPrivate *priv;
-
 	g_return_if_fail (backend != NULL);
 	g_return_if_fail (IS_CAL_BACKEND (backend));
-
-	priv = backend->priv;
-	g_return_if_fail (!priv->loaded);
-
 	g_return_if_fail (uri != NULL);
 
-	/* Create the new calendar information */
-
-	g_assert (priv->object_hash == NULL);
-	priv->object_hash = g_hash_table_new (g_str_hash, g_str_equal);
-
-	priv->dirty = TRUE;
-
-	/* Done */
-
-	gnome_vfs_uri_ref (uri);
-
-	priv->uri = uri;
-	priv->loaded = TRUE;
-
-	save (backend);
+	g_assert (CLASS (backend)->create != NULL);
+	(* CLASS (backend)->create) (backend, uri);
 }
 
 /**
@@ -850,66 +191,12 @@ cal_backend_create (CalBackend *backend, GnomeVFSURI *uri)
 char *
 cal_backend_get_object (CalBackend *backend, const char *uid)
 {
-	CalBackendPrivate *priv;
-	iCalObject *ico;
-	char *buf;
-
 	g_return_val_if_fail (backend != NULL, NULL);
 	g_return_val_if_fail (IS_CAL_BACKEND (backend), NULL);
-
-	priv = backend->priv;
-	g_return_val_if_fail (priv->loaded, NULL);
-
 	g_return_val_if_fail (uid != NULL, NULL);
 
-	g_assert (priv->object_hash != NULL);
-
-	ico = lookup_object (backend, uid);
-
-	if (!ico){
-		return NULL;
-	}
-
-	buf = ical_object_to_string (ico);
-
-	return buf;
-}
-
-struct get_uids_closure {
-	CalObjType type;
-	GList *uid_list;
-};
-
-/* Builds a list of UIDs for objects that match the sought type.  Called from
- * g_hash_table_foreach().
- */
-static void
-build_uids_list (gpointer key, gpointer value, gpointer data)
-{
-	iCalObject *ico;
-	struct get_uids_closure *c;
-	gboolean store;
-
-	ico = value;
-	c = data;
-
-	store = FALSE;
-
-	/*
-	if (c->type & CALOBJ_TYPE_ANY)
-		store = TRUE;
-	else */
-	if (ico->type == ICAL_EVENT)
-		store = (c->type & CALOBJ_TYPE_EVENT) ? TRUE : FALSE;
-	else if (ico->type == ICAL_TODO)
-		store = (c->type & CALOBJ_TYPE_TODO) ? TRUE : FALSE;
-	else if (ico->type == ICAL_JOURNAL)
-		store = (c->type & CALOBJ_TYPE_JOURNAL) ? TRUE : FALSE;
-	else
-		store = (c->type & CALOBJ_TYPE_OTHER) ? TRUE : FALSE;
-
-	if (store)
-		c->uid_list = g_list_prepend (c->uid_list, g_strdup (ico->uid));
+	g_assert (CLASS (backend)->get_object != NULL);
+	return (* CLASS (backend)->get_object) (backend, uid);
 }
 
 /**
@@ -925,68 +212,11 @@ build_uids_list (gpointer key, gpointer value, gpointer data)
 GList *
 cal_backend_get_uids (CalBackend *backend, CalObjType type)
 {
-	CalBackendPrivate *priv;
-	struct get_uids_closure c;
-
 	g_return_val_if_fail (backend != NULL, NULL);
 	g_return_val_if_fail (IS_CAL_BACKEND (backend), NULL);
 
-	priv = backend->priv;
-	g_return_val_if_fail (priv->loaded, NULL);
-
-	/* We go through the hash table instead of the lists of particular
-	 * object types so that we can pick up CALOBJ_TYPE_OTHER objects.
-	 */
-
-	c.type = type;
-	c.uid_list = NULL;
-	g_hash_table_foreach (priv->object_hash, build_uids_list, &c);
-
-	return c.uid_list;
-}
-
-struct build_event_list_closure {
-	CalBackend *backend;
-	GList *event_list;
-};
-
-/* Builds a sorted list of event object instances.  Used as a callback from
- * ical_object_generate_events().
- */
-static int
-build_event_list (iCalObject *ico, time_t start, time_t end, void *data)
-{
-	CalObjInstance *icoi;
-	struct build_event_list_closure *c;
-
-	c = data;
-
-	icoi = g_new (CalObjInstance, 1);
-
-	g_assert (ico->uid != NULL);
-	icoi->uid = g_strdup (ico->uid);
-	icoi->start = start;
-	icoi->end = end;
-
-	c->event_list = g_list_prepend (c->event_list, 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;
+	g_assert (CLASS (backend)->get_uids != NULL);
+	return (* CLASS (backend)->get_uids) (backend, type);
 }
 
 /**
@@ -1005,67 +235,13 @@ compare_instance_func (gconstpointer a, gconstpointer b)
 GList *
 cal_backend_get_events_in_range (CalBackend *backend, time_t start, time_t end)
 {
-	CalBackendPrivate *priv;
-	struct build_event_list_closure c;
-	GList *l;
-
 	g_return_val_if_fail (backend != NULL, NULL);
 	g_return_val_if_fail (IS_CAL_BACKEND (backend), NULL);
-
-	priv = backend->priv;
-	g_return_val_if_fail (priv->loaded, NULL);
-
 	g_return_val_if_fail (start != -1 && end != -1, NULL);
 	g_return_val_if_fail (start <= end, NULL);
 
-	c.backend = backend;
-	c.event_list = NULL;
-
-	for (l = priv->events; l; l = l->next) {
-		iCalObject *ico;
-
-		ico = l->data;
-		ical_object_generate_events (ico, start, end,
-					     build_event_list, &c);
-	}
-
-	c.event_list = g_list_sort (c.event_list, compare_instance_func);
-
-	return c.event_list;
-}
-
-/* Notifies a backend's clients that an object was updated */
-static void
-notify_update (CalBackend *backend, const char *uid)
-{
-	CalBackendPrivate *priv;
-	GList *l;
-
-	priv = backend->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 (CalBackend *backend, const char *uid)
-{
-	CalBackendPrivate *priv;
-	GList *l;
-
-	priv = backend->priv;
-
-	for (l = priv->clients; l; l = l->next) {
-		Cal *cal;
-
-		cal = CAL (l->data);
-		cal_notify_remove (cal, uid);
-	}
+	g_assert (CLASS (backend)->get_events_in_range != NULL);
+	return (* CLASS (backend)->get_events_in_range) (backend, start, end);
 }
 
 /**
@@ -1081,45 +257,15 @@ notify_remove (CalBackend *backend, const char *uid)
  * Return value: TRUE on success, FALSE on being passed an invalid object.
  **/
 gboolean
-cal_backend_update_object (CalBackend *backend, const char *uid,
-			   const char *calobj)
+cal_backend_update_object (CalBackend *backend, const char *uid, const char *calobj)
 {
-	CalBackendPrivate *priv;
-	iCalObject *ico, *new_ico;
-	CalObjFindStatus status;
-
 	g_return_val_if_fail (backend != NULL, FALSE);
 	g_return_val_if_fail (IS_CAL_BACKEND (backend), FALSE);
-
-	priv = backend->priv;
-	g_return_val_if_fail (priv->loaded, FALSE);
-	
 	g_return_val_if_fail (uid != NULL, FALSE);
 	g_return_val_if_fail (calobj != NULL, FALSE);
 
-	/* Pull the object from the string */
-
-	status = ical_object_find_in_string (uid, calobj, &new_ico);
-
-	if (status != CAL_OBJ_FIND_SUCCESS){
-		return FALSE;
-	}
-
-	/* Update the object */
-
-	ico = lookup_object (backend, uid);
-
-	if (ico)
-		remove_object (backend, ico);
-
-	add_object (backend, new_ico);
-	save (backend);
-
-	/* FIXME: do the notification asynchronously */
-
-	notify_update (backend, new_ico->uid);
-
-	return TRUE;
+	g_assert (CLASS (backend)->update_object != NULL);
+	return (* CLASS (backend)->update_object) (backend, uid, calobj);
 }
 
 /**
@@ -1136,29 +282,26 @@ cal_backend_update_object (CalBackend *backend, const char *uid,
 gboolean
 cal_backend_remove_object (CalBackend *backend, const char *uid)
 {
-	CalBackendPrivate *priv;
-	iCalObject *ico;
-
 	g_return_val_if_fail (backend != NULL, FALSE);
 	g_return_val_if_fail (IS_CAL_BACKEND (backend), FALSE);
-
-	priv = backend->priv;
-	g_return_val_if_fail (priv->loaded, FALSE);
-	
 	g_return_val_if_fail (uid != NULL, FALSE);
 
-	ico = lookup_object (backend, uid);
-	if (!ico){
-		return FALSE;
-	}
-
-	remove_object (backend, ico);
-
-	priv->dirty = TRUE;
-	save (backend);
+	g_assert (CLASS (backend)->remove_object != NULL);
+	return (* CLASS (backend)->remove_object) (backend, uid);
+}
 
-	/* FIXME: do the notification asynchronously */
-	notify_remove (backend, uid);
+/**
+ * cal_backend_last_client_gone:
+ * @backend: A calendar backend.
+ * 
+ * Emits the "last_client_gone" signal of a calendar backend.  This function is
+ * to be used only by backend implementations.
+ **/
+void
+cal_backend_last_client_gone (CalBackend *backend)
+{
+	g_return_if_fail (backend != NULL);
+	g_return_if_fail (IS_CAL_BACKEND (backend));
 
-	return TRUE;
+	gtk_signal_emit (GTK_OBJECT (backend), cal_backend_signals[LAST_CLIENT_GONE]);
 }
diff --git a/calendar/pcs/cal-backend.h b/calendar/pcs/cal-backend.h
index e5102bf8bc..3c9c76009b 100644
--- a/calendar/pcs/cal-backend.h
+++ b/calendar/pcs/cal-backend.h
@@ -1,4 +1,4 @@
-/* Evolution calendar backend
+/* Evolution calendar - generic backend class
  *
  * Copyright (C) 2000 Helix Code, Inc.
  *
@@ -58,21 +58,24 @@ struct _CalBackendClass {
 
 	/* Notification signals */
 	void (* last_client_gone) (CalBackend *backend);
-};
 
-typedef enum {
-	CAL_VCAL,
-	CAL_ICAL
-} CalendarFormat;
+	/* Virtual methods */
+	GnomeVFSURI *(* get_uri) (CalBackend *backend);
+	void (* add_cal) (CalBackend *backend, Cal *cal);
+	CalBackendLoadStatus (* load) (CalBackend *backend, GnomeVFSURI *uri);
+	void (* create) (CalBackend *backend, GnomeVFSURI *uri);
+	char *(* get_object) (CalBackend *backend, const char *uid);
+	GList *(* get_uids) (CalBackend *backend, CalObjType type);
+	GList *(* get_events_in_range) (CalBackend *backend, time_t start, time_t end);
+	gboolean (* update_object) (CalBackend *backend, const char *uid, const char *calobj);
+	gboolean (* remove_object) (CalBackend *backend, const char *uid);
+};
 
 GtkType cal_backend_get_type (void);
 
-CalBackend *cal_backend_new (void);
-
 GnomeVFSURI *cal_backend_get_uri (CalBackend *backend);
 
 void cal_backend_add_cal (CalBackend *backend, Cal *cal);
-void cal_backend_remove_cal (CalBackend *backend, Cal *cal);
 
 CalBackendLoadStatus cal_backend_load (CalBackend *backend, GnomeVFSURI *uri);
 
@@ -88,6 +91,8 @@ gboolean cal_backend_update_object (CalBackend *backend, const char *uid, const
 
 gboolean cal_backend_remove_object (CalBackend *backend, const char *uid);
 
+void cal_backend_last_client_gone (CalBackend *backend);
+
 
 
 END_GNOME_DECLS
diff --git a/calendar/pcs/cal-factory.c b/calendar/pcs/cal-factory.c
index 6d6c28b889..1112245184 100644
--- a/calendar/pcs/cal-factory.c
+++ b/calendar/pcs/cal-factory.c
@@ -20,6 +20,7 @@
  */
 
 #include <config.h>
+#include <ctype.h>
 #include <gtk/gtksignal.h>
 #include "cal.h"
 #include "cal-backend.h"
@@ -30,6 +31,9 @@
 
 /* Private part of the CalFactory structure */
 typedef struct {
+	/* Hash table from URI method strings to GtkType * for backend class types */
+	GHashTable *methods;
+
 	/* Hash table from GnomeVFSURI structures to CalBackend objects */
 	GHashTable *backends;
 } CalFactoryPrivate;
@@ -128,9 +132,24 @@ cal_factory_init (CalFactory *factory)
 	priv = g_new0 (CalFactoryPrivate, 1);
 	factory->priv = priv;
 
+	priv->methods = g_hash_table_new (g_str_hash, g_str_equal);
 	priv->backends = g_hash_table_new (gnome_vfs_uri_hash, gnome_vfs_uri_hequal);
 }
 
+/* Frees a method/GtkType * pair from the methods hash table */
+static void
+free_method (gpointer key, gpointer value, gpointer data)
+{
+	char *method;
+	GtkType *type;
+
+	method = key;
+	type = value;
+
+	g_free (method);
+	g_free (type);
+}
+
 /* Frees a uri/backend pair from the backends hash table */
 static void
 free_backend (gpointer key, gpointer value, gpointer data)
@@ -158,6 +177,10 @@ cal_factory_destroy (GtkObject *object)
 	factory = CAL_FACTORY (object);
 	priv = factory->priv;
 
+	g_hash_table_foreach (priv->methods, free_method, NULL);
+	g_hash_table_destroy (priv->methods);
+	priv->methods = NULL;
+
 	/* Should we assert that there are no more backends? */
 
 	g_hash_table_foreach (priv->backends, free_backend, NULL);
@@ -165,6 +188,7 @@ cal_factory_destroy (GtkObject *object)
 	priv->backends = NULL;
 
 	g_free (priv);
+	factory->priv = NULL;
 
 	if (GTK_OBJECT_CLASS (parent_class)->destroy)
 		(* GTK_OBJECT_CLASS (parent_class)->destroy) (object);
@@ -172,86 +196,57 @@ cal_factory_destroy (GtkObject *object)
 
 
 
-/* CORBA servant implementation */
+/* Loading and creating calendars */
 
-/* CalFactory::load method */
+/* Job data */
+typedef struct {
+	CalFactory *factory;
+	char *uri;
+	Evolution_Calendar_Listener listener;
+} LoadCreateJobData;
+
+/* Queues a load or create request */
 static void
-CalFactory_load (PortableServer_Servant servant,
-		 const CORBA_char *uri,
-		 Evolution_Calendar_Listener listener,
-		 CORBA_Environment *ev)
+queue_load_create_job (CalFactory *factory, const char *uri, Evolution_Calendar_Listener listener,
+		       JobFunc func)
 {
-	CalFactory *factory;
-	CalFactoryPrivate *priv;
-	CORBA_Environment ev2;
+	LoadCreateJobData *jd;
+	CORBA_Environment ev;
+	Evolution_Calendar_Listener listener_copy;
 	gboolean result;
 
-	factory = CAL_FACTORY (bonobo_object_from_servant (servant));
-	priv = factory->priv;
-
-	CORBA_exception_init (&ev2);
-	result = CORBA_Object_is_nil (listener, &ev2);
-
-	if (ev2._major != CORBA_NO_EXCEPTION || result) {
-		CORBA_exception_set (ev, CORBA_USER_EXCEPTION,
-				     ex_Evolution_Calendar_CalFactory_NilListener,
-				     NULL);
-
-		CORBA_exception_free (&ev2);
+	CORBA_exception_init (&ev);
+	result = CORBA_Object_is_nil (listener, &ev);
+	if (ev._major != CORBA_NO_EXCEPTION) {
+		g_message ("queue_load_create_job(): could not see if the listener was NIL");
+		CORBA_exception_free (&ev);
 		return;
 	}
-	CORBA_exception_free (&ev2);
-
-	cal_factory_load (factory, uri, listener);
-}
+	CORBA_exception_free (&ev);
 
-/* CalFactory::create method */
-static void
-CalFactory_create (PortableServer_Servant servant,
-		   const CORBA_char *uri,
-		   Evolution_Calendar_Listener listener,
-		   CORBA_Environment *ev)
-{
-	CalFactory *factory;
-	CalFactoryPrivate *priv;
+	if (result) {
+		g_message ("queue_load_create_job(): cannot operate on a NIL listener!");
+		return;
+	}
 
-	factory = CAL_FACTORY (bonobo_object_from_servant (servant));
-	priv = factory->priv;
+	listener_copy = CORBA_Object_duplicate (listener, &ev);
 
-	cal_factory_create (factory, uri, listener);
-}
+	if (ev._major != CORBA_NO_EXCEPTION) {
+		g_message ("queue_load_create_job(): could not duplicate the listener");
+		CORBA_exception_free (&ev);
+		return;
+	}
 
-/**
- * cal_factory_get_epv:
- * @void:
- *
- * Creates an EPV for the CalFactory CORBA class.
- *
- * Return value: A newly-allocated EPV.
- **/
-POA_Evolution_Calendar_CalFactory__epv *
-cal_factory_get_epv (void)
-{
-	POA_Evolution_Calendar_CalFactory__epv *epv;
+	CORBA_exception_free (&ev);
 
-	epv = g_new0 (POA_Evolution_Calendar_CalFactory__epv, 1);
-	epv->load = CalFactory_load;
-	epv->create = CalFactory_create;
+	jd = g_new (LoadCreateJobData, 1);
+	jd->factory = factory;
+	jd->uri = g_strdup (uri);
+	jd->listener = listener_copy;
 
-	return epv;
+	job_add (func, jd);
 }
 
-
-
-/* Loading and creating calendars */
-
-/* Job data */
-typedef struct {
-	CalFactory *factory;
-	char *uri;
-	Evolution_Calendar_Listener listener;
-} LoadCreateJobData;
-
 /* Looks up a calendar backend in a factory's hash table of uri->cal */
 static CalBackend *
 lookup_backend (CalFactory *factory, GnomeVFSURI *uri)
@@ -316,21 +311,64 @@ add_backend (CalFactory *factory, GnomeVFSURI *uri, CalBackend *backend)
 			    factory);
 }
 
+/* Tries to launch a backend for the method of the specified URI.  If there is
+ * no such method registered in the factory, it sends the listener the
+ * MethodNotSupported error code.
+ */
+static CalBackend *
+launch_backend_for_uri (CalFactory *factory, GnomeVFSURI *uri, Evolution_Calendar_Listener listener)
+{
+	CalFactoryPrivate *priv;
+	char *method;
+	GtkType *type;
+	CalBackend *backend;
+
+	priv = factory->priv;
+
+	/* FIXME: add an accessor function to gnome-vfs */
+	method = uri->method_string;
+
+	type = g_hash_table_lookup (priv->methods, method);
+	g_free (method);
+
+	if (!type) {
+		CORBA_Environment ev;
+
+		CORBA_exception_init (&ev);
+		Evolution_Calendar_Listener_cal_loaded (
+			listener,
+			Evolution_Calendar_Listener_METHOD_NOT_SUPPORTED,
+			CORBA_OBJECT_NIL,
+			&ev);
+
+		if (ev._major != CORBA_NO_EXCEPTION)
+			g_message ("launch_backend_for_uri(): could not notify the listener");
+
+		CORBA_exception_free (&ev);
+		return NULL;
+	}
+
+	backend = gtk_type_new (*type);
+	if (!backend)
+		g_message ("launch_backend_for_uri(): could not launch the backend");
+
+	return backend;
+}
+
 /* Loads a calendar backend and puts it in the factory's backend hash table */
 static CalBackend *
-load_backend (CalFactory *factory, GnomeVFSURI *uri)
+load_backend (CalFactory *factory, GnomeVFSURI *uri, Evolution_Calendar_Listener listener)
 {
 	CalFactoryPrivate *priv;
 	CalBackend *backend;
 	CalBackendLoadStatus status;
+	CORBA_Environment ev;
 
 	priv = factory->priv;
 
-	backend = cal_backend_new ();
-	if (!backend) {
-		g_message ("load_backend(): could not create the backend");
+	backend = launch_backend_for_uri (factory, uri, listener);
+	if (!backend)
 		return NULL;
-	}
 
 	status = cal_backend_load (backend, uri);
 
@@ -341,6 +379,17 @@ load_backend (CalFactory *factory, GnomeVFSURI *uri)
 
 	case CAL_BACKEND_LOAD_ERROR:
 		gtk_object_unref (GTK_OBJECT (backend));
+
+		CORBA_exception_init (&ev);
+		Evolution_Calendar_Listener_cal_loaded (listener,
+							Evolution_Calendar_Listener_ERROR,
+							CORBA_OBJECT_NIL,
+							&ev);
+
+		if (ev._major != CORBA_NO_EXCEPTION)
+			g_message ("load_backend(): could not notify the listener");
+
+		CORBA_exception_free (&ev);
 		return NULL;
 
 	default:
@@ -351,20 +400,37 @@ load_backend (CalFactory *factory, GnomeVFSURI *uri)
 
 /* Creates a calendar backend and puts it in the factory's backend hash table */
 static CalBackend *
-create_backend (CalFactory *factory, GnomeVFSURI *uri)
+create_backend (CalFactory *factory, GnomeVFSURI *uri, Evolution_Calendar_Listener listener)
 {
 	CalFactoryPrivate *priv;
 	CalBackend *backend;
 
 	priv = factory->priv;
 
-	backend = cal_backend_new ();
-	if (!backend) {
-		g_message ("create_backend(): could not create the backend");
+	backend = launch_backend_for_uri (factory, uri, listener);
+	if (!backend)
 		return NULL;
-	}
 
 	cal_backend_create (backend, uri);
+
+	/* FIXME: add error reporting to cal_backend_create() */
+#if 0
+	{
+		CORBA_Environment ev;
+
+		CORBA_exception_init (&ev);
+		Evolution_Calendar_Listener_cal_loaded (listener,
+							Evolution_Calendar_Listener_ERROR,
+							CORBA_OBJECT_NIL,
+							&ev);
+
+		if (ev._major != CORBA_NO_EXCEPTION)
+			g_message ("create_fn(): could not notify the listener");
+
+		CORBA_exception_free (&ev);
+	}
+#endif
+
 	add_backend (factory, uri, backend);
 
 	return backend;
@@ -438,21 +504,10 @@ load_fn (gpointer data)
 	backend = lookup_backend (factory, uri);
 
 	if (!backend)
-		backend = load_backend (factory, uri);
-
-	if (!backend) {
-		CORBA_exception_init (&ev);
-		Evolution_Calendar_Listener_cal_loaded (listener,
-							Evolution_Calendar_Listener_ERROR,
-							CORBA_OBJECT_NIL,
-							&ev);
+		backend = load_backend (factory, uri, listener);
 
-		if (ev._major != CORBA_NO_EXCEPTION)
-			g_message ("load_fn(): could not notify the listener");
-
-		CORBA_exception_free (&ev);
+	if (!backend)
 		goto out;
-	}
 
 	add_calendar_client (factory, backend, listener);
 
@@ -510,21 +565,10 @@ create_fn (gpointer data)
 
 	/* Create the backend */
 
-	backend = create_backend (factory, uri);
+	backend = create_backend (factory, uri, listener);
 
-	if (!backend) {
-		CORBA_exception_init (&ev);
-		Evolution_Calendar_Listener_cal_loaded (listener,
-							Evolution_Calendar_Listener_ERROR,
-							CORBA_OBJECT_NIL,
-							&ev);
-
-		if (ev._major != CORBA_NO_EXCEPTION)
-			g_message ("create_fn(): could not notify the listener");
-
-		CORBA_exception_free (&ev);
+	if (!backend)
 		goto out;
-	}
 
 	add_calendar_client (factory, backend, listener);
 
@@ -543,6 +587,77 @@ create_fn (gpointer data)
 
 
 
+/* CORBA servant implementation */
+
+/* CalFactory::load method */
+static void
+CalFactory_load (PortableServer_Servant servant,
+		 const CORBA_char *uri,
+		 Evolution_Calendar_Listener listener,
+		 CORBA_Environment *ev)
+{
+	CalFactory *factory;
+	CalFactoryPrivate *priv;
+	CORBA_Environment ev2;
+	gboolean result;
+
+	factory = CAL_FACTORY (bonobo_object_from_servant (servant));
+	priv = factory->priv;
+
+	CORBA_exception_init (&ev2);
+	result = CORBA_Object_is_nil (listener, &ev2);
+
+	if (ev2._major != CORBA_NO_EXCEPTION || result) {
+		CORBA_exception_set (ev, CORBA_USER_EXCEPTION,
+				     ex_Evolution_Calendar_CalFactory_NilListener,
+				     NULL);
+
+		CORBA_exception_free (&ev2);
+		return;
+	}
+	CORBA_exception_free (&ev2);
+
+	queue_load_create_job (factory, uri, listener, load_fn);
+}
+
+/* CalFactory::create method */
+static void
+CalFactory_create (PortableServer_Servant servant,
+		   const CORBA_char *uri,
+		   Evolution_Calendar_Listener listener,
+		   CORBA_Environment *ev)
+{
+	CalFactory *factory;
+	CalFactoryPrivate *priv;
+
+	factory = CAL_FACTORY (bonobo_object_from_servant (servant));
+	priv = factory->priv;
+
+	queue_load_create_job (factory, uri, listener, create_fn);
+}
+
+/**
+ * cal_factory_get_epv:
+ * @void:
+ *
+ * Creates an EPV for the CalFactory CORBA class.
+ *
+ * Return value: A newly-allocated EPV.
+ **/
+POA_Evolution_Calendar_CalFactory__epv *
+cal_factory_get_epv (void)
+{
+	POA_Evolution_Calendar_CalFactory__epv *epv;
+
+	epv = g_new0 (POA_Evolution_Calendar_CalFactory__epv, 1);
+	epv->load = CalFactory_load;
+	epv->create = CalFactory_create;
+
+	return epv;
+}
+
+
+
 /**
  * cal_factory_construct:
  * @factory: A calendar factory.
@@ -634,78 +749,61 @@ cal_factory_new (void)
 	return cal_factory_construct (factory, corba_factory);
 }
 
-/* Queues a load or create request */
-static void
-queue_load_create_job (CalFactory *factory, const char *uri, Evolution_Calendar_Listener listener,
-		       JobFunc func)
+/* Returns the lowercase version of a string */
+static char *
+str_tolower (const char *s)
 {
-	LoadCreateJobData *jd;
-	CORBA_Environment ev;
-	Evolution_Calendar_Listener listener_copy;
-	gboolean result;
+	char *str;
+	char *p;
 
-	CORBA_exception_init (&ev);
-	result = CORBA_Object_is_nil (listener, &ev);
-	if (ev._major != CORBA_NO_EXCEPTION) {
-		g_message ("queue_load_create_job(): could not see if the listener was NIL");
-		CORBA_exception_free (&ev);
-		return;
-	}
-	CORBA_exception_free (&ev);
+	str = g_strdup (s);
+	for (p = str; *p; p++)
+		if (isalpha (*p))
+			*p = tolower (*p);
 
-	if (result) {
-		g_message ("queue_load_create_job(): cannot operate on a NIL listener!");
-		return;
-	}
-
-	listener_copy = CORBA_Object_duplicate (listener, &ev);
-
-	if (ev._major != CORBA_NO_EXCEPTION) {
-		g_message ("queue_load_create_job(): could not duplicate the listener");
-		CORBA_exception_free (&ev);
-		return;
-	}
-
-	CORBA_exception_free (&ev);
-
-	jd = g_new (LoadCreateJobData, 1);
-	jd->factory = factory;
-	jd->uri = g_strdup (uri);
-	jd->listener = listener_copy;
-
-	job_add (func, jd);
-}
-
-/**
- * cal_factory_load:
- * @factory: A calendar factory.
- * @uri: URI of calendar to load.
- * @listener: Listener for notification of the load result.
- *
- * Initiates a load request in a calendar factory.  A calendar will be loaded
- * asynchronously and the result code will be reported to the specified
- * listener.
- **/
-void
-cal_factory_load (CalFactory *factory, const char *uri, Evolution_Calendar_Listener listener)
-{
-	queue_load_create_job (factory, uri, listener, load_fn);
+	return str;
 }
 
 /**
- * cal_factory_create:
+ * cal_factory_register_method:
  * @factory: A calendar factory.
- * @uri: URI of calendar to create.
- * @listener: Listener for notification of the create result.
+ * @method: Method for the URI, i.e. "http", "file", etc.
+ * @backend_type: Class type of the backend to create for this @method.
  * 
- * Initiates a create request in a calendar factory.  A calendar will be created
- * asynchronously and the result code will be reported to the specified
- * listener.
+ * Registers the type of a #CalBackend subclass that will be used to handle URIs
+ * with a particular method.  When the factory is asked to load a particular
+ * URI, it will look in its list of registered methods and create a backend of
+ * the appropriate type.
  **/
 void
-cal_factory_create (CalFactory *factory, const char *uri, Evolution_Calendar_Listener listener)
+cal_factory_register_method (CalFactory *factory, const char *method, GtkType backend_type)
 {
-	queue_load_create_job (factory, uri, listener, create_fn);
+	CalFactoryPrivate *priv;
+	GtkType *type;
+	char *method_str;
+
+	g_return_if_fail (factory != NULL);
+	g_return_if_fail (IS_CAL_FACTORY (factory));
+	g_return_if_fail (method != NULL);
+	g_return_if_fail (backend_type != 0);
+	g_return_if_fail (gtk_type_is_a (backend_type, CAL_BACKEND_TYPE));
+
+	priv = factory->priv;
+
+	method_str = str_tolower (method);
+
+	type = g_hash_table_lookup (priv->methods, method_str);
+	if (type) {
+		g_message ("cal_factory_register_method(): Method `%s' already registered!",
+			   method_str);
+		g_free (method_str);
+		return;
+	}
+
+	type = g_new (GtkType, 1);
+	*type = backend_type;
+
+	g_hash_table_insert (priv->methods, method_str, type);
 }
 
 /**
diff --git a/calendar/pcs/cal-factory.h b/calendar/pcs/cal-factory.h
index 03b2cc8dc3..f96ba4ba92 100644
--- a/calendar/pcs/cal-factory.h
+++ b/calendar/pcs/cal-factory.h
@@ -62,8 +62,7 @@ Evolution_Calendar_CalFactory cal_factory_corba_object_create (BonoboObject *obj
 
 CalFactory *cal_factory_new (void);
 
-void cal_factory_load (CalFactory *factory, const char *uri, Evolution_Calendar_Listener listener);
-void cal_factory_create (CalFactory *factory, const char *uri, Evolution_Calendar_Listener listener);
+void cal_factory_register_method (CalFactory *factory, const char *method, GtkType backend_type);
 
 int cal_factory_get_n_backends (CalFactory *factory);