path: root/calendar/pcs/cal-backend.c

/* Evolution calendar 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-backend.h"
#include "calobj.h"
#include "../libversit/vcc.h"



/* VCalendar product ID */
#define PRODID "-//Helix Code//NONSGML Tlacuache//EN"



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

    /* 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;
} CalBackendPrivate;



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;



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

    if (!cal_backend_type) {
        static const GtkTypeInfo cal_backend_info = {
            "CalBackend",
            sizeof (CalBackend),
            sizeof (CalBackendClass),
            (GtkClassInitFunc) cal_backend_class_init,
            (GtkObjectInitFunc) cal_backend_init,
            NULL, /* reserved_1 */
            NULL, /* reserved_2 */
            (GtkClassInitFunc) NULL
        };

        cal_backend_type = gtk_type_unique (GTK_TYPE_OBJECT, &cal_backend_info);
    }

    return cal_backend_type;
}

/* Class initialization function for the calendar backend */
static void
cal_backend_class_init (CalBackendClass *class)
{
    GtkObjectClass *object_class;

    object_class = (GtkObjectClass *) class;

    parent_class = gtk_type_class (GTK_TYPE_OBJECT);

    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;
}

/* Saves a calendar */
static void
save (CalBackend *backend)
{
    /* FIXME */
}

/* 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);

    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);

    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);
    }
}

/* Creates a VObject with the base information of a calendar */
static VObject *
get_calendar_base_vobject (CalBackend *backend)
{
    VObject *vobj;
    time_t now;
    struct tm tm;

    /* We call localtime for the side effect of setting tzname */

    now = time (NULL);
    tm = *localtime (&now);

    vobj = newVObject (VCCalProp);

    addPropValue (vobj, VCProdIdProp, PRODID);

#if defined (HAVE_TM_ZONE)
    addPropValue (vobj, VCTimeZoneProp, tm.tm_zone);
#elif defined (HAVE_TZNAME)
    addPropValue (vobj, VCTimeZoneProp, tzname[0]);
#endif

    /* Per the vCalendar spec, this must be "1.0" */
    addPropValue (vobj, VCVersionProp, "1.0");

    return vobj;
}

/* Builds the string representation of a complete calendar object wrapping the
 * specified object --- a complete calendar is needed because of the timezone
 * information.  The return value must be freed with free(), not g_free(), since
 * the internal implementation calls writeMemVObject() from libversit, which
 * uses realloc() to allocate this string.
 */
static char *
string_from_ical_object (CalBackend *backend, iCalObject *ico)
{
    VObject *vcalobj, *vobj;
    char *buf;

    vcalobj = get_calendar_base_vobject (backend);
    vobj = ical_object_to_vobject (ico);
    addVObjectProp (vcalobj, vobj);

    buf = writeMemVObject (NULL, NULL, vcalobj);

    cleanVObject (vcalobj);
    cleanStrTbl ();

    return buf;
}



/**
 * 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.
 *
 * Queries the URI of a calendar backend, which must already have a loaded
 * calendar.
 *
 * Return value: The URI where the calendar is stored.
 **/
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, the backend can go away, too.  Commit
         * suicide here.
     */

    if (!priv->clients)
        gtk_object_unref (GTK_OBJECT (backend));
}

/**
 * cal_backend_add_cal:
 * @backend: A calendar backend.
 * @cal: A calendar client interface object.
 *
 * Adds a calendar client interface object to a calendar @backend.  The calendar
 * backend must already have a loaded calendar.
 **/
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);
}

/**
 * cal_backend_load:
 * @backend: A calendar backend.
 * @uri: URI that contains the calendar data.
 *
 * Loads a calendar backend with data from a calendar stored at the specified
 * URI.
 *
 * Return value: An operation status code.
 **/
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 (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));

    vobject = Parse_MIME_FromFileName (str_uri);
    g_free (str_uri);

    if (!vobject)
        return CAL_BACKEND_LOAD_ERROR;

    load_from_vobject (backend, vobject);
    cleanVObject (vobject);
    cleanStrTbl ();

    gnome_vfs_uri_ref (uri);

    priv->uri = uri;
    priv->loaded = TRUE;
    return CAL_BACKEND_LOAD_SUCCESS;
}

/**
 * cal_backend_create:
 * @backend: A calendar backend.
 * @uri: URI that will contain the calendar data.
 *
 * Creates a new empty calendar in a calendar backend.
 **/
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);

    /* Done */

    gnome_vfs_uri_ref (uri);

    priv->uri = uri;
    priv->loaded = TRUE;
}

/**
 * cal_backend_get_object:
 * @backend: A calendar backend.
 * @uid: Unique identifier for a calendar object.
 *
 * Queries a calendar backend for a calendar object based on its unique
 * identifier.
 *
 * Return value: The string representation of a complete calendar wrapping the
 * the sought object, or NULL if no object had the specified UID.  A complete
 * calendar is returned because you also need the timezone data.
 **/
char *
cal_backend_get_object (CalBackend *backend, const char *uid)
{
    CalBackendPrivate *priv;
    iCalObject *ico;
    char *buf, *retval;

    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;

    /* string_from_ical_object() uses writeMemVObject(), which uses
     * realloc(), so we must free its result with free() instead of
     * g_free().  We take a copy of the result so that callers can use the
     * normal glib function to free it.
     */

    buf = string_from_ical_object (backend, ico);
    retval = g_strdup (buf);
    free (buf);

    return retval;
}

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));
}

/**
 * cal_backend_get_uids:
 * @backend: A calendar backend.
 * @type: Bitmask with types of objects to return.
 *
 * Builds a list of unique identifiers corresponding to calendar objects whose
 * type matches one of the types specified in the @type flags.
 *
 * Return value: A list of strings that are the sought UIDs.
 **/
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->calobj = string_from_ical_object (c->backend, ico);
    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;
}

/**
 * cal_backend_get_events_in_range:
 * @backend: A calendar backend.
 * @start: Start time for query.
 * @end: End time for query.
 *
 * Builds a sorted list of calendar event object instances that occur or recur
 * within the specified time range.  Each object instance contains the object
 * itself and the start/end times at which it occurs or recurs.
 *
 * Return value: A list of calendar event object instances, sorted by their
 * start times.
 **/
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);
    }
}

/**
 * cal_backend_update_object:
 * @backend: A calendar backend.
 * @uid: Unique identifier of the object to update.
 * @calobj: String representation of the new calendar object.
 * 
 * Updates an object in a calendar backend.  It will replace any existing 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.
 **/
gboolean
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);

    notify_update (backend, new_ico->uid);
    return TRUE;
}

void
cal_backend_remove_object (CalBackend *backend, const char *uid)
{
    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 (uid != NULL);

    /* FIXME */
}