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

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/* Evolution calendar - generic backend class
 *
 * Copyright (C) 2000 Helix Code, Inc.
 *
 * Authors: Federico Mena-Quintero <federico@helixcode.com>
 *          JP Rosevear <jpr@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/gtk.h>
#include <gnome-xml/parser.h>
#include <gnome-xml/parserInternals.h>
#include <gnome-xml/xmlmemory.h>

#include "cal-backend.h"
#include "libversit/vcc.h"



/* Signal IDs */
enum {
    LAST_CLIENT_GONE,
    LAST_SIGNAL
};

static void cal_backend_class_init (CalBackendClass *class);
static void cal_backend_init (CalBackend *backend);
static void cal_backend_destroy (GtkObject *object);
static gboolean cal_backend_log_sync (CalBackend *backend);
static GHashTable *cal_backend_get_log_entries (CalBackend *backend, 
                        CalObjType type,
                        time_t since);

static GtkObjectClass *parent_class;

static guint cal_backend_signals[LAST_SIGNAL];

#define CLASS(backend) (CAL_BACKEND_CLASS (GTK_OBJECT (backend)->klass))



/**
 * 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;

    cal_backend_signals[LAST_CLIENT_GONE] =
        gtk_signal_new ("last_client_gone",
                GTK_RUN_FIRST,
                object_class->type,
                GTK_SIGNAL_OFFSET (CalBackendClass, last_client_gone),
                gtk_marshal_NONE__NONE,
                GTK_TYPE_NONE, 0);

    gtk_object_class_add_signals (object_class, cal_backend_signals, LAST_SIGNAL);
}

/* Per instance initialization function */
static void
cal_backend_init (CalBackend *backend)
{
    backend->uri = NULL;
    backend->entries = NULL;
    backend->timer = -1;
}

static void
cal_backend_destroy (GtkObject *object)
{
    CalBackend *backend;
    
    g_return_if_fail (object != NULL);
    g_return_if_fail (IS_CAL_BACKEND (object));

    backend = CAL_BACKEND (object);

    if (backend->timer != -1) {
        gtk_timeout_remove (backend->timer);
        backend->timer = -1;
    }

    if (backend->uri) {
        cal_backend_log_sync (backend);
        gnome_vfs_uri_unref (backend->uri);
    }
    
    if (GTK_OBJECT_CLASS (parent_class)->destroy)
        (* GTK_OBJECT_CLASS (parent_class)->destroy) (object);
}



/**
 * 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)
{
    g_return_val_if_fail (backend != NULL, NULL);
    g_return_val_if_fail (IS_CAL_BACKEND (backend), NULL);

    g_assert (CLASS (backend)->get_uri != NULL);
    return (* CLASS (backend)->get_uri) (backend);
}

static void
cal_backend_set_uri (CalBackend *backend, GnomeVFSURI *uri)
{
    if (backend->uri)
        gnome_vfs_uri_unref (backend->uri);

    if (backend->timer != -1)
        gtk_timeout_remove (backend->timer);


    gnome_vfs_uri_ref (uri);
    backend->uri = uri;
    backend->timer = gtk_timeout_add (60000, 
                      (GtkFunction)cal_backend_log_sync, 
                      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)
{
    g_return_if_fail (backend != NULL);
    g_return_if_fail (IS_CAL_BACKEND (backend));

    g_assert (CLASS (backend)->add_cal != NULL);
    (* CLASS (backend)->add_cal) (backend, 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)
{
    CalBackendLoadStatus result;

    g_return_val_if_fail (backend != NULL, 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);

    g_assert (CLASS (backend)->load != NULL);
    result =  (* CLASS (backend)->load) (backend, uri);

    /* Remember the URI for saving the log file in the same dir and add
     * a timeout handler so for saving pending entries sometimes */
    if (result == CAL_BACKEND_LOAD_SUCCESS)
        cal_backend_set_uri (backend, uri);
    
    return result;
}

/**
 * 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)
{
    g_return_if_fail (backend != NULL);
    g_return_if_fail (IS_CAL_BACKEND (backend));
    g_return_if_fail (uri != NULL);

    g_assert (CLASS (backend)->create != NULL);
    (* CLASS (backend)->create) (backend, uri);

    /* Remember the URI for saving the log file in the same dir and add
     * a timeout handler so for saving pending entries sometimes */
    cal_backend_set_uri (backend, uri);
}

/**
 * cal_backend_get_n_objects:
 * @backend: A calendar backend.
 * @type: Types of objects that will be included in the count.
 * 
 * Queries the number of calendar objects of a particular type.
 * 
 * Return value: Number of objects of the specified @type.
 **/
int
cal_backend_get_n_objects (CalBackend *backend, CalObjType type)
{
    g_return_val_if_fail (backend != NULL, -1);
    g_return_val_if_fail (IS_CAL_BACKEND (backend), -1);

    g_assert (CLASS (backend)->get_n_objects != NULL);
    return (* CLASS (backend)->get_n_objects) (backend, type);
}

/**
 * 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)
{
    g_return_val_if_fail (backend != NULL, NULL);
    g_return_val_if_fail (IS_CAL_BACKEND (backend), NULL);
    g_return_val_if_fail (uid != NULL, NULL);

    g_assert (CLASS (backend)->get_object != NULL);
    return (* CLASS (backend)->get_object) (backend, 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.  The list should be
 * freed using the cal_obj_uid_list_free() function.
 **/
GList *
cal_backend_get_uids (CalBackend *backend, CalObjType type)
{
    g_return_val_if_fail (backend != NULL, NULL);
    g_return_val_if_fail (IS_CAL_BACKEND (backend), NULL);

    g_assert (CLASS (backend)->get_uids != NULL);
    return (* CLASS (backend)->get_uids) (backend, type);
}


static void
cal_backend_foreach_changed (gpointer key, gpointer value, gpointer data) 
{
    GList **list = data;
    
    *list = g_list_append (*list, value);
}

/**
 * cal_backend_get_changed_uids:
 * @backend: 
 * @type: 
 * @since: 
 * 
 * 
 * 
 * Return value: 
 **/
GList *
cal_backend_get_changed_uids (CalBackend *backend, CalObjType type, time_t since) 
{
    GHashTable *hash;
    GList *uids = NULL;
    
    g_return_val_if_fail (backend != NULL, NULL);
    g_return_val_if_fail (IS_CAL_BACKEND (backend), NULL);

    hash = cal_backend_get_log_entries (backend, type, since);

    if (hash)
        g_hash_table_foreach (hash, cal_backend_foreach_changed, &uids);
    
    return uids;
}


/**
 * cal_backend_get_objects_in_range:
 * @backend: A calendar backend.
 * @type: Bitmask with types of objects to return.
 * @start: Start time for query.
 * @end: End time for query.
 * 
 * Builds a list of unique identifiers corresponding to calendar objects of the
 * specified type that occur or recur within the specified time range.
 * 
 * Return value: A list of UID strings.  The list should be freed using the
 * cal_obj_uid_list_free() function.
 **/
GList *
cal_backend_get_objects_in_range (CalBackend *backend, CalObjType type,
                  time_t start, time_t end)
{
    g_return_val_if_fail (backend != NULL, NULL);
    g_return_val_if_fail (IS_CAL_BACKEND (backend), NULL);
    g_return_val_if_fail (start != -1 && end != -1, NULL);
    g_return_val_if_fail (start <= end, NULL);

    g_assert (CLASS (backend)->get_objects_in_range != NULL);
    return (* CLASS (backend)->get_objects_in_range) (backend, type, start, end);
}

/**
 * cal_backend_get_alarms_in_range:
 * @backend: A calendar backend.
 * @start: Start time for query.
 * @end: End time for query.
 * 
 * Builds a sorted list of the alarms that trigger in the specified time range.
 * 
 * Return value: A list of #CalAlarmInstance structures, sorted by trigger time.
 **/
GList *
cal_backend_get_alarms_in_range (CalBackend *backend, time_t start, time_t end)
{
    g_return_val_if_fail (backend != NULL, NULL);
    g_return_val_if_fail (IS_CAL_BACKEND (backend), NULL);
    g_return_val_if_fail (start != -1 && end != -1, NULL);
    g_return_val_if_fail (start <= end, NULL);

    g_assert (CLASS (backend)->get_alarms_in_range != NULL);
    return (* CLASS (backend)->get_alarms_in_range) (backend, start, end);
}

/**
 * cal_backend_get_alarms_for_object:
 * @backend: A calendar backend.
 * @uid: Unique identifier for a calendar object.
 * @start: Start time for query.
 * @end: End time for query.
 * @alarms: Return value for the list of alarm instances.
 * 
 * Builds a sorted list of the alarms of the specified event that trigger in a
 * particular time range.
 * 
 * Return value: TRUE on success, FALSE if the object was not found.
 **/
gboolean
cal_backend_get_alarms_for_object (CalBackend *backend, const char *uid,
                   time_t start, time_t end,
                   GList **alarms)
{
    g_return_val_if_fail (backend != NULL, FALSE);
    g_return_val_if_fail (IS_CAL_BACKEND (backend), FALSE);
    g_return_val_if_fail (uid != NULL, FALSE);
    g_return_val_if_fail (start != -1 && end != -1, FALSE);
    g_return_val_if_fail (start <= end, FALSE);
    g_return_val_if_fail (alarms != NULL, FALSE);

    g_assert (CLASS (backend)->get_alarms_for_object != NULL);
    return (* CLASS (backend)->get_alarms_for_object) (backend, uid, start, end, alarms);
}

/* Internal logging stuff */
typedef enum {
    CAL_BACKEND_UPDATED,
    CAL_BACKEND_REMOVED
} CalBackendLogEntryType;

typedef struct {
    char *uid;
    CalObjType type;
    
    CalBackendLogEntryType event_type;

    time_t time_stamp;
} CalBackendLogEntry;

typedef struct {
    CalObjType type;
    time_t since;

    gboolean in_valid_timestamp;
    
    GHashTable *hash;
} CalBackendParseState;

static gchar *
cal_backend_log_name (GnomeVFSURI *uri)
{   
    const gchar *path;
    gchar *filename;
    
    path = gnome_vfs_uri_get_path (uri);
    filename = g_strdup_printf ("%s.log.xml", path);

    return filename;
}

static void
cal_backend_set_node_timet (xmlNodePtr node, const char *name, time_t t)
{
    char *tstring;
    
    tstring = g_strdup_printf ("%ld", t);
    xmlSetProp (node, name, tstring);
    g_free (tstring);
}

static void
cal_backend_log_entry (CalBackend *backend, 
               const char *uid,
               CalObjType cot,
               CalBackendLogEntryType type)
{
    CalBackendLogEntry *entry;
    
    g_assert (CLASS (backend)->get_type_by_uid != NULL);

    /* Only log todos and events */
    if (cot != CALOBJ_TYPE_EVENT && cot != CALOBJ_TYPE_TODO)
        return;

    entry = g_new0 (CalBackendLogEntry, 1);
    entry->uid = g_strdup (uid);
    entry->type = cot;
    entry->event_type = type;   
    entry->time_stamp = time (NULL);

    /* Append so they get stored in chronological order */
    backend->entries = g_slist_append (backend->entries, entry);
}

static gboolean
cal_backend_log_sync (CalBackend *backend)
{   
    xmlDocPtr doc;
    xmlNodePtr tnode;
    gchar *filename;
    GSList *l;
    int ret;
    time_t start_time = (time_t) - 1;
    time_t end_time = (time_t) - 1;

    g_return_val_if_fail (backend->uri != NULL, FALSE);
    
    if (backend->entries == NULL)
        return TRUE;
    
    filename = cal_backend_log_name (backend->uri);
    
    doc = xmlParseFile (filename);
    if (doc == NULL) {
        /* Create the document */
        doc = xmlNewDoc ("1.0");
        if (doc == NULL) {
            g_warning ("Log file could not be created\n");
            return FALSE;
        }
        
        
        doc->root = xmlNewDocNode(doc, NULL, "CalendarLog", NULL);
    }

    tnode = xmlNewChild (doc->root, NULL, "timestamp", NULL);
    for (l = backend->entries; l != NULL; l = l->next) {
        xmlNodePtr node;
        CalBackendLogEntry *entry;
        
        entry = (CalBackendLogEntry *)l->data;
        node = xmlNewChild (tnode, NULL, "status", NULL);

        xmlSetProp (node, "uid", entry->uid);
        
        switch (entry->type) {
        case CALOBJ_TYPE_EVENT:
            xmlSetProp (node, "type", "event");
            break;
        case CALOBJ_TYPE_TODO:
            xmlSetProp (node, "type", "todo");
            break;
        default:
        }

        switch (entry->event_type) {
        case (CAL_BACKEND_UPDATED):
            xmlSetProp (node, "operation", "updated");
            break;
        case (CAL_BACKEND_REMOVED):
            xmlSetProp (node, "operation", "removed");
            break;
        }

        if (start_time == (time_t) - 1 
            || entry->time_stamp < start_time)
            start_time = entry->time_stamp;

        if (end_time == (time_t) - 1 
            || entry->time_stamp > end_time)
            end_time = entry->time_stamp;

        g_free (entry->uid);
        g_free (entry);
    }
    cal_backend_set_node_timet (tnode, "start", start_time);
    cal_backend_set_node_timet (tnode, "end", end_time);

    g_slist_free (backend->entries);
    backend->entries = NULL;
    
    /* Write the file */
    xmlSetDocCompressMode (doc, 0);
    ret = xmlSaveFile (filename, doc);
    if (ret < 0) {
        g_warning ("Log file could not be saved\n");
        return FALSE;
    }
    
    xmlFreeDoc (doc);

    g_free (filename);

    return TRUE;
}

static void
cal_backend_log_sax_start_element (CalBackendParseState *state, const CHAR *name, 
                   const CHAR **attrs)
{
    if (!strcmp (name, "timestamp")) {
        while (attrs && *attrs != NULL) {
            const xmlChar **val = attrs;
            
            val++;
            if (!strcmp (*attrs, "start")) {
                time_t start = (time_t)strtoul (*val, NULL, 0);
                
                if (start >= state->since) 
                    state->in_valid_timestamp = TRUE;
                break;
            }   
            attrs = ++val;
        }       
    }

    if (state->in_valid_timestamp && !strcmp (name, "status")) {
        CalObjChange *coc = g_new0 (CalObjChange, 1);
        CalObjType cot = 0;

        while (attrs && *attrs != NULL) {
            const xmlChar **val = attrs;

            
            val++;
            if (!strcmp (*attrs, "uid")) 
                coc->uid = g_strdup (*val);
            
            if (!strcmp (*attrs, "type")) {
                if (!strcmp (*val, "event"))
                    cot = CALOBJ_TYPE_EVENT;
                else if (!strcmp (*val, "todo"))
                    cot = CALOBJ_TYPE_TODO;
            }

            if (!strcmp (*attrs, "operation")) {
                if (!strcmp (*val, "updated"))
                    coc->type = CALOBJ_UPDATED;
                else if (!strcmp (*val, "removed"))
                    coc->type = CALOBJ_REMOVED;
            }
            
            attrs = ++val;
        }

        if (state->type == CALOBJ_TYPE_ANY || state->type == cot)
            g_hash_table_insert (state->hash, coc->uid, coc);
    }
}

static void
cal_backend_log_sax_end_element (CalBackendParseState *state, const CHAR *name)
{
    if (!strcmp (name, "timestamp")) {
        state->in_valid_timestamp = FALSE;
    }
}

static GHashTable *
cal_backend_get_log_entries (CalBackend *backend, CalObjType type, time_t since)
{
    xmlSAXHandler handler;
    CalBackendParseState state;
    GHashTable *hash;
    char *filename;

    g_return_val_if_fail (backend != NULL, NULL);
    g_return_val_if_fail (backend->uri != NULL, NULL);
    g_return_val_if_fail (IS_CAL_BACKEND (backend), NULL);

    if (!cal_backend_log_sync (backend))
        return NULL;

    memset (&handler, 0, sizeof (xmlSAXHandler));
    handler.startElement = (startElementSAXFunc)cal_backend_log_sax_start_element;
    handler.endElement = (endElementSAXFunc)cal_backend_log_sax_end_element;

    hash = g_hash_table_new (g_str_hash, g_str_equal);
    
    state.type = type;
    state.since = since;
    state.in_valid_timestamp = FALSE;
    state.hash = hash;

    filename = cal_backend_log_name (backend->uri); 
    if (xmlSAXUserParseFile (&handler, &state, filename) < 0)
        return NULL;
    
    return hash;
}

/**
 * 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 or one
 * with an unsupported type.
 **/
gboolean
cal_backend_update_object (CalBackend *backend, const char *uid, const char *calobj)
{
    CalObjType cot;
    gboolean result;
    
    g_return_val_if_fail (backend != NULL, FALSE);
    g_return_val_if_fail (IS_CAL_BACKEND (backend), FALSE);
    g_return_val_if_fail (uid != NULL, FALSE);
    g_return_val_if_fail (calobj != NULL, FALSE);

    g_assert (CLASS (backend)->update_object != NULL);
    result =  (* CLASS (backend)->update_object) (backend, uid, calobj);

    if (result) {
        cot = (* CLASS (backend)->get_type_by_uid) (backend, uid);
        cal_backend_log_entry (backend, uid, cot, CAL_BACKEND_UPDATED);
    }
    
    return result;
}

/**
 * cal_backend_remove_object:
 * @backend: A calendar backend.
 * @uid: Unique identifier of the object to remove.
 * 
 * Removes an object in a calendar backend.  The backend will notify all of its
 * clients about the change.
 * 
 * Return value: TRUE on success, FALSE on being passed an UID for an object
 * that does not exist in the backend.
 **/
gboolean
cal_backend_remove_object (CalBackend *backend, const char *uid)
{
    CalObjType cot;
    gboolean result;

    g_return_val_if_fail (backend != NULL, FALSE);
    g_return_val_if_fail (IS_CAL_BACKEND (backend), FALSE);
    g_return_val_if_fail (uid != NULL, FALSE);

    g_assert (CLASS (backend)->remove_object != NULL);
    cot = (* CLASS (backend)->get_type_by_uid) (backend, uid);
    result = (* CLASS (backend)->remove_object) (backend, uid);

    if (result)
        cal_backend_log_entry (backend, uid, cot, CAL_BACKEND_REMOVED);

    return result;
}

/**
 * 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));

    gtk_signal_emit (GTK_OBJECT (backend), cal_backend_signals[LAST_CLIENT_GONE]);
}