path: root/calendar/cal-util/calobj.c

/*
 * Calendar objects implementations.
 * Copyright (C) 1998 the Free Software Foundation
 *
 * Authors:
 *   Miguel de Icaza (miguel@gnu.org)
 *   Federico Mena (quartic@gimp.org)
 */
#include <string.h>
#include <glib.h>
#include "calobj.h"
#include "timeutil.h"
#include "versit/vcc.h"

iCalObject *
ical_object_new (void)
{
    iCalObject *ico;

    ico = g_new0 (iCalObject, 1);
    
    ico->seq = -1;
    ico->dtstamp = time (NULL);

    return ico;
}

static void
default_alarm (iCalObject *ical, CalendarAlarm *alarm, char *def_mail, enum AlarmType type)
{
    alarm->enabled = 0;
    alarm->type    = type;

    if (type != ALARM_MAIL){
        alarm->count   = 15;
        alarm->units   = ALARM_MINUTES;
    } else {
        alarm->count   = 1;
        alarm->units   = ALARM_DAYS;
    }

    if (type == ALARM_MAIL)
        alarm->data = g_strdup (def_mail);
    else
        alarm->data = g_strdup ("");
}

iCalObject *
ical_new (char *comment, char *organizer, char *summary)
{
    iCalObject *ico;

    ico = ical_object_new ();

    ico->comment   = g_strdup (comment);
    ico->organizer = g_strdup (organizer);
    ico->summary   = g_strdup (summary);
    ico->class     = g_strdup ("PUBLIC");

    default_alarm  (ico, &ico->dalarm, organizer, ALARM_DISPLAY);
    default_alarm  (ico, &ico->palarm, organizer, ALARM_PROGRAM);
    default_alarm  (ico, &ico->malarm, organizer, ALARM_MAIL);
    default_alarm  (ico, &ico->aalarm, organizer, ALARM_AUDIO);
    
    return ico;
}

static void
my_free (gpointer data, gpointer user_dat_ignored)
{
    g_free (data);
}

static void
list_free (GList *list)
{
    g_list_foreach (list, my_free, 0);
    g_list_free (list);
}

#define free_if_defined(x) if (x){ g_free (x); x = 0; }
#define lfree_if_defined(x) if (x){ list_free (x); x = 0; }
void
ical_object_destroy (iCalObject *ico)
{
    /* Regular strings */
    free_if_defined  (ico->comment);
    free_if_defined  (ico->organizer);
    free_if_defined  (ico->summary);
    free_if_defined  (ico->uid);
    free_if_defined  (ico->status);
    free_if_defined  (ico->class);
    free_if_defined  (ico->url);

    /* Lists */
    lfree_if_defined (ico->exdate);
    lfree_if_defined (ico->categories);
    lfree_if_defined (ico->resources);
    lfree_if_defined (ico->related);
    lfree_if_defined (ico->attach);

    /* Alarms */
    g_free (ico->dalarm.data);
    g_free (ico->palarm.data);
    g_free (ico->malarm.data);
    g_free (ico->aalarm.data);

    g_free (ico);
}

static GList *
set_list (char *str, char *sc)
{
    GList *list = 0;
    char *s;
    
    for (s = strtok (str, sc); s; s = strtok (NULL, sc))
        list = g_list_prepend (list, g_strdup (s));
    
    return list;
}

static GList *
set_date_list (char *str)
{
    GList *list = 0;
    char *s;

    for (s = strtok (str, ";"); s; s = strtok (NULL, ";")){
        time_t *t = g_new (time_t, 1);

        *t = time_from_isodate (s);
        list = g_list_prepend (list, t);
    }
    return list;
}

static void
ignore_space(char **str)
{
    while (**str && isspace (**str))
        (*str)++;
}

static void
skip_numbers (char **str)
{
    while (**str){
        ignore_space (str);
        if (!isdigit (**str))
            return;
        while (**str && isdigit (**str))
            ;
    }
}

static void
weekdaylist (iCalObject *o, char **str)
{
    int i;
    struct {
        char first_letter, second_letter;
        int  index;
    } days [] = {
        { 'S', 'U', 0 },
        { 'M', 'O', 1 },
        { 'T', 'U', 2 },
        { 'W', 'E', 3 },
        { 'T', 'H', 4 },
        { 'F', 'R', 5 },
        { 'S', 'A', 6 }
    };

    ignore_space (str);
    do {
        for (i = 0; i < 7; i++){
            if (**str == days [i].first_letter && *(*str+1) == days [i].second_letter){
                o->recur->weekday |= 1 << i;
                *str += 2;
                if (**str == ' ')
                    (*str)++;
            }
        }
    } while (isalpha (**str));
    
    if (o->recur->weekday == 0){
        struct tm *tm = localtime (&o->dtstart);

        o->recur->weekday = 1 << tm->tm_wday;
    }
}

static void
ocurrencelist (iCalObject *o, char **str)
{
    char *p;
    
    ignore_space (str);
    p = *str;
    if (!isdigit (*p))
        return;
    
    if (!(*p >= '1' && *p <= '5'))
        return;

    if (!(*(p+1) == '+' || *(p+1) == '-'))
        return;
    
    o->recur->u.month_pos = (*p-'0') * (*(p+1) == '+' ? 1 : -1);
    *str += 2;
}

static void
daynumber (iCalObject *o, char **str)
{
    int val = 0;
    char *p = *str;

    ignore_space (str);
    if (strcmp (p, "LD")){
        o->recur->u.month_day = DAY_LASTDAY;
        *str += 2;
        return;
    }
    
    if (!(isdigit (*p)))
        return;

    while (**str && isdigit (**str)){
        val = val * 10 + (**str - '0');
        (*str)++;
    }

    if (**str == '+')
        (*str)++;

    if (**str == '-')
        val *= -1;
    o->recur->u.month_day = val;
}

static void
daynumberlist (iCalObject *o, char **str)
{
    int first = 0;
    int val = 0;
        
    ignore_space (str);

    while (**str){
        if (!isdigit (**str))
            return;
        while (**str && isdigit (**str)){
            val = 10 * val + (**str - '0');
            (*str)++;
        }
        if (!first){
            o->recur->u.month_day = val;
            first = 1;
            val = 0;
        }
    }
}

static void
load_recur_weekly (iCalObject *o, char **str)
{
    weekdaylist (o, str);
}

static void
load_recur_monthly_pos (iCalObject *o, char **str)
{
    ocurrencelist (o, str);
    weekdaylist (o, str);
}

static void
load_recur_monthly_day (iCalObject *o, char **str)
{
    daynumberlist (o, str);
}

static void
load_recur_yearly_month (iCalObject *o, char **str)
{
    /* Skip as we do not support multiple months and we do expect
     * the dtstart to agree with the value on this field
     */
    skip_numbers (str);
}

static void
load_recur_yearly_day (iCalObject *o, char **str)
{
    /* Skip as we do not support multiple days and we do expect
     * the dtstart to agree with the value on this field
     */
    skip_numbers (str);
}

static void
duration (iCalObject *o, char **str)
{
    int duration = 0;
    
    ignore_space (str);
    if (**str != '#')
        return;
    (*str)++;
    while (**str && isdigit (**str)){
        duration = duration * 10 + (**str - '0');
        (*str)++;
    }
    o->recur->duration = duration;
}

static void
enddate (iCalObject *o, char **str)
{
    ignore_space (str);
    if (isdigit (**str)){
        o->recur->_enddate = time_from_isodate (*str);
        *str += 16;
    }
}

static int
load_recurrence (iCalObject *o, char *str)
{
    enum RecurType type;
    int  interval = 0;
    
    type = -1;
    switch (*str++){
    case 'D':
        type = RECUR_DAILY;
        break;
        
    case 'W':
        type = RECUR_WEEKLY;
        break;
        
    case 'M':
        if (*str == 'P')
            type = RECUR_MONTHLY_BY_POS;
            else if (*str == 'D')
            type = RECUR_MONTHLY_BY_DAY;
        str++;
        break;
        
    case 'Y':
        if (*str == 'M')
            type = RECUR_YEARLY_BY_MONTH;
        else if (*str == 'D')
            type = RECUR_YEARLY_BY_DAY;
        str++;
        break;
    }
    if (type == -1)
        return 0;

    o->recur = g_new0 (Recurrence, 1);
    o->recur->type = type;
    ignore_space (&str);

    /* Get the interval */
    for (;*str && isdigit (*str);str++)
        interval = interval * 10 + (*str-'0');
    o->recur->interval = interval;

    /* this is the default per the spec */
    o->recur->duration = 2;
    
    ignore_space (&str);
    
    switch (type){
    case RECUR_DAILY:
        break;
    case RECUR_WEEKLY:
        load_recur_weekly (o, &str);
        break;
    case RECUR_MONTHLY_BY_POS:
        load_recur_monthly_pos (o, &str);
        break;
    case RECUR_MONTHLY_BY_DAY:
        load_recur_monthly_day (o, &str);
        break;
    case RECUR_YEARLY_BY_MONTH:
        load_recur_yearly_month (o, &str);
        break;
    case RECUR_YEARLY_BY_DAY:
        load_recur_yearly_day (o, &str);
        break;
    default:
        g_warning ("Unimplemented recurrence type %d", (int) type);
        break;
    }
    duration (o, &str);
    enddate (o, &str);

    /* Compute the enddate */
    if (o->recur->_enddate == 0){
        if (o->recur->duration != 0){
            ical_object_compute_end (o);
        } else
            o->recur->enddate = 0;
    } else {
        o->recur->enddate = o->recur->_enddate;
    }
    return 1;
}

/*
 * FIXME: This is loosing precission.  Enhanec the thresholds
 */
#define HOURS(n) (n*(60*60))

static void
setup_alarm_at (time_t base, CalendarAlarm *alarm, char *iso_time)
{
    time_t alarm_time = time_from_isodate (iso_time);
    int d = difftime (base, alarm_time);

    if (d > HOURS (2)){
        if (d > HOURS (48)){
            alarm->count = d / HOURS (24);
            alarm->units = ALARM_DAYS;
        } else {
            alarm->count = d / 60*60;
            alarm->units = ALARM_HOURS;
        }
    } else {
        alarm->count = d / 60;
        alarm->units = ALARM_MINUTES;
    }
}

#define is_a_prop_of(obj,prop) isAPropertyOf (obj,prop)
#define str_val(obj) the_str = fakeCString (vObjectUStringZValue (obj))
#define has(obj,prop) (vo = isAPropertyOf (obj, prop))

/* FIXME: we need to load the recurrence properties */
iCalObject *
ical_object_create_from_vobject (VObject *o, const char *object_name)
{
    time_t  now = time (NULL);
    iCalObject *ical;
    VObject *vo, *a;
    VObjectIterator i;
    char *the_str;

    ical = g_new0 (iCalObject, 1);
    
    if (strcmp (object_name, VCEventProp) == 0)
        ical->type = ICAL_EVENT;
    else if (strcmp (object_name, VCTodoProp) == 0)
        ical->type = ICAL_TODO;
    else {
        g_free (ical);
        return 0;
    }

    /* uid */
    if (has (o, VCUniqueStringProp)){
        ical->uid = g_strdup (str_val (vo));
        free (the_str);
    }
    
    /* seq */
    if (has (o, VCSequenceProp)){
        ical->seq = atoi (str_val (vo));
        free (the_str);
    } else
        ical->seq = 0;
    
    /* dtstart */
    if (has (o, VCDTstartProp)){
        ical->dtstart = time_from_isodate (str_val (vo));
        free (the_str);
    } else
        ical->dtstart = 0;

    /* dtend */
    if (has (o, VCDTendProp)){
        ical->dtend = time_from_isodate (str_val (vo));
        free (the_str);
    } else
        ical->dtend = 0;

    /* dcreated */
    if (has (o, VCDCreatedProp)){
        ical->created = time_from_isodate (str_val (vo));
        free (the_str);
    }
    
    /* completed */
    if (has (o, VCCompletedProp)){
        ical->completed = time_from_isodate (str_val (vo));
        free (the_str);
    }
    
    /* last_mod */
    if (has (o, VCLastModifiedProp)){
        ical->last_mod = time_from_isodate (str_val (vo));
        free (the_str);
    } else
        ical->last_mod = now;

    /* exdate */
    if (has (o, VCExpDateProp)){
        ical->exdate = set_date_list (str_val (vo));
        free (the_str);
    }

    /* description/comment */
    if (has (o, VCDescriptionProp)){
        ical->comment = g_strdup (str_val (vo));
        free (the_str);
    }
    
    /* summary */
    if (has (o, VCSummaryProp)){
        ical->summary = g_strdup (str_val (vo));
        free (the_str);
    } else
        ical->summary = g_strdup ("");

    /* status */
    if (has (o, VCStatusProp)){
        ical->status = g_strdup (str_val (vo));
        free (the_str);
    } else
        ical->status = g_strdup ("NEEDS ACTION");

    if (has (o, VCClassProp)){
        ical->class = g_strdup (str_val (vo));
        free (the_str);
    } else
        ical->class = "PUBLIC";

    /* categories */
    if (has (o, VCCategoriesProp)){
        ical->categories = set_list (str_val (vo), ",");
        free (the_str);
    }
    
    /* resources */
    if (has (o, VCResourcesProp)){
        ical->resources = set_list (str_val (vo), ";");
        free (the_str);
    }
    
    /* priority */
    if (has (o, VCPriorityProp)){
        ical->priority = atoi (str_val (vo));
        free (the_str);
    }
    
    /* tranparency */
    if (has (o, VCTranspProp)){
        ical->transp = atoi (str_val (vo)) ? ICAL_TRANSPARENT : ICAL_OPAQUE;
        free (the_str);
    }

    /* related */
    if (has (o, VCRelatedToProp)){
        ical->related = set_list (str_val (vo), ";");
        free (the_str);
    }
    
    /* attach */
    initPropIterator (&i, o);
    while (moreIteration (&i)){
        vo = nextVObject (&i);
        if (strcmp (vObjectName (vo), VCAttachProp) == 0){
            ical->attach = g_list_prepend (ical->attach, g_strdup (str_val (vo)));
            free (the_str);
        }
    }

    /* url */
    if (has (o, VCURLProp)){
        ical->url = g_strdup (str_val (vo));
        free (the_str);
    }
    
    /* dalarm */
    ical->dalarm.type = ALARM_DISPLAY;
    ical->dalarm.enabled = 0;
    if (has (o, VCDAlarmProp)){
        if ((a = is_a_prop_of (o, VCRunTimeProp))){
            ical->dalarm.enabled = 1;
            setup_alarm_at (ical->dtstart, &ical->dalarm, str_val (a));
            free (the_str);
        }
    }
    
    /* aalarm */
    ical->aalarm.type = ALARM_AUDIO;
    ical->aalarm.enabled = 0;
    if (has (o, VCAAlarmProp)){
        if ((a = is_a_prop_of (o, VCRunTimeProp))){
            ical->aalarm.enabled = 1;
            setup_alarm_at (ical->dtstart, &ical->aalarm, str_val (a));
            free (the_str);
        }
    }

    /* palarm */
    ical->palarm.type = ALARM_PROGRAM;
    ical->palarm.enabled = 0;
    if (has (o, VCPAlarmProp)){
        ical->palarm.type = ALARM_PROGRAM;
        if ((a = is_a_prop_of (o, VCRunTimeProp))){
            ical->palarm.enabled = 1;
            setup_alarm_at (ical->dtstart, &ical->palarm, str_val (a));
            free (the_str);

            if ((a = is_a_prop_of (o, VCProcedureNameProp))){
                ical->palarm.data = g_strdup (str_val (a));
                free (the_str);
            }
        }
    }

    /* malarm */
    ical->malarm.type = ALARM_MAIL;
    ical->malarm.enabled = 0;
    if (has (o, VCMAlarmProp)){
        ical->malarm.type = ALARM_MAIL;
        if ((a = is_a_prop_of (o, VCRunTimeProp))){
            ical->malarm.enabled = 1;
            setup_alarm_at (ical->dtstart, &ical->malarm, str_val (a));
            free (the_str);
            
            if ((a = is_a_prop_of (o, VCEmailAddressProp))){
                ical->malarm.data = g_strdup (str_val (a));
                free (the_str);
            }
        }
    }

    /* rrule */
    if (has (o, VCRRuleProp)){
        if (!load_recurrence (ical, str_val (vo))) {
            ical_object_destroy (ical);
            return NULL;
        }
        free (the_str);
    }
    return ical;
}

static char *
to_str (int num)
{
    static char buf [40];

    sprintf (buf, "%d", num);
    return buf;
}

/*
 * stores a GList in the property, using SEP as the value separator
 */
static void
store_list (VObject *o, char *prop, GList *values, char sep)
{
    GList *l;
    int len;
    char *result, *p;
    
    for (len = 0, l = values; l; l = l->next)
        len += strlen (l->data) + 1;

    result = g_malloc (len);
    for (p = result, l = values; l; l = l->next){
        int len = strlen (l->data);
        
        strcpy (p, l->data);
        p [len] = sep;
        p += len+1;
    }
    addPropValue (o, prop, result);
    g_free (p);
}

static char *recur_type_name [] = { "D", "W", "MP", "MD", "YM", "YD" };
static char *recur_day_list  [] = { "SU", "MO", "TU","WE", "TH", "FR", "SA" };
static char *alarm_names [] = { VCMAlarmProp, VCPAlarmProp, VCDAlarmProp, VCAAlarmProp };

static VObject *
save_alarm (VObject *o, CalendarAlarm *alarm, iCalObject *ical)
{
    VObject *alarm_object;
    struct tm *tm;
    time_t alarm_time;
    
    if (!alarm->enabled)
        return NULL;
    tm = localtime (&ical->dtstart);
    switch (alarm->units){
    case ALARM_MINUTES:
        tm->tm_min -= alarm->count;
        break;
        
    case ALARM_HOURS:
        tm->tm_hour -= alarm->count;
        break;
        
    case ALARM_DAYS:
        tm->tm_mday -= alarm->count;
        break;
    }
    
    alarm_time = mktime (tm);
    alarm_object = addProp (o, alarm_names [alarm->type]);
    addPropValue (alarm_object, VCRunTimeProp, isodate_from_time_t (alarm_time));
    addPropValue (alarm_object, VCRepeatCountProp, "1");
    addPropValue (alarm_object, VCDisplayStringProp, "GNOME appointment alarm");

    return alarm_object;
}

VObject *
ical_object_to_vobject (iCalObject *ical)
{
    VObject *o, *alarm;
    GList *l;
    
    if (ical->type == ICAL_EVENT)
        o = newVObject (VCEventProp);
    else
        o = newVObject (VCTodoProp);

    /* uid */
    if (ical->uid)
        addPropValue (o, VCUniqueStringProp, ical->uid);

    /* seq */
    addPropValue (o, VCSequenceProp, to_str (ical->seq));

    /* dtstart */
    addPropValue (o, VCDTstartProp, isodate_from_time_t (ical->dtstart));

    /* dtend */
    addPropValue (o, VCDTendProp, isodate_from_time_t (ical->dtend));

    /* dcreated */
    addPropValue (o, VCDTendProp, isodate_from_time_t (ical->created));

    /* completed */
    if (ical->completed)
        addPropValue (o, VCDTendProp, isodate_from_time_t (ical->completed));

    /* last_mod */
    addPropValue (o, VCLastModifiedProp, isodate_from_time_t (ical->last_mod));

    /* exdate */
    if (ical->exdate)
        store_list (o, VCExpDateProp, ical->exdate, ',');

    /* description/comment */
    if (ical->comment)
        addPropValue (o, VCDescriptionProp, ical->comment);

    /* summary */
    if (ical->summary)
        addPropValue (o, VCSummaryProp, ical->summary);
    
    /* status */
    addPropValue (o, VCStatusProp, ical->status);

    /* class */
    addPropValue (o, VCClassProp, ical->class);

    /* categories */
    if (ical->categories)
        store_list (o, VCCategoriesProp, ical->categories, ',');

    /* resources */
    if (ical->categories)
        store_list (o, VCCategoriesProp, ical->resources, ';');

    /* priority */
    addPropValue (o, VCPriorityProp, to_str (ical->priority));

    /* transparency */
    addPropValue (o, VCTranspProp, to_str (ical->transp));

    /* related */
    store_list (o, VCRelatedToProp, ical->related, ';');

    /* attach */
    for (l = ical->attach; l; l = l->next)
        addPropValue (o, VCAttachProp, l->data);

    /* url */
    if (ical->url)
        addPropValue (o, VCURLProp, ical->url);

    if (ical->recur){
        char result [256];
        char buffer [80];
        int i;
        
        sprintf (result, "%s%d ", recur_type_name [ical->recur->type], ical->recur->interval);
        switch (ical->recur->type){
        case RECUR_DAILY:
            break;
            
        case RECUR_WEEKLY:
            for (i = 0; i < 7; i++){
                if (ical->recur->weekday & (1 << i)){
                    sprintf (buffer, "%s ", recur_day_list [i]);
                    strcat (result, buffer);
                }
            }
            break;
            
        case RECUR_MONTHLY_BY_POS: {
            int nega = ical->recur->u.month_pos < 0;
                
            sprintf (buffer, "%d%s ", nega ? -ical->recur->u.month_pos : ical->recur->u.month_pos,
                 nega ? "-" : "+");
            strcat (result, buffer);
            for (i = 0; i < 7; i++){
                if (ical->recur->weekday & (1 << i)){
                    sprintf (buffer, "%s ", recur_day_list [i]);
                    strcat (result, buffer);
                }
            }
        }
        break;
            
        case RECUR_MONTHLY_BY_DAY:
            sprintf (buffer, "%d ", ical->recur->u.month_pos);
            strcat (result, buffer);
            break;
            
        case RECUR_YEARLY_BY_MONTH:
            break;
            
        case RECUR_YEARLY_BY_DAY:
            break;
        }
        if (ical->recur->_enddate == 0)
            sprintf (buffer, "#%d ",ical->recur->duration);
        else
            sprintf (buffer, "%s ", isodate_from_time_t (ical->recur->_enddate));
        strcat (result, buffer);
        addPropValue (o, VCRRuleProp, result);
    }
    
    save_alarm (o, &ical->aalarm, ical);
    save_alarm (o, &ical->dalarm, ical);
    
    if ((alarm = save_alarm (o, &ical->palarm, ical)))
        addPropValue (alarm, VCProcedureNameProp, ical->palarm.data);
    if ((alarm = save_alarm (o, &ical->malarm, ical)))
        addPropValue (alarm, VCEmailAddressProp, ical->malarm.data);
    return o;
}

void
ical_foreach (GList *events, calendarfn fn, void *closure)
{
    for (; events; events = events->next){
        iCalObject *ical = events->data;
        
        (*fn) (ical, ical->dtstart, ical->dtend, closure);
    }
}

static int
generate (iCalObject *ico, time_t reference, calendarfn cb, void *closure)
{
    struct tm dt_start, dt_end, ref;
    time_t s_t, e_t;

    dt_start = *localtime (&ico->dtstart);
    dt_end   = *localtime (&ico->dtend);
    ref      = *localtime (&reference);

    dt_start.tm_mday = ref.tm_mday;
    dt_start.tm_mon  = ref.tm_mon;
    dt_start.tm_year = ref.tm_year;

    dt_end.tm_mday = ref.tm_mday;
    dt_end.tm_mon  = ref.tm_mon;
    dt_end.tm_year = ref.tm_year;

    s_t = mktime (&dt_start);
    e_t = mktime (&dt_end);
    if (s_t == -1 || e_t == -1){
        g_warning ("Produced invalid dates!\n");
        return 0;
    }
    return (*cb)(ico, s_t, e_t, closure);
}

#define time_in_range(x,a,b) ((x >= a) && (b ? x <= b : 1))
#define recur_in_range(t,r) (r->enddate ? (t < r->enddate) : 1)

/*
 * Generate every possible event.  Invokes the callback routine for
 * every occurrence of the event in the [START, END] time interval.
 *
 * If END is zero, the event is generated forever.
 * The callback routine is expected to return 0 when no further event
 * generation is requested.
 */
void
ical_object_generate_events (iCalObject *ico, time_t start, time_t end, calendarfn cb, void *closure)
{
    Recurrence *recur = ico->recur;
    time_t current;
    int first_week_day, i;
    
    if (!ico->recur){
        if (time_in_range (ico->dtstart, start, end) ||
            time_in_range (ico->dtend, start, end)){
            time_t ev_s, ev_e;

            ev_s = ico->dtstart < start ? start : ico->dtstart;
            ev_e = ico->dtend > end ? end : ico->dtend;
            (*cb)(ico, ev_s, ev_e, closure);
        }
        return;
    }

    /* The event has a recurrence rule */
    if (end != 0){
        if (ico->dtstart > end)
            return;
        if (!IS_INFINITE (recur) && recur->enddate < start)
            return;
    }

    current = ico->dtstart;
    switch (recur->type){
    case RECUR_DAILY:
        do {
            if (time_in_range (current, start, end) && recur_in_range (current, recur)){
                if (!generate (ico, current, cb, closure))
                    return;
            }

            /* Advance */
            current = time_add_day (current, recur->interval);
            
            if (current == -1){
                g_warning ("RECUR_DAILY: mktime error\n");
                return;
            }
        } while (current < end || (end == 0));
        break;
        
    case RECUR_WEEKLY:
        do {
            struct tm *tm = localtime (&current);
            
            if (time_in_range (current, start, end) && recur_in_range (current, recur)){
                if (recur->weekday & (1 << tm->tm_wday))
                    if (!generate (ico, current, cb, closure))
                        return;
            }

            /* Advance by day for scanning the week or by interval at week end */
            if (tm->tm_wday == 6)
                current = time_add_day (current, recur->interval);
            else
                current = time_add_day (current, 1);

            if (current == -1){
                g_warning ("RECUR_WEEKLY: mktime error\n");
                return;
            }
        } while (current < end || (end == 0));
        break;
        
    case RECUR_MONTHLY_BY_POS:
        /* FIXME: We only deal with positives now */
        if (recur->u.month_pos < 0)
            return;
        
        if (recur->u.month_pos == 0)
            return;
        
        first_week_day = 7;
        for (i = 6; i >= 0; i--)
            if (recur->weekday & (1 << i))
                first_week_day = i;

        /* This should not happen, but take it into account */
        if (first_week_day == 7)
            return;

        do {
            struct tm tm;
            time_t t;
            int    week_day_start;

            tm = *localtime (&current);
            tm.tm_mday = 1;
            t = mktime (&tm);
            tm = *localtime (&t);
            week_day_start = tm.tm_wday;

            tm.tm_mday = 7 * (recur->u.month_pos -
                      ((week_day_start <= first_week_day ) ? 1 : 0)) -
                (week_day_start - first_week_day) + 1;
            
            t = mktime (&tm);
            
            if (time_in_range (t, start, end) && recur_in_range (current, recur))
                if (!generate (ico, t, cb, closure))
                    return;

            /* Advance a month */
            current = mktime (&tm);
            
            tm.tm_mday = 1;
            tm.tm_mon += recur->interval;
            current = mktime (&tm);

            if (current == -1){
                g_warning ("RECUR_MONTHLY_BY_DAY: mktime error\n");
                return;
            }
        } while (current < end || (end == 0));
        break;

    case RECUR_MONTHLY_BY_DAY:
        do {
            struct tm *tm = localtime (&current);
            time_t t;
            int    p;

            p = tm->tm_mday;
            tm->tm_mday = recur->u.month_day;
            t = mktime (tm);
            if (time_in_range (t, start, end) && recur_in_range (current, recur))
                if (!generate (ico, t, cb, closure))
                    return;

            /* Advance a month */
            tm->tm_mday = p;
            tm->tm_mon += recur->interval;
            current = mktime (tm);
            if (current == -1){
                g_warning ("RECUR_MONTHLY_BY_DAY: mktime error\n");
                return;
            }
        } while (current < end || (end == 0));
        
    case RECUR_YEARLY_BY_MONTH:
    case RECUR_YEARLY_BY_DAY:
        do {
            if (time_in_range (current, start, end) && recur_in_range (current, recur))
                if (!generate (ico, current, cb, closure))
                    return;
            
            /* Advance */
            current = time_add_year (current, recur->interval);
        } while (current < end || (end == 0));
    }
}

static int
duration_callback (iCalObject *ico, time_t start, time_t end, void *closure)
{
    int *count = closure;

    (*count)++;
    if (ico->recur->duration == *count) {
        ico->recur->enddate = end;
        return 0;
    }
    return 1;
}

/* Computes ico->recur->enddate from ico->recur->duration */
void
ical_object_compute_end (iCalObject *ico)
{
    int count = 0;

    g_return_if_fail (ico->recur != NULL);

    ico->recur->_enddate = 0;
    ical_object_generate_events (ico, ico->dtstart, 0, duration_callback, &count);
}