path: root/src/recur.c

/*
 * Calcurse - text-based organizer
 *
 * Copyright (c) 2004-2012 calcurse Development Team <misc@calcurse.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the
 *        following disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the
 *        following disclaimer in the documentation and/or other
 *        materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Send your feedback or comments to : misc@calcurse.org
 * Calcurse home page : http://calcurse.org
 *
 */

#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <sys/types.h>
#include <time.h>

#include "calcurse.h"

llist_ts_t recur_alist_p;
llist_t recur_elist;

static void free_exc(struct excp *exc)
{
  mem_free(exc);
}

static void free_exc_list(llist_t * exc)
{
  LLIST_FREE_INNER(exc, free_exc);
  LLIST_FREE(exc);
}

static int exc_cmp_day(struct excp *a, struct excp *b)
{
  return a->st < b->st ? -1 : (a->st == b->st ? 0 : 1);
}

static void recur_add_exc(llist_t * exc, long day)
{
  struct excp *o = mem_malloc(sizeof(struct excp));
  o->st = day;

  LLIST_ADD_SORTED(exc, o, exc_cmp_day);
}

static void exc_dup(llist_t * in, llist_t * exc)
{
  llist_item_t *i;

  LLIST_INIT(in);

  if (exc) {
    LLIST_FOREACH(exc, i) {
      struct excp *p = LLIST_GET_DATA(i);
      recur_add_exc(in, p->st);
    }
  }
}

struct recur_event *recur_event_dup(struct recur_event *in)
{
  EXIT_IF(!in, _("null pointer"));

  struct recur_event *rev = mem_malloc(sizeof(struct recur_event));

  rev->id = in->id;
  rev->day = in->day;
  rev->mesg = mem_strdup(in->mesg);

  rev->rpt = mem_malloc(sizeof(struct rpt));
  rev->rpt->type = in->rpt->type;
  rev->rpt->freq = in->rpt->freq;
  rev->rpt->until = in->rpt->until;

  exc_dup(&rev->exc, &in->exc);

  if (in->note)
    rev->note = mem_strdup(in->note);
  else
    rev->note = NULL;

  return rev;
}

struct recur_apoint *recur_apoint_dup(struct recur_apoint *in)
{
  EXIT_IF(!in, _("null pointer"));

  struct recur_apoint *rapt = mem_malloc(sizeof(struct recur_apoint));

  rapt->start = in->start;
  rapt->dur = in->dur;
  rapt->state = in->state;
  rapt->mesg = mem_strdup(in->mesg);

  rapt->rpt = mem_malloc(sizeof(struct rpt));
  rapt->rpt->type = in->rpt->type;
  rapt->rpt->freq = in->rpt->freq;
  rapt->rpt->until = in->rpt->until;

  exc_dup(&rapt->exc, &in->exc);

  if (in->note)
    rapt->note = mem_strdup(in->note);
  else
    rapt->note = NULL;

  return rapt;
}

void recur_apoint_llist_init(void)
{
  LLIST_TS_INIT(&recur_alist_p);
}

void recur_apoint_free(struct recur_apoint *rapt)
{
  mem_free(rapt->mesg);
  if (rapt->note)
    mem_free(rapt->note);
  if (rapt->rpt)
    mem_free(rapt->rpt);
  free_exc_list(&rapt->exc);
  mem_free(rapt);
}

void recur_event_free(struct recur_event *rev)
{
  mem_free(rev->mesg);
  if (rev->note)
    mem_free(rev->note);
  if (rev->rpt)
    mem_free(rev->rpt);
  free_exc_list(&rev->exc);
  mem_free(rev);
}

void recur_apoint_llist_free(void)
{
  LLIST_TS_FREE_INNER(&recur_alist_p, recur_apoint_free);
  LLIST_TS_FREE(&recur_alist_p);
}

void recur_event_llist_free(void)
{
  LLIST_FREE_INNER(&recur_elist, recur_event_free);
  LLIST_FREE(&recur_elist);
}

static int
recur_apoint_cmp_start(struct recur_apoint *a, struct recur_apoint *b)
{
  return a->start < b->start ? -1 : (a->start == b->start ? 0 : 1);
}

static int recur_event_cmp_day(struct recur_event *a, struct recur_event *b)
{
  return a->day < b->day ? -1 : (a->day == b->day ? 0 : 1);
}

/* Insert a new recursive appointment in the general linked list */
struct recur_apoint *recur_apoint_new(char *mesg, char *note, long start,
                                      long dur, char state, int type, int freq,
                                      long until, llist_t * except)
{
  struct recur_apoint *rapt = mem_malloc(sizeof(struct recur_apoint));

  rapt->rpt = mem_malloc(sizeof(struct rpt));
  rapt->mesg = mem_strdup(mesg);
  rapt->note = (note != NULL) ? mem_strdup(note) : 0;
  rapt->start = start;
  rapt->state = state;
  rapt->dur = dur;
  rapt->rpt->type = type;
  rapt->rpt->freq = freq;
  rapt->rpt->until = until;
  if (except) {
    exc_dup(&rapt->exc, except);
    free_exc_list(except);
  } else
    LLIST_INIT(&rapt->exc);

  LLIST_TS_LOCK(&recur_alist_p);
  LLIST_TS_ADD_SORTED(&recur_alist_p, rapt, recur_apoint_cmp_start);
  LLIST_TS_UNLOCK(&recur_alist_p);

  return rapt;
}

/* Insert a new recursive event in the general linked list */
struct recur_event *recur_event_new(char *mesg, char *note, long day, int id,
                                    int type, int freq, long until,
                                    llist_t * except)
{
  struct recur_event *rev = mem_malloc(sizeof(struct recur_event));

  rev->rpt = mem_malloc(sizeof(struct rpt));
  rev->mesg = mem_strdup(mesg);
  rev->note = (note != NULL) ? mem_strdup(note) : 0;
  rev->day = day;
  rev->id = id;
  rev->rpt->type = type;
  rev->rpt->freq = freq;
  rev->rpt->until = until;
  if (except) {
    exc_dup(&rev->exc, except);
    free_exc_list(except);
  } else
    LLIST_INIT(&rev->exc);

  LLIST_ADD_SORTED(&recur_elist, rev, recur_event_cmp_day);

  return rev;
}

/*
 * Correspondance between the defines on recursive type,
 * and the letter to be written in file.
 */
char recur_def2char(enum recur_type define)
{
  char recur_char;

  switch (define) {
  case RECUR_DAILY:
    recur_char = 'D';
    break;
  case RECUR_WEEKLY:
    recur_char = 'W';
    break;
  case RECUR_MONTHLY:
    recur_char = 'M';
    break;
  case RECUR_YEARLY:
    recur_char = 'Y';
    break;
  default:
    EXIT(_("unknown repetition type"));
    return 0;
  }

  return recur_char;
}

/*
 * Correspondance between the letters written in file and the defines
 * concerning the recursive type.
 */
int recur_char2def(char type)
{
  int recur_def;

  switch (type) {
  case 'D':
    recur_def = RECUR_DAILY;
    break;
  case 'W':
    recur_def = RECUR_WEEKLY;
    break;
  case 'M':
    recur_def = RECUR_MONTHLY;
    break;
  case 'Y':
    recur_def = RECUR_YEARLY;
    break;
  default:
    EXIT(_("unknown character"));
    return 0;
  }
  return recur_def;
}

/* Write days for which recurrent items should not be repeated. */
static void recur_write_exc(llist_t * lexc, FILE * f)
{
  llist_item_t *i;
  struct tm lt;
  time_t t;
  int st_mon, st_day, st_year;

  LLIST_FOREACH(lexc, i) {
    struct excp *exc = LLIST_GET_DATA(i);
    t = exc->st;
    localtime_r(&t, &lt);
    st_mon = lt.tm_mon + 1;
    st_day = lt.tm_mday;
    st_year = lt.tm_year + 1900;
    fprintf(f, " !%02u/%02u/%04u", st_mon, st_day, st_year);
  }
}

/* Load the recursive appointment description */
struct recur_apoint *recur_apoint_scan(FILE * f, struct tm start, struct tm end,
                                       char type, int freq, struct tm until,
                                       char *note, llist_t * exc, char state)
{
  char buf[BUFSIZ], *nl;
  time_t tstart, tend, tuntil;

  /* Read the appointment description */
  if (!fgets(buf, sizeof buf, f))
    return NULL;

  nl = strchr(buf, '\n');
  if (nl) {
    *nl = '\0';
  }
  start.tm_sec = end.tm_sec = 0;
  start.tm_isdst = end.tm_isdst = -1;
  start.tm_year -= 1900;
  start.tm_mon--;
  end.tm_year -= 1900;
  end.tm_mon--;
  tstart = mktime(&start);
  tend = mktime(&end);

  if (until.tm_year != 0) {
    until.tm_hour = 23;
    until.tm_min = 59;
    until.tm_sec = 0;
    until.tm_isdst = -1;
    until.tm_year -= 1900;
    until.tm_mon--;
    tuntil = mktime(&until);
  } else {
    tuntil = 0;
  }
  EXIT_IF(tstart == -1 || tend == -1 || tstart > tend || tuntil == -1,
          _("date error in appointment"));

  return recur_apoint_new(buf, note, tstart, tend - tstart, state,
                          recur_char2def(type), freq, tuntil, exc);
}

/* Load the recursive events from file */
struct recur_event *recur_event_scan(FILE * f, struct tm start, int id,
                                     char type, int freq, struct tm until,
                                     char *note, llist_t * exc)
{
  char buf[BUFSIZ], *nl;
  time_t tstart, tuntil;

  /* Read the event description */
  if (!fgets(buf, sizeof buf, f))
    return NULL;

  nl = strchr(buf, '\n');
  if (nl) {
    *nl = '\0';
  }
  start.tm_hour = until.tm_hour = 0;
  start.tm_min = until.tm_min = 0;
  start.tm_sec = until.tm_sec = 0;
  start.tm_isdst = until.tm_isdst = -1;
  start.tm_year -= 1900;
  start.tm_mon--;
  if (until.tm_year != 0) {
    until.tm_year -= 1900;
    until.tm_mon--;
    tuntil = mktime(&until);
  } else {
    tuntil = 0;
  }
  tstart = mktime(&start);
  EXIT_IF(tstart == -1 || tuntil == -1, _("date error in event"));

  return recur_event_new(buf, note, tstart, id, recur_char2def(type), freq,
                         tuntil, exc);
}

/* Writting of a recursive appointment into file. */
void recur_apoint_write(struct recur_apoint *o, FILE * f)
{
  struct tm lt;
  time_t t;

  t = o->start;
  localtime_r(&t, &lt);
  fprintf(f, "%02u/%02u/%04u @ %02u:%02u", lt.tm_mon + 1, lt.tm_mday,
          1900 + lt.tm_year, lt.tm_hour, lt.tm_min);

  t = o->start + o->dur;
  localtime_r(&t, &lt);
  fprintf(f, " -> %02u/%02u/%04u @ %02u:%02u", lt.tm_mon + 1, lt.tm_mday,
          1900 + lt.tm_year, lt.tm_hour, lt.tm_min);

  t = o->rpt->until;
  if (t == 0) {                 /* We have an endless recurrent appointment. */
    fprintf(f, " {%d%c", o->rpt->freq, recur_def2char(o->rpt->type));
  } else {
    localtime_r(&t, &lt);
    fprintf(f, " {%d%c -> %02u/%02u/%04u", o->rpt->freq,
            recur_def2char(o->rpt->type), lt.tm_mon + 1, lt.tm_mday,
            1900 + lt.tm_year);
  }
  recur_write_exc(&o->exc, f);
  fputs("} ", f);
  if (o->note != NULL)
    fprintf(f, ">%s ", o->note);
  if (o->state & APOINT_NOTIFY)
    fputc('!', f);
  else
    fputc('|', f);
  fprintf(f, "%s\n", o->mesg);
}

/* Writting of a recursive event into file. */
void recur_event_write(struct recur_event *o, FILE * f)
{
  struct tm lt;
  time_t t;
  int st_mon, st_day, st_year;
  int end_mon, end_day, end_year;

  t = o->day;
  localtime_r(&t, &lt);
  st_mon = lt.tm_mon + 1;
  st_day = lt.tm_mday;
  st_year = lt.tm_year + 1900;
  t = o->rpt->until;
  if (t == 0) {                 /* We have an endless recurrent event. */
    fprintf(f, "%02u/%02u/%04u [%d] {%d%c", st_mon, st_day, st_year, o->id,
            o->rpt->freq, recur_def2char(o->rpt->type));
  } else {
    localtime_r(&t, &lt);
    end_mon = lt.tm_mon + 1;
    end_day = lt.tm_mday;
    end_year = lt.tm_year + 1900;
    fprintf(f, "%02u/%02u/%04u [%d] {%d%c -> %02u/%02u/%04u", st_mon,
            st_day, st_year, o->id, o->rpt->freq,
            recur_def2char(o->rpt->type), end_mon, end_day, end_year);
  }
  recur_write_exc(&o->exc, f);
  fputs("} ", f);
  if (o->note != NULL)
    fprintf(f, ">%s ", o->note);
  fprintf(f, "%s\n", o->mesg);
}

/* Write recursive items to file. */
void recur_save_data(FILE * f)
{
  llist_item_t *i;

  LLIST_FOREACH(&recur_elist, i) {
    struct recur_event *rev = LLIST_GET_DATA(i);
    recur_event_write(rev, f);
  }

  LLIST_TS_LOCK(&recur_alist_p);
  LLIST_TS_FOREACH(&recur_alist_p, i) {
    struct recur_apoint *rapt = LLIST_GET_DATA(i);
    recur_apoint_write(rapt, f);
  }
  LLIST_TS_UNLOCK(&recur_alist_p);
}

/*
 * The two following defines together with the diff_days, diff_months and
 * diff_years functions were provided by Lukas Fleischer to correct the wrong
 * calculation of recurrent dates after a turn of year.
 */
#define BC(start, end, bs)                                              \
  (((end) - (start) + ((start) % bs) - ((end) % bs)) / bs               \
   + ((((start) % bs) == 0) ? 1 : 0))

#define LEAPCOUNT(start, end)                                           \
  (BC(start, end, 4) - BC(start, end, 100) + BC(start, end, 400))

/* Calculate the difference in days between two dates. */
static long diff_days(struct tm lt_start, struct tm lt_end)
{
  long diff;

  if (lt_end.tm_year < lt_start.tm_year)
    return 0;

  diff = lt_end.tm_yday - lt_start.tm_yday;

  if (lt_end.tm_year > lt_start.tm_year) {
    diff += (lt_end.tm_year - lt_start.tm_year) * YEARINDAYS;
    diff += LEAPCOUNT(lt_start.tm_year + TM_YEAR_BASE,
                      lt_end.tm_year + TM_YEAR_BASE - 1);
  }

  return diff;
}

/* Calculate the difference in months between two dates. */
static long diff_months(struct tm lt_start, struct tm lt_end)
{
  long diff;

  if (lt_end.tm_year < lt_start.tm_year)
    return 0;

  diff = lt_end.tm_mon - lt_start.tm_mon;
  diff += (lt_end.tm_year - lt_start.tm_year) * YEARINMONTHS;

  return diff;
}

/* Calculate the difference in years between two dates. */
static long diff_years(struct tm lt_start, struct tm lt_end)
{
  return lt_end.tm_year - lt_start.tm_year;
}

static int exc_inday(struct excp *exc, long *day_start)
{
  return (exc->st >= *day_start && exc->st < *day_start + DAYINSEC);
}

/*
 * Check if the recurrent item belongs to the selected day, and if yes, store
 * the start date of the occurrence that belongs to the day in a buffer.
 *
 * This function was improved thanks to Tony's patch.
 * Thanks also to youshe for reporting daylight saving time related problems.
 * And finally thanks to Lukas for providing a patch to correct the wrong
 * calculation of recurrent dates after a turn of years.
 */
unsigned
recur_item_find_occurrence(long item_start, long item_dur, llist_t * item_exc,
                           int rpt_type, int rpt_freq, long rpt_until,
                           long day_start, unsigned *occurrence)
{
  struct date start_date;
  long diff, span;
  struct tm lt_day, lt_item, lt_item_day;
  time_t t;

  if (day_start < item_start - DAYINSEC + 1)
    return 0;

  if (rpt_until != 0 && day_start >= rpt_until + item_dur)
    return 0;

  t = day_start;
  localtime_r(&t, &lt_day);

  t = item_start;
  localtime_r(&t, &lt_item);

  lt_item_day = lt_item;
  lt_item_day.tm_sec = lt_item_day.tm_min = lt_item_day.tm_hour = 0;

  span = (item_start - mktime(&lt_item_day) + item_dur - 1) / DAYINSEC;

  switch (rpt_type) {
  case RECUR_DAILY:
    diff = diff_days(lt_item_day, lt_day) % rpt_freq;
    lt_item_day.tm_mday = lt_day.tm_mday - diff;
    lt_item_day.tm_mon = lt_day.tm_mon;
    lt_item_day.tm_year = lt_day.tm_year;
    break;
  case RECUR_WEEKLY:
    diff = diff_days(lt_item_day, lt_day) % (rpt_freq * WEEKINDAYS);
    lt_item_day.tm_mday = lt_day.tm_mday - diff;
    lt_item_day.tm_mon = lt_day.tm_mon;
    lt_item_day.tm_year = lt_day.tm_year;
    break;
  case RECUR_MONTHLY:
    diff = diff_months(lt_item_day, lt_day) % rpt_freq;
    if (lt_day.tm_mday < lt_item_day.tm_mday)
      diff++;
    lt_item_day.tm_mon = lt_day.tm_mon - diff;
    lt_item_day.tm_year = lt_day.tm_year;
    break;
  case RECUR_YEARLY:
    diff = diff_years(lt_item_day, lt_day) % rpt_freq;
    if (lt_day.tm_mon < lt_item_day.tm_mon ||
        (lt_day.tm_mon == lt_item_day.tm_mon &&
         lt_day.tm_mday < lt_item_day.tm_mday))
      diff++;
    lt_item_day.tm_year = lt_day.tm_year - diff;
    break;
  default:
    EXIT(_("unknown item type"));
  }

  lt_item_day.tm_isdst = lt_day.tm_isdst;
  t = mktime(&lt_item_day);

  if (LLIST_FIND_FIRST(item_exc, &t, exc_inday))
    return 0;

  if (rpt_until != 0 && t > rpt_until)
    return 0;

  localtime_r(&t, &lt_item_day);
  diff = diff_days(lt_item_day, lt_day);

  if (diff <= span) {
    if (occurrence) {
      start_date.dd = lt_item_day.tm_mday;
      start_date.mm = lt_item_day.tm_mon + 1;
      start_date.yyyy = lt_item_day.tm_year + 1900;

      *occurrence = date2sec(start_date, lt_item.tm_hour, lt_item.tm_min);
    }

    return 1;
  } else
    return 0;
}

unsigned
recur_apoint_find_occurrence(struct recur_apoint *rapt, long day_start,
                             unsigned *occurrence)
{
  return recur_item_find_occurrence(rapt->start, rapt->dur, &rapt->exc,
                                    rapt->rpt->type, rapt->rpt->freq,
                                    rapt->rpt->until, day_start, occurrence);
}

unsigned
recur_event_find_occurrence(struct recur_event *rev, long day_start,
                            unsigned *occurrence)
{
  return recur_item_find_occurrence(rev->day, DAYINSEC, &rev->exc,
                                    rev->rpt->type, rev->rpt->freq,
                                    rev->rpt->until, day_start, occurrence);
}

/* Check if a recurrent item belongs to the selected day. */
unsigned
recur_item_inday(long item_start, long item_dur, llist_t * item_exc,
                 int rpt_type, int rpt_freq, long rpt_until, long day_start)
{
  /* We do not need the (real) start time of the occurrence here, so just
   * ignore the buffer. */
  return recur_item_find_occurrence(item_start, item_dur, item_exc, rpt_type,
                                    rpt_freq, rpt_until, day_start, NULL);
}

unsigned recur_apoint_inday(struct recur_apoint *rapt, long *day_start)
{
  return recur_item_inday(rapt->start, rapt->dur, &rapt->exc, rapt->rpt->type,
                          rapt->rpt->freq, rapt->rpt->until, *day_start);
}

unsigned recur_event_inday(struct recur_event *rev, long *day_start)
{
  return recur_item_inday(rev->day, DAYINSEC, &rev->exc, rev->rpt->type,
                          rev->rpt->freq, rev->rpt->until, *day_start);
}

/* Add an exception to a recurrent event. */
void
recur_event_add_exc(struct recur_event *rev, long date)
{
  recur_add_exc(&rev->exc, date);
}

/* Add an exception to a recurrent appointment. */
void
recur_apoint_add_exc(struct recur_apoint *rapt, long date)
{
  int need_check_notify = 0;

  if (notify_bar())
    need_check_notify = notify_same_recur_item(rapt);
  recur_add_exc(&rapt->exc, date);
  if (need_check_notify)
    notify_check_next_app(0);
}

/*
 * Delete a recurrent event from the list (if delete_whole is not null),
 * or delete only one occurence of the recurrent event.
 */
void
recur_event_erase(struct recur_event *rev)
{
  llist_item_t *i = LLIST_FIND_FIRST(&recur_elist, rev, NULL);

  if (!i)
    EXIT(_("event not found"));

  LLIST_REMOVE(&recur_elist, i);
}

/*
 * Delete a recurrent appointment from the list (if delete_whole is not null),
 * or delete only one occurence of the recurrent appointment.
 */
void
recur_apoint_erase(struct recur_apoint *rapt)
{
  LLIST_TS_LOCK(&recur_alist_p);

  llist_item_t *i = LLIST_TS_FIND_FIRST(&recur_alist_p, rapt, NULL);
  int need_check_notify = 0;

  if (!i)
    EXIT(_("appointment not found"));

  if (notify_bar())
    need_check_notify = notify_same_recur_item(rapt);
  LLIST_TS_REMOVE(&recur_alist_p, i);
  if (need_check_notify)
    notify_check_next_app(0);

  LLIST_TS_UNLOCK(&recur_alist_p);
}

/*
 * Read days for which recurrent items must not be repeated
 * (such days are called exceptions).
 */
void recur_exc_scan(llist_t * lexc, FILE * data_file)
{
  int c = 0;
  struct tm day;

  LLIST_INIT(lexc);
  while ((c = getc(data_file)) == '!') {
    ungetc(c, data_file);
    if (fscanf(data_file, "!%d / %d / %d ",
               &day.tm_mon, &day.tm_mday, &day.tm_year) != 3) {
      EXIT(_("syntax error in item date"));
    }
    day.tm_hour = 0;
    day.tm_min = day.tm_sec = 0;
    day.tm_isdst = -1;
    day.tm_year -= 1900;
    day.tm_mon--;
    struct excp *exc = mem_malloc(sizeof(struct excp));
    exc->st = mktime(&day);
    LLIST_ADD(lexc, exc);
  }
}

static int recur_apoint_starts_before(struct recur_apoint *rapt, long time)
{
  return rapt->start < time;
}

/*
 * Look in the appointment list if we have an item which starts before the item
 * stored in the notify_app structure (which is the next item to be notified).
 */
struct notify_app *recur_apoint_check_next(struct notify_app *app, long start,
                                           long day)
{
  llist_item_t *i;
  unsigned real_recur_start_time;

  LLIST_TS_LOCK(&recur_alist_p);
  LLIST_TS_FIND_FOREACH(&recur_alist_p, &app->time, recur_apoint_starts_before,
                        i) {
    struct recur_apoint *rapt = LLIST_TS_GET_DATA(i);

    if (recur_apoint_find_occurrence(rapt, day, &real_recur_start_time) &&
        real_recur_start_time > start) {
      app->time = real_recur_start_time;
      app->txt = mem_strdup(rapt->mesg);
      app->state = rapt->state;
      app->got_app = 1;
    }
  }
  LLIST_TS_UNLOCK(&recur_alist_p);

  return app;
}

/* Switch recurrent item notification state. */
void recur_apoint_switch_notify(struct recur_apoint *rapt)
{
  LLIST_TS_LOCK(&recur_alist_p);

  rapt->state ^= APOINT_NOTIFY;
  if (notify_bar())
    notify_check_repeated(rapt);

  LLIST_TS_UNLOCK(&recur_alist_p);
}

void recur_event_paste_item(struct recur_event *rev, long date)
{
  long time_shift;
  llist_item_t *i;

  time_shift = date - rev->day;
  rev->day += time_shift;

  if (rev->rpt->until != 0)
    rev->rpt->until += time_shift;

  LLIST_FOREACH(&rev->exc, i) {
    struct excp *exc = LLIST_GET_DATA(i);
    exc->st += time_shift;
  }

  LLIST_ADD_SORTED(&recur_elist, rev, recur_event_cmp_day);
}

void recur_apoint_paste_item(struct recur_apoint *rapt, long date)
{
  long time_shift;
  llist_item_t *i;

  time_shift = (date + get_item_time(rapt->start)) - rapt->start;
  rapt->start += time_shift;

  if (rapt->rpt->until != 0)
    rapt->rpt->until += time_shift;

  LLIST_FOREACH(&rapt->exc, i) {
    struct excp *exc = LLIST_GET_DATA(i);
    exc->st += time_shift;
  }

  LLIST_TS_LOCK(&recur_alist_p);
  LLIST_TS_ADD_SORTED(&recur_alist_p, rapt, recur_apoint_cmp_start);
  LLIST_TS_UNLOCK(&recur_alist_p);

  if (notify_bar())
    notify_check_repeated(rapt);
}