Support durations in recurrence ending dates

When spending the end date of recurring items, allow date duration
specifiers such as "+5d" or "+3w2d".

Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

src/calcurse.h

@@ -1113,6 +1113,7 @@ time_t date2sec(struct date, unsigned, unsigned);
 time_t utcdate2sec(struct date, unsigned, unsigned);
 char *date_sec2date_str(long, const char *);
 void date_sec2date_fmt(long, const char *, char *);
+int date_change(struct tm *, int, int);
 long date_sec_change(long, int, int);
 long update_time_in_date(long, unsigned, unsigned);
 time_t get_sec_date(struct date);
@@ -1131,6 +1132,7 @@ int parse_date(const char *, enum datefmt, int *, int *, int *,
 int check_time(unsigned, unsigned);
 int parse_time(const char *, unsigned *, unsigned *);
 int parse_duration(const char *, unsigned *);
+int parse_date_duration(const char *, unsigned *);
 void file_close(FILE *, const char *);
 void psleep(unsigned);
 int fork_exec(int *, int *, const char *, const char *const *);

src/ui-calendar.c

@@ -256,26 +256,6 @@ static long ymd_to_scalar(unsigned year, unsigned month, unsigned day)
 	return scalar;
 }
 
-/*
- * Used to change date by adding a certain amount of days or weeks.
- * Returns 0 on success, 1 otherwise.
- */
-static int date_change(struct tm *date, int delta_month, int delta_day)
-{
-	struct tm t;
-
-	t = *date;
-	t.tm_mon += delta_month;
-	t.tm_mday += delta_day;
-
-	if (mktime(&t) == -1) {
-		return 1;
-	} else {
-		*date = t;
-		return 0;
-	}
-}
-
 void ui_calendar_monthly_view_cache_set_invalid(void)
 {
 	monthly_view_cache_valid = 0;

src/ui-day.c

@@ -254,6 +254,7 @@ static void update_rept(struct rpt **rpt, const long start)
 		time_t t;
 		struct date new_date;
 		int newmonth, newday, newyear;
+		unsigned days;
 
 		asprintf(&outstr, _("Enter the new ending date: [%s] or '0'"),
 			 DATEFMT_DESC(conf.input_datefmt));
@@ -270,21 +271,38 @@ static void update_rept(struct rpt **rpt, const long start)
 			newuntil = 0;
 			break;
 		}
-		if (!parse_date
-		    (timstr, conf.input_datefmt, &newyear, &newmonth,
-		     &newday, ui_calendar_get_slctd_day())) {
-			asprintf(&outstr, msg_fmts,
-				 DATEFMT_DESC(conf.input_datefmt));
-			status_mesg(msg_wrong_date, outstr);
-			mem_free(outstr);
-			wgetch(win[KEY].p);
-			continue;
+		if (*timstr == '+') {
+			if (!parse_date_duration(timstr + 1, &days)) {
+				asprintf(&outstr, msg_fmts,
+					 DATEFMT_DESC(conf.input_datefmt));
+				status_mesg(msg_wrong_date, outstr);
+				mem_free(outstr);
+				wgetch(win[KEY].p);
+				continue;
+			}
+			t = start;
+			localtime_r(&t, &lt);
+			date_change(&lt, 0, days);
+			new_date.dd = lt.tm_mday;
+			new_date.mm = lt.tm_mon + 1;
+			new_date.yyyy = lt.tm_year + 1900;
+		} else {
+			if (!parse_date(timstr, conf.input_datefmt, &newyear,
+					&newmonth, &newday,
+					ui_calendar_get_slctd_day())) {
+				asprintf(&outstr, msg_fmts,
+					 DATEFMT_DESC(conf.input_datefmt));
+				status_mesg(msg_wrong_date, outstr);
+				mem_free(outstr);
+				wgetch(win[KEY].p);
+				continue;
+			}
+			t = start;
+			localtime_r(&t, &lt);
+			new_date.dd = newday;
+			new_date.mm = newmonth;
+			new_date.yyyy = newyear;
 		}
-		t = start;
-		localtime_r(&t, &lt);
-		new_date.dd = newday;
-		new_date.mm = newmonth;
-		new_date.yyyy = newyear;
 		newuntil = date2sec(new_date, lt.tm_hour, lt.tm_min);
 		if (newuntil >= start)
 			break;

src/utils.c

@@ -453,6 +453,26 @@ void date_sec2date_fmt(long sec, const char *fmt, char *datef)
 #endif
 }
 
+/*
+ * Used to change date by adding a certain amount of days or weeks.
+ * Returns 0 on success, 1 otherwise.
+ */
+int date_change(struct tm *date, int delta_month, int delta_day)
+{
+	struct tm t;
+
+	t = *date;
+	t.tm_mon += delta_month;
+	t.tm_mday += delta_day;
+
+	if (mktime(&t) == -1) {
+		return 1;
+	} else {
+		*date = t;
+		return 0;
+	}
+}
+
 /*
  * Used to change date by adding a certain amount of days or weeks.
  */
@@ -839,6 +859,77 @@ parse_date(const char *date_string, enum datefmt datefmt, int *year,
 	return 1;
 }
 
+/*
+ * Convert a date duration string into a number of days.
+ *
+ * Returns 1 on success and 0 on failure.
+ */
+int parse_date_duration(const char *string, unsigned *days)
+{
+	enum {
+		STATE_INITIAL,
+		STATE_WWDD_DD,
+		STATE_DONE
+	} state = STATE_INITIAL;
+
+	const char *p;
+	unsigned in = 0, frac = 0, denom = 1;
+	unsigned dur = 0;
+
+	if (!string || *string == '\0')
+		return 0;
+
+	/* parse string using a simple state machine */
+	for (p = string; *p; p++) {
+		if (state == STATE_DONE) {
+			return 0;
+		} else if ((*p >= '0') && (*p <= '9')) {
+			in = in * 10 + (int)(*p - '0');
+			if (frac)
+				denom *= 10;
+		} else if (*p == '.') {
+			if (frac)
+				return 0;
+			frac++;
+		} else {
+			switch (state) {
+			case STATE_INITIAL:
+				if (*p == 'w') {
+					dur += in * WEEKINDAYS / denom;
+					state = STATE_WWDD_DD;
+				} else if (*p == 'd') {
+					dur += in / denom;
+					state = STATE_DONE;
+				} else {
+					return 0;
+				}
+				break;
+			case STATE_WWDD_DD:
+				if (*p == 'd') {
+					dur += in / denom;
+					state = STATE_DONE;
+				} else {
+					return 0;
+				}
+				break;
+			default:
+				break;
+			}
+
+			in = frac = 0;
+			denom = 1;
+		}
+	}
+
+	if (state == STATE_DONE && in > 0)
+		return 0;
+
+	dur += in;
+	*days = dur;
+
+	return 1;
+}
+
 /*
  * Check if time is valid.
  */