From 95151e3f0c2a9935abe6e498fd056a57075ea0c5 Mon Sep 17 00:00:00 2001
From: Lars Henriksen <LarsHenriksen@get2net.dk>
Date: Wed, 7 Oct 2020 19:51:18 +0200
Subject: Add p(revious) command

The p(rev) command finds the previous occurrence of a recurrent item, analogous
to the n(ext) command.

A bug in the next command is corrected..

Signed-off-by: Lars Henriksen <LarsHenriksen@get2net.dk>
Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>
---
 src/calcurse.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
 src/calcurse.h |  1 +
 src/recur.c    | 24 ++++++++++++++++++++++++
 3 files changed, 74 insertions(+), 3 deletions(-)

diff --git a/src/calcurse.c b/src/calcurse.c
index 8a65fba..3083f86 100644
--- a/src/calcurse.c
+++ b/src/calcurse.c
@@ -557,7 +557,8 @@ static inline void key_generic_cmd(void)
 	int valid = 0, force = 0, ret;
 	char *error_msg;
 
-	status_mesg(_("Command: [ h(elp) | w(rite)(!) | q(uit)(!) | wq(!) | n(ext) ]"), "");
+	status_mesg(_("Command: "
+		"[ h(elp) | w(rite)(!) | q(uit)(!) | wq(!) | n(ext) | p(rev) ]"), "");
 	if (getstring(win[STA].p, cmd, BUFSIZ, 0, 1) != GETSTRING_VALID)
 		goto cleanup;
 	cmd_name = strtok(cmd, " ");
@@ -638,17 +639,62 @@ static inline void key_generic_cmd(void)
 			goto cleanup;
 		}
 		if (!more) {
-			error_msg = _("Last repetition.");
+			error_msg = _("Last occurrence.");
 			warnbox(error_msg);
 			goto cleanup;
 		}
-		item->start = next;
+		item->order = next;
 		ui_calendar_set_slctd_day(sec2date(next));
 		day_set_sel_data(item);
 		do_storage(1);
 
 		valid = 1;
 	}
+	if (!strcmp(cmd_name, "prev") || !strcmp(cmd_name, "p")) {
+		struct day_item *item;
+		time_t day, prev;
+		struct recur_apoint *rapt;
+		struct recur_event *rev;
+		int more = 0;
+
+		if (wins_slctd() != APP) {
+			error_msg = _("Select a repeating item in the"
+				" appointments panel.");
+			warnbox(error_msg);
+			goto cleanup;
+		}
+		item = ui_day_get_sel();
+		/*
+		 * The selected day need not be the (item) start day
+		 * for multi-day occurrences.
+		 */
+		day = update_time_in_date(item->start, 0, 0);
+		if (item->type == RECUR_EVNT) {
+			rev = item->item.rev;
+			more = recur_prev_occurrence(rev->day, -1, rev->rpt,
+						     &rev->exc, day, &prev);
+		} else if (item->type == RECUR_APPT) {
+			rapt = item->item.rapt;
+			more = recur_prev_occurrence(rapt->start, rapt->dur,
+						     rapt->rpt, &rapt->exc,
+						     day, &prev);
+		} else {
+			error_msg = _("Not a repeating item.");
+			warnbox(error_msg);
+			goto cleanup;
+		}
+		if (!more) {
+			error_msg = _("First occurrence.");
+			warnbox(error_msg);
+			goto cleanup;
+		}
+		item->order = prev;
+		ui_calendar_set_slctd_day(sec2date(prev));
+		day_set_sel_data(item);
+		do_storage(1);
+
+		valid = 1;
+	}
 
 	if (!valid) {
 		asprintf(&error_msg, _("No such command: %s"), cmd);
diff --git a/src/calcurse.h b/src/calcurse.h
index 39a2af1..dca9d8b 100644
--- a/src/calcurse.h
+++ b/src/calcurse.h
@@ -1105,6 +1105,7 @@ void recur_event_paste_item(struct recur_event *, time_t);
 void recur_apoint_paste_item(struct recur_apoint *, time_t);
 int recur_next_occurrence(time_t, long, struct rpt *, llist_t *, time_t, time_t *);
 int recur_nth_occurrence(time_t, long, struct rpt *, llist_t *, int, time_t *);
+int recur_prev_occurrence(time_t, long, struct rpt *, llist_t *, time_t, time_t *);
 
 
 /* sigs.c */
diff --git a/src/recur.c b/src/recur.c
index 3c93de2..3a16d1e 100644
--- a/src/recur.c
+++ b/src/recur.c
@@ -1846,3 +1846,27 @@ int recur_nth_occurrence(time_t s, long d, struct rpt *r, llist_t *e, int n,
 	}
 	return !n;
 }
+
+/*
+ * Finds the previous occurrence - the most recent before day - and returns it
+ * in the provided buffer.
+ */
+int recur_prev_occurrence(time_t s, long d, struct rpt *r, llist_t *e,
+			  time_t day, time_t *prev)
+{
+	time_t prev_day, next;
+
+	if (day <= update_time_in_date(s, 0, 0))
+		return 0;
+	next = *prev = s;
+	while (update_time_in_date(next, 0, 0) < day) {
+		/* Set new previous and next. */
+		*prev = next;
+		prev_day = update_time_in_date(*prev, 0, 0);
+		recur_next_occurrence(s, d, r, e, prev_day, &next);
+		/* Multi-day appointment */
+		if (next == *prev)
+			next = NEXTDAY(*prev);
+	}
+	return 1;
+}
-- 
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