From 407d4e1d4e96461087bfee99c5a770ef2dc0593b Mon Sep 17 00:00:00 2001
From: Milan Crha <mcrha@redhat.com>
Date: Tue, 22 Aug 2017 13:29:25 +0200
Subject: [PATCH] [ECompEditor] Preserve original duration when changing time

When changing start time after end or end time before start, the other
time had been modified to be one hour duration. This change uses the original
duration instead, if possible.

Reported downstream at:
https://bugzilla.redhat.com/show_bug.cgi?id=1480029
---
 src/calendar/gui/e-comp-editor.c | 47 ++++++++++++++++++++++++++++----
 1 file changed, 41 insertions(+), 6 deletions(-)

diff --git a/src/calendar/gui/e-comp-editor.c b/src/calendar/gui/e-comp-editor.c
index 391b9105d5..8a43cbc43a 100644
--- a/src/calendar/gui/e-comp-editor.c
+++ b/src/calendar/gui/e-comp-editor.c
@@ -3151,14 +3151,36 @@ e_comp_editor_add_error (ECompEditor *comp_editor,
 
 
 static gboolean
-ece_check_start_before_end (struct icaltimetype *start_tt,
+ece_check_start_before_end (ECompEditor *comp_editor,
+			    struct icaltimetype *start_tt,
 			    struct icaltimetype *end_tt,
 			    gboolean adjust_end_time)
 {
 	struct icaltimetype end_tt_copy;
 	icaltimezone *start_zone, *end_zone;
+	gint duration = -1;
 	gint cmp;
 
+	if ((e_comp_editor_get_flags (comp_editor) & E_COMP_EDITOR_FLAG_IS_NEW) == 0) {
+		icalcomponent *icomp;
+
+		icomp = e_comp_editor_get_component (comp_editor);
+		if (icomp &&
+		    icalcomponent_get_first_property (icomp, ICAL_DTSTART_PROPERTY) &&
+		    (icalcomponent_get_first_property (icomp, ICAL_DTEND_PROPERTY) ||
+		     icalcomponent_get_first_property (icomp, ICAL_DUE_PROPERTY))) {
+			struct icaltimetype orig_start, orig_end;
+
+			orig_start = icalcomponent_get_dtstart (icomp);
+			orig_end = icalcomponent_get_dtend (icomp);
+
+			if (icaltime_is_valid_time (orig_start) &&
+			    icaltime_is_valid_time (orig_end)) {
+				duration = icaltime_as_timet (orig_end) - icaltime_as_timet (orig_start);
+			}
+		}
+	}
+
 	start_zone = (icaltimezone *) start_tt->zone;
 	end_zone = (icaltimezone *) end_tt->zone;
 
@@ -3182,10 +3204,18 @@ ece_check_start_before_end (struct icaltimetype *start_tt,
 			if (start_zone && end_zone && start_zone != end_zone)
 				icaltimezone_convert_time (&end_tt_copy, end_zone, start_zone);
 
+			if (duration > 0)
+				icaltime_adjust (&end_tt_copy, 0, 0, 0, -duration);
+
 			if (icaltime_compare (*start_tt, end_tt_copy) >= 0) {
-				/* Modify the end time, to be the start + 1 hour/day. */
 				*end_tt = *start_tt;
-				icaltime_adjust (end_tt, 0, start_tt->is_date ? 24 : 1, 0, 0);
+
+				if (duration >= 0) {
+					icaltime_adjust (end_tt, 0, 0, 0, duration);
+				} else {
+					/* Modify the end time, to be the start + 1 hour/day. */
+					icaltime_adjust (end_tt, 0, start_tt->is_date ? 24 : 1, 0, 0);
+				}
 
 				if (start_zone && end_zone && start_zone != end_zone)
 					icaltimezone_convert_time (end_tt, start_zone, end_zone);
@@ -3197,9 +3227,14 @@ ece_check_start_before_end (struct icaltimetype *start_tt,
 			start_tt->day = end_tt->day;
 
 			if (icaltime_compare (*start_tt, end_tt_copy) >= 0) {
-				/* Modify the start time, to be the end - 1 hour/day. */
 				*start_tt = *end_tt;
-				icaltime_adjust (start_tt, 0, start_tt->is_date ? -24 : -1, 0, 0);
+
+				if (duration >= 0) {
+					icaltime_adjust (start_tt, 0, 0, 0, -duration);
+				} else {
+					/* Modify the start time, to be the end - 1 hour/day. */
+					icaltime_adjust (start_tt, 0, start_tt->is_date ? -24 : -1, 0, 0);
+				}
 
 				if (start_zone && end_zone && start_zone != end_zone)
 					icaltimezone_convert_time (start_tt, end_zone, start_zone);
@@ -3258,7 +3293,7 @@ e_comp_editor_ensure_start_before_end (ECompEditor *comp_editor,
 			}
 		}
 	} else {
-		if (ece_check_start_before_end (&start_tt, &end_tt, change_end_datetime)) {
+		if (ece_check_start_before_end (comp_editor, &start_tt, &end_tt, change_end_datetime)) {
 			if (change_end_datetime)
 				set_dtend = TRUE;
 			else