From 71dea696eda9d52d73e68d2263a73daf02df9b5e Mon Sep 17 00:00:00 2001
From: guilhermeb <guilherme.barreto@retarus.pt>
Date: Tue, 11 Jun 2024 09:31:39 +0200
Subject: [PATCH] Fixed #15818 - Fix calendar range selection shown date

---
 src/app/components/calendar/calendar.spec.ts | 39 ++++++++++++++++++++
 src/app/components/calendar/calendar.ts      |  2 +-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/src/app/components/calendar/calendar.spec.ts b/src/app/components/calendar/calendar.spec.ts
index 861b9c3bac7..72ff5f1f022 100755
--- a/src/app/components/calendar/calendar.spec.ts
+++ b/src/app/components/calendar/calendar.spec.ts
@@ -2018,4 +2018,43 @@ describe('Calendar', () => {
         expect(selectdateSpy).toHaveBeenCalled();
         expect(calendar.value).toEqual(minDate);
     });
+
+    it('should display end date instead of start date in range selection', () => {
+        calendar.selectionMode = 'range';
+        calendar.value = [new Date('2024-03-01'), new Date('2024-04-01')];
+
+        calendar.updateUI();
+        expect(calendar.currentMonth).toBe(3);
+        expect(calendar.currentYear).toBe(2024);
+    });
+
+    it('should display start date instead of default date in range selection', () => {
+        calendar.selectionMode = 'range';
+        calendar.value = [new Date('2024-03-01'), null];
+
+        calendar.updateUI();
+        expect(calendar.currentMonth).toBe(2);
+        expect(calendar.currentYear).toBe(2024);
+    });
+
+    it('should use default date when no range is selected in range selection', () => {
+        calendar.selectionMode = 'range';
+        calendar.defaultDate = new Date('2024-01-01');
+
+        calendar.updateUI();
+        expect(calendar.currentMonth).toBe(0);
+        expect(calendar.currentYear).toBe(2024);
+    });
+
+    it('should use current date when no default date and no range is selected in range selection', () => {
+        jasmine.clock().install();
+        jasmine.clock().mockDate(new Date('2024-06-11'));
+        calendar.selectionMode = 'range';
+
+        calendar.updateUI();
+        expect(calendar.currentMonth).toBe(5);
+        expect(calendar.currentYear).toBe(2024);
+
+        jasmine.clock().uninstall();
+    });
 });
diff --git a/src/app/components/calendar/calendar.ts b/src/app/components/calendar/calendar.ts
index e9f45cfdca1..5d181410f6f 100644
--- a/src/app/components/calendar/calendar.ts
+++ b/src/app/components/calendar/calendar.ts
@@ -2958,7 +2958,7 @@ export class Calendar implements OnInit, OnDestroy, ControlValueAccessor {
     updateUI() {
         let propValue = this.value;
         if (Array.isArray(propValue)) {
-            propValue = propValue.length === 2 ? propValue[1] : propValue[0];
+            propValue = propValue[1] || propValue[0];
         }
 
         let val = this.defaultDate && this.isValidDate(this.defaultDate) && !this.value ? this.defaultDate : propValue && this.isValidDate(propValue) ? propValue : new Date();