From 16f26db852ccd7be15e257a3d5bb7c21cf9db649 Mon Sep 17 00:00:00 2001
From: mdlufy <german.panov.2018@mail.ru>
Date: Tue, 8 Oct 2024 17:10:31 +0300
Subject: [PATCH] fix(kit): `CalendarRange` show actual `defaultViewedMonth`

---
 .../primitive-calendar-range.component.ts     | 30 +++++++++++++++----
 ...primitive-calendar-range.component.spec.ts | 16 ++++++++++
 2 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/projects/kit/internal/primitive-calendar-range/primitive-calendar-range.component.ts b/projects/kit/internal/primitive-calendar-range/primitive-calendar-range.component.ts
index e05159e0a046..22f0674938bd 100644
--- a/projects/kit/internal/primitive-calendar-range/primitive-calendar-range.component.ts
+++ b/projects/kit/internal/primitive-calendar-range/primitive-calendar-range.component.ts
@@ -5,10 +5,12 @@ import {
     EventEmitter,
     Inject,
     Input,
+    OnChanges,
     OnInit,
     Optional,
     Output,
     Self,
+    SimpleChanges,
 } from '@angular/core';
 import {
     ALWAYS_FALSE_HANDLER,
@@ -37,7 +39,7 @@ import {takeUntil} from 'rxjs/operators';
     changeDetection: ChangeDetectionStrategy.OnPush,
     providers: [TuiDestroyService],
 })
-export class TuiPrimitiveCalendarRangeComponent implements OnInit {
+export class TuiPrimitiveCalendarRangeComponent implements OnInit, OnChanges {
     @Input()
     disabledItemHandler: TuiBooleanHandler<TuiDay> = ALWAYS_FALSE_HANDLER;
 
@@ -99,6 +101,16 @@ export class TuiPrimitiveCalendarRangeComponent implements OnInit {
     monthOffset: TuiTypedMapper<[TuiMonth, number], TuiMonth> = (value, offset) =>
         value.append({month: offset});
 
+    ngOnChanges({
+        defaultViewedMonthFirst,
+        defaultViewedMonthSecond,
+    }: SimpleChanges): void {
+        this.updateViewedMonths(
+            defaultViewedMonthFirst?.currentValue,
+            defaultViewedMonthSecond?.currentValue,
+        );
+    }
+
     ngOnInit(): void {
         this.setInitialMonths();
     }
@@ -157,10 +169,18 @@ export class TuiPrimitiveCalendarRangeComponent implements OnInit {
         return month;
     }
 
-    private updateViewedMonths(): void {
-        this.userViewedMonthFirst =
-            this.value === null ? this.defaultViewedMonthFirst : this.value.from;
+    private updateViewedMonths(firstMonth?: TuiMonth, secondMonth?: TuiMonth): void {
+        if (this.value) {
+            this.userViewedMonthFirst = this.value.from;
+            this.userViewedMonthSecond = this.userViewedMonthFirst.append({month: 1});
+        } else {
+            this.userViewedMonthSecond = this.updatedViewedMonthSecond(
+                secondMonth ?? this.userViewedMonthSecond,
+            );
 
-        this.userViewedMonthSecond = this.userViewedMonthFirst.append({month: 1});
+            this.userViewedMonthFirst = this.updatedViewedMonthFirst(
+                firstMonth ?? this.userViewedMonthFirst,
+            );
+        }
     }
 }
diff --git a/projects/kit/internal/primitive-calendar-range/test/primitive-calendar-range.component.spec.ts b/projects/kit/internal/primitive-calendar-range/test/primitive-calendar-range.component.spec.ts
index d8c8c3e9f32e..89171c221365 100644
--- a/projects/kit/internal/primitive-calendar-range/test/primitive-calendar-range.component.spec.ts
+++ b/projects/kit/internal/primitive-calendar-range/test/primitive-calendar-range.component.spec.ts
@@ -141,4 +141,20 @@ describe('PrimitiveRangeCalendar component', () => {
             expect(component.cappedUserViewedMonthSecond).toBe(day);
         });
     });
+
+    it('When handle any changes, current viewed month do not updates', () => {
+        const date = TuiMonth.currentLocal().append({month: 3});
+
+        component.userViewedMonthFirst = date;
+        component.userViewedMonthSecond = date.append({month: 1});
+
+        component.markerHandler = (day: TuiDay) =>
+            day.day % 2 === 0 ? ['first'] : ['second'];
+        component.ngOnChanges({});
+
+        expect(component.userViewedMonthFirst.toString()).toBe(date.toString());
+        expect(component.userViewedMonthSecond.toString()).toBe(
+            date.append({month: 1}).toString(),
+        );
+    });
 });