fix(datetime): do not animate to new value when multiple values in different months are set (#28847)

Issue number: resolves #28602

---------

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## What is the current behavior?
<!-- Please describe the current behavior that you are modifying. -->

We animate to the new date when the value is changed, but we do not
account for multiple selection. This behavior is valuable for when the
value is set asynchronously on a different month than what it shown.

However, this is confusing when there are multiple dates selected in
different months, because we do not reasonably know which date to
animate to.

## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

Datetime no longer animates to the new value if more than one date is
selected, and the selected dates aren't all in the same month.

An alternative strategy would be to always animate unless one of the
selected dates is in the month currently being viewed. However, this
would still mean guessing at which value the user wants to see, which we
are trying to avoid.

Based on this PR:
#28605

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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screenshots of how the component looks before and after the change. -->

Co-authored-by: Liam DeBeasi <[email protected]>

---------

Co-authored-by: Liam DeBeasi <[email protected]>

Author: averyjohnston

core/src/components/datetime/datetime.tsx

@@ -1284,21 +1284,42 @@ export class Datetime implements ComponentInterface {
       (month !== undefined && month !== workingParts.month) || (year !== undefined && year !== workingParts.year);
     const bodyIsVisible = el.classList.contains('datetime-ready');
     const { isGridStyle, showMonthAndYear } = this;
-    if (isGridStyle && didChangeMonth && bodyIsVisible && !showMonthAndYear) {
-      this.animateToDate(targetValue);
-    } else {
-      /**
-       * We only need to do this if we didn't just animate to a new month,
-       * since that calls prevMonth/nextMonth which calls setWorkingParts for us.
-       */
-      this.setWorkingParts({
-        month,
-        day,
-        year,
-        hour,
-        minute,
-        ampm,
-      });
+
+    let areAllSelectedDatesInSameMonth = true;
+    if (Array.isArray(valueToProcess)) {
+      const firstMonth = valueToProcess[0].month;
+      for (const date of valueToProcess) {
+        if (date.month !== firstMonth) {
+          areAllSelectedDatesInSameMonth = false;
+          break;
+        }
+      }
+    }
+
+    /**
+     * If there is more than one date selected
+     * and the dates aren't all in the same month,
+     * then we should neither animate to the date
+     * nor update the working parts because we do
+     * not know which date the user wants to view.
+     */
+    if (areAllSelectedDatesInSameMonth) {
+      if (isGridStyle && didChangeMonth && bodyIsVisible && !showMonthAndYear) {
+        this.animateToDate(targetValue);
+      } else {
+        /**
+         * We only need to do this if we didn't just animate to a new month,
+         * since that calls prevMonth/nextMonth which calls setWorkingParts for us.
+         */
+        this.setWorkingParts({
+          month,
+          day,
+          year,
+          hour,
+          minute,
+          ampm,
+        });
+      }
     }
   };
 

core/src/components/datetime/test/multiple/datetime.e2e.ts

@@ -5,7 +5,7 @@ import { configs, test } from '@utils/test/playwright';
 
 const SINGLE_DATE = '2022-06-01';
 const MULTIPLE_DATES = ['2022-06-01', '2022-06-02', '2022-06-03'];
-const MULTIPLE_DATES_SEPARATE_MONTHS = ['2022-04-01', '2022-05-01', '2022-06-01'];
+const MULTIPLE_DATES_SEPARATE_MONTHS = ['2022-03-01', '2022-04-01', '2022-05-01'];
 
 interface DatetimeMultipleConfig {
   multiple?: boolean;
@@ -158,10 +158,32 @@ configs({ modes: ['md'], directions: ['ltr'] }).forEach(({ title, config }) => {
       });
     });
 
-    test('multiple default values across months should display at least one value', async () => {
+    test('should scroll to new month when value is updated with multiple dates in the same month', async ({ page }) => {
+      test.info().annotations.push({
+        type: 'issue',
+        description: 'https://github.com/ionic-team/ionic-framework/issues/28602',
+      });
       const datetime = await datetimeFixture.goto(config, MULTIPLE_DATES_SEPARATE_MONTHS);
+      await datetime.evaluate((el: HTMLIonDatetimeElement, dates: string[]) => {
+        el.value = dates;
+      }, MULTIPLE_DATES);
+
+      await page.waitForChanges();
+
+      const monthYear = datetime.locator('.calendar-month-year');
+      await expect(monthYear).toHaveText(/June 2022/);
+    });
+
+    test('should not scroll to new month when value is updated with dates in different months', async ({ page }) => {
+      const datetime = await datetimeFixture.goto(config, MULTIPLE_DATES);
+      await datetime.evaluate((el: HTMLIonDatetimeElement, dates: string[]) => {
+        el.value = dates;
+      }, MULTIPLE_DATES_SEPARATE_MONTHS);
+
+      await page.waitForChanges();
+
       const monthYear = datetime.locator('.calendar-month-year');
-      await expect(monthYear).toHaveText(/April 2022/);
+      await expect(monthYear).toHaveText(/June 2022/);
     });
 
     test('with buttons, should only update value when confirm is called', async ({ page }) => {