[Controls] Debounce time slider selections (#201885)

## Summary

This PR fixes the [[Controls] Debounce time slider
selections](#193227) issue.

Previously when the user was dragging the time slider, the dashboard
would be updating constantly causing lagging on more complex dashboards.
This PR adds a local state that will hold the updating values while the
user is dragging, and updates the dashboards once the user stops
dragging with a delay of 300.


https://github.com/user-attachments/assets/45bca92e-f92a-4c1f-8417-a0a0818c7415

---------

Co-authored-by: Hannah Mudge <[email protected]>
Co-authored-by: kibanamachine <[email protected]>

src/plugins/controls/public/controls/timeslider_control/components/time_slider_popover_content.tsx

@@ -8,6 +8,8 @@
  */
 
 import React from 'react';
+import { useMemo, useEffect, useState } from 'react';
+import { debounce } from 'lodash';
 import { EuiButtonIcon, EuiRangeTick, EuiFlexGroup, EuiFlexItem, EuiToolTip } from '@elastic/eui';
 
 import { TimeSliderStrings } from './time_slider_strings';
@@ -27,29 +29,63 @@ interface Props {
   compressed: boolean;
 }
 
-export function TimeSliderPopoverContent(props: Props) {
-  const rangeInput = props.isAnchored ? (
+export function TimeSliderPopoverContent({
+  isAnchored,
+  setIsAnchored,
+  value,
+  onChange,
+  stepSize,
+  ticks,
+  timeRangeMin,
+  timeRangeMax,
+  compressed,
+}: Props) {
+  const [displayedValue, setDisplayedValue] = useState<Timeslice>(value);
+
+  const debouncedOnChange = useMemo(
+    () =>
+      debounce((updateTimeslice: Timeslice | undefined) => {
+        onChange(updateTimeslice);
+      }, 750),
+    [onChange]
+  );
+
+  /**
+   * The following `useEffect` ensures that the changes to the value that come from the embeddable (for example,
+   * from the `clear` button on the dashboard) are reflected in the displayed value
+   */
+  useEffect(() => {
+    setDisplayedValue(value);
+  }, [value]);
+
+  const rangeInput = isAnchored ? (
     <TimeSliderAnchoredRange
-      value={props.value}
-      onChange={props.onChange}
-      stepSize={props.stepSize}
-      ticks={props.ticks}
-      timeRangeMin={props.timeRangeMin}
-      timeRangeMax={props.timeRangeMax}
-      compressed={props.compressed}
+      value={[displayedValue[0] || timeRangeMin, displayedValue[1] || timeRangeMax]}
+      onChange={(newValue) => {
+        setDisplayedValue(newValue as Timeslice);
+        debouncedOnChange(newValue);
+      }}
+      stepSize={stepSize}
+      ticks={ticks}
+      timeRangeMin={timeRangeMin}
+      timeRangeMax={timeRangeMax}
+      compressed={compressed}
     />
   ) : (
     <TimeSliderSlidingWindowRange
-      value={props.value}
-      onChange={props.onChange}
-      stepSize={props.stepSize}
-      ticks={props.ticks}
-      timeRangeMin={props.timeRangeMin}
-      timeRangeMax={props.timeRangeMax}
-      compressed={props.compressed}
+      value={[displayedValue[0] || timeRangeMin, displayedValue[1] || timeRangeMax]}
+      onChange={(newValue) => {
+        setDisplayedValue(newValue as Timeslice);
+        debouncedOnChange(newValue);
+      }}
+      stepSize={stepSize}
+      ticks={ticks}
+      timeRangeMin={timeRangeMin}
+      timeRangeMax={timeRangeMax}
+      compressed={compressed}
     />
   );
-  const anchorStartToggleButtonLabel = props.isAnchored
+  const anchorStartToggleButtonLabel = isAnchored
     ? TimeSliderStrings.control.getUnpinStart()
     : TimeSliderStrings.control.getPinStart();
 
@@ -59,17 +95,24 @@ export function TimeSliderPopoverContent(props: Props) {
       gutterSize="none"
       data-test-subj="timeSlider-popoverContents"
       responsive={false}
+      onMouseUp={() => {
+        // when the pin is dropped (on mouse up), cancel any pending debounced changes and force the change
+        // in value to happen instantly (which, in turn, will re-calculate the from/to for the slider due to
+        // the `useEffect` above.
+        debouncedOnChange.cancel();
+        onChange(displayedValue);
+      }}
     >
       <EuiFlexItem grow={false}>
         <EuiToolTip content={anchorStartToggleButtonLabel} position="left">
           <EuiButtonIcon
-            iconType={props.isAnchored ? 'pinFilled' : 'pin'}
+            iconType={isAnchored ? 'pinFilled' : 'pin'}
             onClick={() => {
-              const nextIsAnchored = !props.isAnchored;
+              const nextIsAnchored = !isAnchored;
               if (nextIsAnchored) {
-                props.onChange([props.timeRangeMin, props.value[1]]);
+                onChange([timeRangeMin, value[1]]);
               }
-              props.setIsAnchored(nextIsAnchored);
+              setIsAnchored(nextIsAnchored);
             }}
             aria-label={anchorStartToggleButtonLabel}
             data-test-subj="timeSlider__anchorStartToggleButton"

src/plugins/controls/public/controls/timeslider_control/get_timeslider_control_factory.tsx

@@ -270,7 +270,6 @@ export const getTimesliderControlFactory = (): ControlFactory<
         Component: (controlPanelClassNames) => {
           const [isAnchored, isPopoverOpen, timeRangeMeta, timeslice] =
             useBatchedPublishingSubjects(isAnchored$, isPopoverOpen$, timeRangeMeta$, timeslice$);
-
           useEffect(() => {
             return () => {
               cleanupTimeRangeSubscription();
@@ -284,6 +283,9 @@ export const getTimesliderControlFactory = (): ControlFactory<
           const to = useMemo(() => {
             return timeslice ? timeslice[TO_INDEX] : timeRangeMeta.timeRangeMax;
           }, [timeslice, timeRangeMeta.timeRangeMax]);
+          const value: Timeslice = useMemo(() => {
+            return [from, to];
+          }, [from, to]);
 
           return (
             <EuiInputPopover
@@ -306,7 +308,7 @@ export const getTimesliderControlFactory = (): ControlFactory<
               <TimeSliderPopoverContent
                 isAnchored={typeof isAnchored === 'boolean' ? isAnchored : false}
                 setIsAnchored={setIsAnchored}
-                value={[from, to]}
+                value={value}
                 onChange={onChange}
                 stepSize={timeRangeMeta.stepSize}
                 ticks={timeRangeMeta.ticks}