From 015651f860552009c030037c8aec1699db4e0695 Mon Sep 17 00:00:00 2001
From: Gilles De Mey <gilles.de.mey@gmail.com>
Date: Wed, 5 Oct 2022 10:33:47 +0200
Subject: [PATCH] @grafana/ui: adds a virtualized options for the Select
 component (#55629)

---
 .../src/components/Select/Select.story.tsx    | 20 +++++++-
 .../src/components/Select/Select.tsx          |  6 ++-
 .../src/components/Select/SelectBase.tsx      | 11 ++--
 .../src/components/Select/SelectMenu.tsx      | 51 +++++++++++++++++++
 .../src/components/Select/mockOptions.tsx     | 10 ++++
 .../grafana-ui/src/components/Select/types.ts |  7 +++
 .../grafana-ui/src/components/Select/utils.ts |  7 +++
 7 files changed, 106 insertions(+), 6 deletions(-)

diff --git a/packages/grafana-ui/src/components/Select/Select.story.tsx b/packages/grafana-ui/src/components/Select/Select.story.tsx
index d4fca54b60b..7c69d7aa3d1 100644
--- a/packages/grafana-ui/src/components/Select/Select.story.tsx
+++ b/packages/grafana-ui/src/components/Select/Select.story.tsx
@@ -10,7 +10,7 @@ import { getAvailableIcons } from '../../types';
 import { withCenteredStory, withHorizontallyCenteredStory } from '../../utils/storybook/withCenteredStory';
 
 import mdx from './Select.mdx';
-import { generateOptions } from './mockOptions';
+import { generateOptions, generateThousandsOfOptions } from './mockOptions';
 import { SelectCommonProps } from './types';
 
 const meta: Meta = {
@@ -105,6 +105,24 @@ export const Basic: Story<StoryProps> = (args) => {
     </>
   );
 };
+export const BasicVirtualizedList: Story<StoryProps> = (args) => {
+  const [value, setValue] = useState<SelectableValue<string>>();
+
+  return (
+    <>
+      <Select
+        options={generateThousandsOfOptions()}
+        virtualized
+        value={value}
+        onChange={(v) => {
+          setValue(v);
+          action('onChange')(v);
+        }}
+        {...args}
+      />
+    </>
+  );
+};
 /**
  * Uses plain values instead of SelectableValue<T>
  */
diff --git a/packages/grafana-ui/src/components/Select/Select.tsx b/packages/grafana-ui/src/components/Select/Select.tsx
index a8e8d888d23..ccdd24b8180 100644
--- a/packages/grafana-ui/src/components/Select/Select.tsx
+++ b/packages/grafana-ui/src/components/Select/Select.tsx
@@ -4,7 +4,7 @@ import { SelectableValue } from '@grafana/data';
 
 import { SelectBase } from './SelectBase';
 import { SelectContainer, SelectContainerProps } from './SelectContainer';
-import { SelectCommonProps, MultiSelectCommonProps, SelectAsyncProps } from './types';
+import { SelectCommonProps, MultiSelectCommonProps, SelectAsyncProps, VirtualizedSelectProps } from './types';
 
 export function Select<T>(props: SelectCommonProps<T>) {
   return <SelectBase {...props} />;
@@ -24,6 +24,10 @@ export function AsyncSelect<T>(props: AsyncSelectProps<T>) {
   return <SelectBase {...props} />;
 }
 
+export function VirtualizedSelect<T>(props: VirtualizedSelectProps<T>) {
+  return <SelectBase virtualized {...props} />;
+}
+
 interface AsyncMultiSelectProps<T> extends Omit<MultiSelectCommonProps<T>, 'options'>, SelectAsyncProps<T> {
   // AsyncSelect has options stored internally. We cannot enable plain values as we don't have access to the fetched options
   value?: Array<SelectableValue<T>>;
diff --git a/packages/grafana-ui/src/components/Select/SelectBase.tsx b/packages/grafana-ui/src/components/Select/SelectBase.tsx
index f47ce710f34..eb4dfe47e87 100644
--- a/packages/grafana-ui/src/components/Select/SelectBase.tsx
+++ b/packages/grafana-ui/src/components/Select/SelectBase.tsx
@@ -15,14 +15,14 @@ import { IndicatorsContainer } from './IndicatorsContainer';
 import { InputControl } from './InputControl';
 import { MultiValueContainer, MultiValueRemove } from './MultiValue';
 import { SelectContainer } from './SelectContainer';
-import { SelectMenu, SelectMenuOptions } from './SelectMenu';
+import { SelectMenu, SelectMenuOptions, VirtualizedSelectMenu } from './SelectMenu';
 import { SelectOptionGroup } from './SelectOptionGroup';
 import { SingleValue } from './SingleValue';
 import { ValueContainer } from './ValueContainer';
 import { getSelectStyles } from './getSelectStyles';
 import { useCustomSelectStyles } from './resetSelectStyles';
 import { ActionMeta, SelectBaseProps } from './types';
-import { cleanValue, findSelectedValue } from './utils';
+import { cleanValue, findSelectedValue, omitDescriptions } from './utils';
 
 interface ExtraValuesIndicatorProps {
   maxVisibleValues?: number | undefined;
@@ -139,6 +139,7 @@ export function SelectBase<T>({
   showAllSelectedWhenOpen = true,
   tabSelectsValue = true,
   value,
+  virtualized = false,
   width,
   isValidNewOption,
   formatOptionLabel,
@@ -241,7 +242,7 @@ export function SelectBase<T>({
     onFocus,
     formatOptionLabel,
     openMenuOnFocus,
-    options,
+    options: virtualized ? omitDescriptions(options) : options,
     placeholder,
     prefix,
     renderControl,
@@ -268,12 +269,14 @@ export function SelectBase<T>({
     };
   }
 
+  const SelectMenuComponent = virtualized ? VirtualizedSelectMenu : SelectMenu;
+
   return (
     <>
       <ReactSelectComponent
         ref={reactSelectRef}
         components={{
-          MenuList: SelectMenu,
+          MenuList: SelectMenuComponent,
           Group: SelectOptionGroup,
           ValueContainer,
           IndicatorsContainer(props: any) {
diff --git a/packages/grafana-ui/src/components/Select/SelectMenu.tsx b/packages/grafana-ui/src/components/Select/SelectMenu.tsx
index dcef18531c3..9d7f4f4596e 100644
--- a/packages/grafana-ui/src/components/Select/SelectMenu.tsx
+++ b/packages/grafana-ui/src/components/Select/SelectMenu.tsx
@@ -1,5 +1,8 @@
 import { cx } from '@emotion/css';
+import { max } from 'lodash';
 import React, { FC, RefCallback } from 'react';
+import { MenuListProps } from 'react-select';
+import { FixedSizeList as List } from 'react-window';
 
 import { SelectableValue, toIconName } from '@grafana/data';
 
@@ -30,6 +33,54 @@ export const SelectMenu: FC<SelectMenuProps> = ({ children, maxHeight, innerRef,
 
 SelectMenu.displayName = 'SelectMenu';
 
+const VIRTUAL_LIST_ITEM_HEIGHT = 37;
+const VIRTUAL_LIST_WIDTH_ESTIMATE_MULTIPLIER = 7;
+
+// A virtualized version of the SelectMenu, descriptions for SelectableValue options not supported since those are of a variable height.
+//
+// To support the virtualized list we have to "guess" the width of the menu container based on the longest available option.
+// the reason for this is because all of the options will be positioned absolute, this takes them out of the document and no space
+// is created for them, thus the container can't grow to accomodate.
+//
+// VIRTUAL_LIST_ITEM_HEIGHT and WIDTH_ESTIMATE_MULTIPLIER are both magic numbers.
+// Some characters (such as emojis and other unicode characters) may consist of multiple code points in which case the width would be inaccurate (but larger than needed).
+export const VirtualizedSelectMenu: FC<MenuListProps<SelectableValue>> = ({
+  children,
+  maxHeight,
+  options,
+  getValue,
+}) => {
+  const theme = useTheme2();
+  const styles = getSelectStyles(theme);
+  const [value] = getValue();
+
+  const valueIndex = value ? options.findIndex((option: SelectableValue<unknown>) => option.value === value.value) : 0;
+  const initialOffset = valueIndex * VIRTUAL_LIST_ITEM_HEIGHT;
+
+  if (!Array.isArray(children)) {
+    return null;
+  }
+
+  const longestOption = max(options.map((option) => option.label?.length)) ?? 0;
+  const widthEstimate = longestOption * VIRTUAL_LIST_WIDTH_ESTIMATE_MULTIPLIER;
+
+  return (
+    <List
+      className={styles.menu}
+      height={maxHeight}
+      width={widthEstimate}
+      aria-label="Select options menu"
+      itemCount={children.length}
+      itemSize={VIRTUAL_LIST_ITEM_HEIGHT}
+      initialScrollOffset={initialOffset}
+    >
+      {({ index, style }) => <div style={{ ...style, overflow: 'hidden' }}>{children[index]}</div>}
+    </List>
+  );
+};
+
+VirtualizedSelectMenu.displayName = 'VirtualizedSelectMenu';
+
 interface SelectMenuOptionProps<T> {
   isDisabled: boolean;
   isFocused: boolean;
diff --git a/packages/grafana-ui/src/components/Select/mockOptions.tsx b/packages/grafana-ui/src/components/Select/mockOptions.tsx
index de67501cd00..12d56b0bdc0 100644
--- a/packages/grafana-ui/src/components/Select/mockOptions.tsx
+++ b/packages/grafana-ui/src/components/Select/mockOptions.tsx
@@ -32,3 +32,13 @@ export const generateOptions = (desc = false) => {
     description: desc ? `This is a description of ${name}` : undefined,
   }));
 };
+
+export const generateThousandsOfOptions = () => {
+  const options: Array<SelectableValue<string>> = new Array(10000).fill(null).map((_, index) => ({
+    value: String(index),
+    label: 'Option ' + index,
+    description: 'This is option number ' + index,
+  }));
+
+  return options;
+};
diff --git a/packages/grafana-ui/src/components/Select/types.ts b/packages/grafana-ui/src/components/Select/types.ts
index eae10ee6f1f..d5cd28098c2 100644
--- a/packages/grafana-ui/src/components/Select/types.ts
+++ b/packages/grafana-ui/src/components/Select/types.ts
@@ -77,6 +77,8 @@ export interface SelectCommonProps<T> {
   renderControl?: ControlComponent<T>;
   tabSelectsValue?: boolean;
   value?: T | SelectValue<T> | null;
+  /** Will wrap the MenuList in a react-window FixedSizeVirtualList for improved performance, does not support options with "description" properties */
+  virtualized?: boolean;
   /** Sets the width to a multiple of 8px. Should only be used with inline forms. Setting width of the container is preferred in other cases.*/
   width?: number | 'auto';
   isOptionDisabled?: () => boolean;
@@ -103,6 +105,11 @@ export interface SelectAsyncProps<T> {
   loadingMessage?: string;
 }
 
+/** The VirtualizedSelect component uses a slightly different SelectableValue, description and other props are not supported */
+export interface VirtualizedSelectProps<T> extends Omit<SelectCommonProps<T>, 'virtualized'> {
+  options?: Array<Pick<SelectableValue<T>, 'label' | 'value'>>;
+}
+
 export interface MultiSelectCommonProps<T> extends Omit<SelectCommonProps<T>, 'onChange' | 'isMulti' | 'value'> {
   value?: Array<SelectableValue<T>> | T[];
   onChange: (item: Array<SelectableValue<T>>) => {} | void;
diff --git a/packages/grafana-ui/src/components/Select/utils.ts b/packages/grafana-ui/src/components/Select/utils.ts
index 5972ec6a888..1f8b45a1206 100644
--- a/packages/grafana-ui/src/components/Select/utils.ts
+++ b/packages/grafana-ui/src/components/Select/utils.ts
@@ -43,3 +43,10 @@ export const findSelectedValue = (
 
   return null;
 };
+
+/**
+ * Omit descriptions from an array of options
+ */
+export const omitDescriptions = (options: SelectableValue[]): SelectableValue[] => {
+  return options.map(({ description, ...rest }) => rest);
+};