Disallow group names longer than 32 extended graphemes

components/GroupTitleInput.scss

@@ -0,0 +1,23 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+.module-GroupTitleInput {
+  margin: 16px;
+  @include font-body-1;
+  padding: 8px 12px;
+  border-radius: 6px;
+  border: 2px solid $color-gray-15;
+  background: $color-white;
+  color: $color-black;
+
+  &:focus {
+    outline: none;
+
+    @include light-theme {
+      border-color: $ultramarine-ui-light;
+    }
+    @include dark-theme {
+      border-color: $ultramarine-ui-dark;
+    }
+  }
+}

stylesheets/_modules.scss

@@ -7433,27 +7433,6 @@ button.module-image__border-overlay:focus {
   }
 }
 
-.module-left-pane__compose-input {
-  margin: 16px;
-  @include font-body-1;
-  padding: 8px 12px;
-  border-radius: 6px;
-  border: 2px solid $color-gray-15;
-  background: $color-white;
-  color: $color-black;
-
-  &:focus {
-    outline: none;
-
-    @include light-theme {
-      border-color: $ultramarine-ui-light;
-    }
-    @include dark-theme {
-      border-color: $ultramarine-ui-dark;
-    }
-  }
-}
-
 .module-left-pane__list--measure {
   flex-grow: 1;
   flex-shrink: 1;

stylesheets/manifest.scss

@@ -32,5 +32,6 @@
 @import './components/Button.scss';
 @import './components/ContactPill.scss';
 @import './components/ContactPills.scss';
-@import './components/GroupDialog.scss';
 @import './components/ConversationHeader.scss';
+@import './components/GroupDialog.scss';
+@import './components/GroupTitleInput.scss';

ts/Intl.d.ts

@@ -0,0 +1,27 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+declare namespace Intl {
+  type SegmenterOptions = {
+    granularity?: 'grapheme' | 'word' | 'sentence';
+  };
+
+  type SegmentData = {
+    index: number;
+    input: string;
+    segment: string;
+  };
+
+  interface Segments {
+    containing(index: number): SegmentData;
+
+    [Symbol.iterator](): Iterator<SegmentData>;
+  }
+
+  // `Intl.Segmenter` is not yet in TypeScript's type definitions, so we add it.
+  class Segmenter {
+    constructor(locale?: string, options?: SegmenterOptions);
+
+    segment(str: string): Segments;
+  }
+}

ts/components/GroupTitleInput.stories.tsx

@@ -0,0 +1,32 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import React, { useState } from 'react';
+
+import { storiesOf } from '@storybook/react';
+
+import { setup as setupI18n } from '../../js/modules/i18n';
+import enMessages from '../../_locales/en/messages.json';
+
+import { GroupTitleInput } from './GroupTitleInput';
+
+const i18n = setupI18n('en', enMessages);
+
+const story = storiesOf('Components/GroupTitleInput', module);
+
+const Wrapper = ({ disabled }: { disabled?: boolean }) => {
+  const [value, setValue] = useState('');
+
+  return (
+    <GroupTitleInput
+      disabled={disabled}
+      i18n={i18n}
+      onChangeValue={setValue}
+      value={value}
+    />
+  );
+};
+
+story.add('Default', () => <Wrapper />);
+
+story.add('Disabled', () => <Wrapper disabled />);

ts/components/GroupTitleInput.tsx

@@ -0,0 +1,100 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import React, { forwardRef, useRef, ClipboardEvent } from 'react';
+
+import { LocalizerType } from '../types/Util';
+import { multiRef } from '../util/multiRef';
+import * as grapheme from '../util/grapheme';
+
+const MAX_GRAPHEME_COUNT = 32;
+
+type PropsType = {
+  disabled?: boolean;
+  i18n: LocalizerType;
+  onChangeValue: (value: string) => void;
+  value: string;
+};
+
+/**
+ * Group titles must have fewer than MAX_GRAPHEME_COUNT glyphs. Ideally, we'd use the
+ * `maxLength` property on inputs, but that doesn't account for glyphs that are more than
+ * one UTF-16 code units. For example: `'💩💩'.length === 4`.
+ *
+ * This component effectively implements a "max grapheme length" on an input.
+ *
+ * At a high level, this component handles two methods of input:
+ *
+ * - `onChange`. *Before* the value is changed (in `onKeyDown`), we save the value and the
+ *   cursor position. Then, in `onChange`, we see if the new value is too long. If it is,
+ *   we revert the value and selection. Otherwise, we fire `onChangeValue`.
+ *
+ * - `onPaste`. If you're pasting something that will fit, we fall back to normal browser
+ *   behavior, which calls `onChange`. If you're pasting something that won't fit, it's a
+ *   noop.
+ */
+export const GroupTitleInput = forwardRef<HTMLInputElement, PropsType>(
+  ({ i18n, disabled = false, onChangeValue, value }, ref) => {
+    const innerRef = useRef<HTMLInputElement | null>(null);
+    const valueOnKeydownRef = useRef<string>(value);
+    const selectionStartOnKeydownRef = useRef<number>(value.length);
+
+    return (
+      <input
+        disabled={disabled}
+        className="module-GroupTitleInput"
+        onKeyDown={() => {
+          const inputEl = innerRef.current;
+          if (!inputEl) {
+            return;
+          }
+
+          valueOnKeydownRef.current = inputEl.value;
+          selectionStartOnKeydownRef.current = inputEl.selectionStart || 0;
+        }}
+        onChange={() => {
+          const inputEl = innerRef.current;
+          if (!inputEl) {
+            return;
+          }
+
+          const newValue = inputEl.value;
+          if (grapheme.count(newValue) <= MAX_GRAPHEME_COUNT) {
+            onChangeValue(newValue);
+          } else {
+            inputEl.value = valueOnKeydownRef.current;
+            inputEl.selectionStart = selectionStartOnKeydownRef.current;
+            inputEl.selectionEnd = selectionStartOnKeydownRef.current;
+          }
+        }}
+        onPaste={(event: ClipboardEvent<HTMLInputElement>) => {
+          const inputEl = innerRef.current;
+          if (!inputEl) {
+            return;
+          }
+
+          const selectionStart = inputEl.selectionStart || 0;
+          const selectionEnd =
+            inputEl.selectionEnd || inputEl.selectionStart || 0;
+          const textBeforeSelection = value.slice(0, selectionStart);
+          const textAfterSelection = value.slice(selectionEnd);
+
+          const pastedText = event.clipboardData.getData('Text');
+
+          const newGraphemeCount =
+            grapheme.count(textBeforeSelection) +
+            grapheme.count(pastedText) +
+            grapheme.count(textAfterSelection);
+
+          if (newGraphemeCount > MAX_GRAPHEME_COUNT) {
+            event.preventDefault();
+          }
+        }}
+        placeholder={i18n('setGroupMetadata__group-name-placeholder')}
+        ref={multiRef<HTMLInputElement>(ref, innerRef)}
+        type="text"
+        value={value}
+      />
+    );
+  }
+);

ts/components/Tooltip.tsx

@@ -6,6 +6,7 @@ import classNames from 'classnames';
 import { noop } from 'lodash';
 import { Manager, Reference, Popper } from 'react-popper';
 import { Theme, themeClassName } from '../util/theme';
+import { multiRef } from '../util/multiRef';
 
 type EventWrapperPropsType = {
   children: React.ReactNode;
@@ -50,22 +51,7 @@ const TooltipEventWrapper = React.forwardRef<
     <span
       onFocus={on}
       onBlur={off}
-      // This is a forward ref that also needs a ref of its own, so we set both here.
-      ref={el => {
-        wrapperRef.current = el;
-
-        // This is a simplified version of [what React does][0] to set a ref.
-        // [0]: https://github.com/facebook/react/blob/29b7b775f2ecf878eaf605be959d959030598b07/packages/react-reconciler/src/ReactFiberCommitWork.js#L661-L677
-        if (typeof ref === 'function') {
-          ref(el);
-        } else if (ref) {
-          // I believe the types for `ref` are wrong in this case, as `ref.current` should
-          //   not be `readonly`. That's why we do this cast. See [the React source][1].
-          // [1]: https://github.com/facebook/react/blob/29b7b775f2ecf878eaf605be959d959030598b07/packages/shared/ReactTypes.js#L78-L80
-          // eslint-disable-next-line no-param-reassign
-          (ref as React.MutableRefObject<HTMLSpanElement | null>).current = el;
-        }
-      }}
+      ref={multiRef<HTMLSpanElement>(ref, wrapperRef)}
     >
       {children}
     </span>

ts/components/leftPane/LeftPaneSetGroupMetadataHelper.tsx

@@ -11,6 +11,7 @@ import { AvatarInput } from '../AvatarInput';
 import { Alert } from '../Alert';
 import { Spinner } from '../Spinner';
 import { Button } from '../Button';
+import { GroupTitleInput } from '../GroupTitleInput';
 
 export type LeftPaneSetGroupMetadataPropsType = {
   groupAvatar: undefined | ArrayBuffer;
@@ -113,15 +114,11 @@ export class LeftPaneSetGroupMetadataHelper extends LeftPaneHelper<
           onChange={setComposeGroupAvatar}
           value={this.groupAvatar}
         />
-        <input
+        <GroupTitleInput
           disabled={disabled}
-          className="module-left-pane__compose-input"
-          onChange={event => {
-            setComposeGroupName(event.target.value);
-          }}
-          placeholder={i18n('setGroupMetadata__group-name-placeholder')}
+          i18n={i18n}
+          onChangeValue={setComposeGroupName}
           ref={focusRef}
-          type="text"
           value={this.groupName}
         />
 

ts/test-both/util/grapheme_test.ts

@@ -0,0 +1,49 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+
+import { count } from '../../util/grapheme';
+
+describe('grapheme utilities', () => {
+  describe('count', () => {
+    it('returns the number of extended graphemes in a string (not necessarily the length)', () => {
+      // These tests modified [from iOS][0].
+      // [0]: https://github.com/signalapp/Signal-iOS/blob/800930110b0386a4c351716c001940a3e8fac942/Signal/test/util/DisplayableTextFilterTest.swift#L40-L71
+
+      // Plain text
+      assert.strictEqual(count(''), 0);
+      assert.strictEqual(count('boring text'), 11);
+      assert.strictEqual(count('Bokmål'), 6);
+
+      // Emojis
+      assert.strictEqual(count('💩💩💩'), 3);
+      assert.strictEqual(count('👩‍❤️‍👩'), 1);
+      assert.strictEqual(count('🇹🇹🌼🇹🇹🌼🇹🇹'), 5);
+      assert.strictEqual(count('🇹🇹'), 1);
+      assert.strictEqual(count('🇹🇹 '), 2);
+      assert.strictEqual(count('👌🏽👌🏾👌🏿'), 3);
+      assert.strictEqual(count('😍'), 1);
+      assert.strictEqual(count('👩🏽'), 1);
+      assert.strictEqual(count('👾🙇💁🙅🙆🙋🙎🙍'), 8);
+      assert.strictEqual(count('🐵🙈🙉🙊'), 4);
+      assert.strictEqual(count('❤️💔💌💕💞💓💗💖💘💝💟💜💛💚💙'), 15);
+      assert.strictEqual(count('✋🏿💪🏿👐🏿🙌🏿👏🏿🙏🏿'), 6);
+      assert.strictEqual(count('🚾🆒🆓🆕🆖🆗🆙🏧'), 8);
+      assert.strictEqual(count('0️⃣1️⃣2️⃣3️⃣4️⃣5️⃣6️⃣7️⃣8️⃣9️⃣🔟'), 11);
+      assert.strictEqual(count('🇺🇸🇷🇺🇦🇫🇦🇲'), 4);
+      assert.strictEqual(count('🇺🇸🇷🇺🇸 🇦🇫🇦🇲🇸'), 7);
+      assert.strictEqual(count('🇺🇸🇷🇺🇸🇦🇫🇦🇲'), 5);
+      assert.strictEqual(count('🇺🇸🇷🇺🇸🇦'), 3);
+      assert.strictEqual(count('１２３'), 3);
+
+      // Normal diacritic usage
+      assert.strictEqual(count('Příliš žluťoučký kůň úpěl ďábelské ódy.'), 39);
+
+      // Excessive diacritics
+      assert.strictEqual(count('Z͑ͫ̓ͪ̂ͫ̽͏̴̙̤̞͉͚̯̞̠͍A̴̵̜̰͔ͫ͗͢L̠ͨͧͩ͘G̴̻͈͍͔̹̑͗̎̅͛́Ǫ̵̹̻̝̳͂̌̌͘'), 5);
+      assert.strictEqual(count('H҉̸̧͘͠A͢͞V̛̛I̴̸N͏̕͏G҉̵͜͏͢ ̧̧́T̶̛͘͡R̸̵̨̢̀O̷̡U͡҉B̶̛͢͞L̸̸͘͢͟É̸ ̸̛͘͏R͟È͠͞A̸͝Ḑ̕͘͜I̵͘҉͜͞N̷̡̢͠G̴͘͠ ͟͞T͏̢́͡È̀X̕҉̢̀T̢͠?̕͏̢͘͢'), 28);
+      assert.strictEqual(count('L̷̳͔̲͝Ģ̵̮̯̤̩̙͍̬̟͉̹̘̹͍͈̮̦̰̣͟͝O̶̴̮̻̮̗͘͡!̴̷̟͓͓'), 4);
+    });
+  });
+});

ts/util/grapheme.ts

@@ -0,0 +1,13 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+export function count(str: string): number {
+  const segments = new Intl.Segmenter().segment(str);
+  const iterator = segments[Symbol.iterator]();
+
+  let result = -1;
+  for (let done = false; !done; result += 1) {
+    done = Boolean(iterator.next().done);
+  }
+  return result;
+}

ts/util/lint/exceptions.json

@@ -14730,6 +14730,33 @@
     "updated": "2020-11-17T23:29:38.698Z",
     "reasonDetail": "Doesn't touch the DOM."
   },
+  {
+    "rule": "React-useRef",
+    "path": "ts/components/GroupTitleInput.js",
+    "line": "    const innerRef = react_1.useRef(null);",
+    "lineNumber": 47,
+    "reasonCategory": "usageTrusted",
+    "updated": "2021-03-05T16:51:54.214Z",
+    "reasonDetail": "Used to handle an <input> element. Only updates the value and selection state."
+  },
+  {
+    "rule": "React-useRef",
+    "path": "ts/components/GroupTitleInput.js",
+    "line": "    const valueOnKeydownRef = react_1.useRef(value);",
+    "lineNumber": 48,
+    "reasonCategory": "usageTrusted",
+    "updated": "2021-03-05T16:51:54.214Z",
+    "reasonDetail": "Only stores a string."
+  },
+  {
+    "rule": "React-useRef",
+    "path": "ts/components/GroupTitleInput.js",
+    "line": "    const selectionStartOnKeydownRef = react_1.useRef(value.length);",
+    "lineNumber": 49,
+    "reasonCategory": "usageTrusted",
+    "updated": "2021-03-05T16:51:54.214Z",
+    "reasonDetail": "Only stores a number."
+  },
   {
     "rule": "jQuery-$(",
     "path": "ts/components/Intl.js",
@@ -14830,7 +14857,7 @@
     "rule": "React-useRef",
     "path": "ts/components/Tooltip.js",
     "line": "    const wrapperRef = react_1.default.useRef(null);",
-    "lineNumber": 19,
+    "lineNumber": 20,
     "reasonCategory": "usageTrusted",
     "updated": "2020-12-04T00:11:08.128Z",
     "reasonDetail": "Used to add (and remove) event listeners."

ts/util/multiRef.ts

@@ -0,0 +1,22 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { Ref } from 'react';
+
+export function multiRef<T>(...refs: Array<Ref<T>>): (topLevelRef: T) => void {
+  return (el: T) => {
+    refs.forEach(ref => {
+      // This is a simplified version of [what React does][0] to set a ref.
+      // [0]: https://github.com/facebook/react/blob/29b7b775f2ecf878eaf605be959d959030598b07/packages/react-reconciler/src/ReactFiberCommitWork.js#L661-L677
+      if (typeof ref === 'function') {
+        ref(el);
+      } else if (ref) {
+        // I believe the types for `ref` are wrong in this case, as `ref.current` should
+        //   not be `readonly`. That's why we do this cast. See [the React source][1].
+        // [1]: https://github.com/facebook/react/blob/29b7b775f2ecf878eaf605be959d959030598b07/packages/shared/ReactTypes.js#L78-L80
+        // eslint-disable-next-line no-param-reassign
+        (ref as React.MutableRefObject<T>).current = el;
+      }
+    });
+  };
+}