Message Context Menu: Introduce Translate feature

.eslintignore

@@ -1,6 +1,7 @@
 
 src/lib/rlottie/rlottie-wasm.js
 src/lib/webp/webp_wasm.js
+src/lib/fasttextweb/fasttext-wasm.js
 
 src/lib/gramjs/tl/types-generator/template.js
 src/lib/gramjs/tl/api.d.ts

src/@types/global.d.ts

@@ -61,6 +61,7 @@ type AllEmojis = Record<string, Emoji | EmojiWithSkins>;
 declare module '*.png';
 declare module '*.svg';
 declare module '*.tgs';
+declare module '*.wasm';
 
 declare module '*.txt' {
   const content: string;

src/api/gramjs/apiBuilders/messages.ts

@@ -1616,3 +1616,12 @@ function buildThreadInfo(
     ...(recentRepliers && { recentReplierIds: recentRepliers.map(getApiChatIdFromMtpPeer) }),
   };
 }
+
+export function buildApiFormattedText(textWithEntities: GramJs.TextWithEntities): ApiFormattedText {
+  const { text, entities } = textWithEntities;
+
+  return {
+    text,
+    entities: entities.map(buildApiMessageEntity),
+  };
+}

src/api/gramjs/gramjsBuilders/index.ts

@@ -22,6 +22,7 @@ import type {
   ApiRequestInputInvoice,
   ApiChatReactions,
   ApiReaction,
+  ApiFormattedText,
 } from '../../types';
 import {
   ApiMessageEntityTypes,
@@ -598,3 +599,10 @@ export function buildInputEmojiStatus(emojiStatus: ApiSticker, expires?: number)
     documentId: BigInt(emojiStatus.id),
   });
 }
+
+export function buildInputTextWithEntities(formatted: ApiFormattedText) {
+  return new GramJs.TextWithEntities({
+    text: formatted.text,
+    entities: formatted.entities?.map(buildMtpMessageEntity) || [],
+  });
+}

src/api/gramjs/methods/index.ts

@@ -30,7 +30,7 @@ export {
   fetchPinnedMessages, fetchScheduledHistory, sendScheduledMessages, rescheduleMessage, deleteScheduledMessages,
   reportMessages, sendMessageAction, fetchSeenBy, fetchSponsoredMessages, viewSponsoredMessage, fetchSendAs,
   saveDefaultSendAs, fetchUnreadReactions, readAllReactions, fetchUnreadMentions, readAllMentions, transcribeAudio,
-  closePoll, fetchExtendedMedia,
+  closePoll, fetchExtendedMedia, translateText,
 } from './messages';
 
 export {

src/api/gramjs/methods/messages.ts

@@ -16,6 +16,7 @@ import type {
   ApiSendMessageAction,
   ApiContact,
   ApiPoll,
+  ApiFormattedText,
 } from '../../types';
 import {
   MAIN_THREAD_ID,
@@ -36,6 +37,7 @@ import {
   buildLocalMessage,
   buildWebPage,
   buildApiSponsoredMessage,
+  buildApiFormattedText,
 } from '../apiBuilders/messages';
 import { buildApiUser } from '../apiBuilders/users';
 import {
@@ -51,6 +53,7 @@ import {
   isServiceMessageWithMedia,
   buildSendMessageAction,
   buildInputPollFromExisting,
+  buildInputTextWithEntities,
 } from '../gramjsBuilders';
 import localDb from '../localDb';
 import { buildApiChatFromPreview, buildApiSendAsPeerId } from '../apiBuilders/chats';
@@ -69,6 +72,15 @@ import { getServerTimeOffset } from '../../../util/serverTime';
 const FAST_SEND_TIMEOUT = 1000;
 const INPUT_WAVEFORM_LENGTH = 63;
 
+type TranslateTextParams = ({
+  text: ApiFormattedText[];
+} | {
+  chat: ApiChat;
+  messageIds: number[];
+}) & {
+  toLanguageCode: string;
+};
+
 let onUpdate: OnApiUpdate;
 
 export function init(_onUpdate: OnApiUpdate) {
@@ -1560,3 +1572,38 @@ export async function transcribeAudio({
 
   return result.transcriptionId.toString();
 }
+
+export async function translateText(params: TranslateTextParams) {
+  let result;
+  const isMessageTranslation = 'chat' in params;
+  if (isMessageTranslation) {
+    const { chat, messageIds, toLanguageCode } = params;
+    result = await invokeRequest(new GramJs.messages.TranslateText({
+      peer: buildInputPeer(chat.id, chat.accessHash),
+      id: messageIds,
+      toLang: toLanguageCode,
+    }));
+  } else {
+    const { text, toLanguageCode } = params;
+    result = await invokeRequest(new GramJs.messages.TranslateText({
+      text: text.map((t) => buildInputTextWithEntities(t)),
+      toLang: toLanguageCode,
+    }));
+  }
+
+  if (!result) return undefined;
+
+  const formattedText = result.result.map((r) => buildApiFormattedText(r));
+
+  if (isMessageTranslation) {
+    onUpdate({
+      '@type': 'updateMessageTranslations',
+      chatId: params.chat.id,
+      messageIds: params.messageIds,
+      translations: formattedText,
+      toLanguageCode: params.toLanguageCode,
+    });
+  }
+
+  return formattedText;
+}

src/api/types/updates.ts

@@ -601,6 +601,14 @@ export type ApiUpdateTopics = {
   chatId: string;
 };
 
+export type ApiUpdateMessageTranslations = {
+  '@type': 'updateMessageTranslations';
+  chatId: string;
+  messageIds: number[];
+  translations: ApiFormattedText[];
+  toLanguageCode: string;
+};
+
 export type ApiUpdate = (
   ApiUpdateReady | ApiUpdateSession | ApiUpdateWebAuthTokenFailed | ApiUpdateRequestUserUpdate |
   ApiUpdateAuthorizationState | ApiUpdateAuthorizationError | ApiUpdateConnectionState | ApiUpdateCurrentUser |
@@ -616,7 +624,7 @@ export type ApiUpdate = (
   ApiUpdateFavoriteStickers | ApiUpdateStickerSet | ApiUpdateStickerSets | ApiUpdateStickerSetsOrder |
   ApiUpdateRecentStickers | ApiUpdateSavedGifs | ApiUpdateNewScheduledMessage | ApiUpdateMoveStickerSetToTop |
   ApiUpdateScheduledMessageSendSucceeded | ApiUpdateScheduledMessage |
-  ApiUpdateDeleteScheduledMessages | ApiUpdateResetMessages |
+  ApiUpdateDeleteScheduledMessages | ApiUpdateResetMessages | ApiUpdateMessageTranslations |
   ApiUpdateTwoFaError | ApiUpdateTwoFaStateWaitCode | ApiUpdateWebViewResultSent |
   ApiUpdateNotifySettings | ApiUpdateNotifyExceptions | ApiUpdatePeerBlocked | ApiUpdatePrivacy |
   ApiUpdateServerTimeOffset | ApiUpdateShowInvite | ApiUpdateMessageReactions |

src/bundles/extra.ts

@@ -28,6 +28,7 @@ export { default as MessageSelectToolbar } from '../components/middle/MessageSel
 export { default as SeenByModal } from '../components/common/SeenByModal';
 export { default as ReactorListModal } from '../components/middle/ReactorListModal';
 export { default as EmojiInteractionAnimation } from '../components/middle/EmojiInteractionAnimation';
+export { default as MessageLanguageModal } from '../components/middle/MessageLanguageModal';
 
 // eslint-disable-next-line import/no-cycle
 export { default as LeftSearch } from '../components/left/search/LeftSearch';

src/components/common/MessageText.tsx

@@ -1,15 +1,17 @@
 import React, { memo, useMemo, useRef } from '../../lib/teact/teact';
 
-import type { ApiMessage } from '../../api/types';
+import type { ApiFormattedText, ApiMessage } from '../../api/types';
 import type { ObserveFn } from '../../hooks/useIntersectionObserver';
 
 import { ApiMessageEntityTypes } from '../../api/types';
 import trimText from '../../util/trimText';
-import { getMessageText } from '../../global/helpers';
+import { getMessageText, stripCustomEmoji } from '../../global/helpers';
 import { renderTextWithEntities } from './helpers/renderTextWithEntities';
 
 interface OwnProps {
   message: ApiMessage;
+  translatedText?: ApiFormattedText;
+  isForAnimation?: boolean;
   emojiSize?: number;
   highlight?: string;
   isSimple?: boolean;
@@ -25,6 +27,8 @@ const MIN_CUSTOM_EMOJIS_FOR_SHARED_CANVAS = 3;
 
 function MessageText({
   message,
+  translatedText,
+  isForAnimation,
   emojiSize,
   highlight,
   isSimple,
@@ -40,7 +44,12 @@ function MessageText({
   // eslint-disable-next-line no-null/no-null
   const sharedCanvasHqRef = useRef<HTMLCanvasElement>(null);
 
-  const { text, entities } = message.content.text || {};
+  const formattedText = translatedText || message.content.text || undefined;
+
+  const adaptedFormattedText = isForAnimation && formattedText ? stripCustomEmoji(formattedText) : formattedText;
+
+  const { text, entities } = adaptedFormattedText || {};
+
   const withSharedCanvas = useMemo(() => {
     const hasSpoilers = entities?.some((e) => e.type === ApiMessageEntityTypes.Spoiler);
     if (hasSpoilers) {

src/components/common/helpers/renderText.tsx

@@ -23,7 +23,6 @@ export type TextFilter = (
   'simple_markdown' | 'simple_markdown_html'
   );
 
-const RE_LETTER_OR_DIGIT = /^[\d\wа-яё]$/i;
 const SIMPLE_MARKDOWN_REGEX = /(\*\*|__).+?\1/g;
 
 export default function renderText(
@@ -186,8 +185,7 @@ function addHighlight(textParts: TextPart[], highlight: string | undefined): Tex
 
     const lowerCaseText = part.toLowerCase();
     const queryPosition = lowerCaseText.indexOf(highlight.toLowerCase());
-    const nextSymbol = lowerCaseText[queryPosition + highlight.length];
+    if (queryPosition < 0) {
-    if (queryPosition < 0 || (nextSymbol && nextSymbol.match(RE_LETTER_OR_DIGIT))) {
       result.push(part);
       return result;
     }
@@ -200,7 +198,6 @@ function addHighlight(textParts: TextPart[], highlight: string | undefined): Tex
       </span>,
     );
     newParts.push(part.substring(queryPosition + highlight.length));
-
     return [...result, ...newParts];
   }, []);
 }

src/components/left/LeftColumn.tsx

@@ -298,6 +298,10 @@ const LeftColumn: FC<StateProps> = ({
         case SettingsScreens.CustomEmoji:
           setSettingsScreen(SettingsScreens.Stickers);
           return;
+
+        case SettingsScreens.DoNotTranslate:
+          setSettingsScreen(SettingsScreens.Language);
+          return;
         default:
           break;
       }

src/components/left/settings/Settings.scss

@@ -306,6 +306,10 @@
     .Radio:last-child {
       margin-bottom: 0;
     }
+
+    .Checkbox {
+      margin-left: 0;
+    }
   }
 
   .Radio + .Radio,

src/components/left/settings/Settings.tsx

@@ -29,6 +29,7 @@ import SettingsQuickReaction from './SettingsQuickReaction';
 import SettingsPasscode from './passcode/SettingsPasscode';
 import SettingsStickers from './SettingsStickers';
 import SettingsCustomEmoji from './SettingsCustomEmoji';
+import SettingsDoNotTranslate from './SettingsDoNotTranslate';
 import SettingsExperimental from './SettingsExperimental';
 
 import './Settings.scss';
@@ -249,7 +250,15 @@ const Settings: FC<OwnProps> = ({
         );
       case SettingsScreens.Language:
         return (
-          <SettingsLanguage isActive={isScreenActive} onReset={handleReset} />
+          <SettingsLanguage
+            isActive={isScreenActive || screen === SettingsScreens.DoNotTranslate}
+            onReset={handleReset}
+            onScreenSelect={onScreenSelect}
+          />
+        );
+      case SettingsScreens.DoNotTranslate:
+        return (
+          <SettingsDoNotTranslate isActive={isScreenActive} onReset={handleReset} />
         );
       case SettingsScreens.Stickers:
         return (

src/components/left/settings/SettingsDoNotTranslate.module.scss

@@ -0,0 +1,20 @@
+@import "../../../styles/mixins";
+
+.root, .item {
+  display: flex;
+  flex-direction: column;
+}
+
+.item {
+  overflow: hidden;
+  min-height: 25rem;
+}
+
+.checkbox {
+  margin: 0;
+}
+
+.languages {
+  overflow-y: auto;
+  @include overflow-y-overlay();
+}

src/components/left/settings/SettingsDoNotTranslate.tsx

@@ -0,0 +1,183 @@
+import React, {
+  memo, useCallback, useEffect, useMemo, useState,
+} from '../../../lib/teact/teact';
+import { getActions, withGlobal } from '../../../global';
+
+import type { FC } from '../../../lib/teact/teact';
+import type { ISettings } from '../../../types';
+import type { IRadioOption } from '../../ui/CheckboxGroup';
+
+import { SUPPORTED_TRANSLATION_LANGUAGES } from '../../../config';
+import { partition, unique } from '../../../util/iteratees';
+import buildClassName from '../../../util/buildClassName';
+
+import useHistoryBack from '../../../hooks/useHistoryBack';
+import useEffectWithPrevDeps from '../../../hooks/useEffectWithPrevDeps';
+import useLang from '../../../hooks/useLang';
+
+import Checkbox from '../../ui/Checkbox';
+import InputText from '../../ui/InputText';
+
+import styles from './SettingsDoNotTranslate.module.scss';
+
+// https://fasttext.cc/docs/en/language-identification.html
+const LOCAL_SUPPORTED_DETECTION_LANGUAGES = [
+  'af', 'als', 'am', 'an', 'ar', 'arz', 'as', 'ast', 'av', 'az',
+  'azb', 'ba', 'bar', 'bcl', 'be', 'bg', 'bh', 'bn', 'bo', 'bpy',
+  'br', 'bs', 'bxr', 'ca', 'cbk', 'ce', 'ceb', 'ckb', 'co', 'cs',
+  'cv', 'cy', 'da', 'de', 'diq', 'dsb', 'dty', 'dv', 'el', 'eml',
+  'en', 'eo', 'es', 'et', 'eu', 'fa', 'fi', 'fr', 'frr', 'fy',
+  'ga', 'gd', 'gl', 'gn', 'gom', 'gu', 'gv', 'he', 'hi', 'hif',
+  'hr', 'hsb', 'ht', 'hu', 'hy', 'ia', 'id', 'ie', 'ilo', 'io',
+  'is', 'it', 'ja', 'jbo', 'jv', 'ka', 'kk', 'km', 'kn', 'ko',
+  'krc', 'ku', 'kv', 'kw', 'ky', 'la', 'lb', 'lez', 'li', 'lmo',
+  'lo', 'lrc', 'lt', 'lv', 'mai', 'mg', 'mhr', 'min', 'mk', 'ml',
+  'mn', 'mr', 'mrj', 'ms', 'mt', 'mwl', 'my', 'myv', 'mzn', 'nah',
+  'nap', 'nds', 'ne', 'new', 'nl', 'nn', 'no', 'oc', 'or', 'os',
+  'pa', 'pam', 'pfl', 'pl', 'pms', 'pnb', 'ps', 'pt', 'qu', 'rm',
+  'ro', 'ru', 'rue', 'sa', 'sah', 'sc', 'scn', 'sco', 'sd', 'sh',
+  'si', 'sk', 'sl', 'so', 'sq', 'sr', 'su', 'sv', 'sw', 'ta', 'te',
+  'tg', 'th', 'tk', 'tl', 'tr', 'tt', 'tyv', 'ug', 'uk', 'ur', 'uz',
+  'vec', 'vep', 'vi', 'vls', 'vo', 'wa', 'war', 'wuu', 'xal', 'xmf',
+  'yi', 'yo', 'yue', 'zh',
+];
+
+const SUPPORTED_LANGUAGES = SUPPORTED_TRANSLATION_LANGUAGES.filter((lang: string) => (
+  LOCAL_SUPPORTED_DETECTION_LANGUAGES.includes(lang)
+));
+
+type OwnProps = {
+  isActive?: boolean;
+  onReset: () => void;
+};
+
+type StateProps = Pick<ISettings, 'language' | 'doNotTranslate'>;
+
+const SettingsDoNotTranslate: FC<OwnProps & StateProps> = ({
+  isActive,
+  language,
+  doNotTranslate,
+  onReset,
+}) => {
+  const { setSettingOption } = getActions();
+
+  const lang = useLang();
+  const [displayedOptions, setDisplayedOptions] = useState<IRadioOption[]>([]);
+  const [search, setSearch] = useState('');
+
+  const options: IRadioOption[] = useMemo(() => {
+    return SUPPORTED_LANGUAGES.map((langCode: string) => {
+      const translatedNames = new Intl.DisplayNames([language], { type: 'language' });
+      const translatedName = translatedNames.of(langCode)!;
+
+      const originalNames = new Intl.DisplayNames([langCode], { type: 'language' });
+      const originalName = originalNames.of(langCode)!;
+
+      return {
+        langCode,
+        translatedName,
+        originalName,
+      };
+    }).map(({ langCode, translatedName, originalName }) => ({
+      label: translatedName,
+      subLabel: originalName,
+      value: langCode,
+      disabled: langCode === language,
+    }));
+  }, [language]);
+
+  const allSelected = useMemo(() => {
+    return unique([...doNotTranslate, language]);
+  }, [doNotTranslate, language]);
+
+  useEffect(() => {
+    if (!isActive) setSearch('');
+  }, [isActive]);
+
+  useEffectWithPrevDeps(([prevIsActive]) => {
+    if (prevIsActive === isActive) return;
+    if (isActive && displayedOptions.length) return;
+
+    const [selected, unselected] = partition(options, (option) => allSelected.includes(option.value));
+    const current = selected.find((option) => option.value === language);
+    const selectedFiltered = selected.filter((option) => option.value !== language);
+
+    setDisplayedOptions([current!, ...selectedFiltered, ...unselected]);
+  }, [isActive, allSelected, displayedOptions.length, language, options]);
+
+  const handleChange = useCallback((event: React.ChangeEvent<HTMLInputElement>) => {
+    const { value, checked } = event.currentTarget;
+    let newDoNotTranslate: string[];
+    if (checked) {
+      newDoNotTranslate = unique([...doNotTranslate, value]);
+    } else {
+      newDoNotTranslate = doNotTranslate.filter((v) => v !== value);
+    }
+
+    setSettingOption({
+      doNotTranslate: newDoNotTranslate,
+    });
+  }, [doNotTranslate, setSettingOption]);
+
+  const handleSearch = useCallback((e: React.ChangeEvent<HTMLInputElement>) => {
+    setSearch(e.target.value);
+  }, []);
+
+  const filteredDisplayedOptions = useMemo(() => {
+    if (!search.trim()) {
+      return displayedOptions;
+    }
+
+    return displayedOptions.filter((option) => (
+      option.label.toLowerCase().includes(search.toLowerCase())
+      || option.subLabel?.toLowerCase().includes(search.toLowerCase())
+      || option.value.toLowerCase().includes(search.toLowerCase())
+    ));
+  }, [displayedOptions, search]);
+
+  useHistoryBack({
+    isActive,
+    onBack: onReset,
+  });
+
+  return (
+    <div className={buildClassName(styles.root, 'settings-content custom-scroll')}>
+      <div className={buildClassName(styles.item, 'settings-item')}>
+        <InputText
+          key="search"
+          value={search}
+          onChange={handleSearch}
+          placeholder={lang('Search')}
+          teactExperimentControlled
+        />
+        <div className={buildClassName(styles.languages, 'radio-group custom-scroll')}>
+          {filteredDisplayedOptions.map((option) => (
+            <Checkbox
+              className={styles.checkbox}
+              label={option.label}
+              subLabel={option.subLabel}
+              checked={allSelected.includes(option.value)}
+              value={option.value}
+              disabled={option.disabled}
+              key={option.value}
+              onChange={handleChange}
+            />
+          ))}
+        </div>
+      </div>
+    </div>
+  );
+};
+
+export default memo(withGlobal<OwnProps>(
+  (global): StateProps => {
+    const {
+      language, doNotTranslate,
+    } = global.settings.byKey;
+
+    return {
+      language,
+      doNotTranslate,
+    };
+  },
+)(SettingsDoNotTranslate));

src/components/left/settings/SettingsHeader.tsx

@@ -97,6 +97,8 @@ const SettingsHeader: FC<OwnProps> = ({
         return <h3>{lang('PrivacySettings')}</h3>;
       case SettingsScreens.Language:
         return <h3>{lang('Language')}</h3>;
+      case SettingsScreens.DoNotTranslate:
+        return <h3>{lang('DoNotTranslate')}</h3>;
       case SettingsScreens.Stickers:
         return <h3>{lang('StickersName')}</h3>;
       case SettingsScreens.Experimental:

src/components/left/settings/SettingsLanguage.tsx

@@ -1,31 +1,44 @@
-import type { FC } from '../../../lib/teact/teact';
 import React, {
   memo, useCallback, useEffect, useMemo, useState,
 } from '../../../lib/teact/teact';
 import { getActions, withGlobal } from '../../../global';
 
+import type { FC } from '../../../lib/teact/teact';
+import { SettingsScreens } from '../../../types';
 import type { ISettings, LangCode } from '../../../types';
 import type { ApiLanguage } from '../../../api/types';
 
 import { setLanguage } from '../../../util/langProvider';
+import { unique } from '../../../util/iteratees';
+
+import useFlag from '../../../hooks/useFlag';
+import useHistoryBack from '../../../hooks/useHistoryBack';
+import useLang from '../../../hooks/useLang';
 
 import RadioGroup from '../../ui/RadioGroup';
 import Loading from '../../ui/Loading';
-import useFlag from '../../../hooks/useFlag';
+import Checkbox from '../../ui/Checkbox';
-import useHistoryBack from '../../../hooks/useHistoryBack';
+import ListItem from '../../ui/ListItem';
 
 type OwnProps = {
   isActive?: boolean;
   onReset: () => void;
+  onScreenSelect: (screen: SettingsScreens) => void;
 };
 
-type StateProps = Pick<ISettings, 'languages' | 'language'>;
+type StateProps = {
+  lastSyncTime?: number;
+} & Pick<ISettings, 'languages' | 'language' | 'canTranslate' | 'doNotTranslate'>;
 
 const SettingsLanguage: FC<OwnProps & StateProps> = ({
   isActive,
-  onReset,
   languages,
   language,
+  canTranslate,
+  doNotTranslate,
+  lastSyncTime,
+  onScreenSelect,
+  onReset,
 }) => {
   const {
     loadLanguages,
@@ -36,10 +49,13 @@ const SettingsLanguage: FC<OwnProps & StateProps> = ({
   const [selectedLanguage, setSelectedLanguage] = useState<string>(language);
   const [isLoading, markIsLoading, unmarkIsLoading] = useFlag();
 
-  // TODO Throttle
+  const lang = useLang();
+
   useEffect(() => {
-    loadLanguages();
+    if (lastSyncTime && !languages?.length) {
-  }, [loadLanguages]);
+      loadLanguages();
+    }
+  }, [languages, lastSyncTime, loadLanguages]);
 
   const handleChange = useCallback((langCode: string) => {
     setSelectedLanguage(langCode);
@@ -58,24 +74,65 @@ const SettingsLanguage: FC<OwnProps & StateProps> = ({
     return languages ? buildOptions(languages) : undefined;
   }, [languages]);
 
+  const handleShouldTranslateChange = useCallback((newValue: boolean) => {
+    setSettingOption({ canTranslate: newValue });
+  }, [setSettingOption]);
+
+  const doNotTranslateText = useMemo(() => {
+    const allDoNotTranslateLanguages = unique([...doNotTranslate, language]);
+    // Do not translate current language
+    if (allDoNotTranslateLanguages.length === 1) {
+      if (!languages) {
+        return lang('Loading');
+      }
+      return languages.find(({ langCode }) => langCode === language)?.nativeName;
+    }
+
+    return lang('Languages', allDoNotTranslateLanguages.length);
+  }, [doNotTranslate, lang, language, languages]);
+
+  const handleDoNotSelectOpen = useCallback(() => {
+    onScreenSelect(SettingsScreens.DoNotTranslate);
+  }, [onScreenSelect]);
+
   useHistoryBack({
     isActive,
     onBack: onReset,
   });
 
   return (
-    <div className="settings-content settings-item settings-language custom-scroll settings-item--first">
+    <div className="settings-content settings-language custom-scroll">
-      {options ? (
+      <div className="settings-item">
-        <RadioGroup
+        <Checkbox
-          name="keyboard-send-settings"
+          label={lang('ShowTranslateButton')}
-          options={options}
+          checked={canTranslate}
-          selected={selectedLanguage}
+          onCheck={handleShouldTranslateChange}
-          loadingOption={isLoading ? selectedLanguage : undefined}
-          onChange={handleChange}
         />
-      ) : (
+        {canTranslate && (
-        <Loading />
+          <ListItem
-      )}
+            onClick={handleDoNotSelectOpen}
+          >
+            {lang('DoNotTranslate')}
+            <span className="settings-item__current-value">{doNotTranslateText}</span>
+          </ListItem>
+        )}
+        <p className="settings-item-description mb-0 mt-1">
+          {lang('lng_translate_settings_about')}
+        </p>
+      </div>
+      <div className="settings-item">
+        {options ? (
+          <RadioGroup
+            name="language-settings"
+            options={options}
+            selected={selectedLanguage}
+            loadingOption={isLoading ? selectedLanguage : undefined}
+            onChange={handleChange}
+          />
+        ) : (
+          <Loading />
+        )}
+      </div>
     </div>
   );
 };
@@ -95,9 +152,16 @@ function buildOptions(languages: ApiLanguage[]) {
 
 export default memo(withGlobal<OwnProps>(
   (global): StateProps => {
+    const {
+      language, languages, canTranslate, doNotTranslate,
+    } = global.settings.byKey;
+
     return {
-      languages: global.settings.byKey.languages,
+      lastSyncTime: global.lastSyncTime,
-      language: global.settings.byKey.language,
+      languages,
+      language,
+      canTranslate,
+      doNotTranslate,
     };
   },
 )(SettingsLanguage));

src/components/middle/MessageLanguageModal.async.tsx

@@ -0,0 +1,17 @@
+import React, { memo } from '../../lib/teact/teact';
+
+import type { FC } from '../../lib/teact/teact';
+import type { OwnProps } from './MessageLanguageModal';
+
+import { Bundles } from '../../util/moduleLoader';
+import useModuleLoader from '../../hooks/useModuleLoader';
+
+const MessageLanguageModalAsync: FC<OwnProps> = (props) => {
+  const { isOpen } = props;
+  const MessageLanguageModal = useModuleLoader(Bundles.Extra, 'MessageLanguageModal', !isOpen);
+
+  // eslint-disable-next-line react/jsx-props-no-spreading
+  return MessageLanguageModal ? <MessageLanguageModal {...props} /> : undefined;
+};
+
+export default memo(MessageLanguageModalAsync);

src/components/middle/MessageLanguageModal.module.scss

@@ -0,0 +1,30 @@
+@import "../../styles/mixins";
+
+.root {
+  :global(.modal-content) {
+    min-height: min(75vh, 32rem);
+    display: flex;
+    flex-direction: column;
+  }
+
+  :global(.matching-text-highlight) {
+    color: var(--color-primary);
+  }
+}
+
+.list-item {
+  text-align: left;
+
+  &[dir="rtl"] {
+    text-align: right;
+  }
+}
+
+.title, .subtitle {
+  text-align: inherit !important;
+}
+
+.languages {
+  overflow-y: auto;
+  @include overflow-y-overlay();
+}

src/components/middle/MessageLanguageModal.tsx

@@ -0,0 +1,147 @@
+import React, {
+  memo, useCallback, useEffect, useMemo, useState,
+} from '../../lib/teact/teact';
+import { getActions, withGlobal } from '../../global';
+
+import type { FC } from '../../lib/teact/teact';
+
+import { selectLanguageCode, selectRequestedTranslationLanguage, selectTabState } from '../../global/selectors';
+import { SUPPORTED_TRANSLATION_LANGUAGES } from '../../config';
+import buildClassName from '../../util/buildClassName';
+import renderText from '../common/helpers/renderText';
+
+import useLang from '../../hooks/useLang';
+
+import Modal from '../ui/Modal';
+import ListItem from '../ui/ListItem';
+import InputText from '../ui/InputText';
+
+import styles from './MessageLanguageModal.module.scss';
+
+type LanguageItem = {
+  langCode: string;
+  translatedName: string;
+  originalName: string;
+};
+
+export type OwnProps = {
+  isOpen?: boolean;
+};
+
+type StateProps = {
+  chatId?: string;
+  messageId?: number;
+  activeTranslationLanguage?: string;
+  currentLanguageCode: string;
+};
+
+const MessageLanguageModal: FC<OwnProps & StateProps> = ({
+  isOpen,
+  chatId,
+  messageId,
+  activeTranslationLanguage,
+  currentLanguageCode,
+}) => {
+  const { requestMessageTranslation, closeMessageLanguageModal } = getActions();
+
+  const [search, setSearch] = useState('');
+  const lang = useLang();
+
+  const handleSelect = useCallback((toLanguageCode: string) => {
+    if (!chatId || !messageId) return;
+
+    requestMessageTranslation({ chatId, id: messageId, toLanguageCode });
+    closeMessageLanguageModal();
+  }, [chatId, closeMessageLanguageModal, messageId, requestMessageTranslation]);
+
+  const handleSearch = useCallback((e: React.ChangeEvent<HTMLInputElement>) => {
+    setSearch(e.target.value);
+  }, []);
+
+  const translateLanguages = useMemo(() => SUPPORTED_TRANSLATION_LANGUAGES.map((langCode: string) => {
+    const translatedNames = new Intl.DisplayNames([currentLanguageCode], { type: 'language' });
+    const translatedName = translatedNames.of(langCode)!;
+
+    const originalNames = new Intl.DisplayNames([langCode], { type: 'language' });
+    const originalName = originalNames.of(langCode)!;
+
+    return {
+      langCode,
+      translatedName,
+      originalName,
+    } satisfies LanguageItem;
+  }), [currentLanguageCode]);
+
+  useEffect(() => {
+    if (!isOpen) setSearch('');
+  }, [isOpen]);
+
+  const filteredDisplayedLanguages = useMemo(() => {
+    if (!search.trim()) {
+      return translateLanguages;
+    }
+
+    return translateLanguages.filter(({ langCode, translatedName, originalName }) => (
+      translatedName.toLowerCase().includes(search.toLowerCase())
+      || originalName.toLowerCase().includes(search.toLowerCase())
+      || langCode.toLowerCase().includes(search.toLowerCase())
+    ));
+  }, [translateLanguages, search]);
+
+  return (
+    <Modal
+      className={styles.root}
+      isSlim
+      isOpen={isOpen}
+      hasCloseButton
+      title={lang('Language')}
+      onClose={closeMessageLanguageModal}
+    >
+      <InputText
+        key="search"
+        value={search}
+        onChange={handleSearch}
+        placeholder={lang('Search')}
+        teactExperimentControlled
+      />
+      <div className={buildClassName(styles.languages, 'custom-scroll')}>
+        {filteredDisplayedLanguages.map(({ langCode, originalName, translatedName }) => (
+          <ListItem
+            key={langCode}
+            className={styles.listItem}
+            secondaryIcon={activeTranslationLanguage === langCode ? 'check' : undefined}
+            disabled={activeTranslationLanguage === langCode}
+            multiline
+            narrow
+            // eslint-disable-next-line react/jsx-no-bind
+            onClick={() => handleSelect(langCode)}
+          >
+            <span className={buildClassName('title', styles.title)}>
+              {renderText(originalName, ['highlight'], { highlight: search })}
+            </span>
+            <span className={buildClassName('subtitle', styles.subtitle)}>
+              {renderText(translatedName, ['highlight'], { highlight: search })}
+            </span>
+          </ListItem>
+        ))}
+      </div>
+    </Modal>
+  );
+};
+
+export default memo(withGlobal<OwnProps>(
+  (global): StateProps => {
+    const { chatId, messageId } = selectTabState(global).messageLanguageModal || {};
+
+    const currentLanguageCode = selectLanguageCode(global);
+    const activeTranslationLanguage = chatId && messageId
+      ? selectRequestedTranslationLanguage(global, chatId, messageId) : undefined;
+
+    return {
+      chatId,
+      messageId,
+      activeTranslationLanguage,
+      currentLanguageCode,
+    };
+  },
+)(MessageLanguageModal));

src/components/middle/MiddleColumn.tsx

@@ -77,6 +77,7 @@ import SeenByModal from '../common/SeenByModal.async';
 import EmojiInteractionAnimation from './EmojiInteractionAnimation.async';
 import ReactorListModal from './ReactorListModal.async';
 import GiftPremiumModal from '../main/premium/GiftPremiumModal.async';
+import MessageLanguageModal from './MessageLanguageModal.async';
 
 import './MiddleColumn.scss';
 import styles from './MiddleColumn.module.scss';
@@ -111,6 +112,7 @@ type StateProps = {
   isSeenByModalOpen: boolean;
   isReactorListModalOpen: boolean;
   isGiftPremiumModalOpen?: boolean;
+  isMessageLanguageModalOpen?: boolean;
   animationLevel: AnimationLevel;
   shouldSkipHistoryAnimations?: boolean;
   currentTransitionKey: number;
@@ -156,6 +158,7 @@ const MiddleColumn: FC<OwnProps & StateProps> = ({
   isSeenByModalOpen,
   isReactorListModalOpen,
   isGiftPremiumModalOpen,
+  isMessageLanguageModalOpen,
   animationLevel,
   shouldSkipHistoryAnimations,
   currentTransitionKey,
@@ -551,6 +554,7 @@ const MiddleColumn: FC<OwnProps & StateProps> = ({
                 />
                 <SeenByModal isOpen={isSeenByModalOpen} />
                 <ReactorListModal isOpen={isReactorListModalOpen} />
+                <MessageLanguageModal isOpen={isMessageLanguageModalOpen} />
               </div>
             </Transition>
 
@@ -596,6 +600,7 @@ export default memo(withGlobal<OwnProps>(
     const {
       messageLists, isLeftColumnShown, activeEmojiInteractions,
       seenByModal, giftPremiumModal, reactorModal, audioPlayer, shouldSkipHistoryAnimations,
+      messageLanguageModal,
     } = selectTabState(global);
     const currentMessageList = selectCurrentMessageList(global);
     const { chats: { listIds }, lastSyncTime } = global;
@@ -613,6 +618,7 @@ export default memo(withGlobal<OwnProps>(
       isSeenByModalOpen: Boolean(seenByModal),
       isReactorListModalOpen: Boolean(reactorModal),
       isGiftPremiumModalOpen: giftPremiumModal?.isOpen,
+      isMessageLanguageModalOpen: Boolean(messageLanguageModal),
       animationLevel: global.settings.byKey.animationLevel,
       currentTransitionKey: Math.max(0, messageLists.length - 1),
       activeEmojiInteractions,

src/components/middle/message/ContextMenuContainer.tsx

@@ -20,6 +20,8 @@ import {
   selectIsMessageProtected,
   selectIsPremiumPurchaseBlocked,
   selectMessageCustomEmojiSets,
+  selectMessageTranslations,
+  selectRequestedTranslationLanguage,
   selectStickerSet,
 } from '../../../global/selectors';
 import {
@@ -27,6 +29,7 @@ import {
   isChatGroup, isOwnMessage, areReactionsEmpty, isUserId, isMessageLocal, getMessageVideo, getChatMessageLink,
 } from '../../../global/helpers';
 import { SERVICE_NOTIFICATIONS_USER_ID } from '../../../config';
+import { IS_TRANSLATION_SUPPORTED } from '../../../util/environment';
 import buildClassName from '../../../util/buildClassName';
 import { copyTextToClipboard } from '../../../util/clipboard';
 
@@ -49,6 +52,7 @@ export type OwnProps = {
   anchor: IAnchorPosition;
   messageListType: MessageListType;
   noReplies?: boolean;
+  detectedLanguage?: string;
   onClose: () => void;
   onCloseAnimationEnd: () => void;
   repliesThreadInfo?: ApiThreadInfo;
@@ -74,6 +78,9 @@ type StateProps = {
   canFaveSticker?: boolean;
   canUnfaveSticker?: boolean;
   canCopy?: boolean;
+  canTranslate?: boolean;
+  canShowOriginal?: boolean;
+  canSelectLanguage?: boolean;
   isPrivate?: boolean;
   isCurrentUserPremium?: boolean;
   hasFullInfo?: boolean;
@@ -101,8 +108,6 @@ const ContextMenuContainer: FC<OwnProps & StateProps> = ({
   customEmojiSets,
   album,
   anchor,
-  onClose,
-  onCloseAnimationEnd,
   noOptions,
   canSendNow,
   hasFullInfo,
@@ -135,7 +140,12 @@ const ContextMenuContainer: FC<OwnProps & StateProps> = ({
   noReplies,
   canShowSeenBy,
   canScheduleUntilOnline,
+  canTranslate,
+  canShowOriginal,
+  canSelectLanguage,
   threadId,
+  onClose,
+  onCloseAnimationEnd,
 }) => {
   const {
     openChat,
@@ -161,6 +171,9 @@ const ContextMenuContainer: FC<OwnProps & StateProps> = ({
     cancelPollVote,
     closePoll,
     toggleReaction,
+    requestMessageTranslation,
+    showOriginalMessage,
+    openMessageLanguageModal,
   } = getActions();
 
   const lang = useLang();
@@ -393,6 +406,30 @@ const ContextMenuContainer: FC<OwnProps & StateProps> = ({
     closeMenu();
   }, [closeMenu, message, toggleReaction]);
 
+  const handleTranslate = useCallback(() => {
+    requestMessageTranslation({
+      chatId: message.chatId,
+      id: message.id,
+    });
+    closeMenu();
+  }, [closeMenu, message, requestMessageTranslation]);
+
+  const handleShowOriginal = useCallback(() => {
+    showOriginalMessage({
+      chatId: message.chatId,
+      id: message.id,
+    });
+    closeMenu();
+  }, [closeMenu, message, showOriginalMessage]);
+
+  const handleSelectLanguage = useCallback(() => {
+    openMessageLanguageModal({
+      chatId: message.chatId,
+      id: message.id,
+    });
+    closeMenu();
+  }, [closeMenu, message.chatId, message.id, openMessageLanguageModal]);
+
   const reportMessageIds = useMemo(() => (album ? album.messages : [message]).map(({ id }) => id), [album, message]);
 
   if (noOptions) {
@@ -438,6 +475,9 @@ const ContextMenuContainer: FC<OwnProps & StateProps> = ({
         canRevote={canRevote}
         canClosePoll={canClosePoll}
         canShowSeenBy={canShowSeenBy}
+        canTranslate={canTranslate}
+        canShowOriginal={canShowOriginal}
+        canSelectLanguage={canSelectLanguage}
         hasCustomEmoji={hasCustomEmoji}
         customEmojiSets={customEmojiSets}
         isDownloading={isDownloading}
@@ -467,6 +507,9 @@ const ContextMenuContainer: FC<OwnProps & StateProps> = ({
         onShowSeenBy={handleOpenSeenByModal}
         onToggleReaction={handleToggleReaction}
         onShowReactors={handleOpenReactorListModal}
+        onTranslate={handleTranslate}
+        onShowOriginal={handleShowOriginal}
+        onSelectLanguage={handleSelectLanguage}
       />
       <DeleteMessageModal
         isOpen={isDeleteModalOpen}
@@ -499,7 +542,7 @@ const ContextMenuContainer: FC<OwnProps & StateProps> = ({
 };
 
 export default memo(withGlobal<OwnProps>(
-  (global, { message, messageListType }): StateProps => {
+  (global, { message, messageListType, detectedLanguage }): StateProps => {
     const { threadId } = selectCurrentMessageList(global) || {};
     const activeDownloads = selectActiveDownloadIds(global, message.chatId);
     const chat = selectChat(global, message.chatId);
@@ -524,6 +567,7 @@ export default memo(withGlobal<OwnProps>(
       canClosePoll,
     } = (threadId && selectAllowedMessageActions(global, message, threadId)) || {};
 
+    const isOwn = isOwnMessage(message);
     const isPinned = messageListType === 'pinned';
     const isScheduled = messageListType === 'scheduled';
     const isChannel = chat && isChatChannel(chat);
@@ -532,7 +576,7 @@ export default memo(withGlobal<OwnProps>(
       && seenByMaxChatMembers
       && seenByExpiresAt
       && isChatGroup(chat)
-      && isOwnMessage(message)
+      && isOwn
       && !isScheduled
       && chat.membersCount
       && chat.membersCount <= seenByMaxChatMembers
@@ -550,6 +594,18 @@ export default memo(withGlobal<OwnProps>(
     const customEmojiSets = customEmojiSetsNotFiltered?.every<ApiStickerSet>(Boolean)
       ? customEmojiSetsNotFiltered : undefined;
 
+    const translationRequestLanguage = selectRequestedTranslationLanguage(global, message.chatId, message.id);
+    const hasTranslation = translationRequestLanguage
+      ? Boolean(selectMessageTranslations(global, message.chatId, translationRequestLanguage)[message.id]?.text)
+      : undefined;
+
+    const { canTranslate: isTranslationEnabled, language, doNotTranslate } = global.settings.byKey;
+
+    const canTranslateLanguage = !detectedLanguage
+      || (!doNotTranslate.includes(detectedLanguage) && language !== detectedLanguage);
+    const canTranslate = IS_TRANSLATION_SUPPORTED && isTranslationEnabled && message.content.text
+      && canTranslateLanguage && !isLocal && !isScheduled && !isAction && !hasTranslation && !message.emojiOnlyCount;
+
     return {
       availableReactions: global.availableReactions,
       noOptions,
@@ -585,6 +641,9 @@ export default memo(withGlobal<OwnProps>(
       customEmojiSets,
       canScheduleUntilOnline: selectCanScheduleUntilOnline(global, message.chatId),
       threadId,
+      canTranslate,
+      canShowOriginal: hasTranslation,
+      canSelectLanguage: hasTranslation,
     };
   },
 )(ContextMenuContainer));

src/components/middle/message/Message.tsx

@@ -9,7 +9,9 @@ import React, {
 } from '../../../lib/teact/teact';
 import { getActions, withGlobal } from '../../../global';
 
-import type { ActiveEmojiInteraction, ActiveReaction, MessageListType } from '../../../global/types';
+import type {
+  ActiveEmojiInteraction, ActiveReaction, ChatTranslatedMessages, MessageListType,
+} from '../../../global/types';
 import type {
   ApiMessage,
   ApiMessageOutgoingStatus,
@@ -63,6 +65,8 @@ import {
   selectIsChatProtected,
   selectTopicFromMessage,
   selectTabState,
+  selectChatTranslations,
+  selectRequestedTranslationLanguage,
 } from '../../../global/selectors';
 import {
   getMessageContent,
@@ -113,6 +117,9 @@ import useInnerHandlers from './hooks/useInnerHandlers';
 import useAppLayout from '../../../hooks/useAppLayout';
 import useResizeObserver from '../../../hooks/useResizeObserver';
 import useThrottledCallback from '../../../hooks/useThrottledCallback';
+import useMessageTranslation from './hooks/useMessageTranslation';
+import usePrevious from '../../../hooks/usePrevious';
+import useTextLanguage from '../../../hooks/useTextLanguage';
 
 import Button from '../../ui/Button';
 import Avatar from '../../common/Avatar';
@@ -233,6 +240,9 @@ type StateProps = {
   senderAdminMember?: ApiChatMember;
   messageTopic?: ApiTopic;
   hasTopicChip?: boolean;
+  chatTranslations?: ChatTranslatedMessages;
+  areTranslationsEnabled?: boolean;
+  requestedTranslationLanguage?: string;
 };
 
 type MetaPosition =
@@ -329,6 +339,9 @@ const Message: FC<OwnProps & StateProps> = ({
   senderAdminMember,
   messageTopic,
   hasTopicChip,
+  chatTranslations,
+  areTranslationsEnabled,
+  requestedTranslationLanguage,
 }) => {
   const {
     toggleMessageSelection,
@@ -468,6 +481,7 @@ const Message: FC<OwnProps & StateProps> = ({
     handleAudioPlay,
     handleAlbumMediaClick,
     handleMetaClick,
+    handleTranslationClick,
     handleOpenThread,
     handleReadMedia,
     handleCancelUpload,
@@ -537,6 +551,17 @@ const Message: FC<OwnProps & StateProps> = ({
     text, photo, video, audio, voice, document, sticker, contact, poll, webPage, invoice, location, action, game,
   } = getMessageContent(message);
 
+  const { result: detectedLanguage } = useTextLanguage(areTranslationsEnabled ? text?.text : undefined);
+
+  const { isPending: isTranslationPending, translatedText } = useMessageTranslation(
+    chatTranslations, chatId, messageId, requestedTranslationLanguage,
+  );
+  // Used to display previous result while new one is loading
+  const previousTranslatedText = usePrevious(translatedText, true);
+
+  const currentText = isTranslationPending ? (previousTranslatedText || text) : translatedText;
+  const currentTranslatedText = translatedText || previousTranslatedText;
+
   const { phoneCall } = action || {};
 
   const withCommentButton = repliesThreadInfo && !isInDocumentGroupNotLast && messageListType === 'thread'
@@ -663,13 +688,15 @@ const Message: FC<OwnProps & StateProps> = ({
     }
 
     if (width) {
-      calculatedWidth = Math.max(getMinMediaWidth(Boolean(text), withCommentButton), width);
+      calculatedWidth = Math.max(getMinMediaWidth(Boolean(currentText), withCommentButton), width);
       if (invoice?.extendedMedia && calculatedWidth - width > NO_MEDIA_CORNERS_THRESHOLD) {
         noMediaCorners = true;
       }
     }
   } else if (albumLayout) {
-    calculatedWidth = Math.max(getMinMediaWidth(Boolean(text), withCommentButton), albumLayout.containerStyle.width);
+    calculatedWidth = Math.max(
+      getMinMediaWidth(Boolean(currentText), withCommentButton), albumLayout.containerStyle.width,
+    );
     if (calculatedWidth - albumLayout.containerStyle.width > NO_MEDIA_CORNERS_THRESHOLD) {
       noMediaCorners = true;
     }
@@ -707,6 +734,22 @@ const Message: FC<OwnProps & StateProps> = ({
     );
   }
 
+  function renderMessageText(isForAnimation?: boolean) {
+    return (
+      <MessageText
+        message={message}
+        translatedText={requestedTranslationLanguage ? currentTranslatedText : undefined}
+        isForAnimation={isForAnimation}
+        emojiSize={emojiSize}
+        highlight={highlight}
+        isProtected={isProtected}
+        observeIntersectionForLoading={observeIntersectionForLoading}
+        observeIntersectionForPlaying={observeIntersectionForPlaying}
+        withTranslucentThumbs={isCustomShape}
+      />
+    );
+  }
+
   function renderReactionsAndMeta() {
     const meta = (
       <MessageMeta
@@ -717,7 +760,9 @@ const Message: FC<OwnProps & StateProps> = ({
         signature={signature}
         withReactionOffset={reactionsPosition === 'inside'}
         availableReactions={availableReactions}
+        isTranslated={Boolean(requestedTranslationLanguage ? currentTranslatedText : undefined)}
         onClick={handleMetaClick}
+        onTranslationClick={handleTranslationClick}
         onOpenThread={handleOpenThread}
       />
     );
@@ -749,6 +794,7 @@ const Message: FC<OwnProps & StateProps> = ({
     const hasCustomAppendix = isLastInGroup && !hasText && !asForwarded && !hasThread;
     const textContentClass = buildClassName(
       'text-content',
+      'clearfix',
       metaPosition === 'in-text' && 'with-meta',
       outgoingStatus && 'with-outgoing-icon',
     );
@@ -954,15 +1000,14 @@ const Message: FC<OwnProps & StateProps> = ({
 
         {!hasAnimatedEmoji && hasText && (
           <div className={textContentClass} dir="auto">
-            <MessageText
+            {renderMessageText()}
-              message={message}
+            {isTranslationPending && (
-              emojiSize={emojiSize}
+              <div className="translation-animation">
-              highlight={highlight}
+                <div className="text-loading">
-              isProtected={isProtected}
+                  {renderMessageText(true)}
-              observeIntersectionForLoading={observeIntersectionForLoading}
+                </div>
-              observeIntersectionForPlaying={observeIntersectionForPlaying}
+              </div>
-              withTranslucentThumbs={isCustomShape}
+            )}
-            />
             {metaPosition === 'in-text' && renderReactionsAndMeta()}
           </div>
         )}
@@ -1208,6 +1253,7 @@ const Message: FC<OwnProps & StateProps> = ({
           onCloseAnimationEnd={handleContextMenuHide}
           repliesThreadInfo={repliesThreadInfo}
           noReplies={noReplies}
+          detectedLanguage={detectedLanguage}
         />
       )}
     </div>
@@ -1300,6 +1346,8 @@ export default memo(withGlobal<OwnProps>(
       : undefined;
 
     const isLocation = Boolean(getMessageLocation(message));
+    const chatTranslations = selectChatTranslations(global, chatId);
+    const requestedTranslationLanguage = selectRequestedTranslationLanguage(global, chatId, message.id);
 
     return {
       theme: selectTheme(global),
@@ -1355,6 +1403,9 @@ export default memo(withGlobal<OwnProps>(
       messageTopic,
       genericEffects: global.genericEmojiEffects,
       hasTopicChip,
+      chatTranslations,
+      areTranslationsEnabled: global.settings.byKey.canTranslate,
+      requestedTranslationLanguage,
       ...((canShowSender || isLocation) && { sender }),
       ...(isOutgoing && { outgoingStatus: selectOutgoingStatus(global, message, messageListType === 'scheduled') }),
       ...(typeof uploadProgress === 'number' && { uploadProgress }),

src/components/middle/message/MessageContextMenu.tsx

@@ -61,6 +61,9 @@ type OwnProps = {
   canCopy?: boolean;
   canCopyLink?: boolean;
   canSelect?: boolean;
+  canTranslate?: boolean;
+  canShowOriginal?: boolean;
+  canSelectLanguage?: boolean;
   isPrivate?: boolean;
   isCurrentUserPremium?: boolean;
   canDownload?: boolean;
@@ -99,6 +102,9 @@ type OwnProps = {
   onShowReactors?: () => void;
   onAboutAds?: () => void;
   onSponsoredHide?: () => void;
+  onTranslate?: () => void;
+  onShowOriginal?: () => void;
+  onSelectLanguage?: () => void;
   onToggleReaction?: (reaction: ApiReaction) => void;
 };
 
@@ -135,6 +141,9 @@ const MessageContextMenu: FC<OwnProps> = ({
   canSaveGif,
   canRevote,
   canClosePoll,
+  canTranslate,
+  canShowOriginal,
+  canSelectLanguage,
   isDownloading,
   repliesThreadInfo,
   canShowSeenBy,
@@ -170,6 +179,9 @@ const MessageContextMenu: FC<OwnProps> = ({
   onCopyMessages,
   onAboutAds,
   onSponsoredHide,
+  onTranslate,
+  onShowOriginal,
+  onSelectLanguage,
 }) => {
   const { showNotification, openStickerSet, openCustomEmojiSets } = getActions();
   // eslint-disable-next-line no-null/no-null
@@ -319,6 +331,11 @@ const MessageContextMenu: FC<OwnProps> = ({
         {canUnfaveSticker && (
           <MenuItem icon="favorite" onClick={onUnfaveSticker}>{lang('Stickers.RemoveFromFavorites')}</MenuItem>
         )}
+        {canTranslate && <MenuItem icon="language" onClick={onTranslate}>{lang('TranslateMessage')}</MenuItem>}
+        {canShowOriginal && <MenuItem icon="language" onClick={onShowOriginal}>{lang('ShowOriginalButton')}</MenuItem>}
+        {canSelectLanguage && (
+          <MenuItem icon="web" onClick={onSelectLanguage}>{lang('lng_settings_change_lang')}</MenuItem>
+        )}
         {canCopy && copyOptions.map((option) => (
           <MenuItem key={option.label} icon={option.icon} onClick={option.handler}>{lang(option.label)}</MenuItem>
         ))}

src/components/middle/message/MessageMeta.scss

@@ -17,7 +17,8 @@
   .message-imported,
   .message-signature,
   .message-views,
-  .message-replies {
+  .message-replies,
+  .message-translated {
     font-size: 0.75rem;
     white-space: nowrap;
   }
@@ -36,6 +37,10 @@
     margin-inline-start: 0.1875rem;
   }
 
+  .message-translated {
+    margin-inline-end: 0.25rem;
+  }
+
   .message-imported,
   .message-signature {
     overflow: hidden;

src/components/middle/message/MessageMeta.tsx

@@ -27,8 +27,10 @@ type OwnProps = {
   availableReactions?: ApiAvailableReaction[];
   noReplies?: boolean;
   repliesThreadInfo?: ApiThreadInfo;
-  onClick: (e: React.MouseEvent<HTMLDivElement, MouseEvent>) => void;
+  isTranslated?: boolean;
-  onOpenThread: () => void;
+  onClick: (e: React.MouseEvent<HTMLDivElement>) => void;
+  onTranslationClick: (e: React.MouseEvent<HTMLDivElement>) => void;
+  onOpenThread: NoneToVoidFunction;
 };
 
 const MessageMeta: FC<OwnProps> = ({
@@ -38,7 +40,9 @@ const MessageMeta: FC<OwnProps> = ({
   withReactionOffset,
   repliesThreadInfo,
   noReplies,
+  isTranslated,
   onClick,
+  onTranslationClick,
   onOpenThread,
 }) => {
   const { showNotification } = getActions();
@@ -90,6 +94,9 @@ const MessageMeta: FC<OwnProps> = ({
       onClick={onClick}
       data-ignore-on-paste
     >
+      {isTranslated && (
+        <i className="icon-language message-translated" onClick={onTranslationClick} />
+      )}
       {Boolean(message.views) && (
         <>
           <span className="message-views">

src/components/middle/message/_message-content.scss

@@ -41,8 +41,10 @@
     white-space: pre-wrap;
     line-height: 1.3125;
     text-align: initial;
-    display: flow-root;
+    display: block;
     unicode-bidi: plaintext;
+    border-radius: 0.25rem;
+    position: relative;
   }
 
   .transcription {
@@ -68,6 +70,40 @@
     }
   }
 
+  .translation-animation {
+    position: absolute;
+    top: 0;
+    left: 0;
+    right: 0;
+    bottom: 0;
+
+    pointer-events: none;
+  }
+
+  .text-loading {
+    --background-gradient-size: 20rem;
+    --animation-color: var(--color-skeleton-background);
+
+    background-image: linear-gradient(to right, transparent 10%, var(--animation-color) 50%, transparent 90%);
+    background-size: var(--background-gradient-size);
+
+    display: inline;
+    box-decoration-break: clone;
+    color: transparent;
+
+    border-radius: 0.25rem;
+
+    animation: text-loading 1.5s linear infinite;
+
+    .theme-dark & {
+      --animation-color: var(--color-skeleton-foreground);
+    }
+
+    .emoji {
+      opacity: 0;
+    }
+  }
+
   .text-entity-link {
     unicode-bidi: plaintext;
   }
@@ -735,7 +771,6 @@
     }
 
     .text-content {
-      margin-bottom: 1.25rem;
       word-break: normal;
       line-height: var(--emoji-only-size);
       font-size: var(--emoji-only-size);
@@ -747,7 +782,7 @@
 
       .MessageMeta {
         text-shadow: none;
-        bottom: 0;
+        bottom: -1.25rem;
         right: 0;
         line-height: normal;
       }
@@ -903,3 +938,19 @@
   font-family: var(--font-family-monospace);
   font-size: 0.875rem;
 }
+
+@keyframes text-loading {
+  0% {
+    background-position-x: 0;
+    opacity: 1;
+  }
+
+  50% {
+    opacity: 0.8;
+  }
+
+  100% {
+    background-position-x: var(--background-gradient-size);
+    opacity: 1;
+  }
+}

src/components/middle/message/hooks/useInnerHandlers.ts

@@ -29,6 +29,7 @@ export default function useInnerHandlers(
   const {
     openChat, showNotification, focusMessage, openMediaViewer, openAudioPlayer,
     markMessagesRead, cancelSendingMessage, sendPollVote, openForwardMenu, focusMessageInComments,
+    openMessageLanguageModal,
   } = getActions();
 
   const {
@@ -154,12 +155,18 @@ export default function useInnerHandlers(
     focusMessageInComments, replyToTopMessageId,
   ]);
 
-  const selectWithGroupedId = useCallback((e: React.MouseEvent<HTMLDivElement, MouseEvent>) => {
+  const selectWithGroupedId = useCallback((e: React.MouseEvent<HTMLDivElement>) => {
     e.stopPropagation();
 
     selectMessage(e, groupedId);
   }, [selectMessage, groupedId]);
 
+  const handleTranslationClick = useCallback((e: React.MouseEvent<HTMLDivElement>) => {
+    e.stopPropagation();
+
+    openMessageLanguageModal({ chatId, id: messageId });
+  }, [chatId, messageId, openMessageLanguageModal]);
+
   const handleOpenThread = useCallback(() => {
     openChat({
       id: message.chatId,
@@ -185,6 +192,7 @@ export default function useInnerHandlers(
     handleAudioPlay,
     handleAlbumMediaClick,
     handleMetaClick: selectWithGroupedId,
+    handleTranslationClick,
     handleOpenThread,
     handleReadMedia,
     handleCancelUpload,

src/components/middle/message/hooks/useMessageTranslation.ts

@@ -0,0 +1,27 @@
+import { useEffect } from '../../../../lib/teact/teact';
+import { getActions } from '../../../../global';
+import type { ChatTranslatedMessages } from '../../../../global/types';
+
+export default function useMessageTranslation(
+  chatTranslations: ChatTranslatedMessages | undefined,
+  chatId: string,
+  messageId: number,
+  requestedLanguageCode?: string,
+) {
+  const { translateMessages } = getActions();
+  const messageTranslation = requestedLanguageCode
+    ? chatTranslations?.byLangCode[requestedLanguageCode]?.[messageId] : undefined;
+
+  const { isPending, text } = messageTranslation || {};
+
+  useEffect(() => {
+    if (!text && !isPending && requestedLanguageCode) {
+      translateMessages({ chatId, messageIds: [messageId], toLanguageCode: requestedLanguageCode });
+    }
+  }, [chatId, text, isPending, messageId, requestedLanguageCode, translateMessages]);
+
+  return {
+    isPending,
+    translatedText: text,
+  };
+}

src/components/ui/CheckboxGroup.tsx

@@ -4,9 +4,10 @@ import React, { useCallback, memo, useState } from '../../lib/teact/teact';
 
 import Checkbox from './Checkbox';
 
-type IRadioOption = {
+export type IRadioOption = {
   label: string;
   subLabel?: string;
+  disabled?: boolean;
   value: string;
 };
 
@@ -52,7 +53,7 @@ const CheckboxGroup: FC<OwnProps> = ({
           subLabel={option.subLabel}
           value={option.value}
           checked={selected.indexOf(option.value) !== -1}
-          disabled={disabled}
+          disabled={option.disabled || disabled}
           round={round}
           isLoading={loadingOptions ? loadingOptions.indexOf(option.value) !== -1 : undefined}
           onChange={handleChange}

src/components/ui/Modal.scss

@@ -28,6 +28,16 @@
     }
   }
 
+  &.slim {
+    .modal-dialog {
+      max-width: 25rem;
+    }
+
+    .modal-content {
+      max-height: min(92vh, 32rem);
+    }
+  }
+
   .modal-container {
     position: fixed;
     top: 0;

src/components/ui/Modal.tsx

@@ -26,6 +26,7 @@ type OwnProps = {
   className?: string;
   isOpen?: boolean;
   header?: TeactNode;
+  isSlim?: boolean;
   hasCloseButton?: boolean;
   noBackdrop?: boolean;
   noBackdropClose?: boolean;
@@ -46,6 +47,7 @@ const Modal: FC<OwnProps & StateProps> = ({
   title,
   className,
   isOpen,
+  isSlim,
   header,
   hasCloseButton,
   noBackdrop,
@@ -136,6 +138,7 @@ const Modal: FC<OwnProps & StateProps> = ({
     className,
     transitionClassNames,
     noBackdrop && 'transparent-backdrop',
+    isSlim && 'slim',
   );
 
   return (

src/config.ts

@@ -44,7 +44,7 @@ export const CUSTOM_EMOJI_PREVIEW_CACHE_DISABLED = false;
 export const CUSTOM_EMOJI_PREVIEW_CACHE_NAME = 'tt-custom-emoji-preview';
 export const MEDIA_CACHE_MAX_BYTES = 512 * 1024; // 512 KB
 export const CUSTOM_BG_CACHE_NAME = 'tt-custom-bg';
-export const LANG_CACHE_NAME = 'tt-lang-packs-v16';
+export const LANG_CACHE_NAME = 'tt-lang-packs-v17';
 export const ASSET_CACHE_NAME = 'tt-assets';
 export const AUTODOWNLOAD_FILESIZE_MB_LIMITS = [1, 5, 10, 50, 100, 500];
 export const DATA_BROADCAST_CHANNEL_NAME = 'tt-global';
@@ -218,6 +218,25 @@ export const CONTENT_TYPES_WITH_PREVIEW = new Set([
 
 export const CONTENT_NOT_SUPPORTED = 'The message is not supported on this version of Telegram.';
 
+// Taken from https://github.com/telegramdesktop/tdesktop/blob/41d9a9fcbd0c809c60ddbd9350791b1436aff7d9/Telegram/SourceFiles/ui/boxes/choose_language_box.cpp#L28
+export const SUPPORTED_TRANSLATION_LANGUAGES = [
+  // Official
+  'en', 'ar', 'be', 'ca', 'zh', 'nl', 'fr', 'de', 'id',
+  'it', 'ja', 'ko', 'pl', 'pt', 'ru', 'es', 'uk',
+  // Unnofficial
+  'af', 'sq', 'am', 'hy', 'az', 'eu', 'bn', 'bs', 'bg',
+  'ceb', 'zh-CN', 'zh-TW', 'co', 'hr', 'cs', 'da', 'eo',
+  'et', 'fi', 'fy', 'gl', 'ka', 'el', 'gu', 'ht', 'ha',
+  'haw', 'he', 'iw', 'hi', 'hmn', 'hu', 'is', 'ig', 'ga',
+  'jv', 'kn', 'kk', 'km', 'rw', 'ku', 'ky', 'lo', 'la',
+  'lv', 'lt', 'lb', 'mk', 'mg', 'ms', 'ml', 'mt', 'mi',
+  'mr', 'mn', 'my', 'ne', 'no', 'ny', 'or', 'ps', 'fa',
+  'pa', 'ro', 'sm', 'gd', 'sr', 'st', 'sn', 'sd', 'si',
+  'sk', 'sl', 'so', 'su', 'sw', 'sv', 'tl', 'tg', 'ta',
+  'tt', 'te', 'th', 'tr', 'tk', 'ur', 'ug', 'uz', 'vi',
+  'cy', 'xh', 'yi', 'yo', 'zu',
+];
+
 // eslint-disable-next-line max-len
 export const RE_LINK_TEMPLATE = '((ftp|https?):\\/\\/)?((www\\.)?[-a-zA-Z0-9@:%._+~#=]{1,256}\\.[a-zA-Z0-9()]{1,63})\\b([-a-zA-Z0-9()@:%_+.~#?&/=]*)';
 export const RE_MENTION_TEMPLATE = '(@[\\w\\d_-]+)';

src/global/actions/api/messages.ts

@@ -54,6 +54,9 @@ import {
   updateTopic,
   updateThreadInfo,
   replaceTabThreadParam,
+  updateRequestedMessageTranslation,
+  removeRequestedMessageTranslation,
+  updateMessageTranslation,
 } from '../../reducers';
 import {
   selectChat,
@@ -80,7 +83,9 @@ import {
   selectIsCurrentUserPremium,
   selectForwardsContainVoiceMessages,
   selectTabState,
-  selectThreadIdFromMessage, selectForwardsCanBeSentToChat,
+  selectThreadIdFromMessage,
+  selectLanguageCode,
+  selectForwardsCanBeSentToChat,
 } from '../../selectors';
 import {
   debounce, onTickEnd, rafPromise,
@@ -1411,6 +1416,49 @@ addActionHandler('forwardToSavedMessages', (global, actions, payload): ActionRet
   actions.forwardMessages({ isSilent: true, tabId });
 });
 
+addActionHandler('requestMessageTranslation', (global, actions, payload): ActionReturnType => {
+  const {
+    chatId, id, toLanguageCode = selectLanguageCode(global), tabId = getCurrentTabId(),
+  } = payload;
+
+  global = updateRequestedMessageTranslation(global, chatId, id, toLanguageCode, tabId);
+
+  return global;
+});
+
+addActionHandler('showOriginalMessage', (global, actions, payload): ActionReturnType => {
+  const {
+    chatId, id, tabId = getCurrentTabId(),
+  } = payload;
+
+  global = removeRequestedMessageTranslation(global, chatId, id, tabId);
+
+  return global;
+});
+
+addActionHandler('translateMessages', (global, actions, payload): ActionReturnType => {
+  const {
+    chatId, messageIds, toLanguageCode = selectLanguageCode(global),
+  } = payload;
+
+  const chat = selectChat(global, chatId);
+  if (!chat) return undefined;
+
+  messageIds.forEach((id) => {
+    global = updateMessageTranslation(global, chatId, id, toLanguageCode, {
+      isPending: true,
+    });
+  });
+
+  callApi('translateText', {
+    chat,
+    messageIds,
+    toLanguageCode,
+  });
+
+  return global;
+});
+
 function countSortedIds(ids: number[], from: number, to: number) {
   let count = 0;
 

src/global/actions/apiUpdaters/messages.ts

@@ -27,6 +27,8 @@ import {
   updateThreadUnreadFromForwardedMessage,
   updateTopic,
   deleteTopic,
+  updateMessageTranslations,
+  clearMessageTranslation,
 } from '../../reducers';
 import {
   selectChatMessage,
@@ -211,6 +213,10 @@ addActionHandler('apiUpdate', (global, actions, update): ActionReturnType => {
         global = updateReactions(global, chatId, id, message.reactions, chat, newMessage.isOutgoing, currentMessage);
       }
 
+      if (message.content?.text?.text !== currentMessage?.content?.text?.text) {
+        global = clearMessageTranslation(global, chatId, id);
+      }
+
       setGlobal(global);
 
       break;
@@ -639,6 +645,18 @@ addActionHandler('apiUpdate', (global, actions, update): ActionReturnType => {
 
       global = updateChatMessage(global, chatId, localId, { sendingState: 'messageSendingStateFailed' });
       setGlobal(global);
+      break;
+    }
+
+    case 'updateMessageTranslations': {
+      const {
+        chatId, messageIds, toLanguageCode, translations,
+      } = update;
+
+      global = updateMessageTranslations(global, chatId, messageIds, toLanguageCode, translations);
+
+      setGlobal(global);
+      break;
     }
   }
 });
@@ -878,6 +896,8 @@ function deleteMessages<T extends GlobalState>(
         isDeleting: true,
       });
 
+      global = clearMessageTranslation(global, chatId, id);
+
       const newLastMessage = findLastMessage(global, chatId);
       if (newLastMessage) {
         global = updateChatLastMessage(global, chatId, newLastMessage, true);

src/global/actions/apiUpdaters/users.ts

@@ -39,8 +39,17 @@ addActionHandler('apiUpdate', (global, actions, update): ActionReturnType => {
 
     case 'updateUser': {
       Object.values(global.byTabId).forEach(({ id: tabId }) => {
-        if (update.id === global.currentUserId && update.user.isPremium && !selectIsCurrentUserPremium(global)) {
+        if (update.id === global.currentUserId && update.user.isPremium !== selectIsCurrentUserPremium(global)) {
-          actions.openPremiumModal({ isSuccess: true, tabId });
+          // TODO Do not display modal if premium is bought from another device
+          if (update.user.isPremium) actions.openPremiumModal({ isSuccess: true, tabId });
+
+          // Reset translation cache cause premium provides additional formatting
+          global = {
+            ...global,
+            translations: {
+              byChatId: {},
+            },
+          };
         }
       });
 

src/global/actions/ui/messages.ts

@@ -41,6 +41,7 @@ import {
   selectSender,
   selectChatScheduledMessages,
   selectTabState,
+  selectRequestedTranslationLanguage,
 } from '../../selectors';
 import { compact, findLast } from '../../../util/iteratees';
 import { getServerTime } from '../../../util/serverTime';
@@ -74,7 +75,7 @@ addActionHandler('setScrollOffset', (global, actions, payload): ActionReturnType
 });
 
 addActionHandler('setReplyingToId', (global, actions, payload): ActionReturnType => {
-  const { messageId, tabId = getCurrentTabId() } = payload!;
+  const { messageId, tabId = getCurrentTabId() } = payload;
   const currentMessageList = selectCurrentMessageList(global, tabId);
   if (!currentMessageList) {
     return undefined;
@@ -391,9 +392,9 @@ addActionHandler('focusMessage', (global, actions, payload): ActionReturnType =>
     chatId, threadId = MAIN_THREAD_ID, messageListType = 'thread', noHighlight, groupedId, groupedChatId,
     replyMessageId, isResizingContainer, shouldReplaceHistory, noForumTopicPanel,
     tabId = getCurrentTabId(),
-  } = payload!;
+  } = payload;
 
-  let { messageId } = payload!;
+  let { messageId } = payload;
 
   if (groupedId !== undefined) {
     const ids = selectForwardedMessageIdsByGroupId(global, groupedChatId!, groupedId);
@@ -759,7 +760,7 @@ addActionHandler('createServiceNotification', (global, actions, payload): Action
 });
 
 addActionHandler('openReactorListModal', (global, actions, payload): ActionReturnType => {
-  const { chatId, messageId, tabId = getCurrentTabId() } = payload!;
+  const { chatId, messageId, tabId = getCurrentTabId() } = payload;
 
   return updateTabState(global, {
     reactorModal: { chatId, messageId },
@@ -775,7 +776,7 @@ addActionHandler('closeReactorListModal', (global, actions, payload): ActionRetu
 });
 
 addActionHandler('openSeenByModal', (global, actions, payload): ActionReturnType => {
-  const { chatId, messageId, tabId = getCurrentTabId() } = payload!;
+  const { chatId, messageId, tabId = getCurrentTabId() } = payload;
 
   return updateTabState(global, {
     seenByModal: { chatId, messageId },
@@ -790,6 +791,24 @@ addActionHandler('closeSeenByModal', (global, actions, payload): ActionReturnTyp
   }, tabId);
 });
 
+addActionHandler('openMessageLanguageModal', (global, actions, payload): ActionReturnType => {
+  const { chatId, id, tabId = getCurrentTabId() } = payload;
+
+  const activeLanguage = selectRequestedTranslationLanguage(global, chatId, id, tabId);
+
+  return updateTabState(global, {
+    messageLanguageModal: { chatId, messageId: id, activeLanguage },
+  }, tabId);
+});
+
+addActionHandler('closeMessageLanguageModal', (global, actions, payload): ActionReturnType => {
+  const { tabId = getCurrentTabId() } = payload || {};
+
+  return updateTabState(global, {
+    messageLanguageModal: undefined,
+  }, tabId);
+});
+
 addActionHandler('copySelectedMessages', (global, actions, payload): ActionReturnType => {
   const { tabId = getCurrentTabId() } = payload;
   const tabState = selectTabState(global, tabId);

src/global/cache.ts

@@ -257,10 +257,6 @@ function unsafeMigrateCache(cached: GlobalState, initialState: GlobalState) {
     cached.recentCustomEmojis = [];
   }
 
-  if (cached.settings.byKey.shouldSuggestCustomEmoji === undefined) {
-    cached.settings.byKey.shouldSuggestCustomEmoji = true;
-  }
-
   if (!cached.stickers.premiumSet) {
     cached.stickers.premiumSet = {
       stickers: [],

src/global/initialState.ts

@@ -165,6 +165,9 @@ export const INITIAL_GLOBAL_STATE: GlobalState = {
       wasTimeFormatSetManually: false,
       isConnectionStatusMinimized: true,
       shouldArchiveAndMuteNewNonContact: false,
+      canTranslate: false,
+      canTranslateChats: true,
+      doNotTranslate: [],
     },
     themes: {
       light: {
@@ -184,6 +187,9 @@ export const INITIAL_GLOBAL_STATE: GlobalState = {
   trustedBotIds: [],
 
   transcriptions: {},
+  translations: {
+    byChatId: {},
+  },
 
   byTabId: {},
 
@@ -267,4 +273,8 @@ export const INITIAL_TAB_STATE: TabState = {
   pollModal: {
     isOpen: false,
   },
+
+  requestedTranslations: {
+    byChatId: {},
+  },
 };

src/global/reducers/index.ts

@@ -10,3 +10,4 @@ export * from './twoFaSettings';
 export * from './passcode';
 export * from './payments';
 export * from './statistics';
+export * from './translations';

src/global/reducers/messages.ts

@@ -1,7 +1,9 @@
 import type {
   GlobalState, MessageList, MessageListType, TabArgs, Thread, TabThread,
 } from '../types';
-import type { ApiMessage, ApiSponsoredMessage, ApiThreadInfo } from '../../api/types';
+import type {
+  ApiMessage, ApiSponsoredMessage, ApiThreadInfo,
+} from '../../api/types';
 import { MAIN_THREAD_ID } from '../../api/types';
 import type { FocusDirection } from '../../types';
 

src/global/reducers/translations.ts

@@ -0,0 +1,129 @@
+import type { GlobalState, TabArgs, TranslatedMessage } from '../types';
+import type { ApiFormattedText } from '../../api/types';
+
+import { getCurrentTabId } from '../../util/establishMultitabRole';
+import { omit } from '../../util/iteratees';
+import { selectMessageTranslations, selectTabState } from '../selectors';
+import { updateTabState } from './tabs';
+
+export function updateMessageTranslation<T extends GlobalState>(
+  global: T, chatId: string, messageId: number, toLanguageCode: string, translation: Partial<TranslatedMessage>,
+) {
+  const translatedMessages = selectMessageTranslations(global, chatId, toLanguageCode);
+
+  return {
+    ...global,
+    translations: {
+      ...global.translations,
+      byChatId: {
+        ...global.translations.byChatId,
+        [chatId]: {
+          ...global.translations.byChatId[chatId],
+          byLangCode: {
+            ...global.translations.byChatId[chatId]?.byLangCode,
+            [toLanguageCode]: {
+              ...translatedMessages,
+              [messageId]: {
+                ...translatedMessages[messageId],
+                ...translation,
+              },
+            },
+          },
+        },
+      },
+    },
+  };
+}
+
+export function clearMessageTranslation<T extends GlobalState>(
+  global: T, chatId: string, messageId: number,
+) {
+  const chatTranslations = global.translations.byChatId[chatId];
+  if (!chatTranslations) return global;
+
+  const { byLangCode } = chatTranslations;
+  const newByLangCode = Object.keys(byLangCode).reduce((acc, langCode) => {
+    const newTranslatedMessages = omit(byLangCode[langCode], [messageId]);
+    if (Object.keys(newTranslatedMessages).length) {
+      acc[langCode] = newTranslatedMessages;
+    }
+
+    return acc;
+  }, {} as Record<string, Record<number, TranslatedMessage>>);
+
+  return {
+    ...global,
+    translations: {
+      ...global.translations,
+      byChatId: {
+        ...global.translations.byChatId,
+        [chatId]: {
+          ...chatTranslations,
+          byLangCode: newByLangCode,
+        },
+      },
+    },
+  };
+}
+
+export function updateMessageTranslations<T extends GlobalState>(
+  global: T, chatId: string, messageIds: number[], toLanguageCode: string, translations: ApiFormattedText[],
+) {
+  messageIds.forEach((messageId, index) => {
+    global = updateMessageTranslation(global, chatId, messageId, toLanguageCode, {
+      text: translations[index],
+      isPending: false,
+    });
+  });
+
+  return global;
+}
+
+export function updateRequestedMessageTranslation<T extends GlobalState>(
+  global: T, chatId: string, messageId: number, toLanguageCode: string, ...[tabId = getCurrentTabId()]: TabArgs<T>
+) {
+  const tabState = selectTabState(global, tabId);
+  global = updateTabState(global, {
+    requestedTranslations: {
+      ...tabState.requestedTranslations,
+      byChatId: {
+        ...tabState.requestedTranslations.byChatId,
+        [chatId]: {
+          ...tabState.requestedTranslations.byChatId[chatId],
+          manualMessages: {
+            ...tabState.requestedTranslations.byChatId[chatId]?.manualMessages,
+            [messageId]: toLanguageCode,
+          },
+        },
+      },
+    },
+  }, tabId);
+
+  return global;
+}
+
+export function removeRequestedMessageTranslation<T extends GlobalState>(
+  global: T, chatId: string, messageId: number, ...[tabId = getCurrentTabId()]: TabArgs<T>
+) {
+  const tabState = selectTabState(global, tabId);
+
+  const manualMessages = tabState.requestedTranslations.byChatId[chatId]?.manualMessages;
+  if (!manualMessages) return global;
+
+  const newManualMessages = omit(manualMessages, [messageId]);
+
+  global = updateTabState(global, {
+    requestedTranslations: {
+      ...tabState.requestedTranslations,
+      byChatId: {
+        ...tabState.requestedTranslations.byChatId,
+        [chatId]: {
+          ...tabState.requestedTranslations.byChatId[chatId],
+          manualMessages: newManualMessages,
+        },
+      },
+    },
+  }, tabId);
+
+  return global;
+}

src/global/selectors/messages.ts

@@ -1,5 +1,5 @@
 import type {
-  GlobalState, MessageListType, TabArgs, Thread, TabThread,
+  GlobalState, MessageListType, TabArgs, Thread, TabThread, ChatTranslatedMessages,
 } from '../types';
 import type {
   ApiChat,
@@ -1280,6 +1280,24 @@ export function selectForwardsContainVoiceMessages<T extends GlobalState>(
   });
 }
 
+export function selectChatTranslations<T extends GlobalState>(
+  global: T, chatId: string,
+): ChatTranslatedMessages {
+  return global.translations.byChatId[chatId];
+}
+
+export function selectMessageTranslations<T extends GlobalState>(
+  global: T, chatId: string, toLanguageCode: string,
+) {
+  return selectChatTranslations(global, chatId)?.byLangCode[toLanguageCode] || {};
+}
+
+export function selectRequestedTranslationLanguage<T extends GlobalState>(
+  global: T, chatId: string, messageId: number, tabId = getCurrentTabId(),
+): string | undefined {
+  return selectTabState(global, tabId).requestedTranslations.byChatId[chatId]?.manualMessages?.[messageId];
+}
+
 export function selectForwardsCanBeSentToChat<T extends GlobalState>(
   global: T,
   toChatId: string,

src/global/selectors/settings.ts

@@ -7,3 +7,7 @@ export function selectNotifySettings<T extends GlobalState>(global: T) {
 export function selectNotifyExceptions<T extends GlobalState>(global: T) {
   return global.settings.notifyExceptions;
 }
+
+export function selectLanguageCode<T extends GlobalState>(global: T) {
+  return global.settings.byKey.language.replace('-raw', '');
+}

src/global/types.ts

@@ -160,6 +160,20 @@ export type ApiLimitTypeWithModal = Exclude<ApiLimitType, (
   'captionLength' | 'aboutLength' | 'stickersFaved' | 'savedGifs'
 )>;
 
+export type TranslatedMessage = {
+  isPending?: boolean;
+  text?: ApiFormattedText;
+};
+
+export type ChatTranslatedMessages = {
+  byLangCode: Record<string, Record<number, TranslatedMessage>>;
+};
+
+export type ChatRequestedTranslations = {
+  toLanguage?: string;
+  manualMessages?: Record<number, string>;
+};
+
 export type TabState = {
   id: number;
   isMasterTab: boolean;
@@ -520,6 +534,15 @@ export type TabState = {
     topicId: number;
     isLoading?: boolean;
   };
+
+  requestedTranslations: {
+    byChatId: Record<string, ChatRequestedTranslations>;
+  };
+  messageLanguageModal?: {
+    chatId: string;
+    messageId: number;
+    activeLanguage?: string;
+  };
 };
 
 export type GlobalState = {
@@ -786,6 +809,10 @@ export type GlobalState = {
     isMinimized: boolean;
     isHidden: boolean;
   };
+
+  translations: {
+    byChatId: Record<string, ChatTranslatedMessages>;
+  };
 };
 
 export type CallSound = (
@@ -1370,6 +1397,12 @@ export interface ActionPayloads {
   disableContextMenuHint: WithTabId | undefined;
   focusNextReply: WithTabId | undefined;
 
+  openMessageLanguageModal: {
+    chatId: string;
+    id: number;
+  } & WithTabId;
+  closeMessageLanguageModal: WithTabId | undefined;
+
   // poll result
   openPollResults: {
     chatId: string;
@@ -1665,6 +1698,23 @@ export interface ActionPayloads {
     ids: number[];
   };
 
+  requestMessageTranslation: {
+    chatId: string;
+    id: number;
+    toLanguageCode?: string;
+  } & WithTabId;
+
+  showOriginalMessage: {
+    chatId: string;
+    id: number;
+  } & WithTabId;
+
+  translateMessages: {
+    chatId: string;
+    messageIds: number[];
+    toLanguageCode?: string;
+  };
+
   // Reactions
   loadAvailableReactions: undefined;
 

src/hooks/useTextLanguage.ts

@@ -0,0 +1,7 @@
+import { detectLanguage } from '../util/languageDetection';
+import useAsync from './useAsync';
+
+export default function useTextLanguage(text?: string) {
+  const language = useAsync(() => (text ? detectLanguage(text) : Promise.resolve(undefined)), [text], undefined);
+  return language;
+}

src/lib/fasttextweb/fasttext.worker.ts

@@ -0,0 +1,68 @@
+import { createWorkerInterface } from '../../util/createPostMessageInterface';
+import fasttextInitializer from './fasttext-wasm';
+import fasttextWasmPath from './fasttext-wasm.wasm';
+
+type FastTextMethods = {
+  makePrediction: (type: 'predict' | 'predict-prob', text: string, k: string, threshold: string) => Promise<string>;
+};
+
+const LABEL_PREFIX = '__label__';
+
+// Since webpack will change the name and potentially the path of the
+// `.wasm` file, we have to provide a `locateFile()` hook to redirect
+// to the appropriate URL.
+// More details: https://kripken.github.io/emscripten-site/docs/api_reference/module.html
+let fastTextInstance: FastTextMethods;
+const fastTextPromise = fasttextInitializer({
+  locateFile: (path: string, prefix: string) => {
+    if (path.endsWith('.wasm')) {
+      return fasttextWasmPath;
+    }
+    return prefix + path;
+  },
+}).then((fastText: FastTextMethods) => {
+  fastTextInstance = fastText;
+  // eslint-disable-next-line no-console
+  console.log('[FASTTEXT] Worker ready');
+});
+
+function parseLabel(label: string) {
+  return label.split('\n')[0].replace(LABEL_PREFIX, '').trim();
+}
+
+function parseLabelsWithProbabilities(labels: string) {
+  return labels.trim()
+    .split('\n')
+    .map((labelWithProb: string) => {
+      const [label, prob] = labelWithProb.split(' ');
+      return {
+        label: parseLabel(label),
+        prob: parseFloat(prob),
+      };
+    });
+}
+
+export async function detectLanguage(text: string, threshold: number) {
+  if (!fastTextInstance) await fastTextPromise;
+  const label = await fastTextInstance.makePrediction('predict', text, '1', threshold.toString());
+  if (!label.length) return undefined;
+  return parseLabel(label);
+}
+
+export async function detectLanguageProbability(text: string, labelsCount: number, threshold: number) {
+  if (!fastTextInstance) await fastTextPromise;
+  const labels = await fastTextInstance.makePrediction(
+    'predict-prob', text, labelsCount.toString(), threshold.toString(),
+  );
+  if (!labels.length) return undefined;
+  return parseLabelsWithProbabilities(labels);
+}
+
+const api = {
+  detectLanguage,
+  detectLanguageProbability,
+};
+
+createWorkerInterface(api);
+
+export type FastTextApi = typeof api;

src/lib/gramjs/tl/apiTl.js

@@ -1262,6 +1262,7 @@ messages.getMessageReactionsList#461b3f48 flags:# peer:InputPeer id:int reaction
 messages.setChatAvailableReactions#feb16771 peer:InputPeer available_reactions:ChatReactions = Updates;
 messages.getAvailableReactions#18dea0ac hash:int = messages.AvailableReactions;
 messages.setDefaultReaction#4f47a016 reaction:Reaction = Bool;
+messages.translateText#63183030 flags:# peer:flags.0?InputPeer id:flags.0?Vector<int> text:flags.1?Vector<TextWithEntities> to_lang:string = messages.TranslatedText;
 messages.getUnreadReactions#3223495b flags:# peer:InputPeer top_msg_id:flags.0?int offset_id:int add_offset:int limit:int max_id:int min_id:int = messages.Messages;
 messages.readReactions#54aa7f8e flags:# peer:InputPeer top_msg_id:flags.0?int = messages.AffectedHistory;
 messages.getAttachMenuBots#16fcc2cb hash:long = AttachMenuBots;

src/lib/gramjs/tl/static/api.json

@@ -243,6 +243,7 @@
     "messages.setChatAvailableReactions",
     "messages.getAvailableReactions",
     "messages.setDefaultReaction",
+    "messages.translateText",
     "help.getAppConfig",
     "stats.getBroadcastStats",
     "stats.getMegagroupStats",

src/lib/rlottie/RLottie.ts

@@ -1,7 +1,9 @@
+import type { RLottieApi } from './rlottie.worker';
+
 import {
   DPR, IS_SAFARI, IS_ANDROID, IS_IOS,
 } from '../../util/environment';
-import WorkerConnector from '../../util/WorkerConnector';
+import { createConnector } from '../../util/PostMessageConnector';
 import { animate } from '../../util/animation';
 import cycleRestrict from '../../util/cycleRestrict';
 import { fastRaf } from '../../util/schedulers';
@@ -30,7 +32,7 @@ const LOW_PRIORITY_CACHE_MODULO = 0;
 const instancesById = new Map<string, RLottie>();
 
 const workers = new Array(MAX_WORKERS).fill(undefined).map(
-  () => new WorkerConnector(new Worker(new URL('./rlottie.worker.ts', import.meta.url))),
+  () => createConnector<RLottieApi>(new Worker(new URL('./rlottie.worker.ts', import.meta.url))),
 );
 let lastWorkerIndex = -1;
 
@@ -108,7 +110,7 @@ class RLottie {
     onLoad: NoneToVoidFunction | undefined,
     private id: string,
     private tgsUrl: string,
-    private params: Params = {},
+    private params: Params = { },
     private customColor?: [number, number, number],
     private onEnded?: (isDestroyed?: boolean) => void,
     private onLoop?: () => void,
@@ -360,7 +362,7 @@ class RLottie {
         this.id,
         this.tgsUrl,
         this.imgSize,
-        this.params.isLowPriority,
+        this.params.isLowPriority || false,
         this.customColor,
         this.onRendererInit.bind(this),
       ],
@@ -395,7 +397,7 @@ class RLottie {
       args: [
         this.id,
         this.tgsUrl,
-        this.params.isLowPriority,
+        this.params.isLowPriority || false,
         this.onChangeData.bind(this),
       ],
     });

src/lib/rlottie/rlottie.worker.ts

@@ -1,6 +1,6 @@
 import { inflate } from 'pako/dist/pako_inflate';
-import createWorkerInterface from '../../util/createWorkerInterface';
+import { createWorkerInterface } from '../../util/createPostMessageInterface';
-import type { CancellableCallback } from '../../util/WorkerConnector';
+import type { CancellableCallback } from '../../util/PostMessageConnector';
 
 import 'script-loader!./rlottie-wasm';
 
@@ -164,9 +164,13 @@ function destroy(key: string, isRepeated = false) {
   }
 }
 
-createWorkerInterface({
+const api = {
   init,
   changeData,
   renderFrames,
   destroy,
-});
+};
+
+createWorkerInterface(api);
+
+export type RLottieApi = typeof api;

src/serviceWorker.ts

@@ -13,7 +13,7 @@ import { pause } from './util/schedulers';
 
 declare const self: ServiceWorkerGlobalScope;
 
-const NETWORK_FIRST_ASSETS = new Set(['/', '/rlottie-wasm.wasm', '/webp_wasm.wasm']);
+const RE_NETWORK_FIRST_ASSETS = /\.(wasm|html)$/;
 const RE_CACHE_FIRST_ASSETS = /[\da-f]{20}.*\.(js|css|woff2?|svg|png|jpg|jpeg|tgs|json|wasm)$/;
 const ACTIVATE_TIMEOUT = 3000;
 
@@ -64,7 +64,7 @@ self.addEventListener('fetch', (e: FetchEvent) => {
   }
 
   if (url.startsWith('http')) {
-    if (NETWORK_FIRST_ASSETS.has(new URL(url).pathname)) {
+    if (new URL(url).pathname === '/' || url.match(RE_NETWORK_FIRST_ASSETS)) {
       e.respondWith(respondWithCacheNetworkFirst(e));
       return true;
     }

src/styles/index.scss

@@ -125,6 +125,12 @@ body.cursor-ew-resize {
   }
 }
 
+.clearfix::after {
+  content: "";
+  clear: both;
+  display: table;
+}
+
 /*
  See the article for more information on this visually-hidden pattern.
  https://snook.ca/archives/html_and_css/hiding-content-for-accessibility

src/types/index.ts

@@ -89,6 +89,9 @@ export interface ISettings extends NotifySettings, Record<string, any> {
   wasTimeFormatSetManually: boolean;
   isConnectionStatusMinimized: boolean;
   shouldArchiveAndMuteNewNonContact?: boolean;
+  canTranslate: boolean;
+  canTranslateChats: boolean;
+  doNotTranslate: string[];
 }
 
 export interface ApiPrivacySettings {
@@ -216,6 +219,7 @@ export enum SettingsScreens {
   Stickers,
   QuickReaction,
   CustomEmoji,
+  DoNotTranslate,
 }
 
 export type StickerSetOrRecent = Pick<ApiStickerSet, (

src/util/PostMessageConnector.ts

@@ -0,0 +1,216 @@
+import generateIdFor from './generateIdFor';
+
+export interface CancellableCallback {
+  (
+    ...args: any[]
+  ): void;
+
+  isCanceled?: boolean;
+  acceptsBuffer?: boolean;
+}
+
+type InitData = {
+  channel?: string;
+  type: 'init';
+  messageId?: string;
+  name: 'init';
+  args: any;
+};
+
+type CallMethodData = {
+  channel?: string;
+  type: 'callMethod';
+  messageId?: string;
+  name: string;
+  args: any;
+  withCallback?: boolean;
+};
+
+export type OriginMessageData = InitData | CallMethodData | {
+  channel?: string;
+  type: 'cancelProgress';
+  messageId: string;
+};
+
+export interface OriginMessageEvent {
+  data: OriginMessageData;
+}
+
+export type ApiUpdate =
+  { type: string }
+  & any;
+
+export type WorkerMessageData = {
+  channel?: string;
+  type: 'update';
+  update: ApiUpdate;
+} | {
+  channel?: string;
+  type: 'methodResponse';
+  messageId: string;
+  response?: any;
+  error?: { message: string };
+} | {
+  channel?: string;
+  type: 'methodCallback';
+  messageId: string;
+  callbackArgs: any[];
+} | {
+  channel?: string;
+  type: 'unhandledError';
+  error?: { message: string };
+};
+
+export interface WorkerMessageEvent {
+  data: WorkerMessageData;
+}
+
+interface RequestStates {
+  messageId: string;
+  resolve: Function;
+  reject: Function;
+  callback: AnyToVoidFunction;
+}
+
+type InputRequestTypes = Record<string, AnyFunction>;
+
+type Values<T> = T[keyof T];
+export type RequestTypes<T extends InputRequestTypes> = Values<{
+  [Name in keyof (T)]: {
+    name: Name & string;
+    args: Parameters<T[Name]>;
+  }
+}>;
+
+class ConnectorClass<T extends InputRequestTypes> {
+  private requestStates = new Map<string, RequestStates>();
+
+  private requestStatesByCallback = new Map<AnyToVoidFunction, RequestStates>();
+
+  constructor(
+    public target: Worker,
+    private onUpdate?: (update: ApiUpdate) => void,
+    private channel?: string,
+  ) {
+  }
+
+  // eslint-disable-next-line class-methods-use-this
+  public destroy() {
+  }
+
+  init(...args: any[]) {
+    this.postMessage({
+      type: 'init',
+      args,
+    });
+  }
+
+  request(messageData: RequestTypes<T>) {
+    const { requestStates, requestStatesByCallback } = this;
+
+    const messageId = generateIdFor(requestStates);
+    const payload: CallMethodData = {
+      type: 'callMethod',
+      messageId,
+      ...messageData,
+    };
+
+    const requestState = { messageId } as RequestStates;
+
+    // Re-wrap type because of `postMessage`
+    const promise: Promise<any> = new Promise((resolve, reject) => {
+      Object.assign(requestState, { resolve, reject });
+    });
+
+    if (typeof payload.args[payload.args.length - 1] === 'function') {
+      payload.withCallback = true;
+
+      const callback = payload.args.pop() as AnyToVoidFunction;
+      requestState.callback = callback;
+      requestStatesByCallback.set(callback, requestState);
+    }
+
+    requestStates.set(messageId, requestState);
+    promise
+      .catch(() => undefined)
+      .finally(() => {
+        requestStates.delete(messageId);
+
+        if (requestState.callback) {
+          requestStatesByCallback.delete(requestState.callback);
+        }
+      });
+
+    this.postMessage(payload);
+
+    return promise;
+  }
+
+  cancelCallback(progressCallback: CancellableCallback) {
+    progressCallback.isCanceled = true;
+
+    const { messageId } = this.requestStatesByCallback.get(progressCallback) || {};
+    if (!messageId) {
+      return;
+    }
+
+    this.postMessage({
+      type: 'cancelProgress',
+      messageId,
+    });
+  }
+
+  onMessage(data: WorkerMessageData) {
+    const { requestStates, channel } = this;
+    if (data.channel !== channel) {
+      return;
+    }
+
+    if (data.type === 'update' && this.onUpdate) {
+      this.onUpdate(data.update);
+    }
+    if (data.type === 'methodResponse') {
+      const requestState = requestStates.get(data.messageId);
+      if (requestState) {
+        if (data.error) {
+          requestState.reject(data.error);
+        } else {
+          requestState.resolve(data.response);
+        }
+      }
+    } else if (data.type === 'methodCallback') {
+      const requestState = requestStates.get(data.messageId);
+      requestState?.callback?.(...data.callbackArgs);
+    } else if (data.type === 'unhandledError') {
+      throw new Error(data.error?.message);
+    }
+  }
+
+  private postMessage(data: AnyLiteral) {
+    data.channel = this.channel;
+
+    this.target.postMessage(data);
+  }
+}
+
+export function createConnector<T extends InputRequestTypes>(
+  worker: Worker,
+  onUpdate?: (update: ApiUpdate) => void,
+  channel?: string,
+) {
+  const connector = new ConnectorClass<T>(worker, onUpdate, channel);
+
+  function handleMessage({ data }: WorkerMessageEvent) {
+    connector.onMessage(data);
+  }
+
+  worker.addEventListener('message', handleMessage);
+
+  connector.destroy = () => {
+    worker.removeEventListener('message', handleMessage);
+  };
+
+  return connector;
+}
+
+export type Connector<T extends InputRequestTypes> = ReturnType<typeof createConnector<T>>;

src/util/WorkerConnector.ts

@@ -1,140 +0,0 @@
-import generateIdFor from './generateIdFor';
-
-export interface CancellableCallback {
-  (
-    ...args: any[]
-  ): void;
-
-  isCanceled?: boolean;
-  acceptsBuffer?: boolean;
-}
-
-type CallMethodData = {
-  type: 'callMethod';
-  messageId?: string;
-  name: string;
-  args: any;
-  withCallback?: boolean;
-};
-
-type OriginMessageData = CallMethodData | {
-  type: 'cancelProgress';
-  messageId: string;
-};
-
-export interface OriginMessageEvent {
-  data: OriginMessageData;
-}
-
-export type WorkerMessageData = {
-  type: 'methodResponse';
-  messageId: string;
-  response?: any;
-  error?: { message: string };
-} | {
-  type: 'methodCallback';
-  messageId: string;
-  callbackArgs: any[];
-} | {
-  type: 'unhandledError';
-  error?: { message: string };
-};
-
-export interface WorkerMessageEvent {
-  data: WorkerMessageData;
-}
-
-interface RequestStates {
-  messageId: string;
-  resolve: Function;
-  reject: Function;
-  callback: AnyToVoidFunction;
-}
-
-// TODO Replace `any` with proper generics
-export default class WorkerConnector {
-  private requestStates = new Map<string, RequestStates>();
-
-  private requestStatesByCallback = new Map<AnyToVoidFunction, RequestStates>();
-
-  constructor(private worker: Worker) {
-    this.subscribe();
-  }
-
-  request(messageData: { name: string; args: any }) {
-    const { worker, requestStates, requestStatesByCallback } = this;
-
-    const messageId = generateIdFor(requestStates);
-    const payload: CallMethodData = {
-      type: 'callMethod',
-      messageId,
-      ...messageData,
-    };
-
-    const requestState = { messageId } as RequestStates;
-
-    // Re-wrap type because of `postMessage`
-    const promise: Promise<any> = new Promise((resolve, reject) => {
-      Object.assign(requestState, { resolve, reject });
-    });
-
-    if (typeof payload.args[payload.args.length - 1] === 'function') {
-      payload.withCallback = true;
-
-      const callback = payload.args.pop() as AnyToVoidFunction;
-      requestState.callback = callback;
-      requestStatesByCallback.set(callback, requestState);
-    }
-
-    requestStates.set(messageId, requestState);
-    promise
-      .catch(() => undefined)
-      .finally(() => {
-        requestStates.delete(messageId);
-
-        if (requestState.callback) {
-          requestStatesByCallback.delete(requestState.callback);
-        }
-      });
-
-    worker.postMessage(payload);
-
-    return promise;
-  }
-
-  cancelCallback(progressCallback: CancellableCallback) {
-    progressCallback.isCanceled = true;
-
-    const { messageId } = this.requestStatesByCallback.get(progressCallback) || {};
-    if (!messageId) {
-      return;
-    }
-
-    this.worker.postMessage({
-      type: 'cancelProgress',
-      messageId,
-    });
-  }
-
-  private subscribe() {
-    const { worker, requestStates } = this;
-
-    worker.addEventListener('message', ({ data }: WorkerMessageEvent) => {
-      if (data.type === 'methodResponse') {
-        const requestState = requestStates.get(data.messageId);
-        if (requestState) {
-          if (data.error) {
-            requestState.reject(data.error);
-          } else {
-            requestState.resolve(data.response);
-          }
-        }
-      } else if (data.type === 'methodCallback') {
-        const requestState = requestStates.get(data.messageId);
-        requestState?.callback?.(...data.callbackArgs);
-      } else if (data.type === 'unhandledError') {
-        throw new Error(data.error?.message);
-      }
-    });
-  }
-}

src/util/createPostMessageInterface.ts

@@ -0,0 +1,144 @@
+import type {
+  CancellableCallback, OriginMessageEvent, OriginMessageData, WorkerMessageData, ApiUpdate,
+} from './PostMessageConnector';
+
+import { DEBUG } from '../config';
+
+declare const self: WorkerGlobalScope;
+
+const callbackState = new Map<string, CancellableCallback>();
+
+type ApiConfig =
+  ((name: string, ...args: any[]) => any | [any, ArrayBuffer[]])
+  | Record<string, Function>;
+type SendToOrigin = (data: WorkerMessageData, transferables?: Transferable[]) => void;
+
+export function createWorkerInterface(api: ApiConfig, channel?: string) {
+  function sendToOrigin(data: WorkerMessageData, transferables?: Transferable[]) {
+    data.channel = channel;
+
+    if (transferables) {
+      postMessage(data, transferables);
+    } else {
+      postMessage(data);
+    }
+  }
+
+  handleErrors(sendToOrigin);
+
+  onmessage = (message: OriginMessageEvent) => {
+    if (message.data?.channel === channel) {
+      onMessage(api, message.data, sendToOrigin);
+    }
+  };
+}
+
+async function onMessage(
+  api: ApiConfig,
+  data: OriginMessageData,
+  sendToOrigin: SendToOrigin,
+  onUpdate?: (update: ApiUpdate) => void,
+) {
+  if (!onUpdate) {
+    onUpdate = (update: ApiUpdate) => {
+      sendToOrigin({
+        type: 'update',
+        update,
+      });
+    };
+  }
+
+  switch (data.type) {
+    case 'init': {
+      const { args } = data;
+      const promise = typeof api === 'function'
+        ? api('init', onUpdate, ...args)
+        : api.init?.(onUpdate, ...args);
+      await promise;
+
+      break;
+    }
+    case 'callMethod': {
+      const {
+        messageId, name, args, withCallback,
+      } = data;
+      try {
+        if (messageId && withCallback) {
+          const callback = (...callbackArgs: any[]) => {
+            const lastArg = callbackArgs[callbackArgs.length - 1];
+
+            sendToOrigin({
+              type: 'methodCallback',
+              messageId,
+              callbackArgs,
+            }, isTransferable(lastArg) ? [lastArg] : undefined);
+          };
+
+          callbackState.set(messageId, callback);
+
+          args.push(callback as never);
+        }
+
+        const response = typeof api === 'function'
+          ? await api(name, ...args)
+          : await api[name](...args);
+        const { arrayBuffer } = (typeof response === 'object' && 'arrayBuffer' in response && response) || {};
+        if (messageId) {
+          sendToOrigin(
+            {
+              type: 'methodResponse',
+              messageId,
+              response,
+            },
+            arrayBuffer ? [arrayBuffer] : undefined,
+          );
+        }
+      } catch (error: any) {
+        if (DEBUG) {
+          // eslint-disable-next-line no-console
+          console.error(error);
+        }
+
+        if (messageId) {
+          sendToOrigin({
+            type: 'methodResponse',
+            messageId,
+            error: { message: error.message },
+          });
+        }
+      }
+
+      if (messageId) {
+        callbackState.delete(messageId);
+      }
+
+      break;
+    }
+    case 'cancelProgress': {
+      const callback = callbackState.get(data.messageId);
+      if (callback) {
+        callback.isCanceled = true;
+      }
+
+      break;
+    }
+  }
+}
+
+function isTransferable(obj: any) {
+  return obj instanceof ArrayBuffer || obj instanceof ImageBitmap;
+}
+
+function handleErrors(sendToOrigin: SendToOrigin) {
+  self.onerror = (e) => {
+    // eslint-disable-next-line no-console
+    console.error(e);
+    sendToOrigin({ type: 'unhandledError', error: { message: e.error.message || 'Uncaught exception in worker' } });
+  };
+
+  self.addEventListener('unhandledrejection', (e) => {
+    // eslint-disable-next-line no-console
+    console.error(e);
+    sendToOrigin({ type: 'unhandledError', error: { message: e.reason.message || 'Uncaught rejection in worker' } });
+  });
+}

src/util/createWorkerInterface.ts

@@ -1,105 +0,0 @@
-import type { CancellableCallback, OriginMessageEvent, WorkerMessageData } from './WorkerConnector';
-import { DEBUG } from '../config';
-
-declare const self: WorkerGlobalScope;
-
-handleErrors();
-
-const callbackState = new Map<string, CancellableCallback>();
-
-export default function createInterface(api: Record<string, Function>) {
-  onmessage = async (message: OriginMessageEvent) => {
-    const { data } = message;
-
-    switch (data.type) {
-      case 'callMethod': {
-        const {
-          messageId, name, args, withCallback,
-        } = data;
-        try {
-          if (messageId && withCallback) {
-            const callback = (...callbackArgs: any[]) => {
-              const lastArg = callbackArgs[callbackArgs.length - 1];
-
-              sendToOrigin({
-                type: 'methodCallback',
-                messageId,
-                callbackArgs,
-              }, isTransferable(lastArg) ? [lastArg] : undefined);
-            };
-
-            callbackState.set(messageId, callback);
-
-            args.push(callback as never);
-          }
-
-          const [response, arrayBuffers] = (await api[name](...args)) || [];
-
-          if (messageId) {
-            sendToOrigin(
-              {
-                type: 'methodResponse',
-                messageId,
-                response,
-              },
-              arrayBuffers,
-            );
-          }
-        } catch (error: any) {
-          if (DEBUG) {
-            // eslint-disable-next-line no-console
-            console.error(error);
-          }
-
-          if (messageId) {
-            sendToOrigin({
-              type: 'methodResponse',
-              messageId,
-              error: { message: error.message },
-            });
-          }
-        }
-
-        if (messageId) {
-          callbackState.delete(messageId);
-        }
-
-        break;
-      }
-      case 'cancelProgress': {
-        const callback = callbackState.get(data.messageId);
-        if (callback) {
-          callback.isCanceled = true;
-        }
-
-        break;
-      }
-    }
-  };
-}
-
-function isTransferable(obj: any) {
-  return obj instanceof ArrayBuffer || obj instanceof ImageBitmap;
-}
-
-function handleErrors() {
-  self.onerror = (e) => {
-    // eslint-disable-next-line no-console
-    console.error(e);
-    sendToOrigin({ type: 'unhandledError', error: { message: e.error.message || 'Uncaught exception in worker' } });
-  };
-
-  self.addEventListener('unhandledrejection', (e) => {
-    // eslint-disable-next-line no-console
-    console.error(e);
-    sendToOrigin({ type: 'unhandledError', error: { message: e.reason.message || 'Uncaught rejection in worker' } });
-  });
-}
-
-function sendToOrigin(data: WorkerMessageData, transferables?: Transferable[]) {
-  if (transferables) {
-    postMessage(data, transferables);
-  } else {
-    postMessage(data);
-  }
-}

src/util/environment.ts

@@ -113,6 +113,7 @@ export const IS_COMPACT_MENU = !IS_TOUCH_ENV;
 export const IS_SCROLL_PATCH_NEEDED = !IS_MAC_OS && !IS_IOS && !IS_ANDROID;
 export const IS_INSTALL_PROMPT_SUPPORTED = 'onbeforeinstallprompt' in window;
 export const IS_MULTITAB_SUPPORTED = 'BroadcastChannel' in window;
+export const IS_TRANSLATION_SUPPORTED = Boolean(Intl.DisplayNames);
 
 // Smaller area reduces scroll jumps caused by `patchChromiumScroll`
 export const MESSAGE_LIST_SENSITIVE_AREA = IS_SCROLL_PATCH_NEEDED ? 300 : 750;

src/util/iteratees.ts

@@ -117,6 +117,17 @@ export function split<T extends any>(array: T[], chunkSize: number) {
   return result;
 }
 
+export function partition<T extends unknown>(
+  array: T[], filter: (value: T, index: number, array: T[]) => boolean,
+): [T[], T[]] {
+  const pass: T[] = [];
+  const fail: T[] = [];
+
+  array.forEach((e, idx, arr) => (filter(e, idx, arr) ? pass : fail).push(e));
+
+  return [pass, fail];
+}
+
 export function cloneDeep<T>(value: T): T {
   if (!isObject(value)) {
     return value;

src/util/languageDetection.ts

@@ -0,0 +1,38 @@
+import type { FastTextApi } from '../lib/fasttextweb/fasttext.worker';
+import type { Connector } from './PostMessageConnector';
+
+import { createConnector } from './PostMessageConnector';
+import Deferred from './Deferred';
+
+const WORKER_INIT_DELAY = 4000;
+
+const DEFAULT_THRESHOLD = 0.2;
+const DEFAULT_LABELS_COUNT = 5;
+
+let worker: Connector<FastTextApi> | undefined;
+const initializationDeferred = new Deferred();
+
+setTimeout(initWorker, WORKER_INIT_DELAY);
+
+function initWorker() {
+  if (!worker) {
+    worker = createConnector<FastTextApi>(
+      new Worker(new URL('../lib/fasttextweb/fasttext.worker.ts', import.meta.url)),
+    );
+    initializationDeferred.resolve();
+  }
+}
+
+export async function detectLanguage(text: string, threshold = DEFAULT_THRESHOLD) {
+  if (!worker) await initializationDeferred.promise;
+  const result = await worker!.request({ name: 'detectLanguage', args: [text, threshold] });
+  return result;
+}
+
+export async function detectLanguageProbability(
+  text: string, labelsCount = DEFAULT_LABELS_COUNT, threshold = DEFAULT_THRESHOLD,
+) {
+  if (!worker) await initializationDeferred.promise;
+  const result = await worker!.request({ name: 'detectLanguageProbability', args: [text, labelsCount, threshold] });
+  return result;
+}