Restructure to use laude or LanguageDetector

app/javascript/mastodon/features/compose/components/compose_form.jsx

@@ -10,8 +10,6 @@ import ImmutablePureComponent from 'react-immutable-pure-component';
 
 import { length } from 'stringz';
 
-import debounce from 'lodash.debounce';
-
 import { missingAltTextModal } from 'mastodon/initial_state';
 import { changeComposeLanguage } from 'mastodon/actions/compose';
 
@@ -24,6 +22,7 @@ import PrivacyDropdownContainer from '../containers/privacy_dropdown_container';
 import SpoilerButtonContainer from '../containers/spoiler_button_container';
 import UploadButtonContainer from '../containers/upload_button_container';
 import { countableText } from '../util/counter';
+import { debouncedGuess, countLetters } from '../util/language_detection';
 
 import { CharacterCounter } from './character_counter';
 import { EditIndicator } from './edit_indicator';
@@ -50,24 +49,6 @@ const mapStateToProps = (state) => ({
   currentLanguage: state.meta.get('locale'),
 });
 
-const languageDetectorInGlobalThis = 'LanguageDetector' in globalThis;
-let supportsLanguageDetector = languageDetectorInGlobalThis && await globalThis.LanguageDetector.availability() === 'available';
-let languageDetector;
-// If the API is supported, but the model not loaded yet…
-if (languageDetectorInGlobalThis && !supportsLanguageDetector) {
-  // …trigger the model download
-  LanguageDetector.create().then((_languageDetector) => {
-    supportsLanguageDetector = true
-    languageDetector = _languageDetector
-  })
-}
-
-function countLetters(text) {
-  const segmenter = new Intl.Segmenter('und', { granularity: 'grapheme' })
-  const letters = [...segmenter.segment(text)]
-  return letters.length
-}
-
 class ComposeForm extends ImmutablePureComponent {
   static propTypes = {
     intl: PropTypes.object.isRequired,
@@ -112,7 +93,6 @@ class ComposeForm extends ImmutablePureComponent {
   constructor(props) {
     super(props);
     this.textareaRef = createRef(null);
-    this.debouncedHandleKeyUp = debounce(this._handleKeyUp.bind(this), 500);
   }
 
   handleChange = (e) => {
@@ -125,30 +105,21 @@ class ComposeForm extends ImmutablePureComponent {
     }
   };
 
-  handleKeyUp = (e) => {
-   this.debouncedHandleKeyUp(e);
-  }
-
-  _handleKeyUp = async (e) => {
-    if (!supportsLanguageDetector) {
-      return;
-    }
-    if (!languageDetector) {
-      languageDetector = await globalThis.LanguageDetector.create();
-    }
+  handleKeyUp = async (e) => {
     const text = this.getFulltextForCharacterCounting().trim();
     const currentLanguage = this.props.currentLanguage;
     if (!text || countLetters(text) <= 5) {
       this.props.dispatch(changeComposeLanguage(currentLanguage));
       return;
     }
-
     try {
-      let detectedLanguage = (await languageDetector.detect(text))[0].detectedLanguage
-      detectedLanguage = detectedLanguage === 'und' ? currentLanguage : detectedLanguage.substring(0, 2);
+      let detectedLanguage = await debouncedGuess(text);
+      if (!detectedLanguage) {
+        this.props.dispatch(changeComposeLanguage(currentLanguage));
+        return;
+      }
       this.props.dispatch(changeComposeLanguage(detectedLanguage));
-    }
-    catch {
+    } catch {
       this.props.dispatch(changeComposeLanguage(currentLanguage));
     }
   }
@@ -218,7 +189,6 @@ class ComposeForm extends ImmutablePureComponent {
 
   componentWillUnmount () {
     if (this.timeout) clearTimeout(this.timeout);
-    this.debouncedHandleKeyUp.cancel();
   }
 
   componentDidUpdate (prevProps) {

app/javascript/mastodon/features/compose/components/language_dropdown.tsx

@@ -20,7 +20,7 @@ import { languages as preloadedLanguages } from 'mastodon/initial_state';
 import type { RootState } from 'mastodon/store';
 import { useAppSelector, useAppDispatch } from 'mastodon/store';
 
-import { debouncedGuess } from '../util/language_detection';
+import { debouncedGuess, countLetters } from '../util/language_detection';
 
 const messages = defineMessages({
   changeLanguage: {
@@ -375,12 +375,25 @@ export const LanguageDropdown: React.FC = () => {
   );
 
   useEffect(() => {
-    if (text.length > 20) {
-      debouncedGuess(text, setGuess);
+    let canceled = false;
+
+    if (countLetters(text) >= 5) {
+      debouncedGuess(text)
+        .then((lang) => {
+          if (!canceled) {
+            setGuess(lang ?? '');
+          }
+        })
+        .catch(() => {
+          setGuess('');
+        });
     } else {
-      debouncedGuess.cancel();
       setGuess('');
     }
+
+    return () => {
+      canceled = true;
+    };
   }, [text, setGuess]);
 
   return (

app/javascript/mastodon/features/compose/util/language_detection.d.ts

@@ -0,0 +1,5 @@
+export declare const debouncedGuess: (
+  text: string,
+) => Promise<string | undefined>;
+
+export declare const countLetters: (text: string) => number;

app/javascript/mastodon/features/compose/util/language_detection.js

@@ -1,7 +1,5 @@
-import lande from 'lande';
-import { debounce } from 'lodash';
-
-import { urlRegex } from './url_regex';
+const languageDetectorInGlobalThis = 'LanguageDetector' in globalThis;
+let languageDetectorSupportedAndReady = languageDetectorInGlobalThis && await globalThis.LanguageDetector.availability() === 'available';
 
 const ISO_639_MAP = {
   afr: 'af', // Afrikaans
@@ -56,21 +54,23 @@ const ISO_639_MAP = {
   vie: 'vi', // Vietnamese
 };
 
-const guessLanguage = (text) => {
-  text = text
-    .replace(urlRegex, '')
-    .replace(/(^|[^/\w])@(([a-z0-9_]+)@[a-z0-9.-]+[a-z0-9]+)/ig, '');
-
-  if (text.length > 20) {
-    const [lang, confidence] = lande(text)[0];
-  
-    if (confidence > 0.8)
-      return ISO_639_MAP[lang];
-  }
-
-  return '';
+const countLetters = (text) => {
+  const segmenter = new Intl.Segmenter('und', { granularity: 'grapheme' })
+  const letters = [...segmenter.segment(text)]
+  return letters.length
 };
 
-export const debouncedGuess = debounce((text, setGuess) => {
-  setGuess(guessLanguage(text));
-}, 500, { maxWait: 1500, leading: true, trailing: true });
+let module;
+// If the API is supported, but the model not loaded yet…
+if (languageDetectorInGlobalThis) {
+  if (!languageDetectorSupportedAndReady) {
+    // …trigger the model download
+    self.LanguageDetector.create();
+  }
+  module = await import('./language_detection_with_languagedetector');
+} else {
+  module = await import('./language_detection_with_laude');
+}
+const debouncedGuess = module.debouncedGuess;
+
+export { debouncedGuess, countLetters, ISO_639_MAP };

app/javascript/mastodon/features/compose/util/language_detection_with_languagedetector.js

@@ -0,0 +1,50 @@
+import { debounce } from 'lodash';
+
+import { countLetters } from './language_detection';
+import { urlRegex } from './url_regex';
+
+const guessLanguage = async (text) => {
+  text = text
+    .replace(urlRegex, '')
+    .replace(/(^|[^/\w])@(([a-z0-9_]+)@[a-z0-9.-]+[a-z0-9]+)/ig, '');
+
+  if (countLetters(text) > 5) {
+    try {
+      const languageDetector = await self.LanguageDetector.create();
+      let {detectedLanguage, confidence} = (await languageDetector.detect(text))[0];
+      if (confidence > 0.8) {
+        detectedLanguage = detectedLanguage.split('-')[0];
+        return detectedLanguage;
+      }
+    } catch {
+      return '';
+    }
+  }
+
+  return '';
+};
+
+const debouncedGuess = (() => {
+  let resolver = null;
+  let rejecter = null;
+
+  const debounced = debounce(async (text) => {
+    try {
+      const result = await guessLanguage(text);
+      if (resolver) {
+        resolver(result);
+        resolver = null;
+      }
+    } catch {
+      rejecter('');
+    }
+  }, 500, { maxWait: 1500, leading: true, trailing: true });
+
+  return (text) => new Promise((resolve, reject) => {
+    resolver = resolve;
+    rejecter = reject;
+    debounced(text);
+  });
+})();
+
+export { debouncedGuess };

app/javascript/mastodon/features/compose/util/language_detection_with_laude.js

@@ -0,0 +1,38 @@
+import lande from 'lande';
+import { debounce } from 'lodash';
+
+import { countLetters, ISO_639_MAP } from './language_detection';
+import { urlRegex } from './url_regex';
+
+const guessLanguage = (text) => {
+  text = text
+    .replace(urlRegex, '')
+    .replace(/(^|[^/\w])@(([a-z0-9_]+)@[a-z0-9.-]+[a-z0-9]+)/ig, '');
+
+  if (countLetters(text) > 20) {
+    const [lang, confidence] = lande(text)[0];
+    if (confidence > 0.8)
+      return ISO_639_MAP[lang];
+  }
+
+  return '';
+};
+
+const debouncedGuess = (() => {
+  let resolver = null;
+
+  const debounced = debounce((text) => {
+    const result = guessLanguage(text);
+    if (resolver) {
+      resolver(result);
+      resolver = null;
+    }
+  }, 500, { maxWait: 1500, leading: true, trailing: true });
+
+  return (text) => new Promise((resolve) => {
+    resolver = resolve;
+    debounced(text);
+  });
+})();
+
+export { debouncedGuess };