From cb696276daba7913f6ece022e5552c04fff38f25 Mon Sep 17 00:00:00 2001
From: Laurent Cozic <laurent@cozic.net>
Date: Fri, 27 Nov 2020 11:12:28 +0000
Subject: [PATCH] Desktop: Fixes #4146: Prevents crash when invalid spell
 checker language is selected, and provide fallback for invalid language codes

---
 .../SpellCheckerServiceDriverNative.ts        | 29 ++++++++++++++++++-
 packages/lib/locale.ts                        |  8 ++++-
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/packages/app-desktop/services/spellChecker/SpellCheckerServiceDriverNative.ts b/packages/app-desktop/services/spellChecker/SpellCheckerServiceDriverNative.ts
index 72538a740c..9ed44652e5 100644
--- a/packages/app-desktop/services/spellChecker/SpellCheckerServiceDriverNative.ts
+++ b/packages/app-desktop/services/spellChecker/SpellCheckerServiceDriverNative.ts
@@ -2,6 +2,10 @@
 
 import SpellCheckerServiceDriverBase from '@joplin/lib/services/spellChecker/SpellCheckerServiceDriverBase';
 import bridge from '../bridge';
+import { languageCodeOnly, localesFromLanguageCode } from '@joplin/lib/locale';
+import Logger from '@joplin/lib/Logger';
+
+const logger = Logger.create('SpellCheckerServiceDriverNative');
 
 export default class SpellCheckerServiceDriverNative extends SpellCheckerServiceDriverBase {
 
@@ -17,7 +21,30 @@ export default class SpellCheckerServiceDriverNative extends SpellCheckerService
 	public setLanguage(v: string) {
 		// If we pass an empty array, it disables spell checking
 		// https://github.com/electron/electron/issues/25228
-		this.session().setSpellCheckerLanguages(v ? [v] : []);
+		if (!v) {
+			this.session().setSpellCheckerLanguages('');
+			return;
+		}
+
+		// The below function will throw an error if the provided language is
+		// not supported, so we provide fallbacks.
+		// https://github.com/laurent22/joplin/issues/4146
+		const languagesToTry = [
+			v,
+			languageCodeOnly(v),
+		].concat(localesFromLanguageCode(languageCodeOnly(v), this.availableLanguages));
+
+		for (const toTry of languagesToTry) {
+			try {
+				this.session().setSpellCheckerLanguages([toTry]);
+				return;
+			} catch (error) {
+				logger.warn(`Failed to set language to "${toTry}". Will try the next one in this list: ${JSON.stringify(languagesToTry)}`);
+				logger.warn('Error was:', error);
+			}
+		}
+
+		logger.error(`Could not set language to: ${v}`);
 	}
 
 	public get language(): string {
diff --git a/packages/lib/locale.ts b/packages/lib/locale.ts
index dbe32d1abf..d8901340e9 100644
--- a/packages/lib/locale.ts
+++ b/packages/lib/locale.ts
@@ -572,6 +572,12 @@ function languageCode() {
 	return languageCodeOnly(currentLocale_);
 }
 
+function localesFromLanguageCode(languageCode: string, locales: string[]): string[] {
+	return locales.filter((l: string) => {
+		return languageCodeOnly(l) === languageCode;
+	});
+}
+
 function _(s: string, ...args: any[]) {
 	const strings = localeStrings(currentLocale_);
 	let result = strings[s];
@@ -588,4 +594,4 @@ function _n(singular: string, plural: string, n: number, ...args: any[]) {
 	return _(singular, ...args);
 }
 
-export { _, _n, supportedLocales, countryDisplayName, localeStrings, setLocale, supportedLocalesToLanguages, defaultLocale, closestSupportedLocale, languageCode, countryCodeOnly };
+export { _, _n, supportedLocales, localesFromLanguageCode, languageCodeOnly, countryDisplayName, localeStrings, setLocale, supportedLocalesToLanguages, defaultLocale, closestSupportedLocale, languageCode, countryCodeOnly };