server: dynamic language directionality

Use https://www.npmjs.com/package/rtl-detect to determine language
script directionality.

Bug: T209288

package.json

@@ -20,6 +20,7 @@
     "http-status-codes": "^1.3.0",
     "module-alias": "^2.1.0",
     "mwbot": "^1.0.10",
+    "rtl-detect": "^1.0.2",
     "ts-deferred": "^1.0.4",
     "validate.js": "^0.12.0",
     "vue": "^2.5.17",

src/server/data-access/ContentLanguagesLanguageRepo.ts

@@ -2,6 +2,7 @@ import LanguageRepository from '@/common/data-access/LanguageRepository';
 import LanguageCollection from '@/datamodel/LanguageCollection';
 import Language from '@/datamodel/Language';
 import WikibaseContentLanguagesRepo, { WikibaseApiContentLanguages } from './WikibaseContentLanguagesRepo';
+import RtlDetectLib from 'rtl-detect';
 
 export default class ContentLanguagesLanguageRepo implements LanguageRepository {
 	private languagesRepo: WikibaseContentLanguagesRepo;
@@ -17,7 +18,10 @@ export default class ContentLanguagesLanguageRepo implements LanguageRepository
 				Object.entries( contentLanguages ).forEach( ( [ languageCode, language ] ) => {
 					languages[ languageCode ] = {
 						code: languageCode,
-						directionality: 'ltr',
+						// this does not do full justice to the directionality question
+						// * languages do not have directionality - scripts do
+						// * the configured wikibase instance may have more/different languages
+						directionality: RtlDetectLib.getLangDir( languageCode ),
 					} as Language;
 				} );
 

src/types/server/rtl-detect.d.ts

@@ -0,0 +1,5 @@
+declare module 'rtl-detect' {
+	export default class RtlDetectLib {
+		public static getLangDir( code: string ): string;
+	}
+}

tests/unit/server/data-access/ContentLanguagesLanguageRepo.spec.ts

@@ -3,6 +3,7 @@ import MwBotWikibaseContentLanguagesRepo from '@/server/data-access/MwBotWikibas
 import mwbot from 'mwbot';
 import ContentLanguagesLanguageRepo from '@/server/data-access/ContentLanguagesLanguageRepo';
 import { WikibaseApiContentLanguages } from '@/server/data-access/WikibaseContentLanguagesRepo';
+import RtlDetectLib from 'rtl-detect';
 
 function newWikibaseContentLanguagesRepository( contentLanguagesRepo: any ) {
 	return new ContentLanguagesLanguageRepo(
@@ -23,11 +24,11 @@ describe( 'ContentLanguagesLanguageRepo', () => {
 			getContentLanguages.mockResolvedValue( {
 				en: {
 					code: 'en',
-					name: 'Englisch',
+					name: 'English',
 				},
-				de: {
-					code: 'de',
-					name: 'Deutsch',
+				ar: {
+					code: 'ar',
+					name: 'Arabic',
 				},
 			} as WikibaseApiContentLanguages );
 			const contentLanguagesRepo = {
@@ -42,15 +43,42 @@ describe( 'ContentLanguagesLanguageRepo', () => {
 						code: 'en',
 						directionality: 'ltr',
 					},
-					de: {
-						code: 'de',
-						directionality: 'ltr',
+					ar: {
+						code: 'ar',
+						directionality: 'rtl',
 					},
 				} as LanguageCollection );
 				done();
 			} );
 		} );
 
+		it( 'loads language directionality from rtl-detect', ( done ) => {
+			const spyGetLangDir = jest.spyOn( RtlDetectLib, 'getLangDir' );
+
+			const getContentLanguages = jest.fn();
+			getContentLanguages.mockResolvedValue( {
+				en: {
+					code: 'en',
+					name: 'English',
+				},
+				ar: {
+					code: 'ar',
+					name: 'Arabic',
+				},
+			} as WikibaseApiContentLanguages );
+			const contentLanguagesRepo = {
+				getContentLanguages,
+			};
+			const repo = newWikibaseContentLanguagesRepository( contentLanguagesRepo );
+
+			repo.getLanguages().then( ( languages: LanguageCollection ) => {
+				expect( spyGetLangDir ).toBeCalledTimes( 2 );
+				expect( spyGetLangDir ).toBeCalledWith( 'en' );
+				expect( spyGetLangDir ).toBeCalledWith( 'ar' );
+				done();
+			} );
+		} );
+
 	} );
 
 } );