Allow retrieval from languageHashes using environment in order to side-load i18n assets without rebuilding the application

src/config/app-config.interface.ts

@@ -22,6 +22,7 @@ import { HomeConfig } from './homepage-config.interface';
 import { MarkdownConfig } from './markdown-config.interface';
 import { FilterVocabularyConfig } from './filter-vocabulary-config';
 import { DiscoverySortConfig } from './discovery-sort.config';
+import { LanguageHashesConfig } from './languageHashes-config.interface';
 import {QualityAssuranceConfig} from './quality-assurance.config';
 
 interface AppConfig extends Config {
@@ -36,6 +37,7 @@ interface AppConfig extends Config {
   debug: boolean;
   defaultLanguage: string;
   languages: LangConfig[];
+  languageHashes: LanguageHashesConfig[];
   browseBy: BrowseByConfig;
   communityList: CommunityListConfig;
   homePage: HomeConfig;

src/config/config.server.ts

@@ -1,5 +1,5 @@
 import { red, blue, green, bold } from 'colors';
-import { existsSync, readFileSync, writeFileSync } from 'fs';
+import { existsSync, readdirSync, readFileSync, statSync, writeFileSync } from 'fs';
 import { load } from 'js-yaml';
 import { join } from 'path';
 
@@ -9,6 +9,7 @@ import { DefaultAppConfig } from './default-app-config';
 import { ServerConfig } from './server-config.interface';
 import { mergeConfig } from './config.util';
 import { isNotEmpty } from '../app/shared/empty.util';
+import { LanguageHashesConfig } from './languageHashes-config.interface';
 
 const CONFIG_PATH = join(process.cwd(), 'config');
 
@@ -231,6 +232,29 @@ export const buildAppConfig = (destConfigPath?: string): AppConfig => {
   // apply build defined production
   appConfig.production = env === 'production';
 
+  const useDynamicLanguageHashes = isNotEmpty(ENV('DYNAMIC_LANGUAGE_HASHES', true)) ? ENV('DYNAMIC_LANGUAGE_HASHES', true) : false;
+  if (appConfig.production && useDynamicLanguageHashes) {
+    const i18nAssetsDir = 'dist/server/assets/i18n/';
+    const i18nFiles = readdirSync(i18nAssetsDir);
+    //sort all the i18nFiles by mtime descending
+    i18nFiles.sort(function(a, b) {
+      return statSync(i18nAssetsDir + b).mtime.getTime() - statSync(i18nAssetsDir + a).mtime.getTime();
+    });
+
+    i18nFiles.forEach(file => {
+      const match = file.match(/^(.+)\.(.+)\.json$/);
+      // only add language hash to config if no config exists for current language (ensuring the latest language file
+      // is used)
+      if (match && appConfig.languageHashes.filter(((languageHashConfig) => languageHashConfig.lang === match[1])).length === 0) {
+        const languageConfig: LanguageHashesConfig = {
+          lang: match[1],
+          md5: match[2]
+        };
+        appConfig.languageHashes.push(languageConfig);
+      }
+    });
+  }
+
   // build base URLs
   buildBaseUrl(appConfig.ui);
   buildBaseUrl(appConfig.rest);

src/config/default-app-config.ts

@@ -22,6 +22,7 @@ import { HomeConfig } from './homepage-config.interface';
 import { MarkdownConfig } from './markdown-config.interface';
 import { FilterVocabularyConfig } from './filter-vocabulary-config';
 import { DiscoverySortConfig } from './discovery-sort.config';
+import { LanguageHashesConfig } from './languageHashes-config.interface';
 import {QualityAssuranceConfig} from './quality-assurance.config';
 
 export class DefaultAppConfig implements AppConfig {
@@ -243,6 +244,8 @@ export class DefaultAppConfig implements AppConfig {
     { code: 'uk', label: 'Yкраї́нська', active: true}
   ];
 
+  languageHashes: LanguageHashesConfig[] = [];
+
   // Browse-By Pages
   browseBy: BrowseByConfig = {
     // Amount of years to display using jumps of one year (current year - oneYearLimit)

src/config/languageHashes-config.interface.ts

@@ -0,0 +1,10 @@
+import { Config } from './config.interface';
+
+/**
+ * An interface to represent a languageHash in the configuration. A LanguageHashConfig has a lang attribute which should be the official
+ * language code for the language (e.g. ‘fr’) and a md5 string representing the checksum of the language asset file.
+ */
+export interface LanguageHashesConfig extends Config {
+      lang: string;
+      md5: string;
+}

src/environments/environment.test.ts

@@ -216,6 +216,8 @@ export const environment: BuildConfig = {
     active: false,
   }],
 
+  languageHashes: [],
+
   // Browse-By Pages
   browseBy: {
     // Amount of years to display using jumps of one year (current year - oneYearLimit)

src/ngx-translate-loaders/translate-browser.loader.ts

@@ -34,7 +34,11 @@ export class TranslateBrowserLoader implements TranslateLoader {
     if (hasValue(messages)) {
       return observableOf(messages);
     } else {
-      const translationHash: string = environment.production ? `.${(process.env.languageHashes as any)[lang + '.json5']}` : '';
+      let translationHash = '';
+      if (environment.production) {
+        const languageHashesConfigFromEnvironment = environment.languageHashes.filter((languageHashConfig) => languageHashConfig.lang === lang);
+        translationHash = `.${languageHashesConfigFromEnvironment.length > 0 ? languageHashesConfigFromEnvironment[0].md5 : (process.env.languageHashes as any)[lang + '.json5']}`;
+      }
       // If they're not available on the transfer state (e.g. when running in dev mode), retrieve
       // them using HttpClient
       return this.http.get(`${this.prefix}${lang}${translationHash}${this.suffix}`, { responseType: 'text' }).pipe(

src/ngx-translate-loaders/translate-server.loader.ts

@@ -3,6 +3,7 @@ import { Observable, of as observableOf } from 'rxjs';
 import { readFileSync } from 'fs';
 import { TransferState } from '@angular/platform-browser';
 import { NGX_TRANSLATE_STATE, NgxTranslateState } from './ngx-translate-state';
+import { environment } from '../environments/environment';
 
 /**
  * A TranslateLoader for ngx-translate to parse json5 files server-side, and store them in the
@@ -23,7 +24,9 @@ export class TranslateServerLoader implements TranslateLoader {
    * @param lang the language code
    */
   public getTranslation(lang: string): Observable<any> {
-    const translationHash: string = (process.env.languageHashes as any)[lang + '.json5'];
+    const languageHashesConfigFromEnvironment = environment.languageHashes.filter((languageHashConfig) => languageHashConfig.lang === lang);
+    const translationHash = languageHashesConfigFromEnvironment.length > 0 ? languageHashesConfigFromEnvironment[0].md5 : (process.env.languageHashes  as any)[lang + '.json5'];
+
     // Retrieve the file for the given language, and parse it
     const messages = JSON.parse(readFileSync(`${this.prefix}${lang}.${translationHash}${this.suffix}`, 'utf8'));
     // Store the parsed messages in the transfer state so they'll be available immediately when the