Added better caching strategy and fallback to non-region-specific languages (#226)

* Added better caching strategy and fallback to non-region-specific languages

* Added unit test

* Added comment for publishReplay(1).refCount() usage

Author: Blackbaud-PaulCrowder

runtime/i18n/resources.service.spec.ts

@@ -33,7 +33,7 @@ describe('Resources service', () => {
       }
     };
 
-    const providers = [
+    const providers: any[] = [
       SkyAppAssetsService,
       SkyAppResourcesService,
       {
@@ -44,7 +44,7 @@ describe('Resources service', () => {
         provide: SkyAppAssetsService,
         useValue: {
           getUrl: (path) => {
-            if (path.indexOf('en_AU') >= 0) {
+            if (path.indexOf('en_AU') >= 0 || path.indexOf('es_MX') >= 0) {
               return undefined;
             }
 
@@ -189,6 +189,33 @@ describe('Resources service', () => {
 
     beforeEach(injectServices());
 
+    it('should fall back to the default locale if a blank locale is specified', (done) => {
+      addTestResourceResponse();
+
+      currentLocale = '';
+
+      resources.getString('hi').subscribe((value) => {
+        expect(value).toBe('hello');
+        done();
+      });
+    });
+
+    it(
+      'should fall back to the non-region-specific locale if the specified locale does not have ' +
+      'corresponding resource file',
+      (done) => {
+
+        backend.connections.subscribe((connection) => {
+          expect(connection.request.url).toBe('https://example.com/locales/resources_es.json');
+          done();
+        });
+
+        currentLocale = 'es-MX';
+
+        resources.getString('hi').subscribe((value) => { });
+      }
+    );
+
     it(
       'should fall back to the default locale if the specified locale does not have a ' +
       'corresponding resource file',

runtime/i18n/resources.service.ts

@@ -60,15 +60,30 @@ export class SkyAppResourcesService {
       this.resourcesObs = localeObs
         .switchMap((localeInfo) => {
           let obs: Observable<any>;
+          let resourcesUrl: string;
 
-          const resourcesUrl =
-            this.getUrlForLocale(localeInfo.locale) ||
-            this.getUrlForLocale(DEFAULT_LOCALE);
+          const locale = localeInfo.locale;
+
+          if (locale) {
+            resourcesUrl =
+              this.getUrlForLocale(locale) ||
+              // Try falling back to the non-region-specific language.
+              this.getUrlForLocale(locale.substr(0, 2));
+          }
+
+          // Finally fall back to the default locale.
+          resourcesUrl = resourcesUrl || this.getUrlForLocale(DEFAULT_LOCALE);
 
           if (resourcesUrl) {
             obs = this.httpObs[resourcesUrl] || this.http
               .get(resourcesUrl)
-              .share()
+              /* tslint:disable max-line-length */
+              // publishReplay(1).refCount() will ensure future subscribers to
+              // this observable will use a cached result.
+              // https://stackoverflow.com/documentation/rxjs/8247/common-recipes/26490/caching-http-responses#t=201612161544428695958
+              /* tslint:enable max-line-length */
+              .publishReplay(1)
+              .refCount()
               .catch(() => {
                 // The resource file for the specified locale failed to load;
                 // fall back to the default locale if it differs from the specified