feat(core): add auth interceptor

pass headers to http request headers via interceptor

make repeated requests on error

Author: loktionov129

.ToDo

@@ -15,12 +15,6 @@ BrowserClient:
         @critical @today 
         ☐ perf: ngFor  + trackBy @created(18-06-13 21:57:46)
 
-        @critical @today
-        ☐ feat(core): catch errors/pass headers via interceptor @created(18-06-13 21:55:41)
-        custom errorhandler (0rl1on)
-        https://angular.io/api/common/http/HttpInterceptor
-        https://www.youtube.com/watch?v=z9U_xYSsVRw
-
         @critical @feature
         ☐ feat(core): notifications - display notification error, when api doesn't available @created(18-06-13 21:27:50)
 
@@ -63,6 +57,11 @@ BrowserClient:
         https://offering.solutions/blog/articles/2018/02/10/separating-state-into-angular-modules-with-ngrx/
 
 Archive:
+    ✔ feat(core): catch errors/pass headers via interceptor @created(18-06-13 21:55:41) @done(18-06-30 12:23:37) @project(BrowserClient.In Progress)
+    custom errorhandler (0rl1on)
+    https://angular.io/api/common/http/HttpInterceptor
+    https://www.youtube.com/watch?v=z9U_xYSsVRw
+    
 ✔ create page submodules with lazyloading   for feature modules if need
 
 Info:

src/app/core/core.module.ts

@@ -1,8 +1,17 @@
+import { HTTP_INTERCEPTORS } from '@angular/common/http';
 import { NgModule } from '@angular/core';
 
+import { AuthInterceptor } from './services/auth.interceptor';
+
+const authInterceptor = {
+  multi: true,
+  provide: HTTP_INTERCEPTORS,
+  useClass: AuthInterceptor,
+};
+
+const providers = [authInterceptor];
+
 @NgModule({
-  exports: [],
-  imports: [],
-  providers: [],
+  providers,
 })
-export class CoreModule { }
+export class CoreModule {}

src/app/core/services/auth.interceptor.ts

@@ -0,0 +1,29 @@
+import { HttpEvent, HttpHandler, HttpInterceptor, HttpRequest } from '@angular/common/http';
+import { Injectable } from '@angular/core';
+import { Observable } from 'rxjs';
+import { delay, retryWhen, scan } from 'rxjs/operators';
+
+@Injectable()
+export class AuthInterceptor implements HttpInterceptor {
+  intercept(request: HttpRequest<{}>, next: HttpHandler): Observable<HttpEvent<{}>> {
+    const newRequest = request.clone({
+      setHeaders: {
+        Authorization: `Bearer ...xAuthToken...`,
+      },
+    });
+
+    return next.handle(newRequest).pipe(
+      retryWhen(err =>
+        err.pipe(
+          scan(retryCount => {
+            if (retryCount < 2) {
+              return retryCount + 1;
+            }
+            throw new Error('Retry limit exceeded!');
+          }, 0), // tslint:disable-line:align
+          delay(2000),
+        ),
+      ),
+    );
+  }
+}