From 857f8c6cae953d17970e0e8bbd5939d7446a8bfa Mon Sep 17 00:00:00 2001
From: Denis Platonov <denis.platonov@bimeister.com>
Date: Sat, 18 Mar 2023 12:59:28 +0300
Subject: [PATCH] feature: add flipFLag rxjs operator function

---
 .../flip-flag-on-finalize.operator.spec.ts    | 31 +++++++++++++++++++
 .../flip-flag-on-finalize.operator.ts         | 17 ++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 packages/rxjs/src/operators/flip-flag-on-finalize.operator.spec.ts
 create mode 100644 packages/rxjs/src/operators/flip-flag-on-finalize.operator.ts

diff --git a/packages/rxjs/src/operators/flip-flag-on-finalize.operator.spec.ts b/packages/rxjs/src/operators/flip-flag-on-finalize.operator.spec.ts
new file mode 100644
index 0000000..e987854
--- /dev/null
+++ b/packages/rxjs/src/operators/flip-flag-on-finalize.operator.spec.ts
@@ -0,0 +1,31 @@
+import { BehaviorSubject, of, throwError } from 'rxjs';
+import { delay } from 'rxjs/operators';
+import { flipFlagOnFinalize } from './flip-flag-on-finalize.operator';
+
+describe('flip-flag-on-finalize.operator.ts', () => {
+  let isLoading$: BehaviorSubject<boolean>;
+
+  beforeEach(() => {
+    isLoading$ = new BehaviorSubject<boolean>(false);
+  });
+
+  it('should set loading state to false after source completes', () => {
+    of('test')
+      .pipe(flipFlagOnFinalize(isLoading$))
+      .subscribe({
+        complete: () => {
+          expect(isLoading$.getValue()).toBe(false);
+        }
+      });
+  });
+
+  it('should set loading state to false after source errors', () => {
+    throwError('error')
+      .pipe(delay(10), flipFlagOnFinalize(isLoading$), delay(10))
+      .subscribe({
+        error: () => {
+          expect(isLoading$.getValue()).toBe(false);
+        }
+      });
+  });
+});
diff --git a/packages/rxjs/src/operators/flip-flag-on-finalize.operator.ts b/packages/rxjs/src/operators/flip-flag-on-finalize.operator.ts
new file mode 100644
index 0000000..c19a2c2
--- /dev/null
+++ b/packages/rxjs/src/operators/flip-flag-on-finalize.operator.ts
@@ -0,0 +1,17 @@
+import { BehaviorSubject, defer, Observable, OperatorFunction, ReplaySubject } from 'rxjs';
+import { finalize, switchMap, take } from 'rxjs/operators';
+
+export function flipFlagOnFinalize<T>(
+  flagSubject$: BehaviorSubject<boolean> | ReplaySubject<boolean>
+): OperatorFunction<T, T> {
+  return (source: Observable<T>): Observable<T> =>
+    defer(() => {
+      flagSubject$.pipe(
+        take(1),
+        switchMap((flagValue: boolean) => {
+          flagSubject$.next(!flagValue);
+          return source.pipe(finalize(() => flagSubject$.next(flagValue)));
+        })
+      );
+    });
+}