From 4abf04c12a6acbbfdd5c699fd18316e0973f1e2d Mon Sep 17 00:00:00 2001
From: MathieuG-P <40181755+Zagrios@users.noreply.github.com>
Date: Mon, 17 Apr 2023 01:17:19 +0200
Subject: [PATCH] [bugfix-157] create cancellable observable

---
 .../models/rx/cancellable-observable.class.ts | 42 +++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 src/shared/models/rx/cancellable-observable.class.ts

diff --git a/src/shared/models/rx/cancellable-observable.class.ts b/src/shared/models/rx/cancellable-observable.class.ts
new file mode 100644
index 00000000..590b4546
--- /dev/null
+++ b/src/shared/models/rx/cancellable-observable.class.ts
@@ -0,0 +1,42 @@
+import { BehaviorSubject, Observable, Observer, filter, lastValueFrom, take } from "rxjs";
+
+export class CancellableObservable<T> extends Observable<T> {
+    
+    private readonly _isCancelled$ = new BehaviorSubject(false);
+
+    constructor(subscriber: (obs: CancellableObserver<T>) => void) {
+
+        super((observer: Observer<T>) => {
+
+            const cancellableObserver: CancellableObserver<T> = Object.assign(observer, { 
+                $isCancelled: () => this.$isCancelled(),
+                onCancel: (callback: () => void) => this.onCancel(callback)
+            });
+
+            subscriber(cancellableObserver);
+        });
+
+        lastValueFrom(this).finally(() => this._isCancelled$.complete());
+    }
+
+    public cancel(): void {
+        this._isCancelled$.next(true);
+    }
+
+    public onCancel(callback: () => void): void {
+        this.$isCancelled().pipe(filter(isCancelled => isCancelled), take(1)).subscribe(callback);
+    }
+
+    public $isCancelled(): Observable<boolean> {
+        return this._isCancelled$.asObservable();
+    }
+
+    public isCancelled(): boolean {
+        return this._isCancelled$.getValue();
+    }
+}
+
+export interface CancellableObserver<T> extends Observer<T> {
+    readonly $isCancelled: () => Observable<boolean>;
+    readonly onCancel: (callback: () => void) => void;
+}
\ No newline at end of file