feat(lib): start of generic lib. Routemonitor (#508)

generics/lib/src/routeMonitor.ts

@@ -0,0 +1,62 @@
+import {interval, merge, of, Subject} from 'rxjs';
+import {distinctUntilChanged, filter, map, repeat, switchMap, take, takeWhile, tap} from 'rxjs/operators';
+
+interface Mc {
+  prev: URL;
+}
+const hasChanged = new Subject<string>();
+const mightChange = new Subject<Mc>();
+
+if (window && history) {
+  window.addEventListener('popstate', ev => hasChanged.next(location.href));
+
+  /**
+   *  monkeyPath ps
+   * used to monitor route changes, this is a 'route-start'
+   */
+  const hps = history.pushState.bind(history);
+  history.pushState = (data: any, tile: string, url: string) => {
+    // console.log('push', url);
+    mightChange.next({prev: new URL(location.href)});
+    hps(data, tile, url);
+  };
+
+  const maxTime = 1000; // use 1 second for now
+  const pollInterval = 5;
+  const maxTakes = maxTime / pollInterval;
+
+  /**
+   * While the polling might seem overkill, it is needed
+   * if a framework is doing things like authentication on routes, or data fetching
+   * it might take longer before the route change is finalized.
+   */
+  mightChange
+    .pipe(
+      switchMap(mc =>
+        /** start polling */
+        interval(pollInterval).pipe(
+          tap(() => console.log('interval')),
+          /** take while its not changed */
+          takeWhile(() => location.pathname === mc.prev.pathname),
+          /** OR the timeout is reached */
+          take(maxTakes),
+          map(() => mc)
+        )
+      ),
+      /** filter out non-url changing pushes */
+      filter(({prev}) => location.pathname !== prev.pathname),
+      /** take 1 change */
+      take(1),
+      /** and start over  */
+      repeat(),
+      /** map to the current URL */
+      map(() => location.href)
+    )
+    .subscribe(hasChanged);
+}
+
+// tslint:disable-next-line: deprecation
+export const route$ = merge(of(location.href), hasChanged).pipe(
+  distinctUntilChanged(),
+  map(u => new URL(u))
+);

scully/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@scullyio/scully",
-  "version": "0.0.87",
+  "version": "0.0.88",
   "description": "Scully CLI",
   "repository": {
     "type": "GIT",