Unified components and observable structure

src/assets/javascripts/browser/document/switch/index.ts

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+/*
+ * Copyright (c) 2016-2020 Martin Donath <martin.donath@squidfunk.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+import { NEVER, Observable } from "rxjs"
+import { ajax } from "rxjs/ajax"
+import {
+  catchError,
+  distinctUntilKeyChanged,
+  pluck,
+  share,
+  skip,
+  switchMap
+} from "rxjs/operators"
+
+import { setLocation } from "../../location"
+
+/* ----------------------------------------------------------------------------
+ * Helper types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch options
+ */
+interface WatchOptions {
+  location$: Observable<URL>           /* Location observable */
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Watch document switch
+ *
+ * This function returns an observables that fetches a document if the provided
+ * location observable emits a new value (i.e. URL). If the emitted URL points
+ * to the same page, the request is effectively ignored (i.e. when only the
+ * fragment identifier changes).
+ *
+ * In case the request fails, the location change is dispatched regularly.
+ *
+ * @param options - Options
+ *
+ * @return Document observable
+ */
+export function watchDocumentSwitch(
+  { location$ }: WatchOptions
+): Observable<Document> {
+  return location$
+    .pipe(
+      distinctUntilKeyChanged("pathname"),
+      skip(1),
+
+      /* Fetch document */
+      switchMap(url => ajax({
+        url: url.href,
+        responseType: "document",
+        withCredentials: true
+      })
+        .pipe<Document, Document>(
+          pluck("response"),
+          catchError(() => {
+            setLocation(url)
+            return NEVER
+          })
+        )
+      ),
+      share()
+    )
+}