From 77d991f033546c4214babab92b7e41fb83e06fde Mon Sep 17 00:00:00 2001
From: griest024 <griest024@gmail.com>
Date: Wed, 15 May 2024 09:59:59 -0400
Subject: [PATCH] feat(router): add service for observing route data (#2778)

---
 .../src/data/helpers/collect-data.spec.ts     | 68 +++++++++++++++++++
 libs/router/src/data/helpers/collect-data.ts  | 24 +++++++
 libs/router/src/data/helpers/public_api.ts    |  1 +
 libs/router/src/data/public_api.ts            |  2 +
 libs/router/src/data/service/data.service.ts  | 52 ++++++++++++++
 5 files changed, 147 insertions(+)
 create mode 100644 libs/router/src/data/helpers/collect-data.spec.ts
 create mode 100644 libs/router/src/data/helpers/collect-data.ts
 create mode 100644 libs/router/src/data/helpers/public_api.ts
 create mode 100644 libs/router/src/data/public_api.ts
 create mode 100644 libs/router/src/data/service/data.service.ts

diff --git a/libs/router/src/data/helpers/collect-data.spec.ts b/libs/router/src/data/helpers/collect-data.spec.ts
new file mode 100644
index 0000000000..255c83af82
--- /dev/null
+++ b/libs/router/src/data/helpers/collect-data.spec.ts
@@ -0,0 +1,68 @@
+import { ActivatedRouteSnapshot } from '@angular/router';
+
+import { daffRouterDataCollect } from './collect-data';
+
+describe('@daffodil/router | daffRouterDataCollect', () => {
+  let route: ActivatedRouteSnapshot;
+  let result: any;
+
+  beforeEach(() => {
+    route = <ActivatedRouteSnapshot><unknown>{
+      data: {
+        root: 'TestClass',
+        overwrite: 'TestClass',
+      },
+      children: [
+        <ActivatedRouteSnapshot><unknown>{
+          data: {
+            '00': 'TestClass',
+          },
+          children: [
+            <ActivatedRouteSnapshot><unknown>{
+              data: {
+                10: 'TestClass',
+              },
+              children: [],
+            },
+            <ActivatedRouteSnapshot><unknown>{
+              data: {
+                11: 'TestClass',
+                overwrite: 'TestClass1',
+              },
+              children: [
+                <ActivatedRouteSnapshot><unknown>{
+                  data: {
+                    20: 'TestClass',
+                  },
+                  children: [],
+                },
+              ],
+            },
+          ],
+        },
+        <ActivatedRouteSnapshot><unknown>{
+          data: {
+            '01': 'TestClass',
+          },
+          children: [],
+        },
+      ],
+    };
+
+    result = daffRouterDataCollect(route);
+  });
+
+  it('should collect all the named views and combine them into a single dict', () => {
+    expect(result['root']).toBeDefined();
+    expect(result['00']).toBeDefined();
+    expect(result['01']).toBeDefined();
+    expect(result[10]).toBeDefined();
+    expect(result[11]).toBeDefined();
+    expect(result[20]).toBeDefined();
+    expect(result['overwrite']).toBeDefined();
+  });
+
+  it('should give precedence to more deeply nested routes when there is a collision', () => {
+    expect(result['overwrite']).toEqual('TestClass1');
+  });
+});
diff --git a/libs/router/src/data/helpers/collect-data.ts b/libs/router/src/data/helpers/collect-data.ts
new file mode 100644
index 0000000000..8d9112d62d
--- /dev/null
+++ b/libs/router/src/data/helpers/collect-data.ts
@@ -0,0 +1,24 @@
+import {
+  ActivatedRouteSnapshot,
+  Route,
+} from '@angular/router';
+
+import { collect } from '@daffodil/core';
+
+/**
+ * Collects data defined in the entire tree of routes.
+ * Shallow merges data, preferring fields of more deeply nested routes.
+ */
+export const daffRouterDataCollect = (route: ActivatedRouteSnapshot): Route['data'] => {
+  const ary = collect(route, (r) => r.children);
+  const ret = ary.reduce(
+    (acc, r) => r.data
+      ? {
+        ...acc,
+        ...r.data,
+      }
+      : acc,
+    {},
+  );
+  return ret;
+};
diff --git a/libs/router/src/data/helpers/public_api.ts b/libs/router/src/data/helpers/public_api.ts
new file mode 100644
index 0000000000..bdd503e8cb
--- /dev/null
+++ b/libs/router/src/data/helpers/public_api.ts
@@ -0,0 +1 @@
+export { daffRouterNamedViewsCollect } from './collect-data';
diff --git a/libs/router/src/data/public_api.ts b/libs/router/src/data/public_api.ts
new file mode 100644
index 0000000000..e04c890d5c
--- /dev/null
+++ b/libs/router/src/data/public_api.ts
@@ -0,0 +1,2 @@
+export * from './helpers/public_api';
+export * from './service/data.service';
diff --git a/libs/router/src/data/service/data.service.ts b/libs/router/src/data/service/data.service.ts
new file mode 100644
index 0000000000..81e9d83b4a
--- /dev/null
+++ b/libs/router/src/data/service/data.service.ts
@@ -0,0 +1,52 @@
+import { Injectable } from '@angular/core';
+import {
+  ActivatedRoute,
+  NavigationEnd,
+  Route,
+  Router,
+} from '@angular/router';
+import {
+  Observable,
+  filter,
+  map,
+  merge,
+} from 'rxjs';
+
+import { daffRouterDataCollect } from '../helpers/collect-data';
+
+@Injectable({
+  providedIn: 'root',
+})
+export class DaffRouterDataService {
+  /**
+   * A collection of all the route data defined in any part of the currently activated route's tree.
+   * Child route's data takes precendence over parent data.
+   */
+  public data$: Observable<Route['data']>;
+
+  constructor(
+    private route: ActivatedRoute,
+    private router: Router,
+  ) {
+    /**
+     * Because data won't reemit for route changes and
+     * the top-level data probably won't have named views
+     * anyway, use `url` and router events to listen for route changes
+     * and pull named views from nested data in the snapshot.
+     *
+     * On first page load, this directive will likely not be instantiated
+     * in time to catch router events so route.url emits for this case.
+     * On subsequent route changes, `route.url` will not change (why????)
+     * so we use router events instead.
+     */
+    this.data$ = merge(
+      this.router.events.pipe(
+        filter((e) => e instanceof NavigationEnd),
+      ),
+      this.route.url,
+    ).pipe(
+      map(() => this.route.snapshot),
+      map(daffRouterDataCollect),
+    );
+  }
+}