From 9afdf265077d5b237c5523e93c211456caa99279 Mon Sep 17 00:00:00 2001
From: Brian Diehr <diehbria@amazon.com>
Date: Fri, 9 Sep 2022 15:10:03 -0700
Subject: [PATCH] feat(core): Add viewportManager to orchestrate viewport
 syncing within groups

---
 .../viewportManager/viewportManager.spec.ts   | 73 +++++++++++++++++++
 .../src/viewportManager/viewportManager.ts    | 56 ++++++++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 packages/core/src/viewportManager/viewportManager.spec.ts
 create mode 100644 packages/core/src/viewportManager/viewportManager.ts

diff --git a/packages/core/src/viewportManager/viewportManager.spec.ts b/packages/core/src/viewportManager/viewportManager.spec.ts
new file mode 100644
index 000000000..98fe8d051
--- /dev/null
+++ b/packages/core/src/viewportManager/viewportManager.spec.ts
@@ -0,0 +1,73 @@
+import { viewportManager } from './viewportManager';
+
+beforeEach(() => {
+  viewportManager.reset();
+});
+
+const VIEWPORT = { duration: '2m' };
+
+it('subscribes to a new viewport group and returned an undefined viewport', () => {
+  const { viewport } = viewportManager.subscribe('some-group', () => {});
+  expect(viewport).toBeUndefined();
+});
+
+it('broadcast updates to viewport group', () => {
+  const listener = jest.fn();
+  viewportManager.subscribe('some-group', listener);
+  viewportManager.update('some-group', VIEWPORT);
+  expect(listener).toHaveBeenLastCalledWith(VIEWPORT);
+});
+
+it('returns current viewport for group is returned upon initial subscription', () => {
+  const listener = jest.fn();
+  viewportManager.update('some-group', VIEWPORT);
+  const { viewport } = viewportManager.subscribe('some-group', listener);
+
+  expect(viewport).toBe(VIEWPORT);
+});
+
+it('returns no viewport is returned on initial subscription when reset is called', () => {
+  const listener = jest.fn();
+  viewportManager.update('some-group', VIEWPORT);
+  viewportManager.reset();
+  const { viewport } = viewportManager.subscribe('some-group', listener);
+
+  expect(viewport).toBeUndefined();
+});
+
+it('does not broadcast viewport updates to different viewport groups ', () => {
+  const listener = jest.fn();
+  viewportManager.subscribe('some-group', listener);
+  viewportManager.update('some-other-group', VIEWPORT);
+  expect(listener).not.toHaveBeenCalled();
+});
+
+it('broadcasts viewports to multiple listeners', () => {
+  const listener = jest.fn();
+  const listener2 = jest.fn();
+  viewportManager.subscribe('some-group', listener);
+  viewportManager.subscribe('some-group', listener2);
+  viewportManager.update('some-group', VIEWPORT);
+
+  expect(listener).toHaveBeenLastCalledWith(VIEWPORT);
+  expect(listener2).toHaveBeenLastCalledWith(VIEWPORT);
+});
+
+it('does not broadcast updates to a unsubscribed listener', () => {
+  const listener = jest.fn();
+  const { unsubscribe } = viewportManager.subscribe('some-group', listener);
+
+  unsubscribe();
+  viewportManager.update('some-group', VIEWPORT);
+  expect(listener).not.toHaveBeenCalled();
+});
+
+it('does not broadcast updates to a listener after reset is called', () => {
+  const listener = jest.fn();
+  viewportManager.subscribe('some-group', listener);
+
+  viewportManager.reset();
+  viewportManager.update('some-group', VIEWPORT);
+
+  expect(listener).not.toHaveBeenCalled();
+});
diff --git a/packages/core/src/viewportManager/viewportManager.ts b/packages/core/src/viewportManager/viewportManager.ts
new file mode 100644
index 000000000..866645cdc
--- /dev/null
+++ b/packages/core/src/viewportManager/viewportManager.ts
@@ -0,0 +1,56 @@
+import { MinimalViewPortConfig } from '@synchro-charts/core';
+import { v4 } from 'uuid';
+
+type ViewportListener = (viewport: MinimalViewPortConfig) => void;
+
+let listenerMap: { [group: string]: { [id: string]: ViewportListener } } = {};
+let viewportMap: { [group: string]: MinimalViewPortConfig } = {};
+/**
+ * Publicly exposed manager of viewport groups. Allows components, both internally to IoT App Kit,
+ * and external components / code to broadcast updates to viewports within a group.
+ *
+ * Utilized to allow widgets to provide a synchronized view into data - an example can be
+ * found at https://synchrocharts.com/#/Features/Synchronization
+ */
+export const viewportManager = {
+  /**
+   * Resets all state related to viewport groups.
+   */
+  reset: () => {
+    listenerMap = {};
+    viewportMap = {};
+  },
+  /**
+   * Subscribe to viewport group
+   *
+   * @param viewportGroup - group to subscribe to
+   * @param viewportListener - listener for viewport group updates. Called every time an update to the group is called. Not called upon initial subscription
+   */
+  subscribe: (
+    viewportGroup: string,
+    viewportListener: (viewport: MinimalViewPortConfig) => void
+  ): {
+    unsubscribe: () => void;
+    viewport: MinimalViewPortConfig | null;
+  } => {
+    const id = v4();
+    if (listenerMap[viewportGroup] == null) {
+      listenerMap[viewportGroup] = {};
+    }
+    listenerMap[viewportGroup][id] = viewportListener;
+
+    return {
+      // Current viewport for the group
+      viewport: viewportMap[viewportGroup],
+      // Leave viewport group, prevents listener from being called in the future
+      unsubscribe: () => {
+        delete listenerMap[viewportGroup][id];
+      },
+    };
+  },
+  update: (viewportGroup: string, viewport: MinimalViewPortConfig): void => {
+    viewportMap[viewportGroup] = viewport;
+    // broadcast update to all listeners within the group
+    Object.keys(listenerMap[viewportGroup] || {}).forEach((id) => listenerMap[viewportGroup][id](viewport));
+  },
+};