chore: Manage motion and text direction in dev pages via URL query params

pages/app/page.tsx

@@ -1,41 +1,38 @@
 // Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 import { Suspense } from "react";
-import { useEffect, useState } from "react";
 
 import { SpaceBetween, Toggle } from "@cloudscape-design/components";
-import { applyDensity, applyMode, Density, Mode } from "@cloudscape-design/global-styles";
+import { Density, Mode } from "@cloudscape-design/global-styles";
 
 import { pagesMap } from "../pages";
 import PageLayout from "./page-layout";
+import useModes from "./use-modes";
 
 export interface PageProps {
   pageId: string;
 }
 
 export default function Page({ pageId }: PageProps) {
   const Component = pagesMap[pageId];
-  const [dark, setDark] = useState(false);
-  const [compact, setCompact] = useState(false);
-
-  useEffect(() => {
-    applyMode(dark ? Mode.Dark : Mode.Light, document.documentElement);
-  }, [dark]);
-
-  useEffect(() => {
-    applyDensity(compact ? Density.Compact : Density.Comfortable, document.documentElement);
-  }, [compact]);
+  const { mode, density, setParams } = useModes();
 
   return (
     <PageLayout>
       <Suspense fallback="Loading">
         <SpaceBetween direction="vertical" size="m">
           <a href="/index.html#">Back to all pages</a>
           <SpaceBetween direction="horizontal" size="m">
-            <Toggle checked={dark} onChange={(event) => setDark(event.detail.checked)}>
+            <Toggle
+              checked={mode === Mode.Dark}
+              onChange={(event) => setParams({ mode: event.detail.checked ? Mode.Dark : Mode.Light })}
+            >
               Dark mode
             </Toggle>
-            <Toggle checked={compact} onChange={(event) => setCompact(event.detail.checked)}>
+            <Toggle
+              checked={density === Density.Compact}
+              onChange={(event) => setParams({ density: event.detail.checked ? Density.Compact : Density.Comfortable })}
+            >
               Compact mode
             </Toggle>
           </SpaceBetween>

pages/app/use-modes.tsx

@@ -0,0 +1,72 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+import { useEffect } from "react";
+import { useSearchParams } from "react-router-dom";
+
+import { applyDensity, applyMode, Density, disableMotion, Mode } from "@cloudscape-design/global-styles";
+
+export interface AppUrlParams {
+  mode: Mode;
+  density: Density;
+  direction: "ltr" | "rtl";
+  motionDisabled: boolean;
+}
+
+export const defaults: AppUrlParams = {
+  mode: Mode.Light,
+  density: Density.Comfortable,
+  direction: "ltr",
+  motionDisabled: false,
+};
+
+function castToBoolean(s: string) {
+  if (s === "true" || s === "false") {
+    return s === "true";
+  }
+  return s;
+}
+
+export function parseQuery(urlParams: URLSearchParams) {
+  const queryParams: Record<string, any> = { ...defaults };
+  urlParams.forEach((value, key) => (queryParams[key] = castToBoolean(value)));
+  return queryParams as AppUrlParams;
+}
+
+export function formatQuery(params: AppUrlParams) {
+  const query: Record<string, string> = {};
+  for (const [key, value] of Object.entries(params)) {
+    if (value === defaults[key as keyof AppUrlParams]) {
+      continue;
+    }
+    query[key] = String(value);
+  }
+  return query;
+}
+
+export default function useModes() {
+  const [searchParams, setSearchParams] = useSearchParams();
+  const urlParams = parseQuery(searchParams);
+  const { density, direction, mode, motionDisabled } = urlParams;
+
+  function setParams(newParams: Partial<AppUrlParams>) {
+    setSearchParams(formatQuery({ ...urlParams, ...newParams }));
+  }
+
+  useEffect(() => {
+    applyMode(mode);
+  }, [mode]);
+
+  useEffect(() => {
+    applyDensity(density);
+  }, [density]);
+
+  useEffect(() => {
+    disableMotion(motionDisabled);
+  }, [motionDisabled]);
+
+  useEffect(() => {
+    document.documentElement.setAttribute("dir", direction);
+  }, [direction]);
+
+  return { density, direction, mode, motionDisabled, setParams };
+}