Extract url utils from app.tsx

docs/APP_REFACTORING_DESIGN.md

@@ -82,7 +82,7 @@ To refactor `app.tsx` safely and maintain continuous code correctness, we will m
 #### Phase 1: Pure Component and Utility Extraction
 *   [x] **Step 1.1:** Create `src/components/error_display.tsx` and move `ErrorMessage` and `ErrorPopup` from `src/app.tsx`. Update imports in `src/app.tsx`.
 *   [x] **Step 1.2:** Create `src/datasource/instances.ts` and move data source class instantiations. Update references in `src/app.tsx`. Refactor `EmbeddedDataSource` to clean up its message event listener when the loading promise resolves or rejects (or track listener state) to prevent duplicate event listener leaks on multiple page mounts.
-*   [ ] **Step 1.3:** Create `src/util/url_args.ts` (the parsing utility) and `src/util/url_args.spec.ts` (its Jest unit test suite) together. Extract URL query parameter parsing functions and types from `src/app.tsx`, write comprehensive tests, update imports in `src/app.tsx`, and run `npm test` to verify.
+*   [x] **Step 1.3:** Create `src/util/url_args.ts` (the parsing utility) and `src/util/url_args.spec.ts` (its Jest unit test suite) together. Extract URL query parameter parsing functions and types from `src/app.tsx`, write comprehensive tests, update imports in `src/app.tsx`, and run `npm test` to verify.
 *   [ ] **Step 1.4:** Modify `src/menu/top_bar.tsx` to make chart-specific props and event handlers optional (e.g. `data`, `allowAllRelativesChart`, `allowPrintAndDownload`, `eventHandlers`, etc.), preparing the component for rendering on the landing screen without dummy properties.
 
 #### Phase 2: WebMCP Bridge Extraction

jest.config.ts

@@ -16,6 +16,8 @@ const config: Config.InitialOptions = {
     "d3-selection": "<rootDir>/node_modules/d3-selection/dist/d3-selection.js",
     "d3-timer": "<rootDir>/node_modules/d3-timer/dist/d3-timer.js",
     "d3-transition": "<rootDir>/node_modules/d3-transition/dist/d3-transition.js",
+    "d3-drag": "<rootDir>/node_modules/d3-drag/dist/d3-drag.js",
+    "d3-zoom": "<rootDir>/node_modules/d3-zoom/dist/d3-zoom.js",
   },
 };
 

src/app.tsx

@@ -1,4 +1,3 @@
-import * as H from 'history';
 import queryString from 'query-string';
 import {useCallback, useEffect, useMemo, useRef, useState} from 'react';
 import {useIntl} from 'react-intl';
@@ -48,7 +47,6 @@ import {Intro} from './intro';
 import {GoogleAuthModal} from './menu/google_auth_modal';
 import {TopBar} from './menu/top_bar';
 import {
-  argsToConfig,
   Config,
   configToArgs,
   DEFALUT_CONFIG,
@@ -60,29 +58,14 @@ import {analyticsEvent} from './util/analytics';
 import {TopolaError} from './util/error';
 import {getI18nMessage} from './util/error_i18n';
 import {idToIndiMap, TopolaData} from './util/gedcom_util';
+import {
+  DataSourceSpec,
+  getArguments,
+  getStaticUrl,
+  getUrlForArgs,
+} from './util/url_args';
 import {WebMcpBridge} from './webmcp';
 
-/**
- * Load GEDCOM URL from environment variable (Vite VITE_STATIC_URL or dynamically
- * injected via a meta tag from Caddy server).
- *
- * If this static URL is provided, the viewer is switched to
- * single-tree mode without the option to load other data.
- */
-function getStaticUrl(): string | undefined {
-  const envUrl = import.meta.env.VITE_STATIC_URL;
-  if (envUrl) return envUrl;
-
-  const metaTag = document.querySelector('meta[name="topola-static-url"]');
-  const metaUrl = metaTag?.getAttribute('content');
-  // Safely ignore if it is empty, the raw caddy template expression, or Vite's raw template placeholder
-  if (metaUrl && !metaUrl.startsWith('__') && !metaUrl.includes('{{ env')) {
-    return metaUrl;
-  }
-
-  return undefined;
-}
-
 const staticUrl = getStaticUrl();
 
 enum AppState {
@@ -93,124 +76,6 @@ enum AppState {
   LOADING_MORE,
 }
 
-type DataSourceSpec =
-  | UrlSourceSpec
-  | UploadSourceSpec
-  | WikiTreeSourceSpec
-  | EmbeddedSourceSpec
-  | GoogleDriveSourceSpec;
-
-/**
- * Arguments passed to the application, primarily through URL parameters.
- * Non-optional arguments get populated with default values.
- */
-interface Arguments {
-  sourceSpec?: DataSourceSpec;
-  selection?: IndiInfo;
-  chartType: ChartType;
-  standalone: boolean;
-  showWikiTreeMenus: boolean;
-  freezeAnimation: boolean;
-  showSidePanel: boolean;
-  config: Config;
-}
-
-function getParamFromSearch(name: string, search: queryString.ParsedQuery) {
-  const value = search[name];
-  return typeof value === 'string' ? value : undefined;
-}
-
-/**
- * Retrieve arguments passed into the application through the URL and uploaded
- * data.
- */
-function getArguments(location: H.Location): Arguments {
-  const search = queryString.parse(location.search);
-  const getParam = (name: string) => getParamFromSearch(name, search);
-
-  const view = getParam('view');
-  const chartTypes = new Map<string | undefined, ChartType>([
-    ['relatives', ChartType.Relatives],
-    ['fancy', ChartType.Fancy],
-    ['donatso', ChartType.Donatso],
-  ]);
-
-  const hash = getParam('file');
-  const url = getParam('url');
-  const embedded = getParam('embedded') === 'true'; // False by default.
-  let sourceSpec: DataSourceSpec | undefined = undefined;
-  if (staticUrl) {
-    sourceSpec = {
-      source: DataSourceEnum.GEDCOM_URL,
-      url: staticUrl,
-      handleCors: false,
-    };
-  } else if (getParam('source') === 'wikitree') {
-    const windowSearch = queryString.parse(window.location.search);
-    sourceSpec = {
-      source: DataSourceEnum.WIKITREE,
-      authcode:
-        getParam('authcode') || getParamFromSearch('authcode', windowSearch),
-    };
-  } else if (getParam('source') === 'google-drive') {
-    const fileId = getParam('fileId');
-    if (fileId) {
-      sourceSpec = {
-        source: DataSourceEnum.GOOGLE_DRIVE,
-        fileId,
-      };
-    }
-  } else if (hash) {
-    sourceSpec = {
-      source: DataSourceEnum.UPLOADED,
-      hash,
-    };
-  } else if (url) {
-    sourceSpec = {
-      source: DataSourceEnum.GEDCOM_URL,
-      url,
-      handleCors: getParam('handleCors') !== 'false', // True by default.
-    };
-  } else if (embedded) {
-    sourceSpec = {source: DataSourceEnum.EMBEDDED};
-  }
-
-  const indi = getParam('indi');
-  const parsedGen = Number(getParam('gen'));
-  const selection = indi
-    ? {id: indi, generation: !isNaN(parsedGen) ? parsedGen : 0}
-    : undefined;
-
-  /**
-   * Determines whether the side panel should be shown taking into account the
-   * URL parameter and the viewport size.
-   *
-   * On mobile devices (max-width: 767px), the side panel is hidden by default.
-   * On tablet and desktop, the side panel is shown by default.
-   */
-  function getShowSidePanel() {
-    if (window.matchMedia('(max-width: 767px)').matches) {
-      // On mobile, hide the side panel by default.
-      return getParam('sidePanel') === 'true';
-    }
-    // On tablet and desktop, show the side panel by default.
-    return getParam('sidePanel') !== 'false';
-  }
-
-  return {
-    sourceSpec,
-    selection,
-    // Hourglass is the default view.
-    chartType: chartTypes.get(view) || ChartType.Hourglass,
-
-    showSidePanel: getShowSidePanel(),
-    standalone: getParam('standalone') !== 'false' && !embedded && !staticUrl,
-    showWikiTreeMenus: getParam('showWikiTreeMenus') !== 'false', // True by default.
-    freezeAnimation: getParam('freeze') === 'true', // False by default
-    config: argsToConfig(search),
-  };
-}
-
 export function App() {
   /** State of the application. */
   const [state, setState] = useState<AppState>(AppState.INITIAL);
@@ -620,13 +485,10 @@ export function App() {
     });
   }, [mcpBridge, location]);
 
-  function updateUrl(args: queryString.ParsedQuery<string>) {
-    const search = queryString.parse(location.search);
-    for (const key in args) {
-      search[key] = args[key];
-    }
-    location.search = queryString.stringify(search);
-    navigate(location);
+  function updateUrl(
+    args: Record<string, string | (string | null)[] | null | undefined>,
+  ) {
+    navigate(getUrlForArgs(location, args));
   }
 
   /**

src/util/url_args.spec.ts

@@ -0,0 +1,315 @@
+import {afterEach, beforeEach, describe, expect, it, jest} from '@jest/globals';
+import * as H from 'history';
+import {ChartType} from '../chart';
+import {DataSourceEnum} from '../datasource/data_source';
+import {ChartColors, Ids, PlaceDisplay, Sex} from '../sidepanel/config/config';
+import {
+  getArguments,
+  getParamFromSearch,
+  getStaticUrl,
+  getUrlForArgs,
+} from './url_args';
+
+describe('url_args', () => {
+  const originalEnv = process.env;
+  let documentMock: {
+    querySelector: jest.Mock;
+  };
+
+  beforeEach(() => {
+    process.env = {...originalEnv};
+    // Mock document globally
+    documentMock = {
+      querySelector: jest.fn().mockReturnValue(null),
+    };
+    Object.defineProperty(global, 'document', {
+      value: documentMock,
+      writable: true,
+      configurable: true,
+    });
+  });
+
+  afterEach(() => {
+    process.env = originalEnv;
+    // Clean up document mock
+    Object.defineProperty(global, 'document', {
+      value: undefined,
+      writable: true,
+      configurable: true,
+    });
+  });
+
+  describe('getStaticUrl', () => {
+    it('returns VITE_STATIC_URL if set', () => {
+      process.env.VITE_STATIC_URL = 'http://example.com/static.ged';
+      expect(getStaticUrl()).toBe('http://example.com/static.ged');
+    });
+
+    it('returns meta tag url if meta tag is present and valid', () => {
+      const mockMeta = {
+        getAttribute: jest.fn().mockReturnValue('http://example.com/meta.ged'),
+      };
+      documentMock.querySelector.mockReturnValue(mockMeta);
+
+      expect(getStaticUrl()).toBe('http://example.com/meta.ged');
+      expect(documentMock.querySelector).toHaveBeenCalledWith(
+        'meta[name="topola-static-url"]',
+      );
+      expect(mockMeta.getAttribute).toHaveBeenCalledWith('content');
+    });
+
+    it('ignores template placeholder in meta tag', () => {
+      const mockMeta = {
+        getAttribute: jest.fn().mockReturnValue('{{ env "STATIC_URL" }}'),
+      };
+      documentMock.querySelector.mockReturnValue(mockMeta);
+
+      expect(getStaticUrl()).toBeUndefined();
+    });
+
+    it('ignores __ placeholder in meta tag', () => {
+      const mockMeta = {
+        getAttribute: jest.fn().mockReturnValue('__STATIC_URL_PLACEHOLDER__'),
+      };
+      documentMock.querySelector.mockReturnValue(mockMeta);
+
+      expect(getStaticUrl()).toBeUndefined();
+    });
+
+    it('returns undefined if neither VITE_STATIC_URL nor meta tag is present', () => {
+      expect(getStaticUrl()).toBeUndefined();
+    });
+  });
+
+  describe('getParamFromSearch', () => {
+    it('extracts query param value', () => {
+      expect(getParamFromSearch('test', {test: 'val'})).toBe('val');
+    });
+
+    it('returns undefined if param is array or missing', () => {
+      expect(
+        getParamFromSearch('test', {test: ['val1', 'val2']}),
+      ).toBeUndefined();
+      expect(getParamFromSearch('missing', {test: 'val'})).toBeUndefined();
+    });
+  });
+
+  describe('getArguments', () => {
+    const createLocation = (search: string): H.Location => ({
+      pathname: '/view',
+      search,
+      hash: '',
+      state: null,
+      key: '',
+    });
+
+    it('returns defaults for empty search', () => {
+      const args = getArguments(createLocation(''));
+      expect(args.sourceSpec).toBeUndefined();
+      expect(args.selection).toBeUndefined();
+      expect(args.detail).toBeUndefined();
+      expect(args.chartType).toBe(ChartType.Hourglass);
+      expect(args.standalone).toBe(true);
+      expect(args.showWikiTreeMenus).toBe(true);
+      expect(args.freezeAnimation).toBe(false);
+      expect(args.showSidePanel).toBe(true); // default on desktop
+      expect(args.config).toEqual({
+        color: ChartColors.COLOR_BY_GENERATION,
+        id: Ids.SHOW,
+        sex: Sex.SHOW,
+        place: PlaceDisplay.FULL,
+        placeCount: 2,
+      });
+    });
+
+    it('parses chart view types correctly', () => {
+      expect(getArguments(createLocation('?view=relatives')).chartType).toBe(
+        ChartType.Relatives,
+      );
+      expect(getArguments(createLocation('?view=fancy')).chartType).toBe(
+        ChartType.Fancy,
+      );
+      expect(getArguments(createLocation('?view=donatso')).chartType).toBe(
+        ChartType.Donatso,
+      );
+      expect(getArguments(createLocation('?view=unknown')).chartType).toBe(
+        ChartType.Hourglass,
+      );
+    });
+
+    it('parses WikiTree source spec', () => {
+      const args = getArguments(
+        createLocation('?source=wikitree&authcode=123'),
+      );
+      expect(args.sourceSpec).toEqual({
+        source: DataSourceEnum.WIKITREE,
+        authcode: '123',
+      });
+    });
+
+    it('parses Google Drive source spec', () => {
+      const args = getArguments(
+        createLocation('?source=google-drive&fileId=abc'),
+      );
+      expect(args.sourceSpec).toEqual({
+        source: DataSourceEnum.GOOGLE_DRIVE,
+        fileId: 'abc',
+      });
+    });
+
+    it('parses Uploaded source spec', () => {
+      const args = getArguments(createLocation('?file=hash123'));
+      expect(args.sourceSpec).toEqual({
+        source: DataSourceEnum.UPLOADED,
+        hash: 'hash123',
+      });
+    });
+
+    it('parses GEDCOM URL source spec', () => {
+      const args = getArguments(
+        createLocation('?url=http://example.com/tree.ged'),
+      );
+      expect(args.sourceSpec).toEqual({
+        source: DataSourceEnum.GEDCOM_URL,
+        url: 'http://example.com/tree.ged',
+        handleCors: true,
+      });
+    });
+
+    it('parses GEDCOM URL source spec with handleCors false', () => {
+      const args = getArguments(
+        createLocation('?url=http://example.com/tree.ged&handleCors=false'),
+      );
+      expect(args.sourceSpec).toEqual({
+        source: DataSourceEnum.GEDCOM_URL,
+        url: 'http://example.com/tree.ged',
+        handleCors: false,
+      });
+    });
+
+    it('parses Embedded source spec', () => {
+      const args = getArguments(createLocation('?embedded=true'));
+      expect(args.sourceSpec).toEqual({
+        source: DataSourceEnum.EMBEDDED,
+      });
+    });
+
+    it('prefers staticUrl over other source specs', () => {
+      process.env.VITE_STATIC_URL = 'http://example.com/static.ged';
+      const args = getArguments(
+        createLocation('?embedded=true&url=http://other.com'),
+      );
+      expect(args.sourceSpec).toEqual({
+        source: DataSourceEnum.GEDCOM_URL,
+        url: 'http://example.com/static.ged',
+        handleCors: false,
+      });
+      expect(args.standalone).toBe(false);
+    });
+
+    it('parses selection correctly', () => {
+      const args = getArguments(createLocation('?indi=I123&gen=4'));
+      expect(args.selection).toEqual({
+        id: 'I123',
+        generation: 4,
+      });
+    });
+
+    it('defaults selection generation to 0 if missing or invalid', () => {
+      const args1 = getArguments(createLocation('?indi=I123'));
+      expect(args1.selection).toEqual({
+        id: 'I123',
+        generation: 0,
+      });
+
+      const args2 = getArguments(createLocation('?indi=I123&gen=abc'));
+      expect(args2.selection).toEqual({
+        id: 'I123',
+        generation: 0,
+      });
+    });
+
+    it('parses detail parameter', () => {
+      const args = getArguments(createLocation('?detail=I456'));
+      expect(args.detail).toBe('I456');
+    });
+
+    it('parses showSidePanel setting', () => {
+      // Mock window.matchMedia for desktop
+      Object.defineProperty(global, 'window', {
+        value: {
+          matchMedia: jest.fn().mockReturnValue({matches: false}),
+        },
+        writable: true,
+        configurable: true,
+      });
+      expect(getArguments(createLocation('')).showSidePanel).toBe(true);
+      expect(
+        getArguments(createLocation('?sidePanel=false')).showSidePanel,
+      ).toBe(false);
+
+      // Mock window.matchMedia for mobile
+      Object.defineProperty(global, 'window', {
+        value: {
+          matchMedia: jest.fn().mockReturnValue({matches: true}),
+        },
+        writable: true,
+        configurable: true,
+      });
+      expect(getArguments(createLocation('')).showSidePanel).toBe(false);
+      expect(
+        getArguments(createLocation('?sidePanel=true')).showSidePanel,
+      ).toBe(true);
+    });
+
+    it('parses boolean settings (standalone, showWikiTreeMenus, freeze)', () => {
+      const args = getArguments(
+        createLocation('?standalone=false&showWikiTreeMenus=false&freeze=true'),
+      );
+      expect(args.standalone).toBe(false);
+      expect(args.showWikiTreeMenus).toBe(false);
+      expect(args.freezeAnimation).toBe(true);
+    });
+
+    it('parses config object from query parameters', () => {
+      const args = getArguments(createLocation('?c=s&i=h&s=h&p=s&pn=5'));
+      expect(args.config).toEqual({
+        color: ChartColors.COLOR_BY_SEX,
+        id: Ids.HIDE,
+        sex: Sex.HIDE,
+        place: PlaceDisplay.SHORT,
+        placeCount: 5,
+      });
+    });
+  });
+
+  describe('getUrlForArgs', () => {
+    const createLocation = (search: string): H.Location => ({
+      pathname: '/view',
+      search,
+      hash: '#hash-val',
+      state: null,
+      key: '',
+    });
+
+    it('updates query parameter value and preserves pathname/hash', () => {
+      const loc = createLocation('?param1=old&param2=keep');
+      const updated = getUrlForArgs(loc, {param1: 'new', param3: 'added'});
+      expect(updated).toEqual({
+        pathname: '/view',
+        search: '?param1=new&param2=keep&param3=added',
+        hash: '#hash-val',
+      });
+    });
+
+    it('deletes query parameters set to null or undefined', () => {
+      const loc = createLocation('?param1=val1&param2=val2');
+      const updated = getUrlForArgs(loc, {param1: null, param2: undefined});
+      expect(updated).toEqual({
+        pathname: '/view',
+        search: '',
+        hash: '#hash-val',
+      });
+    });
+  });
+});

src/util/url_args.ts

@@ -0,0 +1,231 @@
+import * as H from 'history';
+import type {ParsedQuery} from 'query-string';
+import {IndiInfo} from 'topola';
+import {ChartType} from '../chart';
+import {DataSourceEnum} from '../datasource/data_source';
+import {EmbeddedSourceSpec} from '../datasource/embedded';
+import {GoogleDriveSourceSpec} from '../datasource/google_drive';
+import {UploadSourceSpec, UrlSourceSpec} from '../datasource/load_data';
+import {WikiTreeSourceSpec} from '../datasource/wikitree';
+import {argsToConfig, Config} from '../sidepanel/config/config';
+
+export type DataSourceSpec =
+  | UrlSourceSpec
+  | UploadSourceSpec
+  | WikiTreeSourceSpec
+  | EmbeddedSourceSpec
+  | GoogleDriveSourceSpec;
+
+/**
+ * Arguments passed to the application, primarily through URL parameters.
+ * Non-optional arguments get populated with default values.
+ */
+export interface Arguments {
+  sourceSpec?: DataSourceSpec;
+  selection?: IndiInfo;
+  detail?: string;
+  chartType: ChartType;
+  standalone: boolean;
+  showWikiTreeMenus: boolean;
+  freezeAnimation: boolean;
+  showSidePanel: boolean;
+  config: Config;
+}
+
+/**
+ * Parses a query string using URLSearchParams.
+ */
+function parseQuery(search: string): ParsedQuery {
+  const params = new URLSearchParams(search);
+  const result: ParsedQuery = {};
+  params.forEach((value, key) => {
+    const existing = result[key];
+    if (existing !== undefined) {
+      if (Array.isArray(existing)) {
+        existing.push(value);
+      } else {
+        result[key] = [existing as string, value];
+      }
+    } else {
+      result[key] = value;
+    }
+  });
+  return result;
+}
+
+/**
+ * Stringifies a query object using URLSearchParams.
+ */
+function stringifyQuery(query: ParsedQuery): string {
+  const params = new URLSearchParams();
+  for (const key in query) {
+    const val = query[key];
+    if (val !== undefined && val !== null) {
+      if (Array.isArray(val)) {
+        val.forEach((v) => {
+          if (v !== null && v !== undefined) {
+            params.append(key, v);
+          }
+        });
+      } else {
+        params.set(key, val);
+      }
+    }
+  }
+  const str = params.toString();
+  return str ? `?${str}` : '';
+}
+
+/**
+ * Load GEDCOM URL from environment variable (Vite VITE_STATIC_URL or dynamically
+ * injected via a meta tag from Caddy server).
+ *
+ * If this static URL is provided, the viewer is switched to
+ * single-tree mode without the option to load other data.
+ */
+export function getStaticUrl(): string | undefined {
+  const envUrl = import.meta.env.VITE_STATIC_URL;
+  if (envUrl) return envUrl;
+
+  const metaTag = document.querySelector('meta[name="topola-static-url"]');
+  const metaUrl = metaTag?.getAttribute('content');
+  // Safely ignore if it is empty, the raw caddy template expression, or Vite's raw template placeholder
+  if (metaUrl && !metaUrl.startsWith('__') && !metaUrl.includes('{{ env')) {
+    return metaUrl;
+  }
+
+  return undefined;
+}
+
+export function getParamFromSearch(name: string, search: ParsedQuery) {
+  const value = search[name];
+  return typeof value === 'string' ? value : undefined;
+}
+
+/**
+ * Retrieve arguments passed into the application through the URL and uploaded
+ * data.
+ */
+export function getArguments(location: H.Location): Arguments {
+  const search = parseQuery(location.search);
+  const getParam = (name: string) => getParamFromSearch(name, search);
+
+  const view = getParam('view');
+  const chartTypes = new Map<string | undefined, ChartType>([
+    ['relatives', ChartType.Relatives],
+    ['fancy', ChartType.Fancy],
+    ['donatso', ChartType.Donatso],
+  ]);
+
+  const hash = getParam('file');
+  const url = getParam('url');
+  const embedded = getParam('embedded') === 'true'; // False by default.
+  const staticUrl = getStaticUrl();
+  let sourceSpec: DataSourceSpec | undefined = undefined;
+  if (staticUrl) {
+    sourceSpec = {
+      source: DataSourceEnum.GEDCOM_URL,
+      url: staticUrl,
+      handleCors: false,
+    };
+  } else if (getParam('source') === 'wikitree') {
+    const windowSearch =
+      typeof window !== 'undefined' ? parseQuery(window.location.search) : {};
+    sourceSpec = {
+      source: DataSourceEnum.WIKITREE,
+      authcode:
+        getParam('authcode') || getParamFromSearch('authcode', windowSearch),
+    };
+  } else if (getParam('source') === 'google-drive') {
+    const fileId = getParam('fileId');
+    if (fileId) {
+      sourceSpec = {
+        source: DataSourceEnum.GOOGLE_DRIVE,
+        fileId,
+      };
+    }
+  } else if (hash) {
+    sourceSpec = {
+      source: DataSourceEnum.UPLOADED,
+      hash,
+    };
+  } else if (url) {
+    sourceSpec = {
+      source: DataSourceEnum.GEDCOM_URL,
+      url,
+      handleCors: getParam('handleCors') !== 'false', // True by default.
+    };
+  } else if (embedded) {
+    sourceSpec = {source: DataSourceEnum.EMBEDDED};
+  }
+
+  const indi = getParam('indi');
+  const parsedGen = Number(getParam('gen'));
+  const selection = indi
+    ? {id: indi, generation: !isNaN(parsedGen) ? parsedGen : 0}
+    : undefined;
+
+  const detail = getParam('detail');
+
+  /**
+   * Determines whether the side panel should be shown taking into account the
+   * URL parameter and the viewport size.
+   *
+   * On mobile devices (max-width: 767px), the side panel is hidden by default.
+   * On tablet and desktop, the side panel is shown by default.
+   */
+  function getShowSidePanel() {
+    if (
+      typeof window !== 'undefined' &&
+      window.matchMedia &&
+      window.matchMedia('(max-width: 767px)').matches
+    ) {
+      // On mobile, hide the side panel by default.
+      return getParam('sidePanel') === 'true';
+    }
+    // On tablet and desktop, show the side panel by default.
+    return getParam('sidePanel') !== 'false';
+  }
+
+  return {
+    sourceSpec,
+    selection,
+    detail,
+    // Hourglass is the default view.
+    chartType: chartTypes.get(view) || ChartType.Hourglass,
+
+    showSidePanel: getShowSidePanel(),
+    standalone: getParam('standalone') !== 'false' && !embedded && !staticUrl,
+    showWikiTreeMenus: getParam('showWikiTreeMenus') !== 'false', // True by default.
+    freezeAnimation: getParam('freeze') === 'true', // False by default
+    config: argsToConfig(search),
+  };
+}
+
+/**
+ * Returns a path/query object suitable for passing to React Router's `navigate` function
+ * with new values added or removed from the current URL.
+ */
+export function getUrlForArgs(
+  location: H.Location,
+  newArgs: Record<string, string | (string | null)[] | null | undefined>,
+): {pathname: string; search: string; hash: string} {
+  const search = parseQuery(location.search);
+  for (const key in newArgs) {
+    const val = newArgs[key];
+    if (val === undefined || val === null) {
+      delete search[key];
+    } else if (Array.isArray(val)) {
+      search[key] = val.filter(
+        (v): v is string => v !== null && v !== undefined,
+      );
+    } else {
+      search[key] = val;
+    }
+  }
+  return {
+    pathname: location.pathname,
+    search: stringifyQuery(search),
+    hash: location.hash,
+  };
+}