Refactor paths/escape handling, add test coverage

.vscode/settings.json

@@ -14,6 +14,7 @@
     "thephotoblog",
     "trpc",
     "unnest",
+    "UsKSGcbt",
     "WRHGZC",
     "zadd",
     "zrange"

__tests__/path.test.ts

@@ -0,0 +1,81 @@
+import '@testing-library/jest-dom';
+import {
+  getEscapePath,
+  getPathComponents,
+  isPathPhoto,
+  isPathPhotoShare,
+  isPathTag,
+  isPathTagPhoto,
+  isPathTagPhotoShare,
+  isPathTagShare,
+} from '@/site/paths';
+
+const PHOTO_ID = 'UsKSGcbt';
+const TAG = 'tag-name';
+const SHARE = 'share';
+
+const PATH_ROOT = '/';
+const PATH_GRID = '/grid';
+const PATH_ADMIN = '/admin/photos';
+const PATH_PHOTO = `/p/${PHOTO_ID}`;
+const PATH_PHOTO_SHARE = `${PATH_PHOTO}/${SHARE}`;
+const PATH_TAG = `/t/${TAG}`;
+const PATH_TAG_SHARE = `${PATH_TAG}/${SHARE}`;
+const PATH_TAG_PHOTO = `${PATH_TAG}/${PHOTO_ID}`;
+const PATH_TAG_PHOTO_SHARE = `${PATH_TAG}/${PHOTO_ID}/${SHARE}`;
+ 
+describe('Paths', () => {
+  it('can be classified', () => {
+    // Positive
+    expect(isPathPhoto(PATH_PHOTO)).toBe(true);
+    expect(isPathPhotoShare(PATH_PHOTO_SHARE)).toBe(true);
+    expect(isPathTag(PATH_TAG)).toBe(true);
+    expect(isPathTagShare(PATH_TAG_SHARE)).toBe(true);
+    expect(isPathTagPhoto(PATH_TAG_PHOTO)).toBe(true);
+    expect(isPathTagPhotoShare(PATH_TAG_PHOTO_SHARE)).toBe(true);
+    // Negative
+    expect(isPathPhoto(PATH_TAG_PHOTO_SHARE)).toBe(false);
+    expect(isPathPhotoShare(PATH_TAG_PHOTO)).toBe(false);
+    expect(isPathTag(PATH_TAG_SHARE)).toBe(false);
+    expect(isPathTagShare(PATH_TAG)).toBe(false);
+    expect(isPathTagPhoto(PATH_PHOTO_SHARE)).toBe(false);
+    expect(isPathTagPhotoShare(PATH_PHOTO)).toBe(false);
+  });
+  it('can be parsed', () => {
+    expect(getPathComponents(PATH_ROOT)).toEqual({});
+    expect(getPathComponents(PATH_PHOTO)).toEqual({
+      photoId: PHOTO_ID,
+    });
+    expect(getPathComponents(PATH_PHOTO_SHARE)).toEqual({
+      photoId: PHOTO_ID,
+    });
+    expect(getPathComponents(PATH_TAG)).toEqual({
+      tag: TAG,
+    });
+    expect(getPathComponents(PATH_TAG_SHARE)).toEqual({
+      tag: TAG,
+    });
+    expect(getPathComponents(PATH_TAG_PHOTO)).toEqual({
+      photoId: PHOTO_ID,
+      tag: TAG,
+    });
+    expect(getPathComponents(PATH_TAG_PHOTO_SHARE)).toEqual({
+      photoId: PHOTO_ID,
+      tag: TAG,
+    });
+  });
+  it('can be escaped', () => {
+    // Root views
+    expect(getEscapePath(PATH_ROOT)).toEqual(undefined);
+    expect(getEscapePath(PATH_GRID)).toEqual(undefined);
+    expect(getEscapePath(PATH_ADMIN)).toEqual(undefined);
+    // Photo views
+    expect(getEscapePath(PATH_PHOTO)).toEqual(PATH_GRID);
+    expect(getEscapePath(PATH_PHOTO_SHARE)).toEqual(PATH_PHOTO);
+    // Tag views
+    expect(getEscapePath(PATH_TAG)).toEqual(PATH_GRID);
+    expect(getEscapePath(PATH_TAG_SHARE)).toEqual(PATH_TAG);
+    expect(getEscapePath(PATH_TAG_PHOTO)).toEqual(PATH_TAG);
+    expect(getEscapePath(PATH_TAG_PHOTO_SHARE)).toEqual(PATH_TAG_PHOTO);
+  });
+});

jest.config.mjs

@@ -0,0 +1,19 @@
+/* eslint-disable max-len */
+import nextJest from 'next/jest.js';
+ 
+const createJestConfig = nextJest({
+  // Provide the path to your Next.js app to load next.config.js and .env files in your test environment
+  dir: './',
+});
+ 
+// Add any custom config to be passed to Jest
+/** @type {import('jest').Config} */
+const config = {
+  // Add more setup options before each test is run
+  // setupFilesAfterEnv: ['<rootDir>/jest.setup.js'],
+ 
+  testEnvironment: 'jest-environment-jsdom',
+};
+ 
+// createJestConfig is exported this way to ensure that next/jest can load the Next.js config which is async
+export default createJestConfig(config);

package.json

@@ -5,11 +5,15 @@
     "build": "next build",
     "start": "next start",
     "lint": "next lint",
+    "test": "jest --watch",
     "analyze": "ANALYZE=true next build"
   },
   "dependencies": {
     "@next/bundle-analyzer": "^13.5.3",
     "@tailwindcss/forms": "^0.5.6",
+    "@testing-library/jest-dom": "^6.1.3",
+    "@testing-library/react": "^14.0.0",
+    "@types/jest": "^29.5.5",
     "@types/node": "^20.7.1",
     "@types/react": "18.2.23",
     "@types/react-dom": "18.2.8",
@@ -24,6 +28,8 @@
     "eslint": "8.50.0",
     "eslint-config-next": "13.5.3",
     "framer-motion": "^10.16.4",
+    "jest": "^29.7.0",
+    "jest-environment-jsdom": "^29.7.0",
     "nanoid": "^5.0.1",
     "next": "^13.5.3",
     "next-auth": "0.0.0-manual.5749b095",

src/app/(auth-state)/admin/photos/page.tsx

@@ -13,7 +13,11 @@ import {
 import { FaRegEdit } from 'react-icons/fa';
 import SubmitButtonWithStatus from '@/components/SubmitButtonWithStatus';
 import { pathForBlobUrl } from '@/services/blob';
-import { pathForPhoto, pathForPhotoEdit } from '@/site/paths';
+import {
+  pathForAdminPhotos,
+  pathForPhoto,
+  pathForPhotoEdit,
+} from '@/site/paths';
 import { getPhotosLimitForQuery, titleForPhoto } from '@/photo';
 import MorePhotos from '@/components/MorePhotos';
 import {
@@ -123,7 +127,7 @@ export default async function AdminPage({
                   </Fragment>)}
               </AdminGrid>
               {showMorePhotos &&
-                <MorePhotos path={`/admin/photos?next=${offset + 1}`} />}
+                <MorePhotos path={pathForAdminPhotos(offset + 1)} />}
             </div>
           </div>
         </div>}

src/app/(static)/grid/page.tsx

@@ -10,6 +10,7 @@ import { generateOgImageMetaForPhotos, getPhotosLimitForQuery } from '@/photo';
 import PhotoGrid from '@/photo/PhotoGrid';
 import PhotosEmptyState from '@/photo/PhotosEmptyState';
 import { MAX_PHOTOS_TO_SHOW_HOME } from '@/photo/image-response';
+import { pathForGrid } from '@/site/paths';
 import PhotoTag from '@/tag/PhotoTag';
 import { Metadata } from 'next';
 
@@ -45,7 +46,7 @@ export default async function GridPage({
         contentMain={<div className="space-y-4">
           <PhotoGrid photos={photos} />
           {showMorePhotos &&
-            <MorePhotos path={`/grid?next=${offset + 1}`} />}
+            <MorePhotos path={pathForGrid(offset + 1)} />}
         </div>}
         contentSide={tags &&
           <AnimateItems

src/app/(static)/og/page.tsx

@@ -2,6 +2,7 @@ import { getPhotosCached, getPhotosCountCached } from '@/cache';
 import MorePhotos from '@/components/MorePhotos';
 import { getPhotosLimitForQuery } from '@/photo';
 import StaggeredOgPhotos from '@/photo/StaggeredOgPhotos';
+import { pathForOg } from '@/site/paths';
 
 export const runtime = 'edge';
 
@@ -28,7 +29,7 @@ export default async function GridPage({
         <StaggeredOgPhotos photos={photos} />
       </div>
       {showMorePhotos &&
-        <MorePhotos path={`/og?next=${offset + 1}`} />}
+        <MorePhotos path={pathForOg(offset + 1)} />}
     </div>
   );
 }

src/app/(static)/p/[photoId]/layout.tsx

@@ -5,7 +5,11 @@ import {
 } from '@/photo';
 import { Metadata } from 'next';
 import { redirect } from 'next/navigation';
-import { absolutePathForPhoto, absolutePathForPhotoImage } from '@/site/paths';
+import {
+  PATH_ROOT,
+  absolutePathForPhoto,
+  absolutePathForPhotoImage,
+} from '@/site/paths';
 import PhotoDetailPage from '@/photo/PhotoDetailPage';
 import { getPhotoCached, getPhotosCached } from '@/cache';
 import { getPhotos } from '@/services/postgres';
@@ -58,7 +62,7 @@ export default async function PhotoPage({
 }) {
   const photo = await getPhotoCached(photoId);
 
-  if (!photo) { redirect('/'); }
+  if (!photo) { redirect(PATH_ROOT); }
 
   const [
     photosBefore,

src/app/(static)/p/[photoId]/share/page.tsx

@@ -1,5 +1,6 @@
 import { getPhotoCached } from '@/cache';
 import PhotoShareModal from '@/photo/PhotoShareModal';
+import { PATH_ROOT } from '@/site/paths';
 import { redirect } from 'next/navigation';
 
 export const runtime = 'edge';
@@ -11,7 +12,7 @@ export default async function Share({
 }) {
   const photo = await getPhotoCached(photoId);
 
-  if (!photo) { return redirect('/'); }
+  if (!photo) { return redirect(PATH_ROOT); }
 
   return <PhotoShareModal photo={photo} />;
 }

src/app/(static)/page.tsx

@@ -5,6 +5,7 @@ import SiteGrid from '@/components/SiteGrid';
 import { generateOgImageMetaForPhotos, getPhotosLimitForQuery } from '@/photo';
 import PhotoLarge from '@/photo/PhotoLarge';
 import PhotosEmptyState from '@/photo/PhotosEmptyState';
+import { pathForRoot } from '@/site/paths';
 import { Metadata } from 'next';
 
 export const runtime = 'edge';
@@ -49,7 +50,7 @@ export default async function HomePage({
         />
         {showMorePhotos &&
           <SiteGrid
-            contentMain={<MorePhotos path={`?next=${offset + 1}`} />}
+            contentMain={<MorePhotos path={pathForRoot(offset + 1)} />}
           />}
       </div>
       : <PhotosEmptyState />

src/app/(static)/t/[tag]/[photoId]/layout.tsx

@@ -4,7 +4,11 @@ import {
 } from '@/photo';
 import { Metadata } from 'next';
 import { redirect } from 'next/navigation';
-import { absolutePathForPhoto, absolutePathForPhotoImage } from '@/site/paths';
+import {
+  PATH_ROOT,
+  absolutePathForPhoto,
+  absolutePathForPhotoImage,
+} from '@/site/paths';
 import PhotoDetailPage from '@/photo/PhotoDetailPage';
 import { getPhotoCached, getPhotosCached } from '@/cache';
 import { getPhotos, getUniqueTags } from '@/services/postgres';
@@ -64,7 +68,7 @@ export default async function PhotoTagPage({
 }) {
   const photo = await getPhotoCached(photoId);
 
-  if (!photo) { redirect('/'); }
+  if (!photo) { redirect(PATH_ROOT); }
 
   const photos = await getPhotosCached({ tag });
 

src/app/(static)/t/[tag]/[photoId]/share/page.tsx

@@ -1,6 +1,7 @@
 import { getPhotoCached } from '@/cache';
 import PhotoShareModal from '@/photo/PhotoShareModal';
 import { getPhotos, getUniqueTags } from '@/services/postgres';
+import { PATH_ROOT } from '@/site/paths';
 import { redirect } from 'next/navigation';
 
 export async function generateStaticParams() {
@@ -24,7 +25,7 @@ export default async function Share({
 }) {
   const photo = await getPhotoCached(photoId);
 
-  if (!photo) { return redirect('/'); }
+  if (!photo) { return redirect(PATH_ROOT); }
 
   return <PhotoShareModal photo={photo} tag={tag} />;
 }

src/app/layout.tsx

@@ -7,6 +7,7 @@ import StateProvider from '@/state/AppStateProvider';
 import ThemeProviderClient from '@/site/ThemeProviderClient';
 import Nav from '@/components/Nav';
 import ToasterWithThemes from '@/components/ToasterWithThemes';
+import PhotoEscapeHandler from '@/photo/PhotoEscapeHandler';
 
 import '../site/globals.css';
 
@@ -77,6 +78,7 @@ export default function RootLayout({
             </StateProvider>
             <Analytics />
           </main>
+          <PhotoEscapeHandler />
           <ToasterWithThemes />
         </ThemeProviderClient>
       </body>

src/app/sign-in/page.tsx

@@ -1,5 +1,6 @@
 import { auth } from '@/auth';
 import SignInForm from '@/auth/SignInForm';
+import { PATH_ROOT } from '@/site/paths';
 import { cc } from '@/utility/css';
 import { redirect } from 'next/navigation';
 
@@ -9,7 +10,7 @@ export default async function SignInPage() {
   const session = await auth();
 
   if (session?.user) {
-    redirect('/');
+    redirect(PATH_ROOT);
   }
   
   return (

src/components/Modal.tsx

@@ -6,6 +6,7 @@ import { cc } from '@/utility/css';
 import useClickInsideOutside from '@/utility/useClickInsideOutside';
 import { useRouter } from 'next/navigation';
 import AnimateItems from './AnimateItems';
+import { PATH_ROOT } from '@/site/paths';
 
 export default function Modal({
   onClosePath,
@@ -28,7 +29,10 @@ export default function Modal({
 
   useClickInsideOutside({
     htmlElements,
-    onClickOutside: () => router.push(onClosePath ?? '/', { scroll: false}),
+    onClickOutside: () => router.push(
+      onClosePath ?? PATH_ROOT,
+      { scroll: false },
+    ),
   });
 
   return (

src/components/Nav.tsx

@@ -6,6 +6,12 @@ import Link from 'next/link';
 import SiteGrid from './SiteGrid';
 import { SITE_DOMAIN_OR_TITLE } from '@/site/config';
 import ViewSwitcher, { SwitcherSelection } from '@/photo/ViewSwitcher';
+import {
+  PATH_ADMIN,
+  PATH_ROOT,
+  isPathGrid,
+  isPathProtected,
+} from '@/site/paths';
 
 export default function Nav({ showTextLinks }: { showTextLinks?: boolean }) {
   const isLoggedIn = false;
@@ -23,11 +29,11 @@ export default function Nav({ showTextLinks }: { showTextLinks?: boolean }) {
       : <button onClick={linkOrAction}>{text}</button>;
 
   const switcherSelectionForPath = (): SwitcherSelection | undefined => {
-    if (pathname === '/') {
+    if (pathname === PATH_ROOT) {
       return 'full-frame';
-    } else if (pathname === '/grid') {
+    } else if (isPathGrid(pathname)) {
       return 'grid';
-    } else if (pathname.startsWith('/admin')) {
+    } else if (isPathProtected(pathname)) {
       return 'admin';
     }
   };
@@ -47,12 +53,12 @@ export default function Nav({ showTextLinks }: { showTextLinks?: boolean }) {
                 showAdmin={isLoggedIn}
               />
               {showTextLinks && <>
-                {renderLink('Home', '/')}
-                {renderLink('Admin', '/admin')}
+                {renderLink('Home', PATH_ROOT)}
+                {renderLink('Admin', PATH_ADMIN)}
               </>}
             </div>
             <div className="hidden xs:block">
-              {renderLink(SITE_DOMAIN_OR_TITLE, '/')}
+              {renderLink(SITE_DOMAIN_OR_TITLE, PATH_ROOT)}
             </div>
           </>}
         </div>

src/photo/PhotoEscapeHandler.tsx

@@ -0,0 +1,27 @@
+'use client';
+
+import { getEscapePath } from '@/site/paths';
+import { useRouter, usePathname } from 'next/navigation';
+import { useEffect } from 'react';
+
+const LISTENER_KEYUP = 'keyup';
+
+export default function PhotoEscapeHandler() {
+  const router = useRouter();
+ 
+  const pathname = usePathname();
+
+  const escapePath = getEscapePath(pathname);
+
+  useEffect(() => {
+    const onKeyUp = (e: KeyboardEvent) => {
+      if (e.key.toUpperCase() === 'ESCAPE' && escapePath) {
+        router.push(escapePath, { scroll: false });
+      };
+    };
+    window.addEventListener(LISTENER_KEYUP, onKeyUp);
+    return () => window.removeEventListener(LISTENER_KEYUP, onKeyUp);
+  }, [router, escapePath]);
+
+  return null;
+}

src/photo/PhotoGrid.tsx

@@ -2,34 +2,25 @@ import { Photo } from '.';
 import PhotoSmall from './PhotoSmall';
 import { cc } from '@/utility/css';
 import AnimateItems from '@/components/AnimateItems';
-import Link from 'next/link';
-
-const PHOTOS_PER_PAGE = 6;
-const PHOTOS_MAX = 35;
 
 export default function PhotoGrid({
   photos,
   selectedPhoto,
   tag,
-  offset = 0,
   fast,
   animate = true,
   animateOnFirstLoadOnly,
   staggerOnFirstLoadOnly = true,
-  showMore,
 }: {
   photos: Photo[]
   selectedPhoto?: Photo
   tag?: string
-  offset?: number
   fast?: boolean
   animate?: boolean
   animateOnFirstLoadOnly?: boolean
   staggerOnFirstLoadOnly?: boolean
-  showMore?: boolean
 }) {
   return (
-    <>
     <AnimateItems
       className={cc(
         'grid gap-1',
@@ -50,13 +41,5 @@ export default function PhotoGrid({
           selected={photo.id === selectedPhoto?.id}
         />)}
     />
-      {showMore && (offset + PHOTOS_PER_PAGE) < PHOTOS_MAX &&
-        <Link
-          className="button mt-12"
-          href={`/grid/${offset + PHOTOS_PER_PAGE}`}
-        >
-          More
-        </Link>}
-    </>
   );
 };

src/photo/PhotoLinks.tsx

@@ -8,6 +8,8 @@ import { pathForPhoto } from '@/site/paths';
 import { useAppState } from '@/state';
 import { AnimationConfig } from '@/components/AnimateItems';
 
+const LISTENER_KEYUP = 'keyup';
+
 const ANIMATION_LEFT: AnimationConfig = { type: 'left', duration: 0.3 };
 const ANIMATION_RIGHT: AnimationConfig = { type: 'right', duration: 0.3 };
 
@@ -44,14 +46,17 @@ export default function PhotoLinks({
           router.push(pathForPhoto(nextPhoto, tag), { scroll: false });
         }
         break;
-      case 'ESCAPE':
-        router.push('/grid');
-        break;
       };
     };
-    window.addEventListener('keyup', onKeyUp);
-    return () => window.removeEventListener('keyup', onKeyUp);
-  }, [router, setNextPhotoAnimation, previousPhoto, nextPhoto, tag]);
+    window.addEventListener(LISTENER_KEYUP, onKeyUp);
+    return () => window.removeEventListener(LISTENER_KEYUP, onKeyUp);
+  }, [
+    router,
+    setNextPhotoAnimation,
+    previousPhoto,
+    nextPhoto,
+    tag,
+  ]);
   
   return (
     <>

src/photo/ViewSwitcher.tsx

@@ -2,6 +2,7 @@ import Switcher from '@/components/Switcher';
 import SwitcherItem from '@/components/SwitcherItem';
 import IconFullFrame from '@/icons/IconFullFrame';
 import IconGrid from '@/icons/IconGrid';
+import { PATH_GRID } from '@/site/paths';
 import { BiLockAlt } from 'react-icons/bi';
 
 export type SwitcherSelection = 'full-frame' | 'grid' | 'admin';
@@ -23,7 +24,7 @@ export default function ViewSwitcher({
       />
       <SwitcherItem
         icon={<IconGrid />}
-        href="/grid"
+        href={PATH_GRID}
         active={currentSelection === 'grid'}
         noPadding
       />

src/site/paths.ts

@@ -1,55 +1,143 @@
 import { Photo } from '@/photo';
 import { BASE_URL } from './config';
 
+// Prefixes
 const PREFIX_PHOTO = '/p';
 const PREFIX_TAG = '/t';
-const PREFIX_ADMIN = '/admin';
 
+// Modifiers
 const SHARE = 'share';
+const NEXT = 'next';
 
-export const PATH_ADMIN_PHOTOS = `${PREFIX_ADMIN}/photos`;
-export const PATH_ADMIN_UPLOAD = `${PREFIX_ADMIN}/uploads`;
+// Core paths
+export const PATH_ROOT  = '/';
+export const PATH_GRID  = '/grid';
+export const PATH_ADMIN = '/admin';
+export const PATH_OG    = '/og';
+
+// Extended paths
+export const PATH_ADMIN_PHOTOS = `${PATH_ADMIN}/photos`;
+export const PATH_ADMIN_UPLOAD = `${PATH_ADMIN}/uploads`;
 export const PATH_ADMIN_UPLOAD_BLOB_HANDLER = `${PATH_ADMIN_UPLOAD}/blob`;
 
+// Absolute paths
 export const ABSOLUTE_PATH_FOR_HOME_IMAGE = `${BASE_URL}/home-image`;
 
-export const pathForPhoto = (photo: Photo, tag?: string) =>
-  tag
-    ? `${pathForTag(tag)}/${photo.id}`
-    : `${PREFIX_PHOTO}/${photo.id}`;
+const pathWithNext = (path: string, next?: number) =>
+  next !== undefined ? `${path}?${NEXT}=${next}` : path;
 
-export const pathForPhotoShare = (photo: Photo, tag?: string) =>
+export const pathForRoot = (next?: number) =>
+  pathWithNext(PATH_ROOT, next);
+
+export const pathForGrid = (next?: number) =>
+  pathWithNext(PATH_GRID, next);
+
+export const pathForAdminPhotos = (next?: number) =>
+  pathWithNext(PATH_ADMIN_PHOTOS, next);
+
+export const pathForOg = (next?: number) =>
+  pathWithNext(PATH_OG, next);
+
+type PhotoOrPhotoId = Photo | string;
+
+const getPhotoId = (photoOrPhotoId: PhotoOrPhotoId) =>
+  typeof photoOrPhotoId === 'string' ? photoOrPhotoId : photoOrPhotoId.id;
+
+export const pathForPhoto = (photo: PhotoOrPhotoId, tag?: string) =>
+  tag
+    ? `${pathForTag(tag)}/${getPhotoId(photo)}`
+    : `${PREFIX_PHOTO}/${getPhotoId(photo)}`;
+
+export const pathForPhotoShare = (photo: PhotoOrPhotoId, tag?: string) =>
   `${pathForPhoto(photo, tag)}/${SHARE}`;
 
-export const pathForPhotoEdit = (photo: Photo) =>
-  `${PATH_ADMIN_PHOTOS}/${photo.id}/edit`;
+export const pathForPhotoEdit = (photo: PhotoOrPhotoId) =>
+  `${PATH_ADMIN_PHOTOS}/${getPhotoId(photo)}/edit`;
 
 export const pathForTag = (tag: string) => `${PREFIX_TAG}/${tag}`;
 
 export const pathForTagShare = (tag: string) =>
   `${pathForTag(tag)}/${SHARE}`;
 
-export const absolutePathForPhoto = (photo: Photo, tag?: string) =>
+export const absolutePathForPhoto = (photo: PhotoOrPhotoId, tag?: string) =>
   `${BASE_URL}${pathForPhoto(photo, tag)}`;
 
 export const absolutePathForTag = (tag: string) =>
   `${BASE_URL}${pathForTag(tag)}`;
 
-export const absolutePathForPhotoImage = (photo: Photo) =>
+export const absolutePathForPhotoImage = (photo: PhotoOrPhotoId) =>
   `${absolutePathForPhoto(photo)}/image`;
 
 export const absolutePathForTagImage = (tag: string) =>
   `${absolutePathForTag(tag)}/image`;
 
+// p/[photoId]
 export const isPathPhoto = (pathname = '') =>
   /^\/p\/[^/]+\/?$/.test(pathname);
 
+// p/[photoId]/share
 export const isPathPhotoShare = (pathname = '') =>
   /^\/p\/[^/]+\/share\/?$/.test(pathname);
 
+// t/[tagId]
+export const isPathTag = (pathname = '') =>
+  /^\/t\/[^/]+\/?$/.test(pathname);
+
+// t/[tagId]/share
+export const isPathTagShare = (pathname = '') =>
+  /^\/t\/[^/]+\/share\/?$/.test(pathname);
+
+// t/[tagId]/[photoId]
+export const isPathTagPhoto = (pathname = '') =>
+  /^\/t\/[^/]+\/[^/]+\/?$/.test(pathname);
+
+// t/[tagId]/[photoId]/share
+export const isPathTagPhotoShare = (pathname = '') =>
+  /^\/t\/[^/]+\/[^/]+\/share\/?$/.test(pathname);
+
+export const isPathGrid = (pathname = '') =>
+  pathname.startsWith(PATH_GRID);
+
 export const isPathSignIn = (pathname = '') =>
   pathname.startsWith('/sign-in');
 
+export const isPathAdmin = (pathname = '') =>
+  pathname.startsWith('/admin');
+
 export const isPathProtected = (pathname = '') =>
-  pathname.startsWith(PREFIX_ADMIN) ||
+  pathname.startsWith(PATH_ADMIN) ||
   pathname === '/checklist';
+
+export const getPathComponents = (pathname = ''): {
+  photoId?: string
+  tag?: string
+} => {
+  const photoIdFromPhoto = pathname.match(/^\/p\/([^/]+)/)?.[1];
+  const photoIdFromTag = pathname.match(/^\/t\/[^/]+\/((?!share)[^/]+)/)?.[1];
+  const tag = pathname.match(/^\/t\/([^/]+)/)?.[1];
+  return {
+    photoId: (
+      photoIdFromPhoto ||
+      photoIdFromTag
+    ),
+    tag,
+  };
+};
+
+export const getEscapePath = (pathname?: string) => {
+  const { photoId, tag } = getPathComponents(pathname);
+  if (
+    (photoId && isPathPhoto(pathname)) ||
+    (tag && isPathTag(pathname))
+  ) {
+    return PATH_GRID;
+  } else if (photoId && isPathTagPhotoShare(pathname)) {
+    return pathForPhoto(photoId, tag);
+  } else if (photoId && isPathPhotoShare(pathname)) {
+    return pathForPhoto(photoId);
+  } else if (tag && (isPathTagPhoto(pathname) || isPathTagShare(pathname))) {
+    return pathForTag(tag);
+  } else if (tag && isPathTagShare(pathname)) {
+    return pathForTag(tag);
+  }
+};