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[READ-ONLY] Mirror of https://github.com/lukebennett88/luke-ui. ui.lukebennett.dev
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204/** * Pure request-negotiation logic for serving Markdown to agents. Host-agnostic: * it depends only on the standard `Request`/`Response`/`fetch` types, with the * request-forwarding (`next`) and Markdown-fetching (`fetch`) side effects * injected via `HandleRequestDeps`, so any host can drive it from a thin * adapter — see `functions/_middleware.ts` for the Cloudflare Pages one. Kept * free of imports so an edge bundler can load it directly. */
const Q_VALUE_PATTERN = /^(?:0(?:\.\d{0,3})?|1(?:\.0{0,3})?)$/;const TRAILING_SLASH_PATTERN = /\/$/;const LAST_SEGMENT_PATTERN = /\/([^/]*)$/;
/** * True when the Accept header asks for Markdown at least as strongly as HTML. * * Markdown is opt-in: `text/markdown` must be listed explicitly with q > 0. * Wildcards never select it. HTML's q comes from the most specific range that * matches it, per RFC 9110 §12.5.1: `text/html`, then `text/*`, then the full * wildcard. It is 0 when none match. A tie goes to Markdown, because the * client named it explicitly. Parameters other than `q` are ignored, and a * range with an invalid q is skipped. */export function prefersMarkdown(accept: string | null): boolean { if (!accept) return false;
const ranges = parseAcceptHeader(accept); const markdownQ = ranges.get('text/markdown') ?? 0; const htmlQ = ranges.get('text/html') ?? ranges.get('text/*') ?? ranges.get('*/*') ?? 0;
return markdownQ > 0 && markdownQ >= htmlQ;}
/** Maps a request pathname to its Markdown twin. `/` becomes `/index.md`. */export function markdownPathFor(pathname: string): string { if (pathname === '/') return '/index.md'; const withoutTrailingSlash = pathname.replace(TRAILING_SLASH_PATTERN, ''); return `${withoutTrailingSlash}.md`;}
/** * Markdown body for a page that has no Markdown twin. Links are prefixed with * `origin`, or stay root-relative when it is empty. */export function notFoundMarkdown(pathname: string, origin = ''): string { const lines = [ '# Page not found', '', `There is no page at \`${pathname}\` on Luke UI.`, '', 'Try one of these instead:', '', `- [llms.txt](${origin}/llms.txt)`, `- [Sitemap](${origin}/sitemap.xml)`, `- [Installation](${origin}/docs/installation)`, `- [Luke UI home](${origin}/)`, '', ]; return lines.join('\n');}
interface HandleRequestDeps { fetch: (url: URL) => Promise<Response>; next: (request?: Request) => Promise<Response>;}
const PASSTHROUGH_PREFIXES = ['/.well-known/', '/__tsr/'];
/** Negotiates Markdown vs. HTML for GET/HEAD requests to non-asset paths. */export async function handleRequest(request: Request, deps: HandleRequestDeps): Promise<Response> { const url = new URL(request.url); const { pathname } = url;
if (isPassthroughPath(pathname)) return deps.next();
if (request.method !== 'GET' && request.method !== 'HEAD') return deps.next();
const accept = request.headers.get('Accept');
if (prefersMarkdown(accept)) return handleMarkdownRequest(request, url, deps);
return withAcceptVary(await deps.next());}
function isPassthroughPath(pathname: string): boolean { if (PASSTHROUGH_PREFIXES.some((prefix) => pathname === prefix || pathname.startsWith(prefix))) return true; if (isApiPath(pathname)) return true; const lastSegment = LAST_SEGMENT_PATTERN.exec(pathname)?.[1] ?? pathname; return lastSegment.includes('.');}
/** True for `/api` and any path under it, but not a sibling like `/apiary`. */function isApiPath(pathname: string): boolean { return pathname === '/api' || pathname.startsWith('/api/');}
async function handleMarkdownRequest( request: Request, url: URL, deps: HandleRequestDeps,): Promise<Response> { const markdownUrl = new URL(markdownPathFor(url.pathname), request.url); const md = await deps.fetch(markdownUrl); const isMarkdown = (md.headers.get('Content-Type') ?? '').startsWith('text/markdown');
if (md.status === 200 && isMarkdown) return markdownResponse(request.method, md, 200);
// TanStack Start's SSR handler (the dev server, or any SSR host) 406s any // request whose Accept isn't HTML-compatible, so re-request with // Accept: text/html before falling through to it. That's the only way to // see whether the path is a real page (200/redirect, e.g. a page with no // Markdown twin) or genuinely missing (404). On a static host this // re-request is harmless. const htmlHeaders = new Headers(request.headers); htmlHeaders.set('Accept', 'text/html'); const htmlRequest = new Request(request.url, { headers: htmlHeaders, method: request.method });
const res = await deps.next(htmlRequest); if (res.status === 404) { // The `.md` route's own 404 body links to the site's public URL. Without // it, fall back to a body with root-relative links. if (md.status === 404 && isMarkdown) return markdownResponse(request.method, md, 404);
return new Response(bodyForMethod(request.method, notFoundMarkdown(url.pathname)), { headers: { 'Content-Type': 'text/markdown; charset=utf-8', Vary: 'Accept', }, status: 404, }); }
return withAcceptVary(res);}
/** * Re-serves a fetched Markdown response, keeping its caching headers. * `Content-Length` and `Content-Encoding` are dropped, since `fetch` may have * decoded the body. */function markdownResponse(method: string, md: Response, status: number): Response { const headers = withMergedVary(md.headers, 'Accept'); headers.delete('Content-Encoding'); headers.delete('Content-Length'); headers.set('Content-Type', 'text/markdown; charset=utf-8'); return new Response(method === 'HEAD' ? null : md.body, { headers, status });}
/** Passes `res` through with `Accept` merged into its `Vary` header. */function withAcceptVary(res: Response): Response { return new Response(res.body, { headers: withMergedVary(res.headers, 'Accept'), status: res.status, statusText: res.statusText, });}
function bodyForMethod(method: string, body: string): string | null { return method === 'HEAD' ? null : body;}
/** Returns a copy of `source` with `name` merged into its `Vary` header. */function withMergedVary(source: Headers, name: string): Headers { const existing = source.get('Vary'); const values = existing ? existing.split(',').map((value) => value.trim()) : []; if (!values.some((value) => value.toLowerCase() === name.toLowerCase())) values.push(name);
const headers = new Headers(source); headers.set('Vary', values.join(', ')); return headers;}
/** * Maps each lowercased media range (including wildcards) to its q-value. A * range listed more than once keeps its highest q. */function parseAcceptHeader(accept: string): Map<string, number> { const ranges = new Map<string, number>(); for (const part of accept.split(',')) { const [rawType, ...params] = part.split(';'); const type = rawType?.trim().toLowerCase(); if (!type) continue;
const q = parseQuality(params); if (q === null) continue;
ranges.set(type, Math.max(q, ranges.get(type) ?? 0)); } return ranges;}
/** The `q` parameter's value, 1 when absent, or null when it is invalid. */function parseQuality(params: Array<string>): number | null { for (const param of params) { const [name, value] = param.split('='); if (name?.trim().toLowerCase() !== 'q') continue;
const trimmed = value?.trim() ?? ''; return Q_VALUE_PATTERN.test(trimmed) ? Number.parseFloat(trimmed) : null; } return 1;}