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Monorepo for Tangled
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139export default { async fetch(request, env) { // Helper function to generate a color from a string const stringToColor = (str) => { let hash = 0; for (let i = 0; i < str.length; i++) { hash = str.charCodeAt(i) + ((hash << 5) - hash); } let color = "#"; for (let i = 0; i < 3; i++) { const value = (hash >> (i * 8)) & 0xff; color += ("00" + value.toString(16)).substr(-2); } return color; };
const url = new URL(request.url); const { pathname, searchParams } = url;
if (!pathname || pathname === "/") { return new Response(`This is Tangled's avatar service. It fetches your pretty avatar from Bluesky and caches it on Cloudflare.You can't use this directly unfortunately since all requests are signed and may only originate from the appview.`); }
const size = searchParams.get("size"); const resizeToTiny = size === "tiny";
const cache = caches.default; let cacheKey = request.url; let response = await cache.match(cacheKey); if (response) return response;
const pathParts = pathname.slice(1).split("/"); if (pathParts.length < 2) { return new Response("Bad URL", { status: 400 }); }
const [signatureHex, actor] = pathParts; const actorBytes = new TextEncoder().encode(actor);
const key = await crypto.subtle.importKey( "raw", new TextEncoder().encode(env.AVATAR_SHARED_SECRET), { name: "HMAC", hash: "SHA-256" }, false, ["sign", "verify"], );
const computedSigBuffer = await crypto.subtle.sign("HMAC", key, actorBytes); const computedSig = Array.from(new Uint8Array(computedSigBuffer)) .map((b) => b.toString(16).padStart(2, "0")) .join("");
console.log({ level: "debug", message: "avatar request for: " + actor, computedSignature: computedSig, providedSignature: signatureHex, });
const sigBytes = Uint8Array.from( signatureHex.match(/.{2}/g).map((b) => parseInt(b, 16)), ); const valid = await crypto.subtle.verify("HMAC", key, sigBytes, actorBytes);
if (!valid) { return new Response("Invalid signature", { status: 403 }); }
try { const profileResponse = await fetch( `https://public.api.bsky.app/xrpc/app.bsky.actor.getProfile?actor=${actor}`, ); const profile = await profileResponse.json(); const avatar = profile.avatar;
let avatarUrl = profile.avatar;
if (!avatarUrl) { // Generate a random color based on the actor string const bgColor = stringToColor(actor); const size = resizeToTiny ? 32 : 128; const svg = `<svg width="${size}" height="${size}" viewBox="0 0 ${size} ${size}" xmlns="http://www.w3.org/2000/svg"><rect width="${size}" height="${size}" fill="${bgColor}"/></svg>`; const svgData = new TextEncoder().encode(svg);
response = new Response(svgData, { headers: { "Content-Type": "image/svg+xml", "Cache-Control": "public, max-age=43200", }, }); await cache.put(cacheKey, response.clone()); return response; }
// Resize if requested let avatarResponse; if (resizeToTiny) { avatarResponse = await fetch(avatarUrl, { cf: { image: { width: 32, height: 32, fit: "cover", format: "webp", }, }, }); } else { avatarResponse = await fetch(avatarUrl); }
if (!avatarResponse.ok) { return new Response(`failed to fetch avatar for ${actor}.`, { status: avatarResponse.status, }); }
const avatarData = await avatarResponse.arrayBuffer(); const contentType = avatarResponse.headers.get("content-type") || "image/jpeg";
response = new Response(avatarData, { headers: { "Content-Type": contentType, "Cache-Control": "public, max-age=43200", }, });
await cache.put(cacheKey, response.clone()); return response; } catch (error) { return new Response(`error fetching avatar: ${error.message}`, { status: 500, }); } },};