interface Env {}

import { bech32 } from "./bech32";
import { fromHex } from "./hex";

interface NostrJson {
  names: Record<string, string>;
}

const HOST = "snort.social";

async function fetchNostrAddress(name: string, domain: string) {
  try {
    const res = await fetch(`https://${domain}/.well-known/nostr.json?name=${encodeURIComponent(name)}`, {
      signal: AbortSignal.timeout(1000),
    });
    const data: NostrJson = await res.json();
    const match = Object.keys(data.names).find(n => {
      return n.toLowerCase() === name.toLowerCase();
    });
    return match ? data.names[match] : undefined;
  } catch {
    // ignored
  }
}

export const onRequest: PagesFunction<Env> = async context => {
  const u = new URL(context.request.url);

  const prefixes = ["npub1", "nprofile1", "naddr1", "nevent1", "note1"];
  const isEntityPath = () => {
    return prefixes.some(
      a => u.pathname.startsWith(`/${a}`) || u.pathname.startsWith(`/e/${a}`) || u.pathname.startsWith(`/p/${a}`),
    );
  };

  const nostrAddress = u.pathname.match(/^\/([a-zA-Z0-9_]+)$/i);

  const next = await context.next();
  if (u.pathname != "/" && (isEntityPath() || nostrAddress)) {
    try {
      let id = nostrAddress ? nostrAddress[1] : u.pathname.split("/").at(-1);
      if (nostrAddress) {
        const pubkey = await fetchNostrAddress(id, HOST);
        if (pubkey) {
          id = bech32.encode("npub", bech32.toWords(fromHex(pubkey)));
        } else {
          return next;
        }
      }
      const rsp = await fetch(
        `http://nostr.api.v0l.io/api/v1/opengraph/${id}?canonical=${encodeURIComponent(`https://${HOST}/%s`)}`,
        {
          method: "POST",
          body: await next.arrayBuffer(),
          headers: {
            "user-agent": `SnortFunctions/1.0 (https://${HOST})`,
            "content-type": "text/html",
            accept: "text/html",
          },
        },
      );
      if (rsp.ok) {
        const body = await rsp.text();
        if (body.length > 0) {
          return new Response(body, {
            headers: {
              "content-type": "text/html",
            },
          });
        }
      }
    } catch {
      // ignore
    }
  }
  return next;
};