// hub.js — shared client helpers for the Nostr Voice Hub.
// NIP-07: the browser extension (Alby/nos2x) signs WITHOUT ever exposing the
// secret key. We only ask for: the pubkey, a signed event, a signed NIP-98.
// No key material ever leaves the browser.

const HUB = (() => {
  function haveNip07() {
    return !!(window.nostr && (window.nostr.getPublicKey || window.nostr.nip07));
  }

  async function getPubkey() {
    if (!window.nostr || typeof window.nostr.getPublicKey !== 'function') {
      throw new Error('No NIP-07 extension (Alby, nos2x, or similar) detected.');
    }
    return window.nostr.getPublicKey();
  }

  // Build a signed event via NIP-07. kind 1 for a note; content = text.
  async function signEvent(kind, content, extraTags) {
    if (!window.nostr || typeof window.nostr.signEvent !== 'function') {
      throw new Error('No NIP-07 extension capable of signing events.');
    }
    const pubkey = await getPubkey();
    const created_at = Math.floor(Date.now() / 1000);
    const tags = extraTags || [];
    // signEvent receives the full event template; extension fills id + sig.
    const evt = await window.nostr.signEvent({ kind, pubkey, created_at, tags, content });
    return evt;
  }

  // NIP-98 HTTP auth: sign a 27235 event bound to this URL, return "Nostr <b64>".
  async function nip98Auth(url, method = 'POST') {
    const pubkey = await getPubkey();
    const created_at = Math.floor(Date.now() / 1000);
    const evt = await signEvent(27235, '', [['u', url], ['method', method]]);
    const b64 = btoa(unescape(encodeURIComponent(JSON.stringify(evt))));
    return 'Nostr ' + b64;
  }

  // Short display for a hex pubkey (first/last 6).
  function shortPub(pubkey) {
    return pubkey ? pubkey.slice(0, 6) + '…' + pubkey.slice(-6) : '';
  }

  // Convert an integer pubkey (hex) to a bech32 npub for display.
  // Minimal npub encoder (NIP-19). Falls back to 'npub1<hex>' if anything fails.
  function toNpub(pubkeyHex) {
    try {
      return bech32Encode('npub', hexToBytes(pubkeyHex));
    } catch (e) {
      return 'npub1' + pubkeyHex;
    }
  }

  const CHARSET = 'qpzry9x8gf2tvdw0s3jn54khce6mua7l';
  function hexToBytes(hex) {
    const out = new Uint8Array(hex.length / 2);
    for (let i = 0; i < out.length; i++) out[i] = parseInt(hex.substr(i * 2, 2), 16);
    return out;
  }
  function polymod(values) {
    const GEN = [0x3b6a57b2, 0x26508e6d, 0x1ea119fa, 0x3d4233dd, 0x2a1462b3];
    let chk = 1;
    for (const v of values) {
      const b = chk >> 25;
      chk = (chk & 0x1ffffff) << 5 ^ v;
      for (let i = 0; i < 5; i++) if ((b >> i) & 1) chk ^= GEN[i];
    }
    return chk;
  }
  function expandHrp(hrp) { return hrp.split('').map(c => c.charCodeAt(0) >> 5).concat([0], hrp.split('').map(c => c.charCodeAt(0) & 31)); }
  function convert(data, from, to, pad) {
    let acc = 0, bits = 0, out = [];
    const maxv = (1 << to) - 1;
    for (const v of data) {
      acc = (acc << from) | v; bits += from;
      while (bits >= to) { bits -= to; out.push((acc >> bits) & maxv); }
    }
    if (pad && bits > 0) out.push((acc << (to - bits)) & maxv);
    return out;
  }
  function bech32Encode(hrp, data) {
    const bytes = convert(data, 8, 5, true);
    const values = expandHrp(hrp).concat(bytes);
    const plm = polymod(values.concat([0, 0, 0, 0, 0, 0])) ^ 1;
    const checksum = [];
    for (let i = 0; i < 6; i++) checksum.push((plm >> (5 * (5 - i))) & 31);
    return hrp + '1' + bytes.concat(checksum).map(c => CHARSET[c]).join('');
  }

  // Fetch with an Authorization header, return parsed JSON.
  async function authedGet(url) {
    const auth = await nip98Auth(url, 'GET');
    const res = await fetch(url, { headers: { Authorization: auth } });
    return res.json();
  }
  async function authedPost(url, body) {
    const auth = await nip98Auth(url, 'POST');
    const res = await fetch(url, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json', Authorization: auth },
      body: JSON.stringify(body),
    });
    return res.json();
  }

  function timeAgo(ts) {
    const s = Math.floor(Date.now() / 1000) - ts;
    if (s < 60) return s + 's ago';
    if (s < 3600) return Math.floor(s / 60) + 'm ago';
    if (s < 86400) return Math.floor(s / 3600) + 'h ago';
    return Math.floor(s / 86400) + 'd ago';
  }

  return { haveNip07, getPubkey, signEvent, nip98Auth, shortPub, toNpub, authedGet, authedPost, timeAgo };
})();