import { sha256 } from '@noble/hashes/sha256';
import { bytesToHex } from '@noble/hashes/utils';

// Independent public hosts: a phone upload should not fail just because one
// provider is down or rejects a particular container. Order from a
// 2026-09-30 benchmark (4 MB mp4 / 110 KB jpeg, uploaded then fetched):
// ditto took the mp4 in ~0.6 s and serves in ~120 ms; primal ~1.5 s; nostr.
// download ~1-2 s but refuses a JPEG with bytes after its end marker (motion
// photos); blossom.nostr.build ~5 s. The first to accept the file wins.
export const PUBLIC_MEDIA_SERVERS = ['https://blossom.ditto.pub', 'https://blossom.primal.net',
  'https://nostr.download', 'https://blossom.nostr.build'];

export class MediaUploadError extends Error {
  constructor(code, details = '') {
    super(code);
    this.name = 'MediaUploadError';
    this.code = code;
    this.details = details;
  }
}

async function fileHash(file) {
  const hash = sha256.create();
  const chunk = 4 * 1024 * 1024;
  for (let at = 0; at < file.size; at += chunk)
    hash.update(new Uint8Array(await file.slice(at, at + chunk).arrayBuffer()));
  return bytesToHex(hash.digest());
}

const responseUrl = (body) => body?.url
  || body?.data?.[0]?.url
  || (body?.tags || []).find((x) => x?.[0] === 'url')?.[1]
  || null;

function mediaUrl(url, server, file) {
  const out = new URL(url, server);
  const tail = out.pathname.split('/').at(-1) || '';
  if (/^[0-9a-f]{64}$/i.test(tail)) {
    const named = String(file.name || '').match(/\.([a-z0-9]{1,8})$/i)?.[1];
    const byType = { 'video/quicktime': 'mov', 'video/mp4': 'mp4', 'video/webm': 'webm',
      'image/jpeg': 'jpg', 'image/png': 'png', 'image/webp': 'webp', 'image/gif': 'gif', 'image/avif': 'avif' }[file.type];
    const ext = (named || byType || '').toLowerCase();
    if (ext) out.pathname += '.' + ext;
  }
  return out.href;
}

// A PUT that reports how much of the body has gone out: fetch() can't, so in
// the browser (with the real fetch) it's XMLHttpRequest. Answers like fetch.
function putWithProgress(url, { body, headers, signal }, onProgress) {
  return new Promise((resolve, reject) => {
    const xhr = new XMLHttpRequest();
    xhr.open('PUT', url);
    for (const [k, v] of Object.entries(headers)) xhr.setRequestHeader(k, v);
    xhr.upload.onprogress = (e) => { if (e.lengthComputable) onProgress(e.loaded / e.total); };
    xhr.onload = () => resolve(new Response(xhr.responseText, {
      status: xhr.status, headers: { 'x-reason': xhr.getResponseHeader('x-reason') || '' } }));
    xhr.onerror = () => reject(new Error('network error'));
    xhr.ontimeout = () => reject(new Error('timeout'));
    if (signal) signal.addEventListener('abort', () => { xhr.abort(); reject(new Error('timeout')); });
    xhr.send(body);
  });
}

// BUD-02 upload. `signEvent` is deliberately injected: the app can use its
// always-available wallet identity, while tests need no secret key.
export async function uploadPublicMedia(file, signEvent, {
  servers = PUBLIC_MEDIA_SERVERS,
  fetcher = globalThis.fetch,
  timeoutMs = 5 * 60_000,
  onProgress = null, // (fraction 0..1) as the bytes go out
} = {}) {
  const tracked = onProgress && typeof XMLHttpRequest !== 'undefined' && fetcher === globalThis.fetch;
  if (!file || !file.size || typeof signEvent !== 'function') throw new MediaUploadError('failed');
  const x = await fileHash(file);
  const now = Math.floor(Date.now() / 1000);
  const auth = await signEvent({
    kind: 24242, created_at: now - 5, content: 'upload',
    tags: [['t', 'upload'], ['x', x], ['expiration', String(now + Math.ceil(timeoutMs / 1000) + 120)]],
  });
  if (!auth) throw new MediaUploadError('failed');
  const authorization = 'Nostr ' + btoa(JSON.stringify(auth));
  const failures = [];
  for (const [i, server] of servers.entries()) {
    // A host that doesn't answer at all costs a few seconds, not the whole
    // upload timeout. Any HTTP answer, even an error, means it's there.
    if (i < servers.length - 1) {
      try { await fetcher(server.replace(/\/$/, '') + '/upload', { method: 'HEAD', signal: AbortSignal.timeout(5000) }); }
      catch (error) { failures.push({ status: 0, reason: 'unreachable' }); continue; }
    }
    try {
      const init = {
        method: 'PUT', body: file, signal: AbortSignal.timeout(timeoutMs),
        headers: {
          authorization,
          'content-type': file.type || 'application/octet-stream',
          'x-sha-256': x,
          'x-content-length': String(file.size),
        },
      };
      if (onProgress) onProgress(0);
      const target = server.replace(/\/$/, '') + '/upload';
      const response = tracked ? await putWithProgress(target, init, onProgress) : await fetcher(target, init);
      let body = null;
      try { body = await response.json(); } catch {}
      const url = response.ok && responseUrl(body);
      if (url) return mediaUrl(url, server, file);
      failures.push({ status: response.status, reason: response.headers.get('x-reason') || body?.message || '' });
    } catch (error) {
      failures.push({ status: 0, reason: error?.message || '' });
    }
  }
  const details = failures.map((x) => [x.status, x.reason].filter(Boolean).join(' ')).filter(Boolean).join('; ');
  if (failures.length && failures.every((x) => x.status === 413)) throw new MediaUploadError('too-big', details);
  if (failures.length && failures.every((x) => x.status === 415)) throw new MediaUploadError('unsupported', details);
  throw new MediaUploadError('failed', details);
}