'use strict';

const PagerAPI = (() => {
  let apiBase = '';
  let on401 = null;
  // Reads are polled and must never hang a page's refresh loop; writes have
  // server-side timeouts up to 45s (radio deploys) so they get no client
  // abort.
  const GET_TIMEOUT_MS = 20000;
  async function request(method, path, body) {
    const opts = { method, headers: {}, credentials: 'include' };
    if (body !== undefined) {
      opts.headers['Content-Type'] = 'application/json';
      opts.body = JSON.stringify(body);
    }
    const ctl = new AbortController();
    const timer = method === 'GET' ? setTimeout(() => ctl.abort(), GET_TIMEOUT_MS) : null;
    if (timer) opts.signal = ctl.signal;
    let res;
    try {
      res = await fetch(apiBase + path, opts);
    } catch (e) {
      if (timer && e && e.name === 'AbortError') {
        const error = new Error('Request timed out');
        error.status = 0;
        throw error;
      }
      throw e;
    } finally {
      if (timer) clearTimeout(timer);
    }
    if (res.status === 401) {
      if (on401) on401();
      throw new Error('unauthorized');
    }
    const ct = res.headers.get('Content-Type') || '';
    let data;
    if (ct.indexOf('json') !== -1) {
      try { data = await res.json(); }
      catch (e) { data = null; }
    } else {
      data = await res.text();
    }
    if (!res.ok) {
      const detail = data && typeof data.detail === 'string' ? data.detail : '';
      const message = (data && data.error ? data.error : ('HTTP ' + res.status)) +
        (detail ? ': ' + detail : '');
      const error = new Error(message);
      error.status = res.status;
      error.data = data;
      throw error;
    }
    return { status: res.status, data };
  }
  return {
    setBase: (b) => { apiBase = b; },
    on401: (fn) => { on401 = fn; },
    get: (p) => request('GET', p),
    post: (p, b) => request('POST', p, b === undefined ? {} : b),
    del: (p, b) => request('DELETE', p, b === undefined ? {} : b),
    login: async (username, password) => request('POST', '/api/login', { username, password })
  };
})();