// The terdut-server client. The page is served by the server itself, so every
// call is same-origin and carries the session cookie.

export class ApiError extends Error {
  constructor(status, message) {
    super(message);
    this.name = 'ApiError';
    this.status = status;
  }
}

// Called whenever the server says the session is gone, so the app can put the
// login form back up wherever the user happened to be.
let onUnauthorized = () => {};
export function setUnauthorizedHandler(fn) {
  onUnauthorized = fn;
}

async function call(method, path, { query, body, signal } = {}) {
  const url = new URL('/api' + path, location.origin);
  for (const [k, v] of Object.entries(query || {})) {
    if (v === '' || v == null) continue;
    url.searchParams.set(k, v);
  }

  const headers = { Accept: 'application/json' };
  if (body !== undefined) headers['Content-Type'] = 'application/json';

  let resp;
  try {
    resp = await fetch(url, {
      method,
      headers,
      body: body === undefined ? undefined : JSON.stringify(body),
      credentials: 'same-origin',
      signal,
    });
  } catch (err) {
    if (err.name === 'AbortError') throw err;
    throw new ApiError(0, 'Cannot reach the server.');
  }

  if (resp.status === 204) return null;

  let data = null;
  try {
    data = await resp.json();
  } catch {
    /* non-JSON body: keep null */
  }

  if (!resp.ok) {
    if (resp.status === 401 && path !== '/login') onUnauthorized();
    const message = (data && data.error) || `Server answered ${resp.status}.`;
    throw new ApiError(resp.status, message);
  }
  return data;
}

// session
export const me = () => call('GET', '/me');
export const login = (username, password) => call('POST', '/login', { body: { username, password } });
export const logout = () => call('POST', '/logout');
export const setPassword = (userID, password, currentPassword) =>
  call('PUT', `/users/${userID}/password`, { body: { password, current_password: currentPassword } });

// users
export const users = () => call('GET', '/users');

// incidents
export const incidents = (query, opts) => call('GET', '/incidents', { query, ...opts });
export const incident = (id) => call('GET', `/incidents/${id}`);
export const timeline = (id) => call('GET', `/incidents/${id}/timeline`);

export const acknowledge = (id) => call('POST', `/incidents/${id}/acknowledge`);
export const unacknowledge = (id) => call('DELETE', `/incidents/${id}/acknowledge`);
export const resolve = (id) => call('POST', `/incidents/${id}/resolve`);
export const assign = (id, userID) => call('POST', `/incidents/${id}/assign`, { body: { user_id: userID } });
export const snooze = (id, spec) => call('POST', `/incidents/${id}/snooze`, { body: spec });
export const unsnooze = (id) => call('DELETE', `/incidents/${id}/snooze`);
export const archive = (id) => call('POST', `/incidents/${id}/archive`);
export const unarchive = (id) => call('DELETE', `/incidents/${id}/archive`);
export const addNote = (id, content) => call('POST', `/incidents/${id}/notes`, { body: { content } });
export const deleteNote = (id, eventID) => call('DELETE', `/incidents/${id}/notes/${eventID}`);

// alerts
export const alerts = (query, opts) => call('GET', '/alerts', { query, ...opts });

// schedule
export const schedule = (from, to) => call('GET', '/schedule', { query: { from, to } });
export async function onCallNow() {
  try {
    return await call('GET', '/schedule/current');
  } catch (err) {
    if (err instanceof ApiError && err.status === 404) return null;
    throw err;
  }
}