import { CONFIG } from './config.js';

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

// The API's explanation from an error response: FastAPI's {"detail": "..."}, or for validation
// errors {"detail": [{"msg": "..."}, ...]}
async function errorDetail(res) {
  try {
    const { detail } = await res.json();
    if (typeof detail === 'string') return detail;
    if (Array.isArray(detail)) return detail.map((d) => d.msg).filter(Boolean).join('; ');
  } catch {
    // not JSON: fall back to the status code
  }
  return null;
}

async function request(path, { method = 'GET', body } = {}) {
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(), CONFIG.requestTimeoutMs);
  const headers = { Accept: 'application/json' };
  if (method !== 'GET') {
    // Required by the API for changes: another site's page can't add it to a request here
    headers['X-Requested-By'] = 'backup-dashboard';
  }
  if (body !== undefined) headers['Content-Type'] = 'application/json';
  try {
    const res = await fetch(`${CONFIG.apiBaseUrl}${path}`, {
      method,
      headers,
      body: body === undefined ? undefined : JSON.stringify(body),
      credentials: 'same-origin', // the sign-in session cookie
      signal: controller.signal,
    });
    // 401 means the nginx/SSO session lapsed; a reload sends the user back through sign-in
    if (res.status === 401) throw new ApiError('Your session has expired. Reload the page to sign in again', 401);
    if (!res.ok) {
      throw new ApiError((await errorDetail(res)) ?? `Server returned HTTP ${res.status}`, res.status);
    }
    return await res.json();
  } catch (err) {
    if (err.name === 'AbortError') throw new ApiError('Request timed out');
    if (err instanceof ApiError) throw err;
    throw new ApiError(`Network error: ${err.message}`);
  } finally {
    clearTimeout(timer);
  }
}

const httpApi = {
  /** GET /jobs → { generated_at, jobs: Job[] } */
  async listJobs() {
    const data = await request('/jobs');
    if (!Array.isArray(data?.jobs)) throw new ApiError('Unexpected response shape from /jobs');
    return data;
  },
  /** GET /jobs/:id → JobDetail */
  getJob(id) {
    return request(`/jobs/${encodeURIComponent(id)}`);
  },
  /** GET /jobs/:id/runs?days=N → { job_id, since, runs: RunSummary[] } (newest first, no messages) */
  listRuns(id, days) {
    return request(`/jobs/${encodeURIComponent(id)}/runs?days=${encodeURIComponent(days)}`);
  },
  /** GET /runs/:id → Run (with message and details) */
  getRun(id) {
    return request(`/runs/${encodeURIComponent(id)}`);
  },
  /** GET /me → { email, name, is_admin } of the Microsoft 365 user; email/name null without sign-in */
  getMe() {
    return request('/me');
  },

  // ----- Admin (403 for non-admins) -----
  /** GET /admin/keys → { keys: ApiKey[] } (active first) */
  listKeys() {
    return request('/admin/keys');
  },
  /** POST /admin/keys → { key: ApiKey, secret } — the secret is only ever returned here */
  createKey(name) {
    return request('/admin/keys', { method: 'POST', body: { name } });
  },
  /** POST /admin/keys/:id/revoke → { key: ApiKey } */
  revokeKey(id) {
    return request(`/admin/keys/${encodeURIComponent(id)}/revoke`, { method: 'POST' });
  },
};

// Mock is loaded lazily so it never ships in the production request path.
export async function getApi() {
  if (CONFIG.useMock) {
    const { mockApi } = await import('./mock.js');
    return mockApi;
  }
  return httpApi;
}