import { API_BASE } from '../lib/apiBase';

/** Frontend-only fallback when the Node API is not reachable on the host. */
const STATIC_USER = 'admin';
const STATIC_PASS = 'admin123';
export const STATIC_TOKEN = 'static-admin-session';

export function getToken() {
  return localStorage.getItem('admin_token');
}

export function setToken(token) {
  localStorage.setItem('admin_token', token);
}

export function clearToken() {
  localStorage.removeItem('admin_token');
}

export function isStaticSession(token = getToken()) {
  return token === STATIC_TOKEN;
}

function staticLogin(username, password) {
  if (username === STATIC_USER && password === STATIC_PASS) {
    return { token: STATIC_TOKEN, expiresAt: null, mode: 'static' };
  }
  throw new Error('Invalid credentials');
}

async function apiFetch(path, options = {}) {
  const headers = { ...options.headers };
  if (!(options.body instanceof FormData)) {
    headers['Content-Type'] = 'application/json';
  }
  const token = getToken();
  if (token) headers.Authorization = `Bearer ${token}`;

  const res = await fetch(`${API_BASE}${path}`, { ...options, headers });
  const data = await res.json().catch(() => ({}));
  if (!res.ok) {
    const fallback =
      res.status === 404
        ? 'API not found. Deploy server/ and run: npm run server (port 3001)'
        : res.status === 502
          ? 'API server unreachable. Start Node on the host (port 3001).'
          : 'Request failed';
    throw new Error(data.error || fallback);
  }
  return data;
}

export const adminApi = {
  login: async (username, password) => {
    // Prefer Node API when it is up; otherwise allow static admin/admin123.
    try {
      return await apiFetch('/api/auth/login', {
        method: 'POST',
        body: JSON.stringify({ username, password }),
      });
    } catch {
      return staticLogin(username, password);
    }
  },

  me: async () => {
    if (isStaticSession()) {
      return { username: STATIC_USER, mode: 'static' };
    }
    return apiFetch('/api/auth/me');
  },

  getContent: () => apiFetch('/api/content'),

  updateSection: (section, data) =>
    apiFetch(`/api/content/${section}`, { method: 'PUT', body: JSON.stringify(data) }),

  changePassword: (currentPassword, newPassword) =>
    apiFetch('/api/auth/password', { method: 'PUT', body: JSON.stringify({ currentPassword, newPassword }) }),

  upload: async (file) => {
    // Try Node API first; fall back to local data URL when server is unavailable.
    try {
      const form = new FormData();
      form.append('file', file);
      return await apiFetch('/api/upload', { method: 'POST', body: form });
    } catch {
      return new Promise((resolve, reject) => {
        const reader = new FileReader();
        reader.onload = () => resolve({ url: reader.result, filename: file.name });
        reader.onerror = () => reject(new Error('Failed to read file'));
        reader.readAsDataURL(file);
      });
    }
  },
};