export const API_BASE = '/api';

type ApiResponse<T> = {
  success: boolean;
  data?: T;
  error?: { code: string; message: string };
};

let accessToken: string | null = localStorage.getItem('accessToken');
let refreshToken: string | null = localStorage.getItem('refreshToken');

export function setTokens(access: string, refresh: string) {
  accessToken = access;
  refreshToken = refresh;
  localStorage.setItem('accessToken', access);
  localStorage.setItem('refreshToken', refresh);
}

export function clearTokens() {
  accessToken = null;
  refreshToken = null;
  localStorage.removeItem('accessToken');
  localStorage.removeItem('refreshToken');
}

export function getAccessToken() {
  return accessToken;
}

async function refreshAccessToken(): Promise<boolean> {
  if (!refreshToken) return false;
  try {
    const res = await fetch(`${API_BASE}/auth/refresh`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ refreshToken }),
    });
    if (!res.ok) return false;
    const json: ApiResponse<{ accessToken: string; refreshToken: string }> = await res.json();
    if (json.success && json.data) {
      setTokens(json.data.accessToken, json.data.refreshToken);
      return true;
    }
    return false;
  } catch {
    return false;
  }
}

export async function apiFetch<T>(path: string, options: RequestInit = {}): Promise<T> {
  const headers = new Headers(options.headers);
  if (!headers.has('Content-Type') && !(options.body instanceof FormData)) {
    headers.set('Content-Type', 'application/json');
  }
  if (accessToken) {
    headers.set('Authorization', `Bearer ${accessToken}`);
  }

  let res = await fetch(`${API_BASE}${path}`, { ...options, headers });

  if (res.status === 401 && refreshToken) {
    const refreshed = await refreshAccessToken();
    if (refreshed) {
      headers.set('Authorization', `Bearer ${accessToken}`);
      res = await fetch(`${API_BASE}${path}`, { ...options, headers });
    }
  }

  const text = await res.text();
  let json: ApiResponse<T>;
  try {
    json = JSON.parse(text);
  } catch {
    throw new Error(`Server error (${res.status})`);
  }
  if (!json.success) {
    throw new Error(json.error?.message || 'Request failed');
  }
  return json.data as T;
}