const API_BASE_URL = import.meta.env.VITE_API_BASE_URL ?? '';
const ADMIN_LOGIN_URL = '/uat/uia/actionSecurityLogin.do';
const ADMIN_ID = 'admin';
const ADMIN_PASSWORD = '1';

type ApiEnvelope<T> = {
  success?: boolean;
  message?: string;
  data?: T;
};

let loginPromise: Promise<void> | null = null;

function toApiUrl(path: string) {
  if (/^https?:\/\//i.test(path)) {
    return path;
  }

  return `${API_BASE_URL}${path}`;
}

function createHeaders(headers?: HeadersInit) {
  return new Headers(headers);
}

async function adminLogin() {
  if (!loginPromise) {
    loginPromise = fetch(toApiUrl(ADMIN_LOGIN_URL), {
      method: 'POST',
      credentials: 'include',
      headers: {
        'Content-Type': 'application/x-www-form-urlencoded',
        'X-Requested-With': 'XMLHttpRequest',
      },
      body: new URLSearchParams({
        id: ADMIN_ID,
        password: ADMIN_PASSWORD,
      }),
    })
      .then(async (response) => {
        if (!response.ok) {
          throw new Error(`Admin login failed: ${response.status}`);
        }

        const contentType = response.headers.get('content-type') ?? '';
        if (contentType.includes('application/json')) {
          const result = (await response.json()) as ApiEnvelope<unknown>;
          if (result.success === false) {
            throw new Error(result.message ?? 'Admin login failed');
          }
        }
      })
      .finally(() => {
        loginPromise = null;
      });
  }

  return loginPromise;
}

async function needsAdminLogin(response: Response) {
  if (response.type === 'opaqueredirect' || response.status === 0) {
    return true;
  }

  if (response.status >= 300 && response.status < 400) {
    return true;
  }

  if (response.status === 401 || response.status === 403) {
    return true;
  }

  const contentType = response.headers.get('content-type') ?? '';

  if (contentType.includes('text/html')) {
    const html = await response.clone().text();
    return html.includes('/uat/uia/actionMain.do') || html.includes('actionSecurityLogin.do');
  }

  if (contentType.includes('application/json')) {
    try {
      const result = (await response.clone().json()) as ApiEnvelope<unknown>;
      const message = result.message ?? '';
      return result.success === false && /login|로그인|/.test(message);
    } catch {
      return false;
    }
  }

  return false;
}

export async function adminAuthFetch(path: string, init: RequestInit = {}, retry = true): Promise<Response> {
  const response = await fetch(toApiUrl(path), {
    ...init,
    credentials: 'include',
    headers: createHeaders(init.headers),
    redirect: 'manual',
  });

  if (retry && (await needsAdminLogin(response))) {
    await adminLogin();
    return adminAuthFetch(path, init, false);
  }

  return response;
}

export async function adminAuthJson<T>(path: string, init?: RequestInit): Promise<T> {
  const response = await adminAuthFetch(path, init);

  if (!response.ok) {
    throw new Error(`API request failed: ${response.status}`);
  }

  const result = (await response.json()) as ApiEnvelope<T>;
  if (result.success === false) {
    throw new Error(result.message ?? 'API request failed');
  }

  return result.data as T;
}