const API = (() => {
  const BASE = '/api';

  function token() { return localStorage.getItem('ev_token') || ''; }

  async function req(method, path, body = null, isForm = false) {
    const headers = {};
    if (token()) headers['Authorization'] = 'Bearer ' + token();
    let fetchBody = null;
    if (body) {
      if (isForm) {
        fetchBody = body; // FormData
      } else {
        headers['Content-Type'] = 'application/json';
        fetchBody = JSON.stringify(body);
      }
    }
    const res = await fetch(BASE + path, { method, headers, body: fetchBody });
    if (res.status === 401) { Auth.logout(); return; }
    if (!res.ok) {
      const err = await res.json().catch(() => ({ detail: '오류가 발생했습니다.' }));
      throw new Error(err.detail || '오류');
    }
    const ct = res.headers.get('content-type') || '';
    if (ct.includes('spreadsheet') || ct.includes('octet')) return res.blob();
    return res.json().catch(() => ({}));
  }

  return {
    get:    (path)         => req('GET',    path),
    post:   (path, body)   => req('POST',   path, body, body instanceof FormData),
    put:    (path, body)   => req('PUT',    path, body, body instanceof FormData),
    patch:  (path, body)   => req('PATCH',  path, body, body instanceof FormData),
    delete: (path)         => req('DELETE', path),
    download: async (path, filename) => {
      const blob = await req('GET', path);
      const url = URL.createObjectURL(blob);
      const a = document.createElement('a'); a.href = url; a.download = filename;
      a.click(); URL.revokeObjectURL(url);
    }
  };
})();