export async function apiFetch<T>(url: string, options?: RequestInit): Promise<T> {
  const response = await fetch(url, options);
  const payload = await response.json().catch(() => null);
  if (!response.ok || !payload || payload.code !== 0) {
    throw new Error(payload?.msg || `HTTP ${response.status}`);
  }
  return payload.data as T;
}

export async function downloadBlob(url: string, fallbackName: string): Promise<void> {
  const response = await fetch(url);
  if (!response.ok) {
    const payload = await response.json().catch(() => null);
    throw new Error(payload?.msg || `HTTP ${response.status}`);
  }
  const blob = await response.blob();
  const filename = filenameFromDisposition(response.headers.get("Content-Disposition")) || fallbackName;
  const objectURL = URL.createObjectURL(blob);
  try {
    const link = document.createElement("a");
    link.href = objectURL;
    link.download = filename;
    document.body.appendChild(link);
    link.click();
    link.remove();
  } finally {
    URL.revokeObjectURL(objectURL);
  }
}

export function filenameFromDisposition(disposition: string | null): string {
  if (!disposition) return "";
  const utf8 = /filename\*=UTF-8''([^;]+)/i.exec(disposition);
  if (utf8) return decodeURIComponent(utf8[1]);
  const quoted = /filename="([^"]+)"/i.exec(disposition);
  if (quoted) return quoted[1];
  return "";
}

export function downloadText(filename: string, content: string, type: string): void {
  const blob = new Blob([content], { type });
  const objectURL = URL.createObjectURL(blob);
  try {
    const link = document.createElement("a");
    link.href = objectURL;
    link.download = filename;
    document.body.appendChild(link);
    link.click();
    link.remove();
  } finally {
    URL.revokeObjectURL(objectURL);
  }
}