/* Browser-side fetch helper for the JSON API. */

export class ApiError extends Error {
  constructor(
    public status: number,
    message: string,
    public details?: unknown
  ) {
    super(message);
  }
}

export async function api<T = unknown>(url: string, init?: RequestInit & { json?: unknown }): Promise<T> {
  const { json, ...rest } = init ?? {};
  const res = await fetch(url, {
    ...rest,
    headers: json !== undefined ? { "content-type": "application/json", ...rest.headers } : rest.headers,
    body: json !== undefined ? JSON.stringify(json) : rest.body,
  });
  const data = await res.json().catch(() => ({}));
  if (!res.ok) {
    const details = Array.isArray(data.details) ? `: ${data.details.join("; ")}` : "";
    throw new ApiError(res.status, (data.error ?? res.statusText) + details, data.details);
  }
  return data as T;
}