/**
 * Gemeinsame Anfragehilfen der Finanzbuchhaltungs-Module (Kantinenabrechnung,
 * Handelsware; quick-261002-fm5). `credentials: 'include'` fuer Cookie-Auth,
 * `NEXT_PUBLIC_API_URL` als Basis — Muster `custom-modules-api.ts`.
 */

export const ACCOUNTING_API_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:3001';

/** Dateiantwort der API (Base64) — wie beim Zertifikat-Manager. */
export interface FileResponse {
  filename: string;
  content: string;
  mimeType: string;
}

/**
 * Fehler mit HTTP-Status, maschinenlesbarer Kennung (`code`, falls die API
 * eine liefert) und deutscher Servermeldung.
 */
export class AccountingRequestError extends Error {
  constructor(
    readonly status: number,
    readonly code: string | null,
    message: string,
    readonly details: unknown = null,
  ) {
    super(message);
    this.name = 'AccountingRequestError';
  }
}

async function failure(res: Response): Promise<AccountingRequestError> {
  let message = `Request failed (${res.status})`;
  let code: string | null = null;
  let details: unknown = null;
  try {
    const body = await res.json();
    const raw = body?.message;
    if (Array.isArray(raw)) message = raw.join(' ');
    else if (typeof raw === 'string') message = raw;
    if (typeof body?.code === 'string') code = body.code;
    details = body?.errors ?? null;
  } catch {
    // Antwort ohne JSON-Koerper — Standardmeldung bleibt.
  }
  return new AccountingRequestError(res.status, code, message, details);
}

export async function accountingRequest<T>(
  path: string,
  init: { method?: string; json?: unknown; form?: FormData } = {},
): Promise<T> {
  const headers: Record<string, string> = {};
  let body: BodyInit | undefined;
  if (init.form) {
    body = init.form;
  } else if (init.json !== undefined) {
    headers['Content-Type'] = 'application/json';
    body = JSON.stringify(init.json);
  }
  const res = await fetch(`${ACCOUNTING_API_URL}${path}`, {
    method: init.method ?? 'GET',
    credentials: 'include',
    headers,
    body,
  });
  if (!res.ok) throw await failure(res);
  if (res.status === 204) return undefined as T;
  return (await res.json()) as T;
}