frontend/src/utils/http.ts

type JsonMap = Record<string, unknown>;

function asJsonMap(value: unknown): JsonMap | null {
  if (!value || typeof value !== "object" || Array.isArray(value)) return null;
  return value as JsonMap;
}

export type ParsedApiBody = {
  data: JsonMap | null;
  text: string;
};

export async function parseJsonOrText(response: Response): Promise<ParsedApiBody> {
  const text = await response.text().catch(() => "");
  if (!text) return { data: null, text: "" };
  try {
    const parsed = JSON.parse(text);
    return { data: asJsonMap(parsed), text };
  } catch {
    return { data: null, text };
  }
}

export function extractErrorMessage(parsed: ParsedApiBody, fallback: string): string {
  const detail = parsed.data?.detail;
  if (typeof detail === "string" && detail.trim()) return detail.trim();
  const error = parsed.data?.error;
  if (typeof error === "string" && error.trim()) return error.trim();
  if (parsed.text.trim()) return parsed.text.trim();
  return fallback;
}