export const DAV_XML = "application/xml; charset=utf-8";

export function davResponse(body: string | null, status: number, headers: HeadersInit = {}): Response {
  const responseHeaders = new Headers(headers);
  if (body !== null && !responseHeaders.has("content-type")) responseHeaders.set("content-type", DAV_XML);
  return new Response(body, { status, headers: responseHeaders });
}

export function emptyResponse(status: number, headers: HeadersInit = {}): Response {
  return new Response(null, { status, headers });
}

export function methodNotAllowed(allow: string): Response {
  return new Response("Method Not Allowed", { status: 405, headers: { Allow: allow } });
}

export function unauthorizedDav(): Response {
  return new Response("Unauthorized", {
    status: 401,
    headers: { "WWW-Authenticate": 'Basic realm="dab"' },
  });
}

export function davError(status: number, message: string, headers: HeadersInit = {}): Response {
  return new Response(message, { status, headers });
}

// RFC 4791 7.8 / RFC 6352 8.3: signal that the server truncated a query report
// result set with a DAV:error body containing DAV:number-of-matches-within-limits.
export function numberOfMatchesWithinLimitsError(): Response {
  const body =
    '<?xml version="1.0" encoding="utf-8"?>' + '<D:error xmlns:D="DAV:"><D:number-of-matches-within-limits/></D:error>';
  return davResponse(body, 403);
}

export function parseDepth(value: string | null, fallback: "0" | "1" | "infinity"): "0" | "1" | "infinity" | null {
  if (value === null || value === "") return fallback;
  const normalized = value.toLowerCase();
  if (normalized === "0" || normalized === "1" || normalized === "infinity") return normalized;
  return null;
}