export type DeadPropInstruction =
  | { kind: "set"; nsUri: string; localName: string; xmlValue: string }
  | { kind: "remove"; nsUri: string; localName: string };

export function validDavCollectionName(name: string): boolean {
  return name.length > 0 && name.length <= 128 && name !== "." && name !== ".." && !/[\\/]/.test(name);
}

export function davSyncToken(seq: number): string {
  return `sync:${seq}`;
}

export function parseDavSyncToken(token: string | null): number {
  if (!token) return 0;
  const match = /^sync:(\d+)$/.exec(token);
  return match ? Number.parseInt(match[1]!, 10) : 0;
}

export function parseDavSyncTokenStrict(token: string | null): number | null {
  if (!token) return 0;
  const match = /^sync:(\d+)$/.exec(token);
  return match ? Number.parseInt(match[1]!, 10) : null;
}

export function objectNameFromCollectionHref(
  collectionHref: string,
  href: string,
  acceptedOrigins?: string[],
): string | null {
  let pathname: string;
  const absolute = href.startsWith("http://") || href.startsWith("https://");
  try {
    if (absolute) {
      const parsed = new URL(href);
      // RFC 4791 7.9 / RFC 6352 8.7: absolute hrefs in multiget must resolve to
      // the same subject host. Reject foreign authorities outright so a request
      // cannot leak local objects under a different origin's name.
      if (acceptedOrigins && acceptedOrigins.length > 0 && !acceptedOrigins.includes(parsed.origin)) {
        return null;
      }
      pathname = parsed.pathname;
    } else {
      pathname = href;
    }
  } catch {
    return null;
  }
  if (!pathname.startsWith(collectionHref)) return null;
  const rawName = pathname.slice(collectionHref.length);
  if (!rawName || rawName.includes("/")) return null;
  try {
    return decodeURIComponent(rawName);
  } catch {
    return null;
  }
}

export function applyDeadPropInstructions(
  instructions: DeadPropInstruction[],
  handlers: {
    set: (instruction: Extract<DeadPropInstruction, { kind: "set" }>) => void;
    remove: (instruction: Extract<DeadPropInstruction, { kind: "remove" }>) => void;
  },
): void {
  for (const instruction of instructions) {
    if (instruction.kind === "set") handlers.set(instruction);
    else handlers.remove(instruction);
  }
}

// Extract text content from a serialized prop element such as
// "<D:displayname>Family</D:displayname>". The serializer preserves nested
// markup, so we strip the outermost element and decode common entities.
export function extractPropTextValue(xmlValue: string): string {
  const match = /^<[^>]+>([\s\S]*)<\/[^>]+>$/.exec(xmlValue.trim());
  const inner = match ? (match[1] ?? "") : xmlValue;
  return inner
    .replace(/&amp;/g, "&")
    .replace(/&lt;/g, "<")
    .replace(/&gt;/g, ">")
    .replace(/&quot;/g, '"')
    .replace(/&apos;/g, "'");
}