import { parseList } from "structured-headers";

export type ParsedLabelers = {
  dids: string[];
  redact: Set<string>;
};

export const parseLabelerHeader = (
  header: string | undefined,
): ParsedLabelers | null => {
  // An empty header is valid, so we shouldn't return null
  // https://datatracker.ietf.org/doc/html/rfc7230#section-3.2
  if (header === undefined) return null;
  const labelerDids = new Set<string>();
  const redactDids = new Set<string>();
  const parsed = parseList(header);
  for (const item of parsed) {
    const did = item[0].toString();
    if (!did) {
      return null;
    }
    labelerDids.add(did);
    const redact = item[1].get("redact")?.valueOf();
    if (redact === true) {
      redactDids.add(did);
    }
  }
  return {
    dids: [...labelerDids],
    redact: redactDids,
  };
};

export const defaultLabelerHeader = (dids: string[]): ParsedLabelers => {
  return {
    dids,
    redact: new Set(dids),
  };
};

export const formatLabelerHeader = (parsed: ParsedLabelers): string => {
  const parts = parsed.dids.map((did) =>
    parsed.redact.has(did) ? `${did};redact` : did
  );
  return parts.join(",");
};