import type { DirigentConfig } from "../rules.js";

function userIdFromToken(token: string): string | undefined {
  try {
    const segment = token.split(".")[0];
    const padded = segment + "=".repeat((4 - (segment.length % 4)) % 4);
    return Buffer.from(padded, "base64").toString("utf8");
  } catch {
    return undefined;
  }
}

export function extractMentionedUserIds(content: string): string[] {
  const regex = /<@!?(\d+)>/g;
  const ids: string[] = [];
  const seen = new Set<string>();
  let match: RegExpExecArray | null;
  while ((match = regex.exec(content)) !== null) {
    const id = match[1];
    if (!seen.has(id)) {
      seen.add(id);
      ids.push(id);
    }
  }
  return ids;
}

export function getModeratorUserId(config: DirigentConfig): string | undefined {
  if (!config.moderatorBotToken) return undefined;
  return userIdFromToken(config.moderatorBotToken);
}