const SECRET_PATTERNS = [
  /-----BEGIN (?:RSA |EC |OPENSSH )?PRIVATE KEY-----/i,
  /\b(?:password|passwd|api[_ -]?key|access[_ -]?token|refresh[_ -]?token|bearer|client[_ -]?secret)\b/i,
  /(?:密码|口令|令牌|密钥|私钥|验证码)/,
];

export function boundedText(value, maxLength) {
  if (typeof value !== "string") return "";
  return value.trim().slice(0, maxLength);
}

export function safeMemoryText(value, maxLength = 8_000) {
  const text = boundedText(value, maxLength);
  if (SECRET_PATTERNS.some((pattern) => pattern.test(text))) return "[敏感内容未写入记忆]";
  return text;
}

export function words(value) {
  const lowered = boundedText(value, 16_000).toLowerCase();
  const terms = new Set(lowered.match(/[a-z0-9_-]{2,}|[\u3400-\u9fff]{2}/g) ?? []);
  const cjk = [...lowered.matchAll(/[\u3400-\u9fff]/g)].map((match) => match[0]).join("");
  for (let index = 0; index + 1 < cjk.length; index++) terms.add(cjk.slice(index, index + 2));
  return terms;
}

export function similarity(left, right) {
  const a = words(left);
  const b = words(right);
  if (!a.size || !b.size) return 0;
  let overlap = 0;
  for (const term of a) if (b.has(term)) overlap++;
  return overlap / Math.sqrt(a.size * b.size);
}