// 靓号规则：
// 1. 禁止出现数字 '4'
// 2. 全局唯一
// 3. 优先使用连号/豹子号/重复规律号，如 123-123-123, 111-111-111, 888-888-888 等

const ALLOWED_DIGITS = ['0', '1', '2', '3', '5', '6', '7', '8', '9'];

// 预定义优质靓号池 (不含 4)
const PREFERRED_PATTERNS = [
  '888-888-888',
  '666-666-666',
  '999-999-999',
  '123-123-123',
  '555-555-555',
  '333-333-333',
  '111-111-111',
  '777-777-777',
  '520-520-520',
  '135-135-135',
  '168-168-168',
  '888-666-999',
  '168-666-168',
  '123-567-890',
  '666-888-666',
  '888-999-888',
  '112-233-556',
  '888-888-666',
  '666-666-888',
  '999-888-666',
  '888-555-888',
];

// 规则辅助：判断是否包含4
export function containsFour(slug: string): boolean {
  return slug.includes('4');
}

// 动态生成符合格式无4的随机靓号 xxx-xxx-xxx
export function generateRandomNiceSlug(): string {
  const getRandomGroup = (len: number = 3) => {
    let res = '';
    for (let i = 0; i < len; i++) {
      const idx = Math.floor(Math.random() * ALLOWED_DIGITS.length);
      res += ALLOWED_DIGITS[idx];
    }
    return res;
  };

  // 随机挑选模式：连号组、重复组、或三段式
  const randType = Math.random();
  if (randType < 0.3) {
    // 豹子重复组 (如 888-555-888)
    const d1 = ALLOWED_DIGITS[Math.floor(Math.random() * ALLOWED_DIGITS.length)];
    const d2 = ALLOWED_DIGITS[Math.floor(Math.random() * ALLOWED_DIGITS.length)];
    return `${d1}${d1}${d1}-${d2}${d2}${d2}-${d1}${d1}${d1}`;
  } else if (randType < 0.6) {
    // AB-AB-AB 组 (如 12-12-12-12 或 18-18-18)
    const g = getRandomGroup(2);
    return `${g}${g[0]}-${g}${g[1]}-${g}${g[0]}`;
  }

  return `${getRandomGroup()}-${getRandomGroup()}-${getRandomGroup()}`;
}

export async function generateUniqueNiceSlug(existingSlugsCheck: (slug: string) => Promise<boolean>): Promise<string> {
  // 1. 尝试优质靓号池
  for (const preferred of PREFERRED_PATTERNS) {
    if (!containsFour(preferred)) {
      const exists = await existingSlugsCheck(preferred);
      if (!exists) {
        return preferred;
      }
    }
  }

  // 2. 尝试生成重复型/规则型靓号
  for (let i = 0; i < 100; i++) {
    const candidate = generateRandomNiceSlug();
    if (!containsFour(candidate)) {
      const exists = await existingSlugsCheck(candidate);
      if (!exists) {
        return candidate;
      }
    }
  }

  // 3. 兜底逻辑
  let fallback = `${Date.now()}`.replace(/4/g, '5').slice(-9);
  let formatted = `${fallback.slice(0, 3)}-${fallback.slice(3, 6)}-${fallback.slice(6, 9)}`;
  return formatted;
}