# """
# Snowflake ID 生成器，适配三台 MySQL 服务器（IP 尾号 251/252/253）。
# """
# import os
# import socket
# import threading
# import time
# import warnings
# from typing import Dict, Optional
#
# # Snowflake 位分配：41-bit 时间戳 | 5-bit 机房 | 5-bit 节点 | 12-bit 自增序列
# EPOCH_MS = 1704067200000  # 2024-01-01 00:00:00 UTC
# WORKER_ID_BITS = 5
# DATACENTER_ID_BITS = 5
# SEQUENCE_BITS = 12
#
# MAX_WORKER_ID = (1 << WORKER_ID_BITS) - 1
# MAX_DATACENTER_ID = (1 << DATACENTER_ID_BITS) - 1
# SEQUENCE_MASK = (1 << SEQUENCE_BITS) - 1
#
# WORKER_SHIFT = SEQUENCE_BITS
# DATACENTER_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS
# TIMESTAMP_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS + DATACENTER_ID_BITS
#
# # 默认映射：将三台 MySQL 服务器 IP（或尾段）映射到 worker_id
# # DEFAULT_IP_WORKER_MAP: Dict[str, int] = {
# #     "251": 1,
# #     "252": 2,
# #     "253": 3,
# # }
#
#
# # 单机
# DEFAULT_IP_WORKER_MAP: Dict[str, int] = {
#     "168": 1,
# }
#
#
# def _now_ms() -> int:
#     return int(time.time() * 1000)
#
#
# def _wait_next_ms(last_ts: int) -> int:
#     ts = _now_ms()
#     while ts <= last_ts:
#         ts = _now_ms()
#     return ts
#
#
# def _get_host_ip() -> str:
#     """获取当前主机的主 IP 地址。"""
#     s = None
#     try:
#         s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
#         # 连接一个无需真实可达的地址，只为获取本机出站 IP
#         s.connect(("10.255.255.255", 1))
#         ip = s.getsockname()[0]
#     except Exception:
#         ip = socket.gethostbyname(socket.gethostname())
#     finally:
#         if s is not None:
#             s.close()
#     return ip
#
#
# def resolve_worker_id(
#     ip_worker_map: Optional[Dict[str, int]] = None,
#     override_ip: Optional[str] = None,
# ) -> int:
#     """
#     根据主机 IP 推导 worker_id。
#     - 优先读取环境变量 SNOWFLAKE_WORKER_IP 作为 IP。
#     - 其次使用 override_ip。
#     - 再次使用本机 IP。
#     - 支持完整 IP 匹配和末段匹配（如 "192.168.0.251" 或 "251"）。
#     """
#     ip_worker_map = ip_worker_map or DEFAULT_IP_WORKER_MAP
#     chosen_ip = os.getenv("SNOWFLAKE_WORKER_IP") or override_ip or _get_host_ip()
#     if chosen_ip in ip_worker_map:
#         return ip_worker_map[chosen_ip]
#     last_octet = chosen_ip.split(".")[-1]
#     if last_octet in ip_worker_map:
#         return ip_worker_map[last_octet]
#     raise ValueError(
#         f"未能为 IP {chosen_ip} 匹配到 worker_id，请检查映射或设置 SNOWFLAKE_WORKER_IP。"
#     )
#
#
# class SnowflakeGenerator:
#     """
#     线程安全的 Snowflake ID 生成器。
#     默认 datacenter_id=0；worker_id 将根据 IP 映射推导。
#     """
#
#     def __init__(
#         self,
#         datacenter_id: int = 0,
#         worker_id: Optional[int] = None,
#         epoch_ms: int = EPOCH_MS,
#         ip_worker_map: Optional[Dict[str, int]] = None,
#     ):
#         self.datacenter_id = datacenter_id
#         self.worker_id = worker_id or resolve_worker_id(ip_worker_map)
#         self.epoch_ms = epoch_ms
#
#         if not 0 <= self.worker_id <= MAX_WORKER_ID:
#             raise ValueError(f"worker_id 必须在 0-{MAX_WORKER_ID} 之间")
#         if not 0 <= self.datacenter_id <= MAX_DATACENTER_ID:
#             raise ValueError(f"datacenter_id 必须在 0-{MAX_DATACENTER_ID} 之间")
#
#         self.sequence = 0
#         self.last_timestamp = -1
#         self._lock = threading.Lock()
#
#     def next_id(self) -> int:
#         """生成下一个全局唯一 ID。"""
#         with self._lock:
#             timestamp = _now_ms()
#
#             if timestamp < self.last_timestamp:
#                 # 时钟回拨保护
#                 raise RuntimeError("检测到系统时钟回拨，停止发号。")
#
#             if timestamp == self.last_timestamp:
#                 self.sequence = (self.sequence + 1) & SEQUENCE_MASK
#                 if self.sequence == 0:
#                     timestamp = _wait_next_ms(self.last_timestamp)
#             else:
#                 self.sequence = 0
#
#             self.last_timestamp = timestamp
#             return (
#                 ((timestamp - self.epoch_ms) << TIMESTAMP_SHIFT)
#                 | (self.datacenter_id << DATACENTER_SHIFT)
#                 | (self.worker_id << WORKER_SHIFT)
#                 | self.sequence
#             )
#
#
# # 默认生成器：datacenter_id=0，worker_id 按 IP 映射自动推导
# def _build_default_generator() -> SnowflakeGenerator:
#     try:
#         return SnowflakeGenerator()
#     except ValueError as exc:
#         warnings.warn(
#             f"Snowflake 默认生成器未找到匹配的 IP，退回 worker_id=0。详情：{exc}",
#             RuntimeWarning,
#         )
#         return SnowflakeGenerator(worker_id=0)
#
#
# default_generator = _build_default_generator()
#
#
# def next_id() -> int:
#     """便捷函数，返回默认生成器的下一个 ID。"""
#     return default_generator.next_id()
#
#
#