from __future__ import annotations

import logging
import secrets
import time

logger = logging.getLogger(__name__)

CODE_TTL = 300


class DingTalkPairing:
    def __init__(self):
        self._codes: dict[str, tuple[str, float]] = {}

    async def generate_code(self, peer_id: str) -> str:
        code = f"{secrets.randbelow(1_000_000):06d}"
        self._codes[peer_id] = (code, time.monotonic())
        self._evict_expired()
        return code

    async def verify_code(self, peer_id: str, code: str) -> bool:
        self._evict_expired()
        entry = self._codes.get(peer_id)
        if entry is None:
            return False
        stored_code, _ts = entry
        if stored_code == code:
            del self._codes[peer_id]
            return True
        return False

    def _evict_expired(self) -> None:
        now = time.monotonic()
        expired = [pid for pid, (_code, ts) in self._codes.items() if now - ts > CODE_TTL]
        for pid in expired:
            del self._codes[pid]