import secrets
import time
import logging

logger = logging.getLogger(__name__)

CODE_TTL_SECONDS = 600
CODE_CLEANUP_INTERVAL = 300


class MessengerPairing:
    def __init__(self):
        self._codes: dict[str, dict] = {}
        self._last_cleanup = time.monotonic()

    async def generate_code(self, peer_id: str, account_id: str = "default") -> str:
        self._evict_expired()
        key = f"{account_id}:{peer_id}"

        code = str(secrets.randbelow(900000) + 100000)
        self._codes[key] = {
            "code": code,
            "created_at": time.monotonic(),
            "peer_id": peer_id,
            "account_id": account_id,
        }

        logger.info(f"messenger pairing code generated for {peer_id}: {code}")
        return code

    async def verify_code(self, peer_id: str, code: str, account_id: str = "default") -> bool:
        self._evict_expired()
        key = f"{account_id}:{peer_id}"

        entry = self._codes.get(key)
        if not entry:
            return False

        result = entry["code"] == code
        if result:
            del self._codes[key]
            logger.info(f"messenger pairing verified for {peer_id}")

        return result

    def _evict_expired(self):
        now = time.monotonic()
        if now - self._last_cleanup < CODE_CLEANUP_INTERVAL:
            return
        self._last_cleanup = now

        expired = [k for k, v in self._codes.items() if now - v["created_at"] > CODE_TTL_SECONDS]
        for k in expired:
            del self._codes[k]