import logging
import random
import string
import time

logger = logging.getLogger(__name__)

CODE_TTL_SECONDS = 600
CODE_LENGTH = 6
MAX_GENERATE_PER_PEER_PER_MINUTE = 3


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

    async def generate_code(self, peer_id: str) -> str | None:
        now = time.time()
        timestamps = self._gen_timestamps.setdefault(peer_id, [])
        timestamps[:] = [ts for ts in timestamps if now - ts < 60]

        if len(timestamps) >= MAX_GENERATE_PER_PEER_PER_MINUTE:
            logger.warning("Pairing code rate limited for peer %s", peer_id)
            return None

        code = "".join(random.choices(string.digits, k=CODE_LENGTH))
        self._codes[peer_id] = (code, now + CODE_TTL_SECONDS)
        timestamps.append(now)
        return code

    async def verify(self, peer_id: str, code: str) -> bool:
        now = time.time()
        entry = self._codes.get(peer_id)
        if entry is None:
            return False

        saved_code, expires_at = entry
        if now > expires_at:
            del self._codes[peer_id]
            return False

        return saved_code == code

    def cleanup(self):
        now = time.time()
        expired = [k for k, (_, exp) in self._codes.items() if now > exp]
        for k in expired:
            del self._codes[k]