import random
import time
import logging

logger = logging.getLogger(__name__)

PAIRING_CODE_LENGTH = 6
PAIRING_CODE_EXPIRY_SECONDS = 3600
MAX_PENDING_PER_CHANNEL = 3

PAIRING_APPROVED_MESSAGE = "BlueBubbles DM pairing approved. You can now send iMessages to this channel."


class PairingManager:
    def __init__(self):
        self._pending: dict[str, dict] = {}
        self._approved: set[str] = set()

    def generate_code(self, peer_id: str) -> str:
        self._cleanup_expired()
        active = sum(1 for v in self._pending.values() if v["status"] == "pending")
        if active >= MAX_PENDING_PER_CHANNEL:
            raise RuntimeError(f"Maximum pending pairings ({MAX_PENDING_PER_CHANNEL}) reached")

        code = "".join(str(random.randint(0, 9)) for _ in range(PAIRING_CODE_LENGTH))
        self._pending[peer_id] = {
            "code": code,
            "created_at": time.time(),
            "status": "pending",
        }
        return code

    def verify_code(self, peer_id: str, code: str) -> bool:
        entry = self._pending.get(peer_id)
        if not entry:
            return False

        if time.time() - entry["created_at"] > PAIRING_CODE_EXPIRY_SECONDS:
            del self._pending[peer_id]
            return False

        if entry["code"] == code:
            entry["status"] = "approved"
            self._approved.add(peer_id)
            return True

        return False

    def is_approved(self, peer_id: str) -> bool:
        return peer_id in self._approved

    def revoke(self, peer_id: str):
        self._approved.discard(peer_id)
        self._pending.pop(peer_id, None)

    def _cleanup_expired(self):
        now = time.time()
        expired = [
            pid for pid, entry in self._pending.items() if (now - entry["created_at"]) > PAIRING_CODE_EXPIRY_SECONDS
        ]
        for pid in expired:
            del self._pending[pid]

    def pending_count(self) -> int:
        self._cleanup_expired()
        return sum(1 for v in self._pending.values() if v["status"] == "pending")