from __future__ import annotations

import secrets
import time
import logging

logger = logging.getLogger(__name__)

PAIRING_CODE_LENGTH = 8
PAIRING_CODE_EXPIRY_SECONDS = 600
PAIRING_CODE_CHARS = "ABCDEFGHJKMNPQRSTUVWXYZ23456789"  # 无歧义: 排除 0/O/1/I

PAIRING_APPROVED_MESSAGE = (
    "Your access has been approved. "
    "You can now interact with this iMessage bot."
)


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

    def generate_code(self, peer_id: str) -> str:
        self._cleanup_expired()
        code = "".join(secrets.choice(PAIRING_CODE_CHARS) for _ in range(PAIRING_CODE_LENGTH))
        self._pending[peer_id] = {
            "code": code,
            "created_at": time.monotonic(),
            "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.monotonic() - entry["created_at"] > PAIRING_CODE_EXPIRY_SECONDS:
            del self._pending[peer_id]
            return False

        if secrets.compare_digest(entry["code"], code.upper().strip()):
            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) -> None:
        self._approved.discard(peer_id)
        self._pending.pop(peer_id, None)

    def _cleanup_expired(self):
        now = time.monotonic()
        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")