57 lines
1.7 KiB
Python
57 lines
1.7 KiB
Python
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import random
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import time
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CODE_LENGTH = 6
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CODE_TTL_SECONDS = 600
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PENDING_MAX = 3
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RATE_LIMIT_SECONDS = 3600
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class WeChatKFPairing:
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def __init__(self):
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self._pending: dict[str, dict] = {}
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self._user_last_code_at: dict[str, float] = {}
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def generate_code(self, external_user_id: str) -> str | None:
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now = time.time()
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if external_user_id in self._user_last_code_at:
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elapsed = now - self._user_last_code_at[external_user_id]
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if elapsed < RATE_LIMIT_SECONDS:
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return None
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if len(self._pending) >= PENDING_MAX:
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oldest = min(self._pending.values(), key=lambda p: p["created_at"])
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if now - oldest["created_at"] < CODE_TTL_SECONDS:
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return None
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expired_user = next(k for k, v in self._pending.items() if v == oldest)
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del self._pending[expired_user]
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code = _generate_code()
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self._pending[external_user_id] = {"code": code, "created_at": now}
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self._user_last_code_at[external_user_id] = now
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return code
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def verify(self, external_user_id: str, code: str) -> bool:
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entry = self._pending.get(external_user_id)
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if not entry:
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return False
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if time.time() - entry["created_at"] > CODE_TTL_SECONDS:
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del self._pending[external_user_id]
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return False
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if entry["code"] != code.upper().strip():
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return False
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del self._pending[external_user_id]
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return True
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def get_pending_count(self) -> int:
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return len(self._pending)
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def _generate_code() -> str:
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no_ambiguous = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789"
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return "".join(random.choices(no_ambiguous, k=CODE_LENGTH))
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