36 lines
1.3 KiB
Python
36 lines
1.3 KiB
Python
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"""Transit (self-transfer) detection rules.
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Identifies transactions that are internal transfers between the victim's
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own accounts (e.g. bank -> Alipay -> WeChat) and should NOT be counted
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as fraud loss.
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"""
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from app.models.transaction import TransactionRecord
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SELF_KEYWORDS = ["本人", "自己", "余额", "充值", "提现", "银行卡转入", "银行卡充值"]
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def is_self_transfer(tx: TransactionRecord, known_self_accounts: list[str]) -> bool:
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"""Check if a transaction is an inter-account transfer by the victim."""
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counterparty = (tx.counterparty_name or "").lower()
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remark = (tx.remark or "").lower()
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# Rule 1: counterparty matches known self accounts
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for acct in known_self_accounts:
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if acct and acct.lower() in counterparty:
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return True
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# Rule 2: counterparty contains self-transfer keywords
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for kw in SELF_KEYWORDS:
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if kw in counterparty or kw in remark:
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return True
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# Rule 3: counterparty references another payment app owned by victim
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app_keywords = ["支付宝", "微信", "银行卡", "数字钱包"]
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victim_patterns = [f"{app}-" for app in app_keywords] + app_keywords
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for pat in victim_patterns:
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if pat in counterparty:
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if tx.direction.value == "out":
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return True
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return False
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