{
  "type": "object",
  "required": ["type", "details"],
  "properties": {
    "type": {
      "type": "string",
      "enum": ["credit_card", "debit_card", "paypal", "bank_transfer"]
    },
    "details": {
      "type": "object",
      "properties": {
        "cardNumber": {
          "type": "string",
          "pattern": "^[0-9]{13,19}$"
        },
        "expiryMonth": {
          "type": "integer",
          "minimum": 1,
          "maximum": 12
        },
        "expiryYear": {
          "type": "integer",
          "minimum": 2024
        },
        "cvv": {
          "type": "string",
          "pattern": "^[0-9]{3,4}$"
        },
        "accountId": {
          "type": "string"
        }
      }
    }
  }
}