banks2ff/src/adapters/gocardless/mapper.rs

@@ -14,50 +14,33 @@ pub fn map_transaction(tx: Transaction) -> Result<BankTransaction> {
     let date = chrono::NaiveDate::parse_from_str(&date_str, "%Y-%m-%d")?;
 
     let amount = Decimal::from_str(&tx.transaction_amount.amount)?;
+    validate_amount(&amount)?;
     let currency = tx.transaction_amount.currency;
+    validate_currency(&currency)?;
 
     let mut foreign_amount = None;
     let mut foreign_currency = None;
 
     if let Some(exchanges) = tx.currency_exchange {
         if let Some(exchange) = exchanges.first() {
-             if let (Some(source_curr), Some(rate_str)) = (&exchange.source_currency, &exchange.exchange_rate) {
-                 foreign_currency = Some(source_curr.clone());
-                 if let Ok(rate) = Decimal::from_str(rate_str) {
-                     // If instructedAmount is not available (it's not in our DTO yet), we calculate it.
-                     // But wait, normally instructedAmount is the foreign amount. 
-                     // If we don't have it, we estimate: foreign = amount * rate?
-                     // Actually usually: Base (Account) Amount = Foreign Amount / Rate  OR Foreign * Rate
-                     // If I have 100 EUR and rate is 1.10 USD/EUR -> 110 USD.
-                     // Let's check the GoCardless spec definition of exchangeRate. 
-                     // "exchangeRate": "Factor used to convert an amount from one currency into another. This reflects the price at which the acquirer has bought the currency."
-                     
-                     // Without strict direction, simple multiplication is risky.
-                     // ideally we should have `instructedAmount` or `unitCurrency` logic.
-                     // For now, let's assume: foreign_amount = amount * rate is NOT always correct.
-                     // BUT, usually `sourceCurrency` is the original currency.
-                     // If I spent 10 USD, and my account is EUR. 
-                     // sourceCurrency: USD. targetCurrency: EUR.
-                     // transactionAmount: -9.00 EUR.
-                     // exchangeRate: ???
-                     
-                     // Let's implement a safe calculation or just store what we have.
-                     // Actually, simply multiplying might be wrong if the rate is inverted.
-                     // Let's verify with unit tests if we had real data, but for now let's use the logic:
-                     // foreign_amount = amount * rate (if rate > 0) or amount / rate ? 
-                     
-                     // Let's look at the example in my plan: "foreign_amount = amount * currencyExchange[0].exchangeRate"
-                     // I will stick to that plan, but wrap it in a safe calculation.
-                     
-                     let calc = amount.abs() * rate; // Usually rate is positive. 
-                     // We preserve the sign of the transaction amount for the foreign amount.
-                     let sign = amount.signum();
-                     foreign_amount = Some(calc * sign);
-                 }
-             }
+            if let (Some(source_curr), Some(rate_str)) = (&exchange.source_currency, &exchange.exchange_rate) {
+                foreign_currency = Some(source_curr.clone());
+                if let Ok(rate) = Decimal::from_str(rate_str) {
+                    let calc = amount.abs() * rate;
+                    let sign = amount.signum();
+                    foreign_amount = Some(calc * sign);
+                }
+            }
         }
     }
 
+    if let Some(ref fa) = foreign_amount {
+        validate_amount(fa)?;
+    }
+    if let Some(ref fc) = foreign_currency {
+        validate_currency(fc)?;
+    }
+
     // Fallback for description: Remittance Unstructured -> Debtor/Creditor Name -> "Unknown"
     let description = tx.remittance_information_unstructured
         .or(tx.creditor_name.clone())
@@ -77,6 +60,27 @@ pub fn map_transaction(tx: Transaction) -> Result<BankTransaction> {
     })
 }
 
+fn validate_amount(amount: &Decimal) -> Result<()> {
+    let abs = amount.abs();
+    if abs > Decimal::new(1_000_000_000, 0) {
+        return Err(anyhow::anyhow!("Amount exceeds reasonable bounds: {}", amount));
+    }
+    if abs == Decimal::ZERO {
+        return Err(anyhow::anyhow!("Amount cannot be zero"));
+    }
+    Ok(())
+}
+
+fn validate_currency(currency: &str) -> Result<()> {
+    if currency.len() != 3 {
+        return Err(anyhow::anyhow!("Invalid currency code length: {}", currency));
+    }
+    if !currency.chars().all(|c| c.is_ascii_uppercase()) {
+        return Err(anyhow::anyhow!("Invalid currency code format: {}", currency));
+    }
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -144,4 +148,134 @@ mod tests {
         // Description fallback to creditor name
         assert_eq!(res.description, "US Shop");
     }
+
+    #[test]
+    fn test_validate_amount_zero() {
+        let amount = Decimal::ZERO;
+        assert!(validate_amount(&amount).is_err());
+    }
+
+    #[test]
+    fn test_validate_amount_too_large() {
+        let amount = Decimal::new(2_000_000_000, 0);
+        assert!(validate_amount(&amount).is_err());
+    }
+
+
+
+    #[test]
+    fn test_validate_currency_invalid_length() {
+        assert!(validate_currency("EU").is_err());
+        assert!(validate_currency("EURO").is_err());
+    }
+
+    #[test]
+    fn test_validate_currency_not_uppercase() {
+        assert!(validate_currency("eur").is_err());
+        assert!(validate_currency("EuR").is_err());
+    }
+
+    #[test]
+    fn test_validate_currency_valid() {
+        assert!(validate_currency("EUR").is_ok());
+        assert!(validate_currency("USD").is_ok());
+    }
+
+    #[test]
+    fn test_map_transaction_invalid_amount() {
+        let t = Transaction {
+            transaction_id: Some("125".into()),
+            booking_date: Some("2023-01-03".into()),
+            value_date: None,
+            transaction_amount: TransactionAmount {
+                amount: "0.00".into(),
+                currency: "EUR".into(),
+            },
+            currency_exchange: None,
+            creditor_name: Some("Test".into()),
+            creditor_account: None,
+            debtor_name: None,
+            debtor_account: None,
+            remittance_information_unstructured: None,
+            proprietary_bank_transaction_code: None,
+        };
+
+        assert!(map_transaction(t).is_err());
+    }
+
+    #[test]
+    fn test_map_transaction_invalid_currency() {
+        let t = Transaction {
+            transaction_id: Some("126".into()),
+            booking_date: Some("2023-01-04".into()),
+            value_date: None,
+            transaction_amount: TransactionAmount {
+                amount: "100.00".into(),
+                currency: "euro".into(),
+            },
+            currency_exchange: None,
+            creditor_name: Some("Test".into()),
+            creditor_account: None,
+            debtor_name: None,
+            debtor_account: None,
+            remittance_information_unstructured: None,
+            proprietary_bank_transaction_code: None,
+        };
+
+        assert!(map_transaction(t).is_err());
+    }
+
+    #[test]
+    fn test_map_transaction_invalid_foreign_amount() {
+        let t = Transaction {
+            transaction_id: Some("127".into()),
+            booking_date: Some("2023-01-05".into()),
+            value_date: None,
+            transaction_amount: TransactionAmount {
+                amount: "-10.00".into(),
+                currency: "EUR".into(),
+            },
+            currency_exchange: Some(vec![CurrencyExchange {
+                source_currency: Some("USD".into()),
+                exchange_rate: Some("0".into()), // This will make foreign_amount zero
+                unit_currency: None,
+                target_currency: Some("EUR".into()),
+            }]),
+            creditor_name: Some("Test".into()),
+            creditor_account: None,
+            debtor_name: None,
+            debtor_account: None,
+            remittance_information_unstructured: None,
+            proprietary_bank_transaction_code: None,
+        };
+
+        assert!(map_transaction(t).is_err());
+    }
+
+    #[test]
+    fn test_map_transaction_invalid_foreign_currency() {
+        let t = Transaction {
+            transaction_id: Some("128".into()),
+            booking_date: Some("2023-01-06".into()),
+            value_date: None,
+            transaction_amount: TransactionAmount {
+                amount: "-10.00".into(),
+                currency: "EUR".into(),
+            },
+            currency_exchange: Some(vec![CurrencyExchange {
+                source_currency: Some("usd".into()), // lowercase
+                exchange_rate: Some("1.10".into()),
+                unit_currency: None,
+                target_currency: Some("EUR".into()),
+            }]),
+            creditor_name: Some("Test".into()),
+            creditor_account: None,
+            debtor_name: None,
+            debtor_account: None,
+            remittance_information_unstructured: None,
+            proprietary_bank_transaction_code: None,
+        };
+
+        assert!(map_transaction(t).is_err());
+    }
 }