Paypal Express French translation issue + Duplicate transaction accepted as valid

Hello!

ZenCart 1.5.6c
PHP 5.6.40 (I know...)

Quick summary:

1. Paypal WPP French translation is breaking Paypal Express confirmation => easy fix below
2. Transactions rejected as duplicates by Paypal Express appear successful in ZC => I don't have a fix for that

After successfully upgrading to ZC1.5.6c + utf8mb4 to support emojis, I made a quick Paypal Express live purchase and it failed this way:

1. Create Cart
2. Proceed to purchase using Paypal Express
3. Transaction is a success
4. Paypal table is not updated on: PHP Fatal error: 1406: Data too long for column 'payment_type' at row 1 :: INSERT INTO paypal
5. User is not sent back to the purchase confirmation page (WARNING: An Error occurred, please refresh the page and try again.)

Indeed the payment_type is using define('MODULE_PAYMENT_PAYPALWPP_EC_TEXT_TYPE', 'Encaissement avec PayPal Expresst'); found in /includes/languages/french/modules/payment/paypalwpp.php and the resulting field was Encaissement avec PayPal Expresst which is then concatenated with (instant) and ends up at 42 characters when the table only allows 40.

I trimmed the translation (and fixed the typo) to PayPal Express (instant), inserted the missing paypal table entry manually and the world was in balance again.

BEFORE:
ZC Order -> OK
Paypal Payment -> OK
Paypal ZC update -> Failed

AFTER:
ZC Order -> OK
Paypal Payment -> OK
Paypal ZC update -> OK (manually)


Then I tried again Paypal Express to validate the fix. This is where it gets a little more complicated.

1. Cart was still alive from previous attempt
2. Modified the cart (remove/add a different item) but SAME global price
3. Validate purchase choosing Paypal
4. I reached the successful purchase page WITHOUT CONFIRMING Paypal payment => Basically I never saw the Paypal popup
5. ZC thinks the transaction is a success (order+Paypal) but there is no Paypal payment

This is the return from Paypal (selected lines):

Code:

---

Mar-12-2021 15:23:42 (1615559022)
before_process - EC-5
resultset:
Array
(
[TOKEN] => EC-2EX728800F188990X
[SUCCESSPAGEREDIRECTREQUESTED] => false
[TIMESTAMP] => 2021-03-12T14:23:41Z
[ACK] => SuccessWithWarning
[VERSION] => 124.0
[BUILD] => 55384336
[L_ERRORCODE0] => 11607
[L_SHORTMESSAGE0] => Duplicate Request
[L_LONGMESSAGE0] => A successful transaction has already been completed for this token.
[L_SEVERITYCODE0] => Warning
[PAYMENTINFO_0_TRANSACTIONTYPE] => cart
[PAYMENTINFO_0_PAYMENTTYPE] => instant
[PAYMENTINFO_0_ORDERTIME] => 2021-03-12T13:52:11Z
[PAYMENTINFO_0_AMT] => 2.50
[PAYMENTINFO_0_FEEAMT] => 0.42
[PAYMENTINFO_0_TAXAMT] => 0.00
[PAYMENTINFO_0_CURRENCYCODE] => EUR
[PAYMENTINFO_0_PAYMENTSTATUS] => Completed
[PAYMENTINFO_0_PENDINGREASON] => None
[PAYMENTINFO_0_REASONCODE] => None
[PAYMENTINFO_0_ERRORCODE] => 0
[PAYMENTINFO_0_ACK] => Success
[CURL_ERRORS] =>
)

---

ZC Order -> OK (but it shouldn't)
Paypal Payment -> Failed (SuccessWithWarning)
Paypal ZC update -> OK (but it shouldn't)


So it seems that there was 2 issues:

1/ ZenCart kept the same CART ID even though it had been modified (a left-over from the failed paypal insertion that seems to be preceding the cart validation/deletion)
2/ Paypal gently DENIES the transaction but this send a "SuccessWithWarning" thinking it was really the same transaction and acknowledging the success of the PREVIOUS one

Note that Paypal also offers a setting in the Pro Seller's page to either accept or reject payments that seem to be duplicates.
By default it was on "reject", it has been updated to "accept" but I haven't tested that yet.

Julien