f: allow short final collection

Author: matiasedgeandnode

packages/horizon/contracts/payments/collectors/RecurringCollector.sol

@@ -365,13 +365,16 @@ contract RecurringCollector is EIP712, GraphDirectory, Authorizable, IRecurringC
         bytes16 _agreementId,
         uint256 _tokens
     ) private view returns (uint256) {
-        // if canceled by the payer allow collection up to the cancelation time
+        bool canceledOrElapsed = _agreement.state == AgreementState.CanceledByPayer ||
+            block.timestamp > _agreement.endsAt;
         uint256 canceledOrNow = _agreement.state == AgreementState.CanceledByPayer
             ? _agreement.canceledAt
             : block.timestamp;
 
-        // allow collection till endsAt (at most)
-        uint256 collectionEnd = Math.min(canceledOrNow, _agreement.endsAt);
+        // if canceled by the payer allow collection till canceledAt
+        // if elapsed allow collection till endsAt
+        // if both are true, use the earlier one
+        uint256 collectionEnd = canceledOrElapsed ? Math.min(canceledOrNow, _agreement.endsAt) : block.timestamp;
         uint256 collectionStart = _agreementCollectionStartAt(_agreement);
         require(
             collectionEnd != collectionStart,
@@ -380,14 +383,18 @@ contract RecurringCollector is EIP712, GraphDirectory, Authorizable, IRecurringC
         require(collectionEnd > collectionStart, RecurringCollectorFinalCollectionDone(_agreementId, collectionStart));
 
         uint256 collectionSeconds = collectionEnd - collectionStart;
-        require(
-            collectionSeconds >= _agreement.minSecondsPerCollection,
-            RecurringCollectorCollectionTooSoon(
-                _agreementId,
-                uint32(collectionSeconds),
-                _agreement.minSecondsPerCollection
-            )
-        );
+        // Check that the collection window is long enough
+        // If the agreement is canceled or elapsed, allow a shorter collection window
+        if (!canceledOrElapsed) {
+            require(
+                collectionSeconds >= _agreement.minSecondsPerCollection,
+                RecurringCollectorCollectionTooSoon(
+                    _agreementId,
+                    uint32(collectionSeconds),
+                    _agreement.minSecondsPerCollection
+                )
+            );
+        }
         require(
             collectionSeconds <= _agreement.maxSecondsPerCollection,
             RecurringCollectorCollectionTooLate(