fix: Externalize debt position duedate extraction (#118)

src/main/java/it/gov/pagopa/payhub/activities/connector/debtposition/DebtPositionServiceImpl.java

@@ -2,16 +2,14 @@
 
 import it.gov.pagopa.payhub.activities.connector.auth.AuthnService;
 import it.gov.pagopa.payhub.activities.connector.debtposition.client.DebtPositionClient;
+import it.gov.pagopa.payhub.activities.util.DebtPositionUtilities;
 import it.gov.pagopa.pu.debtposition.dto.generated.DebtPositionDTO;
-import it.gov.pagopa.pu.debtposition.dto.generated.InstallmentDTO;
 import it.gov.pagopa.pu.debtposition.dto.generated.IupdSyncStatusUpdateDTO;
 import org.springframework.context.annotation.Lazy;
 import org.springframework.stereotype.Service;
 
 import java.time.OffsetDateTime;
 import java.util.Map;
-import java.util.Objects;
-import java.util.Optional;
 
 @Lazy
 @Service
@@ -36,13 +34,6 @@ public OffsetDateTime checkAndUpdateInstallmentExpiration(Long debtPositionId) {
         String accessToken = authnService.getAccessToken();
         DebtPositionDTO debtPositionDTO = debtPositionClient.checkAndUpdateInstallmentExpiration(accessToken, debtPositionId);
 
-        Optional<OffsetDateTime> dueDate = debtPositionDTO.getPaymentOptions().stream()
-                .flatMap(paymentOption -> paymentOption.getInstallments().stream())
-                .filter(installment -> InstallmentDTO.StatusEnum.UNPAID.equals(installment.getStatus()))
-                .map(InstallmentDTO::getDueDate)
-                .filter(Objects::nonNull)
-                .min(OffsetDateTime::compareTo);
-
-        return dueDate.orElse(null);
+        return DebtPositionUtilities.calcDebtPositionNextDueDate(debtPositionDTO);
     }
 }

src/main/java/it/gov/pagopa/payhub/activities/util/DebtPositionUtilities.java

@@ -0,0 +1,23 @@
+package it.gov.pagopa.payhub.activities.util;
+
+import it.gov.pagopa.pu.debtposition.dto.generated.DebtPositionDTO;
+import it.gov.pagopa.pu.debtposition.dto.generated.InstallmentDTO;
+
+import java.time.OffsetDateTime;
+import java.util.Comparator;
+import java.util.Objects;
+
+public class DebtPositionUtilities {
+    private DebtPositionUtilities(){}
+
+    /** It will return the min dueDate of all active installments */
+    public static OffsetDateTime calcDebtPositionNextDueDate(DebtPositionDTO debtPositionDTO){
+        return debtPositionDTO.getPaymentOptions().stream()
+                .flatMap(po ->po.getInstallments().stream())
+                .filter(i -> InstallmentDTO.StatusEnum.UNPAID.equals(i.getStatus()))
+                .map(InstallmentDTO::getDueDate)
+                .filter(Objects::nonNull)
+                .min(Comparator.naturalOrder())
+                .orElse(null);
+    }
+}