loosen id tag expiration constraints (Closes steve-community#48)

reason: until now, we always used current time + some hours (set in UI)
for id tag expiration, regardless of an expiry date the database had
for this id tag. the idea behind was to better control two possible
situations:
- no expiry date: set an explicit one to prevent the station caching it,
such that after some time, it _has_ to ask Steve.
- expiry date too far in the future: since business rules, contracts,
conditions and therefore expiration of id tags might change, we wanted
to prevent the stations from storing id tags for too long in the white
list.

both of these ideas resulted from the thinking that Steve is the single
point of truth and that we did not trust charging station implementations.
therefore, we always preferred a charging station asking us frequently
about the id tag status. with this commit, this constraint is loosened.

Author: goekay

src/main/java/de/rwth/idsg/steve/service/OcppTagServiceImpl.java

@@ -4,6 +4,8 @@
 import de.rwth.idsg.steve.repository.SettingsRepository;
 import de.rwth.idsg.steve.service.dto.UnidentifiedIncomingObject;
 import jooq.steve.db.tables.records.OcppTagRecord;
+import lombok.AccessLevel;
+import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import ocpp.cp._2015._10.AuthorizationData;
 import ocpp.cs._2015._10.AuthorizationStatus;
@@ -30,18 +32,14 @@ public class OcppTagServiceImpl implements OcppTagService {
 
     @Override
     public List<AuthorizationData> getAuthDataOfAllTags() {
-        int hoursToExpire = settingsRepository.getHoursToExpire();
-
         return ocppTagRepository.getRecords()
-                                .map(new AuthorisationDataMapper(hoursToExpire));
+                                .map(new AuthorisationDataMapper());
     }
 
     @Override
     public List<AuthorizationData> getAuthData(List<String> idTagList) {
-        int hoursToExpire = settingsRepository.getHoursToExpire();
-
         return ocppTagRepository.getRecords(idTagList)
-                                .map(new AuthorisationDataMapper(hoursToExpire));
+                                .map(new AuthorisationDataMapper());
     }
 
     @Override
@@ -59,6 +57,10 @@ public IdTagInfo getIdTagInfo(String idTag) {
             idTagInfo.setStatus(AuthorizationStatus.INVALID);
             invalidOcppTagService.processNewUnidentified(idTag);
         } else {
+
+            DateTime expiryDate = record.getExpiryDate();
+            boolean isExpiryDateSet = expiryDate != null;
+
             if (record.getBlocked()) {
                 log.error("The user with idTag '{}' is BLOCKED.", idTag);
                 idTagInfo.setStatus(AuthorizationStatus.BLOCKED);
@@ -67,16 +69,18 @@ public IdTagInfo getIdTagInfo(String idTag) {
 //                log.warn("The user with idTag '{}' is ALREADY in another transaction.", idTag);
 //                idTagInfo.setStatus(ocpp.cs._2012._06.AuthorizationStatus.CONCURRENT_TX);
 
-            } else if (record.getExpiryDate() != null && DateTime.now().isAfter(record.getExpiryDate())) {
+            } else if (isExpiryDateSet && DateTime.now().isAfter(record.getExpiryDate())) {
                 log.error("The user with idTag '{}' is EXPIRED.", idTag);
                 idTagInfo.setStatus(AuthorizationStatus.EXPIRED);
 
             } else {
                 log.debug("The user with idTag '{}' is ACCEPTED.", idTag);
                 idTagInfo.setStatus(AuthorizationStatus.ACCEPTED);
 
-                int hours = settingsRepository.getHoursToExpire();
-                idTagInfo.setExpiryDate(DateTime.now().plusHours(hours));
+                // If the database contains an actual expiry, use it. Otherwise, calculate an expiry for cached info
+                DateTime expiry = isExpiryDateSet ? expiryDate : DateTime.now().plusHours(settingsRepository.getHoursToExpire());
+
+                idTagInfo.setExpiryDate(expiry);
                 idTagInfo.setParentIdTag(record.getParentIdTag());
             }
         }
@@ -87,18 +91,13 @@ public IdTagInfo getIdTagInfo(String idTag) {
     // Private helpers
     // -------------------------------------------------------------------------
 
+    @RequiredArgsConstructor(access = AccessLevel.PRIVATE)
     private static class AuthorisationDataMapper implements RecordMapper<OcppTagRecord, AuthorizationData> {
-        private final DateTime nowDt;
-        private final DateTime cacheExpiry;
 
-        AuthorisationDataMapper(int hoursToExpire) {
-            this.nowDt = DateTime.now();
-            this.cacheExpiry = nowDt.plus(hoursToExpire);
-        }
+        private final DateTime nowDt = DateTime.now();
 
         @Override
         public AuthorizationData map(OcppTagRecord record) {
-
             String idTag = record.getIdTag();
             String parentIdTag = record.getParentIdTag();
             DateTime expiryDate = record.getExpiryDate();
@@ -119,7 +118,7 @@ public AuthorizationData map(OcppTagRecord record) {
             } else {
                 authStatus = ocpp.cp._2015._10.AuthorizationStatus.ACCEPTED;
                 // When accepted, set the additional fields
-                idTagInfo.setExpiryDate(cacheExpiry);
+                idTagInfo.setExpiryDate(expiryDate);
                 idTagInfo.setParentIdTag(parentIdTag);
             }
             idTagInfo.setStatus(authStatus);