compacted query and count methods for endpointinforservice considerin…

…g redundant code

service/endpoint/internal/src/main/java/org/eclipse/kapua/service/endpoint/internal/EndpointInfoServiceImpl.java

@@ -46,6 +46,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.function.Predicate;
 
 /**
  * {@link EndpointInfoService} implementation.
@@ -212,13 +213,17 @@ public EndpointInfo find(KapuaId scopeId, KapuaId endpointInfoId)
         }
     }
 
-    @Override
-    public EndpointInfoListResult query(KapuaQuery query) throws KapuaException {
-        return query(query, EndpointInfo.ENDPOINT_TYPE_RESOURCE);
-    }
-
-    @Override
-    public EndpointInfoListResult query(KapuaQuery query, String section)
+    /**
+     * Traverse the account hierarchy bottom-up to search for {@link EndpointInfo} respecting the given query,
+     * performing for each layer the given operationToPerform until the given emptinessPredicate dictates to stop OR when endpoints of the same section are found in one layer
+     * In other terms, this method applies a given function to the "nearest usable endpoints", aka the ones that I see in a given scopeID
+     *
+     * @param query  The query to filter the {@link EndpointInfo}s.
+     * @param section section of {@link EndpointInfo} where we want to search the information
+     * @param operationToPerform  function to apply at each layer
+     * @param emptinessPredicate  predicate that dictates to stop the traversal when false
+     */
+    public Object traverse(KapuaQuery query, String section, myBifunction<EntityManager, KapuaQuery, Object, KapuaException> operationToPerform, Predicate<Object> emptinessPredicate)
             throws KapuaException {
         ArgumentValidator.notNull(query, "query");
 
@@ -232,14 +237,14 @@ public EndpointInfoListResult query(KapuaQuery query, String section)
         //
         // Do Query
         return entityManagerSession.doAction(em -> {
-            EndpointInfoListResult endpointInfoListResult = EndpointInfoDAO.query(em, query);
+            Object res = operationToPerform.apply(em, query);
 
-            if (endpointInfoListResult.isEmpty() && query.getScopeId() != null) { //query did not find results
+            if (emptinessPredicate.test(res) && query.getScopeId() != null) { //query did not find results
 
                 KapuaId originalScopeId = query.getScopeId();
 
                 do {
-                    // First check if there are any endpoint AT ALL specified in this scope
+                    // First check if there are any endpoint AT ALL specified in this scope/layer
                     if (countAllEndpointsInScope(em, query.getScopeId(), section)) {
                         // There are endpoints (even not matching the query), exit because I found the "nearest usable" endpoints which don't have what I'm searching
                         break;
@@ -255,14 +260,14 @@ public EndpointInfoListResult query(KapuaQuery query, String section)
                         break;
                     }
                     query.setScopeId(account.getScopeId());
-                    endpointInfoListResult = EndpointInfoDAO.query(em, query);
+                    res = operationToPerform.apply(em, query);
                 }
-                while (query.getScopeId() != null && endpointInfoListResult.isEmpty());
+                while (query.getScopeId() != null && emptinessPredicate.test(res));
 
                 query.setScopeId(originalScopeId);
             }
 
-            return endpointInfoListResult;
+            return res;
         });
     }
 
@@ -272,59 +277,30 @@ public long count(KapuaQuery query) throws KapuaException {
     }
 
     @Override
-    public long count(KapuaQuery query, String section)
-            throws KapuaException {
-        ArgumentValidator.notNull(query, "query");
-
-        //
-        // Check Access
-        AUTHORIZATION_SERVICE.checkPermission(
-                PERMISSION_FACTORY.newPermission(EndpointInfoDomains.ENDPOINT_INFO_DOMAIN, Actions.read, query.getScopeId())
-        );
-        addSectionToPredicate(query, section);
-
-        //
-        // Do count
-        return entityManagerSession.doAction(em -> {
-            long endpointInfoCount = EndpointInfoDAO.count(em, query);
-
-            if (endpointInfoCount == 0 && query.getScopeId() != null) {
-
-                KapuaId originalScopeId = query.getScopeId();
-
-                do {
-                    // First check if there are any endpoint AT ALL specified in this scope
-                    if (countAllEndpointsInScope(em, query.getScopeId(), section)) {
-                        // There are endpoints (even not matching the query), exit because I found the "nearest usable" endpoints which don't have what I'm searching
-                        break;
-                    }
-                    Account account = KapuaSecurityUtils.doPrivileged(() -> ACCOUNT_SERVICE.find(query.getScopeId()));
-
-                    if (account == null) {
-                        throw new KapuaEntityNotFoundException(Account.TYPE, query.getScopeId());
-                    }
-                    if (account.getScopeId() == null) {
-                        // Query was originally on root account, and querying on parent scope id would mean querying in null,
-                        // i.e. querying on all accounts. Since that's not what we want, break away.
-                        break;
-                    }
-
-                    query.setScopeId(account.getScopeId());
-                    endpointInfoCount = EndpointInfoDAO.count(em, query);
-                }
-                while (query.getScopeId() != null && endpointInfoCount == 0);
+    public long count(KapuaQuery query, String section) throws KapuaException {
+        return (long) traverse(query, section, EndpointInfoDAO::count, a -> (long)a == 0);
+    }
 
-                query.setScopeId(originalScopeId);
-            }
+    @Override
+    public EndpointInfoListResult query(KapuaQuery query) throws KapuaException {
+        return query(query, EndpointInfo.ENDPOINT_TYPE_RESOURCE);
+    }
 
-            return endpointInfoCount;
-        });
+    public EndpointInfoListResult query(KapuaQuery query, String section) throws KapuaException {
+        return (EndpointInfoListResult) traverse(query, section, EndpointInfoDAO::query, a -> ((EndpointInfoListResult)a).isEmpty());
     }
 
     //
-    // Private methods
+    // Private methods and interfaces
     //
 
+    //this interface is created solely because java complains if you pass lambdas throwing checked exception
+    //to overcome this, I created this interface which is a custom form of a Bifunction throwing the checked KapuaException
+    @FunctionalInterface
+    private interface myBifunction<A, B, C, E extends KapuaException> {
+        C apply(A input1, B input2) throws E;
+    }
+
     /**
      * Checks whether another {@link EndpointInfo} already exists with the given values.
      *