content: /*
   * Copyright (C) 2012-2023 52°North Spatial Information Research GmbH
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published
   * by the Free Software Foundation.
   *
   * If the program is linked with libraries which are licensed under one of
   * the following licenses, the combination of the program with the linked
   * library is not considered a "derivative work" of the program:
   *
   *     - Apache License, version 2.0
   *     - Apache Software License, version 1.0
   *     - GNU Lesser General Public License, version 3
   *     - Mozilla Public License, versions 1.0, 1.1 and 2.0
   *     - Common Development and Distribution License (CDDL), version 1.0
   *
   * Therefore the distribution of the program linked with libraries licensed
   * under the aforementioned licenses, is permitted by the copyright holders
   * if the distribution is compliant with both the GNU General Public
   * License version 2 and the aforementioned licenses.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
   * Public License for more details.
   */
  package org.n52.sos.ds.hibernate.util;
  
  import java.util.Set;
  import java.util.stream.Collectors;
  
  import javax.persistence.metamodel.EntityType;
  import javax.persistence.metamodel.Metamodel;
  
  import org.hibernate.Session;
  
  import com.google.common.collect.ImmutableSet;
  
  public final class HibernateMetadataCache {
      private static HibernateMetadataCache instance;
  
      private static final Object LOCK = new Object();
  
      private final Set<String> supportedEntities;
  
      private Metamodel classMetadata;
  
      private HibernateMetadataCache(Session session) {
          this.classMetadata = initClassMetadata(session);
          this.supportedEntities = initSupportedEntities(classMetadata);
      }
  
      private Metamodel initClassMetadata(Session session) {
          return session.getEntityManagerFactory().getMetamodel();
          // return
          // ImmutableMap.copyOf(session.getSessionFactory().getAllClassMetadata());
      }
  
      private Set<String> initSupportedEntities(Metamodel classMetadata) {
          return ImmutableSet
                  .copyOf(classMetadata.getEntities().stream().map(e -> e.getName()).collect(Collectors.toSet()));
          // return ImmutableSet.copyOf(classMetadata.keySet());
      }
  
      public boolean isColumnSupported(Class<?> entityClass, String column) {
          if (isEntitySupported(entityClass)) {
              EntityType<?> metadata = this.classMetadata.entity(entityClass);
              for (String propertyName : metadata.getAttributes().stream().map(a -> a.getName())
                      .collect(Collectors.toSet())) {
                  if (propertyName.equals(column)) {
                      return true;
                  }
              }
          }
          return false;
      }
  
      public boolean isEntitySupported(Class<?> entityClass) {
          return entityClass != null
                  && (isEntitySupported(entityClass.getName()) || isEntitySupported(entityClass.getSimpleName()));
      }
  
      public boolean isEntitySupported(String entityClass) {
          return this.supportedEntities.contains(entityClass);
      }
  
      public static void init(Session session) {
          synchronized (LOCK) {
              instance = new HibernateMetadataCache(session);
          }
      }
  
      public static HibernateMetadataCache getInstance() {
          synchronized (LOCK) {
              if (instance != null) {
                  return instance;
              } else {
                  throw new IllegalStateException("Not initialized");
              }
          }
      }
  }
  