content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.ambari.server.orm.dao;
  
  import java.util.Collection;
  import java.util.List;
  
  import jakarta.persistence.EntityManager;
  import jakarta.persistence.TypedQuery;
  
  import org.apache.ambari.server.orm.RequiresSession;
  
  import com.google.inject.Inject;
  import com.google.inject.Provider;
  import com.google.inject.persist.Transactional;
  
  /**
   * CRUD DAO.
   *
   * @param <E> entity class
   * @param <K> primary key class
   */
  public class CrudDAO<E, K> {
    @Inject
    Provider<EntityManager> entityManagerProvider;
    @Inject
    DaoUtils daoUtils;
  
    private Class<E> entityClass;
  
    /**
     * Constructor.
     *
     * @param entityClass entity class
     */
    public CrudDAO(Class<E> entityClass) {
      this.entityClass = entityClass;
    }
  
    /**
     * Retrieves entity by primary key.
     *
     * @param pk primary key
     * @return null if there is no suitable entity
     */
    @RequiresSession
    public E findByPK(K pk) {
      return entityManagerProvider.get().find(entityClass, pk);
    }
  
    /**
     * Retrieves all entities.
     *
     * @return list of all entities
     */
    @RequiresSession
    public List<E> findAll() {
      final TypedQuery<E> query = entityManagerProvider.get().createQuery("SELECT entity FROM " + entityClass.getSimpleName() + " entity", entityClass);
      return daoUtils.selectList(query);
    }
  
    /**
     * Retrieves the maximum ID from the entities.
     *
     * @param idColName name of the column that corresponds to the ID.
     * @return maximum ID, or 0 if none exist.
     */
    @RequiresSession
    public Long findMaxId(String idColName) {
      final TypedQuery<Long> query = entityManagerProvider.get().createQuery("SELECT MAX(entity." + idColName + ") FROM "
          + entityClass.getSimpleName() + " entity", Long.class);
      // May be null if no results.
      Long result = daoUtils.selectOne(query);
      return result == null ? 0 : result;
    }
  
    /**
     * Creates entity.
     *
     * @param entity entity to create
     */
    @Transactional
    protected void create(E entity) {
      entityManagerProvider.get().persist(entity);
    }
  
    /**
     * Updates entity.
     *
     * @param entity entity to update
     * @return updated entity
     */
    @Transactional
    public E merge(E entity) {
      return entityManagerProvider.get().merge(entity);
    }
  
    /**
     * Refreshes entity.
     *
     * @param entity entity to refresh
     */
    @Transactional
    public void refresh(E entity) {
      entityManagerProvider.get().refresh(entity);
    }
  
    /**
     * Deletes entity.
     *
     * @param entity entity to delete
     */
    @Transactional
    public void remove(E entity) {
      entityManagerProvider.get().remove(merge(entity));
      entityManagerProvider.get().getEntityManagerFactory().getCache().evictAll();
    }
  
    /**
     * Deletes entities.
     *
     * @param entities entities to delete
     */
    @Transactional
    public void remove(Collection<E> entities) {
      for (E entity : entities) {
        entityManagerProvider.get().remove(merge(entity));
      }
      entityManagerProvider.get().getEntityManagerFactory().getCache().evictAll();
    }
  
    /**
     * Deletes entity by PK.
     *
     * @param pk primary key
     */
    @Transactional
    public void removeByPK(K pk) {
      remove(findByPK(pk));
    }
  }
  