/*
    * 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 com.tapas.evidence.repository.data;
  
  import java.io.Serializable;
  import java.util.List;
  
  import javax.persistence.EntityManager;
  import javax.persistence.EntityNotFoundException;
  import javax.persistence.NonUniqueResultException;
  import javax.persistence.Query;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.security.core.context.SecurityContextHolder;
  
  import com.tapas.evidence.credential.EvidenceUserDetails;
  import com.tapas.evidence.entity.TenantAware;
  import com.tapas.evidence.entity.user.Tenant;
  
  /**
   * @author Michal Bocek
   * @since 1.0.0
   */
  public class CrudRepositoryImpl<T, ID extends Serializable> implements CrudRepository<T, ID> {
  
  	private static final Logger log = LoggerFactory.getLogger(CrudRepositoryImpl.class);
  	
  	private final EntityManager entityManager;
  
  	private final Class<T> entityClass;
  	
  	public CrudRepositoryImpl(Class<T> entityClass, EntityManager entityManager) {
  		this.entityClass = entityClass;
  		this.entityManager = entityManager;
  	}
  	
  	@Override
  	public void create(T entity) {
  		if (log.isTraceEnabled()) {
  			log.trace("Creating entity: " + entity.getClass());
  			log.trace("  With contents: " + entity); 
  		}
  		if (entity instanceof TenantAware) {
  			Long tenantId = ((EvidenceUserDetails)SecurityContextHolder.getContext().getAuthentication().getPrincipal()).getTenantId();
  			Tenant tenant = this.entityManager.find(Tenant.class, tenantId);
  			((TenantAware)entity).setTenant(tenant);
  		}
  		entityManager.persist(entity);
  	}
  
  	@Override
  	public T read(ID id) {
  		if (log.isTraceEnabled()) {
  			log.trace("Reading entity for id: " + id);
  		}
  		final T entry ;
  		if (entityClass.isInstance(TenantAware.class)) {
  			entry = readTenantAware(id);
  		} else {
  			entry = this.entityManager.find(this.entityClass, id);
  		}	
  		if (entry == null) {
  			throw new EntityNotFoundException("Entity for class " + this.entityClass + " with id " + id
  					+ " can not be found!");
  		} 
  		return entry;
  	}
  
  	@SuppressWarnings({ "rawtypes", "unchecked" })
  	private T readTenantAware(ID id) {
  		final T entry;
  		final Long tenantId = ((EvidenceUserDetails)SecurityContextHolder.getContext().getAuthentication().getPrincipal()).getTenantId();
  		final Query query = this.entityManager.createQuery("from " + this.entityClass.getName() + " where tenant.id = :tenantId");
  		query.setParameter("tenantId", tenantId);
  		final List resultList = query.getResultList();
  		if (resultList.size() == 1) {
  			entry = (T)resultList.get(0);
  		} else if (resultList.size() > 1) {
  			throw new NonUniqueResultException("Non unique entity for class " + this.entityClass + " with id " + id
  				+ "!");
  		} else {
  			entry = null;
 		}
 		return entry;
 	}
 
 	@Override
 	public T update(T entity) {
 		if (log.isTraceEnabled()) {
 			log.trace("Updating entity: " + entity.getClass());
 			log.trace("  With contents: " + entity); 
 		}
 		return entityManager.merge(entity);
 	}
 
 	@Override
 	public void delete(T entity) {
 		if (log.isTraceEnabled()) {
 			log.trace("Deleting entity: " + entity.getClass());
 			log.trace("  With contents: " + entity); 
 		}
 		entityManager.remove(entity);
 	}
 
 	@Override
 	public T findById(ID id) {
 		final T result;
 		if (entityClass.isInstance(TenantAware.class)) {
 			result = readTenantAware(id);
 		} else {
 			result = this.entityManager.find(entityClass, id);
 		}
 		return result;
 	}
 
 	@Override
 	@SuppressWarnings("unchecked")
 	public List<T> findAll() {
 		if (log.isTraceEnabled()) {
 			log.trace("Reading all entities");
 		}
 		final Query query;
 		if (entityClass.isInstance(TenantAware.class)) {
 			final Long tenantId = ((EvidenceUserDetails)SecurityContextHolder.getContext().getAuthentication().getPrincipal()).getTenantId();
 			final String queryString = "from " + this.entityClass.getName() + "where tenant.id = :tenantId";
 			query = this.entityManager.createQuery(queryString);
 			query.setParameter("tenantId", tenantId);
 		} else {
 			final String queryString = "from " + this.entityClass.getName();
 			query = this.entityManager.createQuery(queryString);
 		}
 		return query.getResultList();
 	}
 
 }