/*
    * Copyright 2010-2022 the original author or authors.
    *
    * Licensed 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
    *
    *    https://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.mybatis.spring.batch;
  
  import static org.springframework.util.Assert.notNull;
  import static org.springframework.util.ClassUtils.getShortName;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Optional;
  import java.util.concurrent.CopyOnWriteArrayList;
  import java.util.function.Supplier;
  
  import org.apache.ibatis.session.ExecutorType;
  import org.apache.ibatis.session.SqlSession;
  import org.apache.ibatis.session.SqlSessionFactory;
  import org.mybatis.spring.SqlSessionTemplate;
  import org.springframework.batch.item.database.AbstractPagingItemReader;
  
  /**
   * {@code org.springframework.batch.item.ItemReader} for reading database records using MyBatis in a paging fashion.
   * <p>
   * Provided to facilitate the migration from Spring-Batch iBATIS 2 page item readers to MyBatis 3.
   *
   * @author Eduardo Macarron
   *
   * @since 1.1.0
   */
  public class MyBatisPagingItemReader<T> extends AbstractPagingItemReader<T> {
  
    private String queryId;
  
    private SqlSessionFactory sqlSessionFactory;
  
    private SqlSessionTemplate sqlSessionTemplate;
  
    private Map<String, Object> parameterValues;
  
    private Supplier<Map<String, Object>> parameterValuesSupplier;
  
    public MyBatisPagingItemReader() {
      setName(getShortName(MyBatisPagingItemReader.class));
    }
  
    /**
     * Public setter for {@link SqlSessionFactory} for injection purposes.
     *
     * @param sqlSessionFactory
     *          a factory object for the {@link SqlSession}.
     */
    public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) {
      this.sqlSessionFactory = sqlSessionFactory;
    }
  
    /**
     * Public setter for the statement id identifying the statement in the SqlMap configuration file.
     *
     * @param queryId
     *          the id for the statement
     */
    public void setQueryId(String queryId) {
      this.queryId = queryId;
    }
  
    /**
     * The parameter values to be used for the query execution.
     *
     * @param parameterValues
     *          the values keyed by the parameter named used in the query string.
     */
    public void setParameterValues(Map<String, Object> parameterValues) {
      this.parameterValues = parameterValues;
    }
  
    /**
     * The parameter supplier used to get parameter values for the query execution.
     *
     * @param parameterValuesSupplier
     *          the supplier used to get values keyed by the parameter named used in the query string.
     *
     * @since 2.1.0
     */
    public void setParameterValuesSupplier(Supplier<Map<String, Object>> parameterValuesSupplier) {
      this.parameterValuesSupplier = parameterValuesSupplier;
    }
  
   /**
    * Check mandatory properties.
    *
    * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()
    */
   @Override
   public void afterPropertiesSet() throws Exception {
     super.afterPropertiesSet();
     notNull(sqlSessionFactory, "A SqlSessionFactory is required.");
     notNull(queryId, "A queryId is required.");
   }
 
   @Override
   protected void doReadPage() {
     if (sqlSessionTemplate == null) {
       sqlSessionTemplate = new SqlSessionTemplate(sqlSessionFactory, ExecutorType.BATCH);
     }
     Map<String, Object> parameters = new HashMap<>();
     if (parameterValues != null) {
       parameters.putAll(parameterValues);
     }
     Optional.ofNullable(parameterValuesSupplier).map(Supplier::get).ifPresent(parameters::putAll);
     parameters.put("_page", getPage());
     parameters.put("_pagesize", getPageSize());
     parameters.put("_skiprows", getPage() * getPageSize());
     if (results == null) {
       results = new CopyOnWriteArrayList<>();
     } else {
       results.clear();
     }
     results.addAll(sqlSessionTemplate.selectList(queryId, parameters));
   }
 
 }