/*
    * (c) Copyright 2006-2020 by rapiddweller GmbH & Volker Bergmann. All rights reserved.
    *
    * Redistribution and use in source and binary forms, with or without
    * modification, is permitted under the terms of the
    * GNU General Public License.
    *
    * For redistributing this software or a derivative work under a license other
    * than the GPL-compatible Free Software License as defined by the Free
   * Software Foundation or approved by OSI, you must first obtain a commercial
   * license to this software product from rapiddweller GmbH & Volker Bergmann.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * WITHOUT A WARRANTY OF ANY KIND. ALL EXPRESS OR IMPLIED CONDITIONS,
   * REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE
   * HEREBY EXCLUDED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  package com.rapiddweller.benerator.wrapper;
  
  import com.rapiddweller.benerator.Generator;
  import com.rapiddweller.benerator.GeneratorContext;
  import com.rapiddweller.benerator.IllegalGeneratorStateException;
  import com.rapiddweller.benerator.InvalidGeneratorSetupException;
  import com.rapiddweller.benerator.util.AbstractGenerator;
  import com.rapiddweller.common.IOUtil;
  import com.rapiddweller.common.ThreadAware;
  import com.rapiddweller.format.DataContainer;
  import com.rapiddweller.format.DataIterator;
  import com.rapiddweller.format.DataSource;
  import com.rapiddweller.format.util.ThreadLocalDataContainer;
  
  /**
   * {@link Generator} implementation which reads and forwards data from a {@link DataSource}.<br/><br/>
   * Created: 24.07.2011 08:58:09
   *
   * @param <E> the type parameter
   * @author Volker Bergmann
   * @since 0.7.0
   */
  public class DataSourceGenerator<E> extends AbstractGenerator<E> {
  
    private DataSource<E> source;
    private DataIterator<E> iterator;
    private final ThreadLocalDataContainer<E> container = new ThreadLocalDataContainer<>();
  
    // constructors ----------------------------------------------------------------------------------------------------
  
    /**
     * Instantiates a new Data source generator.
     */
    public DataSourceGenerator() {
      this(null);
    }
  
    /**
     * Instantiates a new Data source generator.
     *
     * @param source the source
     */
    public DataSourceGenerator(DataSource<E> source) {
      this.source = source;
      this.iterator = null;
    }
  
    // properties ------------------------------------------------------------------------------------------------------
  
    /**
     * Gets source.
     *
     * @return the source
     */
    public DataSource<E> getSource() {
      return source;
    }
  
    /**
     * Sets source.
     *
     * @param source the source
     */
    public void setSource(DataSource<E> source) {
      if (this.source != null) {
        throw new IllegalGeneratorStateException("Mutating an initialized generator");
      }
      this.source = source;
    }
  
    // Generator interface ---------------------------------------------------------------------------------------------
  
    @Override
   public boolean isParallelizable() {
     return false;
   }
 
   @Override
   public boolean isThreadSafe() {
     return (source instanceof ThreadAware && ((ThreadAware) source).isThreadSafe());
   }
 
   @Override
   public Class<E> getGeneratedType() {
     return source.getType();
   }
 
   @Override
   public void init(GeneratorContext context) {
     if (source == null) {
       throw new InvalidGeneratorSetupException("source", "is null");
     }
     super.init(context);
   }
 
   @Override
   public ProductWrapper<E> generate(ProductWrapper<E> wrapper) {
     try {
       assertInitialized();
       if (iterator == null) {
         iterator = source.iterator(); // iterator initialized lazily to reflect context state at invocation
       }
       DataContainer<E> tmp = iterator.next(container.get());
       if (tmp == null) {
         IOUtil.close(iterator);
         return null;
       }
       return wrapper.wrap(tmp.getData());
     } catch (Exception e) {
       throw new IllegalGeneratorStateException("Generation failed: ", e);
     }
   }
 
   @Override
   public void reset() {
     IOUtil.close(iterator);
     iterator = null;
     super.reset();
   }
 
   @Override
   public void close() {
     IOUtil.close(iterator);
     super.close();
     IOUtil.close(source);
   }
 
   // java.lang.Object overrides --------------------------------------------------------------------------------------
 
   @Override
   public String toString() {
     return getClass().getSimpleName() + "[" + source + ']';
   }
 
 }