/*
    * 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.giraph.jython.factories;
  
  import org.apache.giraph.conf.ClassConfOption;
  import org.apache.giraph.conf.GiraphConfigurationSettable;
  import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;
  import org.apache.giraph.conf.StrConfOption;
  import org.apache.giraph.factories.ValueFactory;
  import org.apache.giraph.graph.GraphType;
  import org.apache.giraph.jython.JythonOptions;
  import org.apache.giraph.jython.JythonUtils;
  import org.apache.giraph.jython.wrappers.JythonWritableWrapper;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.io.Writable;
  import org.apache.log4j.Logger;
  import org.python.core.PyObject;
  
  /**
   * Base class for Jython factories. These factories are used to create user's
   * graph value types (IVEMM).
   *
   * @param <W> writable type
   */
  public abstract class JythonFactoryBase<W extends Writable>
      implements ValueFactory<W>, GiraphConfigurationSettable {
    /** Logger */
    private static final Logger LOG = Logger.getLogger(JythonFactoryBase.class);
  
    /** Name of class in Jython implementing Vertex ID */
    private String jythonClassName;
    /** Whether the Jython type needs a wrapper */
    private boolean useWrapper;
  
    /**
     * Get the options associated with this graph type
     *
     * @return options
     */
    public abstract JythonOptions.JythonGraphTypeOptions getOptions();
  
    /**
     * Get the graph type this factory is meant for
     *
     * @return GraphType
     */
    public GraphType getGraphType() {
      return getOptions().getGraphType();
    }
  
    /**
     * The {@link org.apache.hadoop.conf.Configuration} option for setting the
     * Jython class name in this factory implementation.
     *
     * @return {@link org.apache.giraph.conf.StrConfOption}
     */
    public StrConfOption jythonClassNameOption() {
      return getOptions().getJythonClassNameOption();
    }
  
    /**
     * The interface class for the value type.
     * For Vertex ID this is {@link org.apache.hadoop.io.WritableComparable}, for
     * others this is {@link org.apache.hadoop.io.Writable}
     *
     * @return interface class for the value type
     */
    public Class<? extends Writable> writableValueClass() {
      return getGraphType().interfaceClass();
    }
  
    @Override
    public void setConf(
        ImmutableClassesGiraphConfiguration conf) {
      jythonClassName = jythonClassNameOption().get(conf);
      useWrapper = conf.getValueNeedsWrappers().get(getGraphType());
    }
  
    /**
     * Instantiate a new value Jython object.
     *
     * @return new value object
     */
    public Writable newJythonClassInstance() {
     if (useWrapper) {
       PyObject jythonObj = JythonUtils.newInstance(jythonClassName);
       JythonWritableWrapper wrapper = new JythonWritableWrapper(jythonObj);
       return wrapper;
     } else {
       return JythonUtils.newInstance(jythonClassName, writableValueClass());
     }
   }
 
   /**
    * Use this factory in the {@link org.apache.hadoop.conf.Configuration}
    *
    * @param conf {@link org.apache.hadoop.conf.Configuration}
    * @param jythonClassName Name of Jython class implementing value type
    */
   public void useThisFactory(Configuration conf, String jythonClassName) {
     if (LOG.isInfoEnabled()) {
       LOG.info("useThisFactory: Setting up Jython factory for " +
           getGraphType() + " reading " + " using Jython type " +
           jythonClassName);
     }
 
     ClassConfOption factoryOption = getGraphType().factoryClassOption();
     factoryOption.set(conf, getClass());
 
     jythonClassNameOption().set(conf, jythonClassName);
   }
 }