/*

  * 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.GiraphConfiguration;

 import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;

 import org.apache.giraph.factories.ComputationFactory;

 import org.apache.giraph.graph.Computation;

 import org.apache.giraph.jython.JythonComputation;

 import org.apache.giraph.jython.JythonGiraphComputation;

 import org.apache.giraph.jython.JythonOptions;

 import org.apache.giraph.jython.JythonUtils;

 import org.apache.giraph.scripting.ScriptLoader;

 import org.apache.log4j.Logger;

 import org.python.core.PyObject;

 import org.python.util.PythonInterpreter;

 import static com.google.common.base.Preconditions.checkNotNull;

 import static org.apache.giraph.scripting.ScriptLoader.SCRIPTS_TO_LOAD;

 /**

  * Factory for creating Jython Computation from python scripts

  */

 public class JythonComputationFactory implements ComputationFactory {

   /** The Jython compute function, cached here for fast access */

   private static volatile PyObject JYTHON_COMPUTATION_MODULE;

   /** Logger */

   private static final Logger LOG = Logger.getLogger(JythonUtils.class);

   /**

    * Set static python computation module stored

    *

    * @param mod python computation module

    */

   private static void setPythonComputationModule(PyObject mod) {

     JYTHON_COMPUTATION_MODULE = mod;

   }

   /**

    * Get python computation module stored

    *

    * @return python computation module

    */

   private static PyObject getPythonComputationModule() {

     return JYTHON_COMPUTATION_MODULE;

   }

   @Override

   public void initialize(ImmutableClassesGiraphConfiguration conf) {

     PythonInterpreter interpreter = JythonUtils.getInterpreter();

     String className = computationName(conf);

     PyObject pyComputationModule = interpreter.get(className);

     checkNotNull(pyComputationModule,

         "Could not find Jython Computation class " + className +

         " in loaded scripts: " + ScriptLoader.getLoadedScripts());

     setPythonComputationModule(pyComputationModule);

   }

   @Override

   public Computation createComputation(

       ImmutableClassesGiraphConfiguration conf) {

     checkNotNull(JYTHON_COMPUTATION_MODULE,

         "Jython Computation class not set in loaded scripts: " +

         ScriptLoader.getLoadedScripts());

     PyObject pyComputationObj = JYTHON_COMPUTATION_MODULE.__call__();

     Object computeObj = pyComputationObj.__tojava__(JythonComputation.class);

     if (!(computeObj instanceof JythonComputation)) {

       throw new IllegalStateException("getComputation: Jython object " +

           computationName(conf) + " is not a JythonComputation");

     }

     JythonComputation jythonCompute = (JythonComputation) computeObj;

     conf.configureIfPossible(jythonCompute);

     JythonGiraphComputation giraphCompute =

         new JythonGiraphComputation(jythonCompute);

     giraphCompute.setConf(conf);

     jythonCompute.setGiraphCompute(giraphCompute);

     return giraphCompute;

   }

   @Override

   public void checkConfiguration(ImmutableClassesGiraphConfiguration conf) {

     if (SCRIPTS_TO_LOAD.isDefaultValue(conf)) {

       throw new IllegalStateException("checkConfiguration: " +

           SCRIPTS_TO_LOAD.getKey() + " not set in configuration");

     }

     if (!JythonOptions.JYTHON_COMPUTATION_CLASS_NAME.contains(conf)) {

       throw new IllegalStateException("checkConfiguration: " +

           JythonOptions.JYTHON_COMPUTATION_CLASS_NAME.getKey() +

           " not set in configuration");

     }

   }

   @Override

   public String computationName(GiraphConfiguration conf) {

     return JythonOptions.JYTHON_COMPUTATION_CLASS_NAME.get(conf);

   }

 }