/*

  * 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.io.formats.multi;

 import org.apache.giraph.io.GiraphInputFormat;

 import org.apache.hadoop.mapreduce.InputSplit;

 import org.apache.hadoop.mapreduce.JobContext;

 import com.google.common.collect.Lists;

 import java.io.DataInput;

 import java.io.DataOutput;

 import java.io.IOException;

 import java.util.List;

 /**

  * Utility methods used by {@link MultiVertexInputFormat} and

  * {@link MultiEdgeInputFormat}

  */

 public class MultiInputUtils {

   /** Do not instantiate */

   private MultiInputUtils() {

   }

   /**

    * Get the list of input splits for all formats.

    *

    * @param context The job context

    * @param minSplitCountHint Minimum number of splits to create (hint)

    * @param inputFormats List of input formats

    * @return The list of input splits

    */

   public static List<InputSplit> getSplits(JobContext context,

       int minSplitCountHint,

       List<? extends GiraphInputFormat> inputFormats) throws IOException,

       InterruptedException {

     List<InputSplit> splits = Lists.newArrayList();

     for (int index = 0; index < inputFormats.size(); index++) {

       List<InputSplit> inputFormatSplits =

           inputFormats.get(index).getSplits(context, minSplitCountHint);

       for (InputSplit split : inputFormatSplits) {

         splits.add(new InputSplitWithInputFormatIndex(split, index));

       }

     }

     return splits;

   }

   /**

    * Write input split info to DataOutput. Input split belongs to one of the

    * formats.

    *

    * @param inputSplit InputSplit

    * @param dataOutput DataOutput

    * @param inputFormats List of input formats

    */

   public static void writeInputSplit(InputSplit inputSplit,

       DataOutput dataOutput,

       List<? extends GiraphInputFormat> inputFormats) throws IOException {

     if (inputSplit instanceof InputSplitWithInputFormatIndex) {

       InputSplitWithInputFormatIndex split =

           (InputSplitWithInputFormatIndex) inputSplit;

       int index = split.getInputFormatIndex();

       dataOutput.writeInt(index);

       inputFormats.get(index).writeInputSplit(split.getSplit(), dataOutput);

     } else {

       throw new IllegalStateException("writeInputSplit: Got InputSplit which " +

           "was not created by multi input: " + inputSplit.getClass().getName());

     }

   }

   /**

    * Read input split info from DataInput. Input split belongs to one of the

    * formats.

    *

    * @param dataInput DataInput

    * @param inputFormats List of input formats

    * @return InputSplit

    */

   public static InputSplit readInputSplit(

       DataInput dataInput,

       List<? extends GiraphInputFormat> inputFormats) throws IOException,

       ClassNotFoundException {

     int index = dataInput.readInt();

     InputSplit split = inputFormats.get(index).readInputSplit(dataInput);

     return new InputSplitWithInputFormatIndex(split, index);

   }

 }