/*
    * 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.block_app.migration;
  
  import java.util.Iterator;
  
  import org.apache.giraph.block_app.framework.AbstractBlockFactory;
  import org.apache.giraph.block_app.framework.block.Block;
  import org.apache.giraph.block_app.framework.block.PieceCount;
  import org.apache.giraph.block_app.framework.block.SequenceBlock;
  import org.apache.giraph.block_app.framework.piece.AbstractPiece;
  import org.apache.giraph.block_app.framework.piece.Piece;
  import org.apache.giraph.block_app.migration.MigrationAbstractComputation.MigrationFullAbstractComputation;
  import org.apache.giraph.block_app.migration.MigrationMasterCompute.MigrationFullMasterCompute;
  import org.apache.giraph.combiner.MessageCombiner;
  import org.apache.giraph.conf.GiraphConfiguration;
  import org.apache.giraph.function.Consumer;
  import org.apache.hadoop.io.Writable;
  import org.apache.hadoop.io.WritableComparable;
  
  import com.google.common.collect.AbstractIterator;
  import com.google.common.collect.Iterators;
  
  /**
   * BlockFactory to extend when using drop-in migration
   */
  public abstract class MigrationFullBlockFactory
      extends AbstractBlockFactory<MigrationSuperstepStage> {
  
    @Override
    public MigrationSuperstepStage createExecutionStage(
        GiraphConfiguration conf) {
      return new MigrationSuperstepStageImpl();
    }
  
    @Override
    protected Class<? extends MigrationWorkerContext> getWorkerContextValueClass(
        GiraphConfiguration conf) {
      return MigrationWorkerContext.class;
    }
  
    @SuppressWarnings("rawtypes")
    public <I extends WritableComparable, V extends Writable, E extends Writable,
    MR extends Writable, MS extends Writable>
    Block createMigrationAppBlock(
        Class<? extends MigrationFullAbstractComputation<I, V, E, MR, MS>>
          computationClass,
        MigrationFullMasterCompute masterCompute,
        Class<MS> messageClass,
        Class<? extends MessageCombiner<? super I, MS>> messageCombinerClass,
        GiraphConfiguration conf) {
      final MigrationPiece<I, V, E, MR, MS> piece =
          MigrationPiece.createFirstFullMigrationPiece(
              computationClass, masterCompute, messageClass,
              messageCombinerClass);
      piece.sanityTypeChecks(conf, null);
  
      return new SequenceBlock(
          new Piece<WritableComparable, Writable, Writable,
              Writable, MigrationSuperstepStage>() {
            @Override
            public MigrationSuperstepStage nextExecutionStage(
                MigrationSuperstepStage executionStage) {
              return executionStage.changedMigrationSuperstep(0);
            }
          },
          new Block() {
            private MigrationPiece curPiece = piece;
  
            @Override
            public Iterator<AbstractPiece> iterator() {
              return Iterators.concat(
                  Iterators.singletonIterator(curPiece),
                  new AbstractIterator<AbstractPiece>() {
                    @Override
                    protected AbstractPiece computeNext() {
                      curPiece = curPiece.getNextPiece();
                      if (curPiece == null) {
                        endOfData();
                      }
                      return curPiece;
                    }
                  });
            }
 
           @Override
           public void forAllPossiblePieces(Consumer<AbstractPiece> consumer) {
             consumer.apply(curPiece);
           }
 
           @Override
           public PieceCount getPieceCount() {
             return curPiece.getPieceCount();
           }
         }
     );
   }
 }