/*
    * 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.framework.block;
  
  import java.util.Iterator;
  
  import org.apache.giraph.block_app.framework.piece.AbstractPiece;
  import org.apache.giraph.function.Consumer;
  import org.apache.giraph.function.Supplier;
  
  import com.google.common.collect.AbstractIterator;
  import com.google.common.collect.Iterators;
  
  /**
   * Block that repeats another block until toQuit supplier returns true,
   * but at most given number of times.
   *
   * If toQuit returns true on first run, block is not going
   * to be executed at all.
   */
  @SuppressWarnings("rawtypes")
  public final class RepeatUntilBlock implements Block {
    private final Block block;
    private final int repeatTimes;
    private final Supplier<Boolean> toQuit;
  
    public RepeatUntilBlock(
        int repeatTimes, Block block, Supplier<Boolean> toQuit) {
      this.block = block;
      this.repeatTimes = repeatTimes;
      this.toQuit = toQuit;
    }
  
    /**
     * Repeat unlimited number of times, until toQuit supplier returns true.
     */
    public static Block unlimited(Block block, Supplier<Boolean> toQuit) {
      return new RepeatUntilBlock(Integer.MAX_VALUE, block, toQuit);
    }
  
    @Override
    public Iterator<AbstractPiece> iterator() {
      return Iterators.concat(new AbstractIterator<Iterator<AbstractPiece>>() {
        private int index = 0;
  
        @Override
        protected Iterator<AbstractPiece> computeNext() {
          if (index >= repeatTimes || Boolean.TRUE.equals(toQuit.get())) {
            return endOfData();
          }
          index++;
          return block.iterator();
        }
      });
    }
  
    @Override
    public void forAllPossiblePieces(Consumer<AbstractPiece> consumer) {
      block.forAllPossiblePieces(consumer);
    }
  
    @Override
    public PieceCount getPieceCount() {
      return PieceCount.createUnknownCount();
    }
  
    @Override
    public String toString() {
      return "RepeatUntilBlock(" + repeatTimes + " * " + block + ")";
    }
  }