/*
    * 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.Collections;
  import java.util.Iterator;
  
  import org.apache.giraph.block_app.framework.piece.AbstractPiece;
  import org.apache.giraph.function.Consumer;
  import org.apache.giraph.function.primitive.IntSupplier;
  
  import com.google.common.collect.Iterables;
  
  /**
   * Block that repeats another block given number of times.
   */
  @SuppressWarnings("rawtypes")
  public final class RepeatBlock implements Block {
    private final Block block;
    private final boolean constantRepeatTimes;
    private final IntSupplier repeatTimes;
  
    public RepeatBlock(final int repeatTimes, Block block) {
      this.block = block;
      this.constantRepeatTimes = true;
      this.repeatTimes = new IntSupplier() {
        @Override
        public int get() {
          return repeatTimes;
        }
      };
    }
  
    /**
     * Creates a repeat block, that before starting execution takes number of
     * iterations from the given supplier.
     *
     * This allows number of iterations to be dynamic, and depend on
     * execution that happens before.
     * Note - it doesn't allow for number of repetitions to change during the
     * loop itself - as it is supplier is called only when this block gets
     * its turn.
     */
    public RepeatBlock(IntSupplier repeatTimes, Block block) {
      this.block = block;
      this.constantRepeatTimes = false;
      this.repeatTimes = repeatTimes;
    }
  
    /**
     * Create a repeat block that executes unlimited number of times.
     *
     * Should rarely be used, as it will cause application never to finish,
     * unless other unconventional ways of termination are used.
     */
    public static Block unlimited(Block block) {
      return new RepeatBlock(Integer.MAX_VALUE, block);
    }
  
    @Override
    public Iterator<AbstractPiece> iterator() {
      return Iterables.concat(
          Collections.nCopies(repeatTimes.get(), block)).iterator();
    }
  
    @Override
    public void forAllPossiblePieces(Consumer<AbstractPiece> consumer) {
      block.forAllPossiblePieces(consumer);
    }
  
    @Override
    public PieceCount getPieceCount() {
      return constantRepeatTimes ?
          block.getPieceCount().multiply(repeatTimes.get()) :
          PieceCount.createUnknownCount();
    }
  
    @Override
    public String toString() {
      return "RepeatBlock(" + repeatTimes + " * " + block + ")";
    }
  }