/*
    * 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.shardingsphere.data.pipeline.core.util;
  
  import org.apache.commons.lang3.Range;
  
  import java.math.BigInteger;
  import java.util.Iterator;
  import java.util.NoSuchElementException;
  
  /**
   * Interval to range iterator.
   * <p>
   * It's not thread-safe.
   * </p>
   */
  public final class IntervalToRangeIterator implements Iterator<Range<Long>> {
      
      private final BigInteger maximum;
      
      private final BigInteger interval;
      
      private BigInteger current;
      
      public IntervalToRangeIterator(final long minimum, final long maximum, final long interval) {
          if (minimum > maximum) {
              throw new IllegalArgumentException("minimum greater than maximum");
          }
          if (interval < 0L) {
              throw new IllegalArgumentException("interval is less than zero");
          }
          this.maximum = BigInteger.valueOf(maximum);
          this.interval = BigInteger.valueOf(interval);
          this.current = BigInteger.valueOf(minimum);
      }
      
      @Override
      public boolean hasNext() {
          return current.compareTo(maximum) <= 0;
      }
      
      @Override
      public Range<Long> next() {
          if (!hasNext()) {
              throw new NoSuchElementException("");
          }
          BigInteger upperLimit = min(maximum, current.add(interval));
          Range<Long> result = Range.between(current.longValue(), upperLimit.longValue());
          current = upperLimit.add(BigInteger.ONE);
          return result;
      }
      
      private BigInteger min(final BigInteger one, final BigInteger another) {
          return one.compareTo(another) < 0 ? one : another;
      }
  }