/*
    * Copyright (C) 2011 The Guava Authors
    *
    * Licensed 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 com.google.common.collect;
  
  import static com.google.common.collect.BoundType.CLOSED;
  import static com.google.common.collect.BoundType.OPEN;
  
  import com.google.common.annotations.GwtCompatible;
  import com.google.common.annotations.GwtIncompatible;
  import com.google.common.collect.Multiset.Entry;
  
  import java.util.Comparator;
  import java.util.Iterator;
  import java.util.NavigableSet;
  import java.util.NoSuchElementException;
  import java.util.SortedSet;
  
  import javax.annotation.Nullable;
  
  /**
   * Provides static utility methods for creating and working with
   * {@link SortedMultiset} instances.
   *
   * @author Louis Wasserman
   */
  @GwtCompatible(emulated = true)
  final class SortedMultisets {
    private SortedMultisets() {
    }
  
    /**
     * A skeleton implementation for {@link SortedMultiset#elementSet}.
     */
    static class ElementSet<E> extends Multisets.ElementSet<E> implements
        SortedSet<E> {
      private final SortedMultiset<E> multiset;
  
      ElementSet(SortedMultiset<E> multiset) {
        this.multiset = multiset;
      }
  
      @Override final SortedMultiset<E> multiset() {
        return multiset;
      }
  
      @Override public Comparator<? super E> comparator() {
        return multiset().comparator();
      }
  
      @Override public SortedSet<E> subSet(E fromElement, E toElement) {
        return multiset().subMultiset(fromElement, CLOSED, toElement, OPEN).elementSet();
      }
  
      @Override public SortedSet<E> headSet(E toElement) {
        return multiset().headMultiset(toElement, OPEN).elementSet();
      }
  
      @Override public SortedSet<E> tailSet(E fromElement) {
        return multiset().tailMultiset(fromElement, CLOSED).elementSet();
      }
  
      @Override public E first() {
        return getElementOrThrow(multiset().firstEntry());
      }
  
      @Override public E last() {
        return getElementOrThrow(multiset().lastEntry());
      }
    }
  
    /**
     * A skeleton navigable implementation for {@link SortedMultiset#elementSet}.
     */
    @GwtIncompatible("Navigable")
    static class NavigableElementSet<E> extends ElementSet<E> implements NavigableSet<E> {
      NavigableElementSet(SortedMultiset<E> multiset) {
        super(multiset);
      }
  
      @Override
      public E lower(E e) {
        return getElementOrNull(multiset().headMultiset(e, OPEN).lastEntry());
      }
  
      @Override
     public E floor(E e) {
       return getElementOrNull(multiset().headMultiset(e, CLOSED).lastEntry());
     }
 
     @Override
     public E ceiling(E e) {
       return getElementOrNull(multiset().tailMultiset(e, CLOSED).firstEntry());
     }
 
     @Override
     public E higher(E e) {
       return getElementOrNull(multiset().tailMultiset(e, OPEN).firstEntry());
     }
 
     @Override
     public NavigableSet<E> descendingSet() {
       return new NavigableElementSet<E>(multiset().descendingMultiset());
     }
 
     @Override
     public Iterator<E> descendingIterator() {
       return descendingSet().iterator();
     }
 
     @Override
     public E pollFirst() {
       return getElementOrNull(multiset().pollFirstEntry());
     }
 
     @Override
     public E pollLast() {
       return getElementOrNull(multiset().pollLastEntry());
     }
 
     @Override
     public NavigableSet<E> subSet(
         E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
       return new NavigableElementSet<E>(multiset().subMultiset(
           fromElement, BoundType.forBoolean(fromInclusive),
           toElement, BoundType.forBoolean(toInclusive)));
     }
 
     @Override
     public NavigableSet<E> headSet(E toElement, boolean inclusive) {
       return new NavigableElementSet<E>(
           multiset().headMultiset(toElement, BoundType.forBoolean(inclusive)));
     }
 
     @Override
     public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
       return new NavigableElementSet<E>(
           multiset().tailMultiset(fromElement, BoundType.forBoolean(inclusive)));
     }
   }
 
   private static <E> E getElementOrThrow(Entry<E> entry) {
     if (entry == null) {
       throw new NoSuchElementException();
     }
     return entry.getElement();
   }
 
   private static <E> E getElementOrNull(@Nullable Entry<E> entry) {
     return (entry == null) ? null : entry.getElement();
   }
 }