package org.eclipse.aether.util.version;
   
   /*
    * 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.
   */
  
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.Set;
  
  import org.eclipse.aether.version.Version;
  import org.eclipse.aether.version.VersionRange;
  
  /**
   * A union of version ranges.
   */
  final class UnionVersionRange
      implements VersionRange
  {
  
      private final Set<VersionRange> ranges;
  
      private final Bound lowerBound;
  
      private final Bound upperBound;
  
      public static VersionRange from( VersionRange... ranges )
      {
          if ( ranges == null )
          {
              return from( Collections.<VersionRange>emptySet() );
          }
          return from( Arrays.asList( ranges ) );
      }
  
      public static VersionRange from( Collection<? extends VersionRange> ranges )
      {
          if ( ranges != null && ranges.size() == 1 )
          {
              return ranges.iterator().next();
          }
          return new UnionVersionRange( ranges );
      }
  
      private UnionVersionRange( Collection<? extends VersionRange> ranges )
      {
          if ( ranges == null || ranges.isEmpty() )
          {
              this.ranges = Collections.emptySet();
              lowerBound = null;
              upperBound = null;
          }
          else
          {
              this.ranges = new HashSet<>( ranges );
              Bound lowerBound = null, upperBound = null;
              for ( VersionRange range : this.ranges )
              {
                  Bound lb = range.getLowerBound();
                  if ( lb == null )
                  {
                      lowerBound = null;
                      break;
                  }
                  else if ( lowerBound == null )
                  {
                      lowerBound = lb;
                  }
                  else
                  {
                      int c = lb.getVersion().compareTo( lowerBound.getVersion() );
                      if ( c < 0 || ( c == 0 && !lowerBound.isInclusive() ) )
                      {
                          lowerBound = lb;
                      }
                  }
              }
              for ( VersionRange range : this.ranges )
              {
                  Bound ub = range.getUpperBound();
                  if ( ub == null )
                  {
                     upperBound = null;
                     break;
                 }
                 else if ( upperBound == null )
                 {
                     upperBound = ub;
                 }
                 else
                 {
                     int c = ub.getVersion().compareTo( upperBound.getVersion() );
                     if ( c > 0 || ( c == 0 && !upperBound.isInclusive() ) )
                     {
                         upperBound = ub;
                     }
                 }
             }
             this.lowerBound = lowerBound;
             this.upperBound = upperBound;
         }
     }
 
     public boolean containsVersion( Version version )
     {
         for ( VersionRange range : ranges )
         {
             if ( range.containsVersion( version ) )
             {
                 return true;
             }
         }
         return false;
     }
 
     public Bound getLowerBound()
     {
         return lowerBound;
     }
 
     public Bound getUpperBound()
     {
         return upperBound;
     }
 
     @Override
     public boolean equals( Object obj )
     {
         if ( obj == this )
         {
             return true;
         }
         else if ( obj == null || !getClass().equals( obj.getClass() ) )
         {
             return false;
         }
 
         UnionVersionRange that = (UnionVersionRange) obj;
 
         return ranges.equals( that.ranges );
     }
 
     @SuppressWarnings( "checkstyle:magicnumber" )
     @Override
     public int hashCode()
     {
         return 97 * ranges.hashCode();
     }
 
     @Override
     public String toString()
     {
         StringBuilder buffer = new StringBuilder( 128 );
         for ( VersionRange range : ranges )
         {
             if ( buffer.length() > 0 )
             {
                 buffer.append( ", " );
             }
             buffer.append( range );
         }
         return buffer.toString();
     }
 
 }