/*
    * 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.eclipse.aether.util.version;
  
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.Set;
  import java.util.stream.Collectors;
  
  import org.eclipse.aether.version.Version;
  import org.eclipse.aether.version.VersionRange;
  
  /**
   * A union of version ranges.
   */
  public final class UnionVersionRange implements VersionRange {
  
      private final Set<VersionRange> ranges;
  
      private final Bound lowerBound;
  
      private final Bound upperBound;
  
      /**
       * Creates union {@link VersionRange}s out of passed in {@link VersionRange} instances.
       *
       * @param ranges The ranges, may be empty array or even {@code null}.
       */
      public static VersionRange from(VersionRange... ranges) {
          if (ranges == null || ranges.length == 0) {
              return from(Collections.emptySet());
          }
          return from(Arrays.asList(ranges));
      }
  
      /**
       * Creates union {@link VersionRange}s out of passed in {@link VersionRange} collection.
       *
       * @param ranges The ranges, may be empty collection or even {@code null}.
       */
      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;
         }
     }
 
     @Override
     public boolean containsVersion(Version version) {
         for (VersionRange range : ranges) {
             if (range.containsVersion(version)) {
                 return true;
             }
         }
         return false;
     }
 
     @Override
     public Bound getLowerBound() {
         return lowerBound;
     }
 
     @Override
     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() {
         return ranges.stream().map(VersionRange::toString).collect(Collectors.joining(", "));
     }
 }