package org.apache.maven.artifact.versioning;
   
   /*
    * 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.ArrayList;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.WeakHashMap;
  import java.util.Objects;
  
  import org.apache.maven.artifact.Artifact;
  
  /**
   * Construct a version range from a specification.
   *
   * @author <a href="mailto:brett@apache.org">Brett Porter</a>
   */
  public class VersionRange
  {
      private static final Map<String, VersionRange> CACHE_SPEC =
          Collections.<String, VersionRange>synchronizedMap( new WeakHashMap<String, VersionRange>() );
  
      private static final Map<String, VersionRange> CACHE_VERSION =
                      Collections.<String, VersionRange>synchronizedMap( new WeakHashMap<String, VersionRange>() );
  
      private final ArtifactVersion recommendedVersion;
  
      private final List<Restriction> restrictions;
  
      private VersionRange( ArtifactVersion recommendedVersion,
                            List<Restriction> restrictions )
      {
          this.recommendedVersion = recommendedVersion;
          this.restrictions = restrictions;
      }
  
      public ArtifactVersion getRecommendedVersion()
      {
          return recommendedVersion;
      }
  
      public List<Restriction> getRestrictions()
      {
          return restrictions;
      }
  
      /**
       * @deprecated VersionRange is immutable, cloning is not useful and even more an issue against the cache 
       * @return a clone
       */
      @Deprecated
      public VersionRange cloneOf()
      {
          List<Restriction> copiedRestrictions = null;
  
          if ( restrictions != null )
          {
              copiedRestrictions = new ArrayList<>();
  
              if ( !restrictions.isEmpty() )
              {
                  copiedRestrictions.addAll( restrictions );
              }
          }
  
          return new VersionRange( recommendedVersion, copiedRestrictions );
      }
  
      /**
       * <p>
       * Create a version range from a string representation
       * </p>
       * Some spec examples are:
       * <ul>
       * <li><code>1.0</code> Version 1.0 as a recommended version</li>
       * <li><code>[1.0]</code> Version 1.0 explicitly only</li>
       * <li><code>[1.0,2.0)</code> Versions 1.0 (included) to 2.0 (not included)</li>
       * <li><code>[1.0,2.0]</code> Versions 1.0 to 2.0 (both included)</li>
       * <li><code>[1.5,)</code> Versions 1.5 and higher</li>
       * <li><code>(,1.0],[1.2,)</code> Versions up to 1.0 (included) and 1.2 or higher</li>
      * </ul>
      *
      * @param spec string representation of a version or version range
      * @return a new {@link VersionRange} object that represents the spec
      * @throws InvalidVersionSpecificationException
      *
      */
     public static VersionRange createFromVersionSpec( String spec )
         throws InvalidVersionSpecificationException
     {
         if ( spec == null )
         {
             return null;
         }
 
         VersionRange cached = CACHE_SPEC.get( spec );
         if ( cached != null )
         {
             return cached;
         }
 
         List<Restriction> restrictions = new ArrayList<>();
         String process = spec;
         ArtifactVersion version = null;
         ArtifactVersion upperBound = null;
         ArtifactVersion lowerBound = null;
 
         while ( process.startsWith( "[" ) || process.startsWith( "(" ) )
         {
             int index1 = process.indexOf( ')' );
             int index2 = process.indexOf( ']' );
 
             int index = index2;
             if ( index2 < 0 || index1 < index2 )
             {
                 if ( index1 >= 0 )
                 {
                     index = index1;
                 }
             }
 
             if ( index < 0 )
             {
                 throw new InvalidVersionSpecificationException( "Unbounded range: " + spec );
             }
 
             Restriction restriction = parseRestriction( process.substring( 0, index + 1 ) );
             if ( lowerBound == null )
             {
                 lowerBound = restriction.getLowerBound();
             }
             if ( upperBound != null )
             {
                 if ( restriction.getLowerBound() == null || restriction.getLowerBound().compareTo( upperBound ) < 0 )
                 {
                     throw new InvalidVersionSpecificationException( "Ranges overlap: " + spec );
                 }
             }
             restrictions.add( restriction );
             upperBound = restriction.getUpperBound();
 
             process = process.substring( index + 1 ).trim();
 
             if ( process.length() > 0 && process.startsWith( "," ) )
             {
                 process = process.substring( 1 ).trim();
             }
         }
 
         if ( process.length() > 0 )
         {
             if ( restrictions.size() > 0 )
             {
                 throw new InvalidVersionSpecificationException(
                     "Only fully-qualified sets allowed in multiple set scenario: " + spec );
             }
             else
             {
                 version = new DefaultArtifactVersion( process );
                 restrictions.add( Restriction.EVERYTHING );
             }
         }
 
         cached = new VersionRange( version, restrictions );
         CACHE_SPEC.put( spec, cached );
         return cached;
     }
 
     private static Restriction parseRestriction( String spec )
         throws InvalidVersionSpecificationException
     {
         boolean lowerBoundInclusive = spec.startsWith( "[" );
         boolean upperBoundInclusive = spec.endsWith( "]" );
 
         String process = spec.substring( 1, spec.length() - 1 ).trim();
 
         Restriction restriction;
 
         int index = process.indexOf( ',' );
 
         if ( index < 0 )
         {
             if ( !lowerBoundInclusive || !upperBoundInclusive )
             {
                 throw new InvalidVersionSpecificationException( "Single version must be surrounded by []: " + spec );
             }
 
             ArtifactVersion version = new DefaultArtifactVersion( process );
 
             restriction = new Restriction( version, lowerBoundInclusive, version, upperBoundInclusive );
         }
         else
         {
             String lowerBound = process.substring( 0, index ).trim();
             String upperBound = process.substring( index + 1 ).trim();
             if ( lowerBound.equals( upperBound ) )
             {
                 throw new InvalidVersionSpecificationException( "Range cannot have identical boundaries: " + spec );
             }
 
             ArtifactVersion lowerVersion = null;
             if ( lowerBound.length() > 0 )
             {
                 lowerVersion = new DefaultArtifactVersion( lowerBound );
             }
             ArtifactVersion upperVersion = null;
             if ( upperBound.length() > 0 )
             {
                 upperVersion = new DefaultArtifactVersion( upperBound );
             }
 
             if ( upperVersion != null && lowerVersion != null && upperVersion.compareTo( lowerVersion ) < 0 )
             {
                 throw new InvalidVersionSpecificationException( "Range defies version ordering: " + spec );
             }
 
             restriction = new Restriction( lowerVersion, lowerBoundInclusive, upperVersion, upperBoundInclusive );
         }
 
         return restriction;
     }
 
     public static VersionRange createFromVersion( String version )
     {
         VersionRange cached = CACHE_VERSION.get( version );
         if ( cached == null )
         {
             List<Restriction> restrictions = Collections.emptyList();
             cached = new VersionRange( new DefaultArtifactVersion( version ), restrictions );
             CACHE_VERSION.put( version, cached );
         }
         return cached;
     }
 
     /**
      * Creates and returns a new <code>VersionRange</code> that is a restriction of this
      * version range and the specified version range.
      * <p>
      * Note: Precedence is given to the recommended version from this version range over the
      * recommended version from the specified version range.
      * </p>
      *
      * @param restriction the <code>VersionRange</code> that will be used to restrict this version
      *                    range.
      * @return the <code>VersionRange</code> that is a restriction of this version range and the
      *         specified version range.
      *         <p>
      *         The restrictions of the returned version range will be an intersection of the restrictions
      *         of this version range and the specified version range if both version ranges have
      *         restrictions. Otherwise, the restrictions on the returned range will be empty.
      *         </p>
      *         <p>
      *         The recommended version of the returned version range will be the recommended version of
      *         this version range, provided that ranges falls within the intersected restrictions. If
      *         the restrictions are empty, this version range's recommended version is used if it is not
      *         <code>null</code>. If it is <code>null</code>, the specified version range's recommended
      *         version is used (provided it is non-<code>null</code>). If no recommended version can be
      *         obtained, the returned version range's recommended version is set to <code>null</code>.
      *         </p>
      * @throws NullPointerException if the specified <code>VersionRange</code> is
      *                              <code>null</code>.
      */
     public VersionRange restrict( VersionRange restriction )
     {
         List<Restriction> r1 = this.restrictions;
         List<Restriction> r2 = restriction.restrictions;
         List<Restriction> restrictions;
 
         if ( r1.isEmpty() || r2.isEmpty() )
         {
             restrictions = Collections.emptyList();
         }
         else
         {
             restrictions = Collections.unmodifiableList( intersection( r1, r2 ) );
         }
 
         ArtifactVersion version = null;
         if ( restrictions.size() > 0 )
         {
             for ( Restriction r : restrictions )
             {
                 if ( recommendedVersion != null && r.containsVersion( recommendedVersion ) )
                 {
                     // if we find the original, use that
                     version = recommendedVersion;
                     break;
                 }
                 else if ( version == null && restriction.getRecommendedVersion() != null
                     && r.containsVersion( restriction.getRecommendedVersion() ) )
                 {
                     // use this if we can, but prefer the original if possible
                     version = restriction.getRecommendedVersion();
                 }
             }
         }
         // Either the original or the specified version ranges have no restrictions
         else if ( recommendedVersion != null )
         {
             // Use the original recommended version since it exists
             version = recommendedVersion;
         }
         else if ( restriction.recommendedVersion != null )
         {
             // Use the recommended version from the specified VersionRange since there is no
             // original recommended version
             version = restriction.recommendedVersion;
         }
 /* TODO should throw this immediately, but need artifact
         else
         {
             throw new OverConstrainedVersionException( "Restricting incompatible version ranges" );
         }
 */
 
         return new VersionRange( version, restrictions );
     }
 
     private List<Restriction> intersection( List<Restriction> r1, List<Restriction> r2 )
     {
         List<Restriction> restrictions = new ArrayList<>( r1.size() + r2.size() );
         Iterator<Restriction> i1 = r1.iterator();
         Iterator<Restriction> i2 = r2.iterator();
         Restriction res1 = i1.next();
         Restriction res2 = i2.next();
 
         boolean done = false;
         while ( !done )
         {
             if ( res1.getLowerBound() == null || res2.getUpperBound() == null
                 || res1.getLowerBound().compareTo( res2.getUpperBound() ) <= 0 )
             {
                 if ( res1.getUpperBound() == null || res2.getLowerBound() == null
                     || res1.getUpperBound().compareTo( res2.getLowerBound() ) >= 0 )
                 {
                     ArtifactVersion lower;
                     ArtifactVersion upper;
                     boolean lowerInclusive;
                     boolean upperInclusive;
 
                     // overlaps
                     if ( res1.getLowerBound() == null )
                     {
                         lower = res2.getLowerBound();
                         lowerInclusive = res2.isLowerBoundInclusive();
                     }
                     else if ( res2.getLowerBound() == null )
                     {
                         lower = res1.getLowerBound();
                         lowerInclusive = res1.isLowerBoundInclusive();
                     }
                     else
                     {
                         int comparison = res1.getLowerBound().compareTo( res2.getLowerBound() );
                         if ( comparison < 0 )
                         {
                             lower = res2.getLowerBound();
                             lowerInclusive = res2.isLowerBoundInclusive();
                         }
                         else if ( comparison == 0 )
                         {
                             lower = res1.getLowerBound();
                             lowerInclusive = res1.isLowerBoundInclusive() && res2.isLowerBoundInclusive();
                         }
                         else
                         {
                             lower = res1.getLowerBound();
                             lowerInclusive = res1.isLowerBoundInclusive();
                         }
                     }
 
                     if ( res1.getUpperBound() == null )
                     {
                         upper = res2.getUpperBound();
                         upperInclusive = res2.isUpperBoundInclusive();
                     }
                     else if ( res2.getUpperBound() == null )
                     {
                         upper = res1.getUpperBound();
                         upperInclusive = res1.isUpperBoundInclusive();
                     }
                     else
                     {
                         int comparison = res1.getUpperBound().compareTo( res2.getUpperBound() );
                         if ( comparison < 0 )
                         {
                             upper = res1.getUpperBound();
                             upperInclusive = res1.isUpperBoundInclusive();
                         }
                         else if ( comparison == 0 )
                         {
                             upper = res1.getUpperBound();
                             upperInclusive = res1.isUpperBoundInclusive() && res2.isUpperBoundInclusive();
                         }
                         else
                         {
                             upper = res2.getUpperBound();
                             upperInclusive = res2.isUpperBoundInclusive();
                         }
                     }
 
                     // don't add if they are equal and one is not inclusive
                     if ( lower == null || upper == null || lower.compareTo( upper ) != 0 )
                     {
                         restrictions.add( new Restriction( lower, lowerInclusive, upper, upperInclusive ) );
                     }
                     else if ( lowerInclusive && upperInclusive )
                     {
                         restrictions.add( new Restriction( lower, lowerInclusive, upper, upperInclusive ) );
                     }
 
                     //noinspection ObjectEquality
                     if ( upper == res2.getUpperBound() )
                     {
                         // advance res2
                         if ( i2.hasNext() )
                         {
                             res2 = i2.next();
                         }
                         else
                         {
                             done = true;
                         }
                     }
                     else
                     {
                         // advance res1
                         if ( i1.hasNext() )
                         {
                             res1 = i1.next();
                         }
                         else
                         {
                             done = true;
                         }
                     }
                 }
                 else
                 {
                     // move on to next in r1
                     if ( i1.hasNext() )
                     {
                         res1 = i1.next();
                     }
                     else
                     {
                         done = true;
                     }
                 }
             }
             else
             {
                 // move on to next in r2
                 if ( i2.hasNext() )
                 {
                     res2 = i2.next();
                 }
                 else
                 {
                     done = true;
                 }
             }
         }
 
         return restrictions;
     }
 
     public ArtifactVersion getSelectedVersion( Artifact artifact )
         throws OverConstrainedVersionException
     {
         ArtifactVersion version;
         if ( recommendedVersion != null )
         {
             version = recommendedVersion;
         }
         else
         {
             if ( restrictions.size() == 0 )
             {
                 throw new OverConstrainedVersionException( "The artifact has no valid ranges", artifact );
             }
 
             version = null;
         }
         return version;
     }
 
     public boolean isSelectedVersionKnown( Artifact artifact )
         throws OverConstrainedVersionException
     {
         boolean value = false;
         if ( recommendedVersion != null )
         {
             value = true;
         }
         else
         {
             if ( restrictions.size() == 0 )
             {
                 throw new OverConstrainedVersionException( "The artifact has no valid ranges", artifact );
             }
         }
         return value;
     }
 
     public String toString()
     {
         if ( recommendedVersion != null )
         {
             return recommendedVersion.toString();
         }
         else
         {
             StringBuilder buf = new StringBuilder();
             for ( Iterator<Restriction> i = restrictions.iterator(); i.hasNext(); )
             {
                 Restriction r = i.next();
 
                 buf.append( r.toString() );
 
                 if ( i.hasNext() )
                 {
                     buf.append( ',' );
                 }
             }
             return buf.toString();
         }
     }
 
     public ArtifactVersion matchVersion( List<ArtifactVersion> versions )
     {
         // TODO could be more efficient by sorting the list and then moving along the restrictions in order?
 
         ArtifactVersion matched = null;
         for ( ArtifactVersion version : versions )
         {
             if ( containsVersion( version ) )
             {
                 // valid - check if it is greater than the currently matched version
                 if ( matched == null || version.compareTo( matched ) > 0 )
                 {
                     matched = version;
                 }
             }
         }
         return matched;
     }
 
     public boolean containsVersion( ArtifactVersion version )
     {
         for ( Restriction restriction : restrictions )
         {
             if ( restriction.containsVersion( version ) )
             {
                 return true;
             }
         }
         return false;
     }
 
     public boolean hasRestrictions()
     {
         return !restrictions.isEmpty() && recommendedVersion == null;
     }
 
     public boolean equals( Object obj )
     {
         if ( this == obj )
         {
             return true;
         }
         if ( !( obj instanceof VersionRange ) )
         {
             return false;
         }
         VersionRange other = (VersionRange) obj;
 
         return Objects.equals( recommendedVersion, other.recommendedVersion )
             && Objects.equals( restrictions, other.restrictions );
     }
 
     public int hashCode()
     {
         int hash = 7;
         hash = 31 * hash + ( recommendedVersion == null ? 0 : recommendedVersion.hashCode() );
         hash = 31 * hash + ( restrictions == null ? 0 : restrictions.hashCode() );
         return hash;
     }
 }