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.ArrayList;
  import java.util.Collection;
  
  import org.eclipse.aether.version.InvalidVersionSpecificationException;
  import org.eclipse.aether.version.Version;
  import org.eclipse.aether.version.VersionConstraint;
  import org.eclipse.aether.version.VersionRange;
  import org.eclipse.aether.version.VersionScheme;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * A version scheme using a generic version syntax and common sense sorting.
   * <p>
   * This scheme accepts versions of any form, interpreting a version as a sequence of numeric and alphabetic segments.
   * The characters '-', '_', and '.' as well as the mere transitions from digit to letter and vice versa delimit the
   * version segments. Delimiters are treated as equivalent.
   * </p>
   * <p>
   * Numeric segments are compared mathematically, alphabetic segments are compared lexicographically and
   * case-insensitively. However, the following qualifier strings are recognized and treated specially: "alpha" = "a" &lt;
   * "beta" = "b" &lt; "milestone" = "m" &lt; "cr" = "rc" &lt; "snapshot" &lt; "final" = "ga" &lt; "sp". All of those
   * well-known qualifiers are considered smaller/older than other strings. An empty segment/string is equivalent to 0.
   * </p>
   * <p>
   * In addition to the above mentioned qualifiers, the tokens "min" and "max" may be used as final version segment to
   * denote the smallest/greatest version having a given prefix. For example, "1.2.min" denotes the smallest version in
   * the 1.2 line, "1.2.max" denotes the greatest version in the 1.2 line. A version range of the form "[M.N.*]" is short
   * for "[M.N.min, M.N.max]".
   * </p>
   * <p>
   * Numbers and strings are considered incomparable against each other. Where version segments of different kind would
   * collide, comparison will instead assume that the previous segments are padded with trailing 0 or "ga" segments,
   * respectively, until the kind mismatch is resolved, e.g. "1-alpha" = "1.0.0-alpha" &lt; "1.0.1-ga" = "1.0.1".
   * </p>
   */
  public final class GenericVersionScheme
      implements VersionScheme
  {
  
      /**
       * Creates a new instance of the version scheme for parsing versions.
       */
      public GenericVersionScheme()
      {
      }
  
      public Version parseVersion( final String version )
          throws InvalidVersionSpecificationException
      {
          requireNonNull( version, "version cannot be null" );
          return new GenericVersion( version );
      }
  
      public VersionRange parseVersionRange( final String range )
          throws InvalidVersionSpecificationException
      {
          requireNonNull( range, "range cannot be null" );
          return new GenericVersionRange( range );
      }
  
      public VersionConstraint parseVersionConstraint( final String constraint )
          throws InvalidVersionSpecificationException
      {
          requireNonNull( constraint, "constraint cannot be null" );
          Collection<VersionRange> ranges = new ArrayList<>();
  
          String process = constraint;
  
          while ( process.startsWith( "[" ) || process.startsWith( "(" ) )
          {
              int index1 = process.indexOf( ')' );
              int index2 = process.indexOf( ']' );
  
              int index = index2;
              if ( index2 < 0 || ( index1 >= 0 && index1 < index2 ) )
              {
                  index = index1;
             }
 
             if ( index < 0 )
             {
                 throw new InvalidVersionSpecificationException( constraint, "Unbounded version range " + constraint );
             }
 
             VersionRange range = parseVersionRange( process.substring( 0, index + 1 ) );
             ranges.add( range );
 
             process = process.substring( index + 1 ).trim();
 
             if ( process.length() > 0 && process.startsWith( "," ) )
             {
                 process = process.substring( 1 ).trim();
             }
         }
 
         if ( process.length() > 0 && !ranges.isEmpty() )
         {
             throw new InvalidVersionSpecificationException( constraint, "Invalid version range " + constraint
                 + ", expected [ or ( but got " + process );
         }
 
         VersionConstraint result;
         if ( ranges.isEmpty() )
         {
             result = new GenericVersionConstraint( parseVersion( constraint ) );
         }
         else
         {
             result = new GenericVersionConstraint( UnionVersionRange.from( ranges ) );
         }
 
         return result;
     }
 
     @Override
     public boolean equals( final Object obj )
     {
         if ( this == obj )
         {
             return true;
         }
 
         return obj != null && getClass().equals( obj.getClass() );
     }
 
     @Override
     public int hashCode()
     {
         return getClass().hashCode();
     }
 
 }