package org.apache.maven.repository.internal;
   
   /*
    * 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 org.apache.maven.artifact.repository.metadata.Metadata;
  import org.apache.maven.artifact.repository.metadata.io.xpp3.MetadataXpp3Reader;
  import org.apache.maven.artifact.repository.metadata.io.xpp3.MetadataXpp3Writer;
  import org.codehaus.plexus.util.ReaderFactory;
  import org.codehaus.plexus.util.WriterFactory;
  import org.codehaus.plexus.util.xml.pull.XmlPullParserException;
  import org.eclipse.aether.RepositoryException;
  import org.eclipse.aether.metadata.AbstractMetadata;
  import org.eclipse.aether.metadata.MergeableMetadata;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.Reader;
  import java.io.Writer;
  import java.util.Collections;
  import java.util.Map;
  
  /**
   * @author Benjamin Bentmann
   */
  abstract class MavenMetadata
      extends AbstractMetadata
      implements MergeableMetadata
  {
  
      static final String MAVEN_METADATA_XML = "maven-metadata.xml";
  
      private final File file;
  
      protected Metadata metadata;
  
      private boolean merged;
  
      protected MavenMetadata( Metadata metadata, File file )
      {
          this.metadata = metadata;
          this.file = file;
      }
  
      public String getType()
      {
          return MAVEN_METADATA_XML;
      }
  
      public File getFile()
      {
          return file;
      }
  
      public void merge( File existing, File result )
          throws RepositoryException
      {
          Metadata recessive = read( existing );
  
          merge( recessive );
  
          write( result, metadata );
  
          merged = true;
      }
  
      public boolean isMerged()
      {
          return merged;
      }
  
      protected abstract void merge( Metadata recessive );
  
      static Metadata read( File metadataFile )
          throws RepositoryException
      {
          if ( metadataFile.length() <= 0 )
          {
              return new Metadata();
          }
  
          try ( Reader reader = ReaderFactory.newXmlReader( metadataFile ) )
          {
             return new MetadataXpp3Reader().read( reader, false );
         }
         catch ( IOException e )
         {
             throw new RepositoryException( "Could not read metadata " + metadataFile + ": " + e.getMessage(), e );
         }
         catch ( XmlPullParserException e )
         {
             throw new RepositoryException( "Could not parse metadata " + metadataFile + ": " + e.getMessage(), e );
         }
     }
 
     private void write( File metadataFile, Metadata metadata )
         throws RepositoryException
     {
         metadataFile.getParentFile().mkdirs();
         try ( Writer writer = WriterFactory.newXmlWriter( metadataFile ) )
         {
             new MetadataXpp3Writer().write( writer, metadata );
         }
         catch ( IOException e )
         {
             throw new RepositoryException( "Could not write metadata " + metadataFile + ": " + e.getMessage(), e );
         }
     }
 
     public Map<String, String> getProperties()
     {
         return Collections.emptyMap();
     }
 
     @Override
     public org.eclipse.aether.metadata.Metadata setProperties( Map<String, String> properties )
     {
         return this;
     }
 
 }