/*
    * 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.apache.maven.internal.transformation.impl;
  
  import javax.xml.stream.XMLStreamException;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.util.Objects;
  import java.util.concurrent.atomic.AtomicReference;
  import java.util.function.Supplier;
  
  import org.apache.maven.artifact.DefaultArtifact;
  import org.apache.maven.internal.transformation.TransformationFailedException;
  import org.apache.maven.model.building.ModelBuildingException;
  import org.apache.maven.project.MavenProject;
  import org.eclipse.aether.RepositorySystemSession;
  
  /**
   * Transformed artifact is derived with some transformation from source artifact.
   *
   * @since TBD
   */
  class TransformedArtifact extends DefaultArtifact {
  
      private static final int SHA1_BUFFER_SIZE = 8192;
      private final DefaultConsumerPomArtifactTransformer defaultConsumerPomArtifactTransformer;
      private final MavenProject project;
      private final Supplier<Path> sourcePathProvider;
      private final Path target;
      private final RepositorySystemSession session;
      private final AtomicReference<String> sourceState;
  
      @SuppressWarnings("checkstyle:ParameterNumber")
      TransformedArtifact(
              DefaultConsumerPomArtifactTransformer defaultConsumerPomArtifactTransformer,
              MavenProject project,
              Path target,
              RepositorySystemSession session,
              org.apache.maven.artifact.Artifact source,
              Supplier<Path> sourcePathProvider,
              String classifier,
              String extension) {
          super(
                  source.getGroupId(),
                  source.getArtifactId(),
                  source.getVersionRange(),
                  source.getScope(),
                  extension,
                  classifier,
                  new TransformedArtifactHandler(
                          classifier, extension, source.getArtifactHandler().getPackaging()));
          this.defaultConsumerPomArtifactTransformer = defaultConsumerPomArtifactTransformer;
          this.project = project;
          this.target = target;
          this.session = session;
          this.sourcePathProvider = sourcePathProvider;
          this.sourceState = new AtomicReference<>(null);
      }
  
      @Override
      public boolean isResolved() {
          return getFile() != null;
      }
  
      @Override
      public void setFile(File file) {
          throw new UnsupportedOperationException("transformed artifact file cannot be set");
      }
  
      @Override
      public synchronized File getFile() {
          try {
              String state = mayUpdate();
              if (state == null) {
                  return null;
              }
              return target.toFile();
         } catch (IOException | NoSuchAlgorithmException | XMLStreamException | ModelBuildingException e) {
             throw new TransformationFailedException(e);
         }
     }
 
     private String mayUpdate()
             throws IOException, NoSuchAlgorithmException, XMLStreamException, ModelBuildingException {
         String result;
         Path src = sourcePathProvider.get();
         if (src == null) {
             Files.deleteIfExists(target);
             result = null;
         } else if (!Files.exists(src)) {
             Files.deleteIfExists(target);
             result = "";
         } else {
             String current = sha1(src);
             String existing = sourceState.get();
             if (!Files.exists(target) || !Objects.equals(current, existing)) {
                 defaultConsumerPomArtifactTransformer.transform(project, session, src, target);
                 Files.setLastModifiedTime(target, Files.getLastModifiedTime(src));
             }
             result = current;
         }
         sourceState.set(result);
         return result;
     }
 
     static String sha1(Path path) throws NoSuchAlgorithmException, IOException {
         MessageDigest md = MessageDigest.getInstance("SHA-1");
         try (InputStream fis = Files.newInputStream(path)) {
             byte[] buffer = new byte[SHA1_BUFFER_SIZE];
             int read;
             while ((read = fis.read(buffer)) != -1) {
                 md.update(buffer, 0, read);
             }
         }
         StringBuilder result = new StringBuilder();
         for (byte b : md.digest()) {
             result.append(String.format("%02x", b));
         }
         return result.toString();
     }
 }