/**
    * Copyright 1&1 Internet AG, https://github.com/1and1/
    *
    * Licensed 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 net.oneandone.maven.plugins.billofmaterials;
  
  import com.google.common.base.*;
  import com.google.common.collect.Collections2;
  import com.google.common.collect.Lists;
  import com.google.common.hash.HashCode;
  import com.google.common.hash.HashFunction;
  import com.google.common.hash.Hashing;
  import com.google.common.io.Files;
  import java.io.File;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Locale;
  
  import org.apache.maven.artifact.Artifact;
  import org.apache.maven.plugin.MojoExecutionException;
  import org.apache.maven.plugin.MojoFailureException;
  import org.apache.maven.plugins.annotations.LifecyclePhase;
  import org.apache.maven.plugins.annotations.Mojo;
  import org.apache.maven.project.MavenProject;
  
  /**
   * Creates a bill of materials for all installed artifacts.
   *
   * <p>This in the standard format for the <tt>sha1sum</tt> command including meta information:</p>
   * <pre>
   * # company:company-parent-pom:1.0-SNAPSHOT user=mirko
   * 2dcb20b977ff170dd802c30b804229264c97ebf6  company-parent-pom-1.0-SNAPSHOT.pom
   * # company:child1:1.0-SNAPSHOT user=mirko
   * ed5b932c3157b347d0f7a4ec773ae5d5890c1ada  child1-1.0-SNAPSHOT-sources.jar
   * 8294565e2a5d99b548b111fe6262719331436143  child1-1.0-SNAPSHOT.jar
   * 082fa2206c4a00e3f428e9100199a0337ad42fdb  child1-1.0-SNAPSHOT.pom
   * # company:child2:1.0-SNAPSHOT user=mirko
   * 05d419cf53e175c6e84ddc1cf2fccdc9dd109c6b  child2-1.0-SNAPSHOT-sources.jar
   * df633b963220ba124ffa80eb6ceab676934bb387  child2-1.0-SNAPSHOT.jar
   * 5661e9270a02c5359be47615bb6ed9911105d878  child2-1.0-SNAPSHOT.pom
   * </pre>
   *
   * @author Mirko Friedenhagen &lt;mirko.friedenhagen@1und1.de&gt;
   */
  @Mojo(name = "create", aggregator = false, defaultPhase = LifecyclePhase.INSTALL)
  public class CreateBillOfMaterialsMojo extends AbstractBillOfMaterialsMojo {
  
      /**
       * SHA1 hash function.
       */
      private final HashFunction sha1 = Hashing.sha1();
  
      /**
       * Function to calculate the hash of a file.
       */
      private final Function<File, String> toBomStringFunction;
  
      /**
       * Function to get the file from the artifact.
       */
      private final Function<Artifact, File> toFileFunction;
  
      /**
       * Default constructor for maven.
       */
      CreateBillOfMaterialsMojo() {
          super();
          toFileFunction = new ToFileFunction();
          toBomStringFunction = new ToBomStringFunction(sha1);
      }
  
      /**
       * Just for tests.
       * @param billOfMaterialsPath path to bom.
       * @param project current project
       */
      CreateBillOfMaterialsMojo(File billOfMaterialsPath, MavenProject project) {
          super(billOfMaterialsPath, project);
          toFileFunction = new ToFileFunction();
          toBomStringFunction = new ToBomStringFunction(sha1);
      }
  
      @Override
      public void execute() throws MojoExecutionException, MojoFailureException {
          try {
              final List<File> files = getListOfArtifactsAsFiles();
              // We need a copy here as transform will return a fixed size list.
             final List<String> hashBaseNames = new ArrayList<>(Lists.transform(files, toBomStringFunction));
             addHashEntryForPom(hashBaseNames);
             writeResults(hashBaseNames);
         } catch (IOException ex) {
             throw new MojoExecutionException(ex.toString(), ex);
         }
     }
 
     /**
      * Creates a list of all artifacts for the build.
      * @return a list of all artifacts for the build including the attached ones.
      */
     final List<File> getListOfArtifactsAsFiles() {
         final MavenProject project = getProject();
         final List<Artifact> attachedArtifacts = project.getAttachedArtifacts();
         // We need a copy here as otherwise install and deploy will choke later on because
         // we attach the POM as well.
         final List<File> files = new ArrayList<>(
                 Collections2.filter(
                     Lists.transform(attachedArtifacts, toFileFunction),
                         Files.isFile()));
         final String packaging = project.getPackaging();
         // POMs return null as their artifact, which will crash the transformation lateron.
         if (!"pom".equals(packaging)) {
             files.add(project.getArtifact().getFile());
         }
         return files;
     }
 
     /**
      * Adds the hash entry for the POM.
      * @param hashBaseNames to add the entry to.
      * @throws IOException when the POM could not be read.
      */
     void addHashEntryForPom(final List<String> hashBaseNames) throws IOException {
         final MavenProject project = getProject();
         final HashCode sha1OfPom = Files.hash(project.getFile(), sha1);
         final String pomLine = String.format(Locale.ENGLISH, "%s  %s-%s.pom",
                     sha1OfPom, project.getArtifactId(), project.getVersion());
         hashBaseNames.add(pomLine);
     }
 
     /**
      * Writes the resulting hash file to {@link CreateBillOfMaterialsMojo#billOfMaterialsPath}.
      *
      * @param hashBaseNames to write
      * @throws IOException when the parent directory could not be created or something went wrong while writing the result.
      */
     void writeResults(final List<String> hashBaseNames) throws IOException {
         final String hashBaseNamesAsString = Joiner.on("\n").join(hashBaseNames) + "\n";
         final String userName = System.getProperty("user.name");
         write(projectCommentToString(userName));
         write(hashBaseNamesAsString);
     }
 
     /**
      * Writes content to the bomFile creating intermediate directories.
      *
      * @param content to write
      * @throws IOException when the target directory could not be created or the content could not be written.
      */
     void write(final String content) throws IOException {
         final File bomFile = calculateBillOfMaterialsFile();
         final File parentDirectory = bomFile.getParentFile();
         if (!createParentDirectory(parentDirectory)) {
             throw new IOException("Could not create parent directory for " + bomFile);
         }
         Files.append(content, bomFile, Charsets.UTF_8);
     }
 
     /**
      * Returns a string representation for the comment.
      *
      * @param userName current user
      * @return string representation for the comment.
      */
     String projectCommentToString(final String userName) {
         final MavenProject project = getProject();
         return String.format(
                 Locale.ENGLISH,
                 "# %s:%s:%s user=%s\n",
                 project.getGroupId(), project.getArtifactId(), project.getVersion(), userName);
     }
 
     /**
      * Creates directory for storage.
      *
      * @param parentDirectory
      * @return true when parentDirectory could not be created.
      */
     boolean createParentDirectory(final File parentDirectory) {
         return parentDirectory.exists() || parentDirectory.mkdirs();
     }
 }