/*
    * 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.plugins.shade.filter;
  
  import java.io.BufferedReader;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.nio.file.Files;
  import java.util.Collections;
  import java.util.Enumeration;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  import java.util.jar.JarEntry;
  import java.util.jar.JarFile;
  import java.util.zip.ZipException;
  
  import org.apache.maven.artifact.Artifact;
  import org.apache.maven.artifact.DependencyResolutionRequiredException;
  import org.apache.maven.plugin.logging.Log;
  import org.apache.maven.project.MavenProject;
  import org.vafer.jdependency.Clazz;
  import org.vafer.jdependency.Clazzpath;
  import org.vafer.jdependency.ClazzpathUnit;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  
  /**
   * A filter that prevents the inclusion of classes not required in the final jar.
   */
  public class MinijarFilter implements Filter {
  
      private Log log;
  
      private Set<Clazz> removable;
  
      private int classesKept;
  
      private int classesRemoved;
  
      // [MSHADE-209] This is introduced only for testing purposes which shows
      // there is something wrong with the design of this class. (SoC?)
      // unfortunately i don't have a better idea at the moment.
      MinijarFilter(int classesKept, int classesRemoved, Log log) {
          this.classesKept = classesKept;
          this.classesRemoved = classesRemoved;
          this.log = log;
      }
  
      /**
       * @param project {@link MavenProject}
       * @param log {@link Log}
       * @throws IOException in case of error.
       */
      public MinijarFilter(MavenProject project, Log log) throws IOException {
          this(project, log, Collections.<SimpleFilter>emptyList(), Collections.<String>emptySet());
      }
  
      /**
       * @param project {@link MavenProject}
       * @param log {@link Log}
       * @param entryPoints
       * @throws IOException in case of error.
       */
      public MinijarFilter(MavenProject project, Log log, Set<String> entryPoints) throws IOException {
          this(project, log, Collections.<SimpleFilter>emptyList(), entryPoints);
      }
  
      /**
       * @param project {@link MavenProject}
       * @param log {@link Log}
       * @param simpleFilters {@link SimpleFilter}
       * @param entryPoints
       * @throws IOException in case of errors.
       * @since 1.6
       */
      public MinijarFilter(MavenProject project, Log log, List<SimpleFilter> simpleFilters, Set<String> entryPoints)
              throws IOException {
          this.log = log;
  
         File artifactFile = project.getArtifact().getFile();
 
         if (artifactFile != null) {
             Clazzpath cp = new Clazzpath();
 
             ClazzpathUnit artifactUnit =
                     cp.addClazzpathUnit(Files.newInputStream(artifactFile.toPath()), project.toString());
 
             for (Artifact dependency : project.getArtifacts()) {
                 addDependencyToClasspath(cp, dependency);
             }
 
             removable = cp.getClazzes();
             if (removable.remove(new Clazz("module-info"))) {
                 log.warn("Removing module-info from " + artifactFile.getName());
             }
             removePackages(artifactUnit);
             if (entryPoints.isEmpty()) {
                 removable.removeAll(artifactUnit.getClazzes());
                 removable.removeAll(artifactUnit.getTransitiveDependencies());
             } else {
                 Set<Clazz> artifactUnitClazzes = artifactUnit.getClazzes();
                 Set<Clazz> entryPointsToKeep = new HashSet<>();
                 for (String entryPoint : entryPoints) {
                     Clazz entryPointFound = null;
                     for (Clazz clazz : artifactUnitClazzes) {
                         if (clazz.getName().equals(entryPoint)) {
                             entryPointFound = clazz;
                             break;
                         }
                     }
                     if (entryPointFound != null) {
                         entryPointsToKeep.add(entryPointFound);
                     }
                 }
                 removable.removeAll(entryPointsToKeep);
                 if (entryPointsToKeep.isEmpty()) {
                     removable.removeAll(artifactUnit.getTransitiveDependencies());
                 } else {
                     for (Clazz entryPoint : entryPointsToKeep) {
                         removable.removeAll(entryPoint.getTransitiveDependencies());
                     }
                 }
             }
             removeSpecificallyIncludedClasses(
                     project, simpleFilters == null ? Collections.<SimpleFilter>emptyList() : simpleFilters);
             removeServices(project, cp);
         }
     }
 
     private void removeServices(final MavenProject project, final Clazzpath cp) {
         boolean repeatScan;
         do {
             repeatScan = false;
             final Set<Clazz> neededClasses = cp.getClazzes();
             neededClasses.removeAll(removable);
             try {
                 // getRuntimeClasspathElements returns a list of
                 //  - the build output directory
                 //  - all the paths to the dependencies' jars
                 // We thereby need to ignore the build directory because we don't want
                 // to remove anything from it, as it's the starting point of the
                 // minification process.
                 for (final String fileName : project.getRuntimeClasspathElements()) {
                     if (new File(fileName).isDirectory()) {
                         repeatScan |= removeServicesFromDir(cp, neededClasses, fileName);
                     } else {
                         repeatScan |= removeServicesFromJar(cp, neededClasses, fileName);
                     }
                 }
             } catch (final DependencyResolutionRequiredException e) {
                 log.warn(e.getMessage());
             }
         } while (repeatScan);
     }
 
     private boolean removeServicesFromDir(Clazzpath cp, Set<Clazz> neededClasses, String fileName) {
         final File servicesDir = new File(fileName, "META-INF/services/");
         if (!servicesDir.isDirectory()) {
             return false;
         }
         final File[] serviceProviderConfigFiles = servicesDir.listFiles();
         if (serviceProviderConfigFiles == null || serviceProviderConfigFiles.length == 0) {
             return false;
         }
 
         boolean repeatScan = false;
         for (File serviceProviderConfigFile : serviceProviderConfigFiles) {
             final String serviceClassName = serviceProviderConfigFile.getName();
             final boolean isNeededClass = neededClasses.contains(cp.getClazz(serviceClassName));
             if (!isNeededClass) {
                 continue;
             }
 
             try (BufferedReader configFileReader =
                     new BufferedReader(new InputStreamReader(new FileInputStream(serviceProviderConfigFile), UTF_8))) {
                 // check whether the found classes use services in turn
                 repeatScan |= scanServiceProviderConfigFile(cp, configFileReader);
             } catch (final IOException e) {
                 log.warn(e.getMessage());
             }
         }
         return repeatScan;
     }
 
     private boolean removeServicesFromJar(Clazzpath cp, Set<Clazz> neededClasses, String fileName) {
         boolean repeatScan = false;
         try (JarFile jar = new JarFile(fileName)) {
             for (final Enumeration<JarEntry> entries = jar.entries(); entries.hasMoreElements(); ) {
                 final JarEntry jarEntry = entries.nextElement();
                 if (jarEntry.isDirectory() || !jarEntry.getName().startsWith("META-INF/services/")) {
                     continue;
                 }
 
                 final String serviceClassName = jarEntry.getName().substring("META-INF/services/".length());
                 final boolean isNeededClass = neededClasses.contains(cp.getClazz(serviceClassName));
                 if (!isNeededClass) {
                     continue;
                 }
 
                 try (BufferedReader configFileReader =
                         new BufferedReader(new InputStreamReader(jar.getInputStream(jarEntry), UTF_8))) {
                     // check whether the found classes use services in turn
                     repeatScan = scanServiceProviderConfigFile(cp, configFileReader);
                 } catch (final IOException e) {
                     log.warn(e.getMessage());
                 }
             }
         } catch (final IOException e) {
             log.warn("Not a JAR file candidate. Ignoring classpath element '" + fileName + "' (" + e + ").");
         }
         return repeatScan;
     }
 
     private boolean scanServiceProviderConfigFile(Clazzpath cp, BufferedReader configFileReader) throws IOException {
         boolean serviceClassFound = false;
         for (String line = configFileReader.readLine(); line != null; line = configFileReader.readLine()) {
             final String className = line.split("#", 2)[0].trim();
             if (className.isEmpty()) {
                 continue;
             }
 
             final Clazz clazz = cp.getClazz(className);
             if (clazz == null || !removable.contains(clazz)) {
                 continue;
             }
 
             log.debug(className + " was not removed because it is a service");
             removeClass(clazz);
             serviceClassFound = true;
         }
         return serviceClassFound;
     }
 
     private void removeClass(final Clazz clazz) {
         removable.remove(clazz);
         removable.removeAll(clazz.getTransitiveDependencies());
     }
 
     private ClazzpathUnit addDependencyToClasspath(Clazzpath cp, Artifact dependency) throws IOException {
         ClazzpathUnit clazzpathUnit = null;
         try (InputStream is = new FileInputStream(dependency.getFile())) {
             clazzpathUnit = cp.addClazzpathUnit(is, dependency.toString());
         } catch (ZipException e) {
             log.warn(dependency.getFile()
                     + " could not be unpacked/read for minimization; dependency is probably malformed.");
             IOException ioe = new IOException(
                     "Dependency " + dependency + " in file " + dependency.getFile()
                             + " could not be unpacked. File is probably corrupt",
                     e);
             throw ioe;
         } catch (ArrayIndexOutOfBoundsException | IllegalArgumentException e) {
             // trap ArrayIndexOutOfBoundsExceptions caused by malformed dependency classes (MSHADE-107)
             log.warn(dependency + " could not be analyzed for minimization; dependency is probably malformed.");
         }
 
         return clazzpathUnit;
     }
 
     private void removePackages(ClazzpathUnit artifactUnit) {
         Set<String> packageNames = new HashSet<>();
         removePackages(artifactUnit.getClazzes(), packageNames);
         removePackages(artifactUnit.getTransitiveDependencies(), packageNames);
     }
 
     private void removePackages(Set<Clazz> clazzes, Set<String> packageNames) {
         for (Clazz clazz : clazzes) {
             String name = clazz.getName();
             while (name.contains(".")) {
                 name = name.substring(0, name.lastIndexOf('.'));
                 if (packageNames.add(name)) {
                     removable.remove(new Clazz(name + ".package-info"));
                 }
             }
         }
     }
 
     private void removeSpecificallyIncludedClasses(MavenProject project, List<SimpleFilter> simpleFilters)
             throws IOException {
         // remove classes specifically included in filters
         Clazzpath checkCp = new Clazzpath();
         for (Artifact dependency : project.getArtifacts()) {
             File jar = dependency.getFile();
 
             for (SimpleFilter simpleFilter : simpleFilters) {
                 if (simpleFilter.canFilter(jar)) {
                     ClazzpathUnit depClazzpathUnit = addDependencyToClasspath(checkCp, dependency);
                     if (depClazzpathUnit != null) {
                         Set<Clazz> clazzes = depClazzpathUnit.getClazzes();
                         for (final Clazz clazz : new HashSet<>(removable)) {
                             if (clazzes.contains(clazz) //
                                     && simpleFilter.isSpecificallyIncluded(
                                             clazz.getName().replace('.', '/'))) {
                                 log.debug(clazz.getName() + " not removed because it was specifically included");
                                 removeClass(clazz);
                             }
                         }
                     }
                 }
             }
         }
     }
 
     @Override
     public boolean canFilter(File jar) {
         return true;
     }
 
     @Override
     public boolean isFiltered(String classFile) {
         String className = classFile.replace('/', '.').replaceFirst("\\.class$", "");
         Clazz clazz = new Clazz(className);
 
         if (removable != null && removable.contains(clazz)) {
             log.debug("Removing " + className);
             classesRemoved += 1;
             return true;
         }
 
         classesKept += 1;
         return false;
     }
 
     @Override
     public void finished() {
         int classesTotal = classesRemoved + classesKept;
         if (classesTotal != 0) {
             log.info("Minimized " + classesTotal + " -> " + classesKept + " (" + 100 * classesKept / classesTotal
                     + "%)");
         } else {
             log.info("Minimized " + classesTotal + " -> " + classesKept);
         }
     }
 }