/*
    * 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.javadoc;
  
  import java.io.File;
  import java.io.IOException;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import java.nio.file.DirectoryStream;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.List;
  
  import org.apache.maven.reporting.MavenReportException;
  import org.codehaus.plexus.languages.java.version.JavaVersion;
  import org.codehaus.plexus.util.StringUtils;
  import org.codehaus.plexus.util.cli.Commandline;
  
  /**
   * Helper class to compute and write data used to detect a
   * stale javadoc.
   */
  public class StaleHelper {
  
      /**
       * Compute the data used to detect a stale javadoc
       *
       * @param cmd the command line
       * @return the stale data
       * @throws MavenReportException if an error occurs
       */
      public static String getStaleData(Commandline cmd) throws MavenReportException {
          try {
              List<String> ignored = new ArrayList<>();
              List<String> options = new ArrayList<>();
              Path dir = cmd.getWorkingDirectory().toPath().toAbsolutePath().normalize();
              String[] args = cmd.getArguments();
              Collections.addAll(options, args);
  
              final Charset cs;
              if (JavaVersion.JAVA_SPECIFICATION_VERSION.isAtLeast("9")
                      && JavaVersion.JAVA_SPECIFICATION_VERSION.isBefore("12")) {
                  cs = StandardCharsets.UTF_8;
              } else {
                  cs = Charset.defaultCharset();
              }
  
              for (String arg : args) {
                  if (arg.startsWith("@")) {
                      String name = arg.substring(1);
                      options.addAll(Files.readAllLines(dir.resolve(name), cs));
                      ignored.add(name);
                  }
              }
              List<String> state = new ArrayList<>(options);
              boolean cp = false;
              boolean sp = false;
              for (String arg : options) {
                  if (cp) {
                      String s = unquote(arg);
                      for (String ps : s.split(File.pathSeparator)) {
                          Path p = dir.resolve(ps);
                          state.add(p + " = " + lastmod(p));
                      }
                  } else if (sp) {
                      String s = unquote(arg);
                      for (String ps : s.split(File.pathSeparator)) {
                          Path p = dir.resolve(ps);
                          for (Path c : walk(p)) {
                              if (Files.isRegularFile(c)) {
                                  state.add(c + " = " + lastmod(c));
                              }
                          }
                          state.add(p + " = " + lastmod(p));
                      }
                  }
                  cp = "-classpath".equals(arg);
                  sp = "-sourcepath".equals(arg);
              }
              for (Path p : walk(dir)) {
                 if (Files.isRegularFile(p) && !ignored.contains(p.getFileName().toString())) {
                     state.add(p + " = " + lastmod(p));
                 }
             }
             return StringUtils.join(state.iterator(), SystemUtils.LINE_SEPARATOR);
         } catch (Exception e) {
             throw new MavenReportException("Unable to compute stale date", e);
         }
     }
 
     /**
      * Write the data used to detect a stale javadoc
      *
      * @param cmd the command line
      * @param path the stale data path
      * @throws MavenReportException if an error occurs
      */
     public static void writeStaleData(Commandline cmd, Path path) throws MavenReportException {
         try {
             String curdata = getStaleData(cmd);
             Files.createDirectories(path.getParent());
             Files.write(path, Collections.singleton(curdata), Charset.defaultCharset());
         } catch (IOException e) {
             throw new MavenReportException("Error checking stale data", e);
         }
     }
 
     private static Collection<Path> walk(Path dir) {
         Collection<Path> paths = new ArrayList<>();
         try (DirectoryStream<Path> directoryStream = Files.newDirectoryStream(dir)) {
             for (Path p : directoryStream) {
                 paths.add(p);
             }
             return paths;
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
     }
 
     private static String unquote(String s) {
         if (s.startsWith("'") && s.endsWith("'")) {
             return s.substring(1, s.length() - 1).replaceAll("\\\\'", "'");
         } else {
             return s;
         }
     }
 
     private static long lastmod(Path p) {
         try {
             return Files.getLastModifiedTime(p).toMillis();
         } catch (IOException e) {
             return 0;
         }
     }
 }