/*
    * 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.scm.provider.svn;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.UncheckedIOException;
  import java.nio.charset.StandardCharsets;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  import java.util.stream.Collectors;
  
  import org.codehaus.plexus.util.Os;
  
  /**
   * @author <a href="mailto:evenisse@apache.org">Emmanuel Venisse</a>
   */
  public class SvnConfigFileReader {
      private File configDirectory;
  
      public File getConfigDirectory() {
          if (configDirectory == null) {
              if (Os.isFamily(Os.FAMILY_WINDOWS)) {
                  configDirectory = new File(System.getenv("APPDATA"), "Subversion");
              } else {
                  configDirectory = new File(System.getProperty("user.home"), ".subversion");
              }
          }
  
          return configDirectory;
      }
  
      public void setConfigDirectory(File configDirectory) {
          this.configDirectory = configDirectory;
      }
  
      public String getProperty(String group, String propertyName) {
          List<String> lines = getConfigLines();
  
          boolean inGroup = false;
          for (Iterator<String> i = lines.iterator(); i.hasNext(); ) {
              String line = i.next().trim();
  
              if (!inGroup) {
                  if (("[" + group + "]").equals(line)) {
                      inGroup = true;
                  }
              } else {
                  if (line.startsWith("[") && line.endsWith("]")) {
                      // a new group start
                      return null;
                  }
  
                  if (line.startsWith("#")) {
                      continue;
                  }
                  if (line.indexOf('=') < 0) {
                      continue;
                  }
  
                  String property = line.substring(0, line.indexOf('=')).trim();
  
                  if (!property.equals(propertyName)) {
                      continue;
                  }
  
                  String value = line.substring(line.indexOf('=') + 1);
                  return value.trim();
              }
          }
  
          return null;
      }
  
      /**
       * Load the svn config file.
       *
       * @return the list of all non-comment, non-empty lines in the config file
       */
      private List<String> getConfigLines() {
         Path configPath = getConfigDirectory().toPath().resolve("config");
         if (Files.exists(configPath)) {
             try {
                 return Files.lines(configPath, StandardCharsets.UTF_8)
                         .filter(line -> !line.isEmpty())
                         .filter(line -> !line.startsWith("#"))
                         .collect(Collectors.toCollection(ArrayList::new));
             } catch (UncheckedIOException | IOException e) {
                 return new ArrayList<>();
             }
         }
         return new ArrayList<>();
     }
 }