/**
    * Copyright (c) 2012-2014, jcabi.com
    * All rights reserved.
    *
    * Redistribution and use in source and binary forms, with or without
    * modification, are permitted provided that the following conditions
    * are met: 1) Redistributions of source code must retain the above
    * copyright notice, this list of conditions and the following
    * disclaimer. 2) Redistributions in binary form must reproduce the above
   * copyright notice, this list of conditions and the following
   * disclaimer in the documentation and/or other materials provided
   * with the distribution. 3) Neither the name of the jcabi.com nor
   * the names of its contributors may be used to endorse or promote
   * products derived from this software without specific prior written
   * permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
   * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
   * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
   * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
   * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
   * OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  package com.jcabi.heroku.maven.plugin;
  
  import com.jcabi.aspects.Immutable;
  import com.jcabi.aspects.RetryOnFailure;
  import com.jcabi.log.Logger;
  import com.jcabi.log.VerboseProcess;
  import java.io.File;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  import javax.validation.constraints.NotNull;
  import lombok.EqualsAndHashCode;
  import lombok.ToString;
  import org.apache.commons.io.FileUtils;
  import org.apache.commons.lang3.StringUtils;
  
  /**
   * Git engine.
   *
   * @author Yegor Bugayenko (yegor@tpc2.com)
   * @version $Id$
   * @since 0.4
   * @checkstyle ClassDataAbstractionCoupling (500 lines)
   */
  @Immutable
  @ToString
  @EqualsAndHashCode(of = "script")
  final class Git {
  
      /**
       * Permissions to set to SSH key file.
       */
      @SuppressWarnings("PMD.AvoidUsingOctalValues")
      private static final int PERMS = 0600;
  
      /**
       * Default SSH location.
       */
      private static final String SSH = "/usr/bin/ssh";
  
      /**
       * Location of shell script.
       */
      private final transient String script;
  
      /**
       * Public ctor.
       * @param key Location of SSH key
       * @param temp Temp directory
       * @throws IOException If some error inside
       */
      public Git(@NotNull final File key,
          @NotNull final File temp) throws IOException {
          if (!new File(Git.SSH).exists()) {
              throw new IllegalStateException(
                  String.format("SSH is not installed at '%s'", Git.SSH)
              );
          }
          final File kfile = new File(temp, "heroku.pem");
          FileUtils.copyFile(key, kfile);
          this.chmod(kfile, Git.PERMS);
          final File file = new File(temp, "git-ssh.sh");
          this.script = file.getAbsolutePath();
          FileUtils.writeStringToFile(
              new File(this.script),
              String.format(
                  // @checkstyle LineLength (1 line)
                  "set -x && %s -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -i '%s' $@",
                  Git.SSH,
                  kfile.getAbsolutePath()
             )
         );
         file.setExecutable(true);
     }
 
     /**
      * Execute git with these arguments.
      * @param dir In which directory to run it
      * @param args Arguments to pass to it
      * @return Stdout
      * @checkstyle MagicNumber (2 lines)
      */
     @RetryOnFailure(delay = 3000, attempts = 2)
     public String exec(@NotNull final File dir, @NotNull final String... args) {
         final List<String> commands = new ArrayList<String>(args.length + 1);
         commands.add("git");
         for (final String arg : args) {
             commands.add(arg);
         }
         Logger.info(this, "%s:...", StringUtils.join(commands, " "));
         final ProcessBuilder builder = new ProcessBuilder(commands);
         builder.directory(dir);
         builder.environment().put("GIT_SSH", this.script);
         return new VerboseProcess(builder).stdout();
     }
 
     /**
      * Change file permissions.
      * @param file The file to change
      * @param mode Permissions to set
      * @throws IOException If some error inside
      * @see http://stackoverflow.com/questions/664432
      * @see http://stackoverflow.com/questions/1556119
      */
     private void chmod(final File file, final int mode) throws IOException {
         new VerboseProcess(
             new ProcessBuilder(
                 "chmod",
                 String.format("%04o", mode),
                 file.getAbsolutePath()
             )
         ).stdout();
         Logger.debug(
             this,
             "chmod(%s, %3o): succeeded",
             file,
             mode
         );
     }
 
 }