/*
    * 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.git.jgit.command.branch;
  
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Set;
  
  import org.apache.maven.scm.ScmException;
  import org.apache.maven.scm.ScmFile;
  import org.apache.maven.scm.ScmFileSet;
  import org.apache.maven.scm.ScmFileStatus;
  import org.apache.maven.scm.ScmResult;
  import org.apache.maven.scm.command.branch.AbstractBranchCommand;
  import org.apache.maven.scm.command.branch.BranchScmResult;
  import org.apache.maven.scm.provider.ScmProviderRepository;
  import org.apache.maven.scm.provider.git.command.GitCommand;
  import org.apache.maven.scm.provider.git.jgit.command.JGitUtils;
  import org.apache.maven.scm.provider.git.repository.GitScmProviderRepository;
  import org.eclipse.jgit.api.Git;
  import org.eclipse.jgit.api.errors.GitAPIException;
  import org.eclipse.jgit.lib.Constants;
  import org.eclipse.jgit.lib.Ref;
  import org.eclipse.jgit.lib.Repository;
  import org.eclipse.jgit.revwalk.RevCommit;
  import org.eclipse.jgit.revwalk.RevWalk;
  import org.eclipse.jgit.transport.RefSpec;
  import org.eclipse.jgit.treewalk.TreeWalk;
  
  /**
   * @author Dominik Bartholdi (imod)
   * @since 1.9
   */
  public class JGitBranchCommand extends AbstractBranchCommand implements GitCommand {
  
      /**
       * {@inheritDoc}
       */
      @Override
      protected ScmResult executeBranchCommand(
              ScmProviderRepository repo, ScmFileSet fileSet, String branch, String message) throws ScmException {
          if (branch == null || branch.trim().isEmpty()) {
              throw new ScmException("branch name must be specified");
          }
  
          if (!fileSet.getFileList().isEmpty()) {
              throw new ScmException("This provider doesn't support branching subsets of a directory");
          }
  
          Git git = null;
          try {
              git = JGitUtils.openRepo(fileSet.getBasedir());
              Ref branchResult = git.branchCreate().setName(branch).call();
              logger.info("created [" + branchResult.getName() + "]");
  
              if (logger.isDebugEnabled()) {
                  for (String branchName : getShortLocalBranchNames(git)) {
                      logger.debug("local branch available: " + branchName);
                  }
              }
  
              if (repo.isPushChanges()) {
                  logger.info("push branch [" + branch + "] to remote...");
                  JGitUtils.push(git, (GitScmProviderRepository) repo, new RefSpec(Constants.R_HEADS + branch));
              }
  
              // search for the tagged files
              final RevWalk revWalk = new RevWalk(git.getRepository());
              RevCommit commit = revWalk.parseCommit(branchResult.getObjectId());
              revWalk.close();
  
              final TreeWalk walk = new TreeWalk(git.getRepository());
              walk.reset(); // drop the first empty tree, which we do not need here
              walk.setRecursive(true);
              walk.addTree(commit.getTree());
  
              List<ScmFile> files = new ArrayList<>();
              while (walk.next()) {
                  files.add(new ScmFile(walk.getPathString(), ScmFileStatus.CHECKED_OUT));
              }
              walk.close();
 
             return new BranchScmResult("JGit branch", files);
 
         } catch (Exception e) {
             throw new ScmException("JGit branch failed!", e);
         } finally {
             JGitUtils.closeRepo(git);
         }
     }
 
     /**
      * gets a set of names of the available branches in the given repo
      *
      * @param git the repo to list the branches for
      * @return set of short branch names
      * @throws GitAPIException
      */
     public static Set<String> getShortLocalBranchNames(Git git) throws GitAPIException {
         Set<String> branches = new HashSet<>();
         Iterator<Ref> iter = git.branchList().call().iterator();
         while (iter.hasNext()) {
             branches.add(Repository.shortenRefName(iter.next().getName()));
         }
         return branches;
     }
 }