/*
    * 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.command.diff;
  
  import java.io.File;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import org.apache.maven.scm.ScmFile;
  import org.apache.maven.scm.ScmFileStatus;
  import org.apache.maven.scm.util.AbstractConsumer;
  
  /**
   * @author <a href="mailto:brett@apache.org">Brett Porter</a>
   * @author <a href="mailto:struberg@yahoo.de">Mark Struberg</a>
   * @author Olivier Lamy
   */
  public class GitDiffConsumer extends AbstractConsumer {
      // diff --git a/readme.txt b/readme.txt
      // index fea1611..9e131cf 100644
      // --- a/readme.txt
      // +++ b/readme.txt
      // @@ -1 +1 @@
      // -/readme.txt
      // \ No newline at end of file
      // +new version of /readme.txt
  
      /**
       * Patern matches the index line of the diff comparison
       * paren.1 matches the first file
       * paren.2 matches the 2nd file.
       */
      private static final Pattern DIFF_FILES_PATTERN = Pattern.compile("^diff --git\\sa/(.*)\\sb/(.*)");
  
      private static final String START_REVISION_TOKEN = "---";
  
      private static final String END_REVISION_TOKEN = "+++";
  
      private static final String ADDED_LINE_TOKEN = "+";
  
      private static final String REMOVED_LINE_TOKEN = "-";
  
      private static final String UNCHANGED_LINE_TOKEN = " ";
  
      private static final String CHANGE_SEPARATOR_TOKEN = "@@";
  
      private static final String NO_NEWLINE_TOKEN = "\\ No newline at end of file";
  
      private static final String INDEX_LINE_TOKEN = "index ";
  
      private static final String SIMILARITY_INDEX_LINE_TOKEN = "similarity index ";
  
      private static final String RENAME_FROM_LINE_TOKEN = "rename from ";
  
      private static final String RENAME_TO_LINE_TOKEN = "rename to ";
  
      private static final String NEW_FILE_MODE_TOKEN = "new file mode ";
  
      private static final String DELETED_FILE_MODE_TOKEN = "deleted file mode ";
  
      private String currentFile;
  
      private StringBuilder currentDifference;
  
      private final List<ScmFile> changedFiles = new ArrayList<>();
  
      private final Map<String, CharSequence> differences = new HashMap<>();
  
      private final StringBuilder patch = new StringBuilder();
  
      // ----------------------------------------------------------------------
      //
      // ----------------------------------------------------------------------
  
      public GitDiffConsumer(File workingDirectory) {
          // empty
      }
  
      // ----------------------------------------------------------------------
     // StreamConsumer Implementation
     // ----------------------------------------------------------------------
 
     /**
      * {@inheritDoc}
      */
     public void consumeLine(String line) {
         Matcher matcher = DIFF_FILES_PATTERN.matcher(line);
         if (matcher.matches()) {
             // start a new file
             currentFile = matcher.group(1);
 
             changedFiles.add(new ScmFile(currentFile, ScmFileStatus.MODIFIED));
 
             currentDifference = new StringBuilder();
 
             differences.put(currentFile, currentDifference);
 
             patch.append(line).append("\n");
 
             return;
         }
 
         if (currentFile == null) {
             if (logger.isWarnEnabled()) {
                 logger.warn("Unparseable line: '" + line + "'");
             }
             patch.append(line).append("\n");
         } else if (line.startsWith(INDEX_LINE_TOKEN)) {
             // skip, though could parse to verify start revision and end revision
             patch.append(line).append("\n");
         } else if (line.startsWith(NEW_FILE_MODE_TOKEN) || line.startsWith(DELETED_FILE_MODE_TOKEN)) {
             // skip, though could parse to verify file mode
             patch.append(line).append("\n");
         } else if (line.startsWith(START_REVISION_TOKEN)) {
             // skip, though could parse to verify filename, start revision
             patch.append(line).append("\n");
         } else if (line.startsWith(END_REVISION_TOKEN)) {
             // skip, though could parse to verify filename, end revision
             patch.append(line).append("\n");
         } else if (line.startsWith(SIMILARITY_INDEX_LINE_TOKEN)) {
             // skip
             patch.append(line).append("\n");
         } else if (line.startsWith(RENAME_FROM_LINE_TOKEN) || line.startsWith(RENAME_TO_LINE_TOKEN)) {
             // skip, though could parse to verify filename
             patch.append(line).append("\n");
         } else if (line.startsWith(ADDED_LINE_TOKEN)
                 || line.startsWith(REMOVED_LINE_TOKEN)
                 || line.startsWith(UNCHANGED_LINE_TOKEN)
                 || line.startsWith(CHANGE_SEPARATOR_TOKEN)
                 || line.equals(NO_NEWLINE_TOKEN)) {
             // add to buffer
             currentDifference.append(line).append("\n");
             patch.append(line).append("\n");
         } else {
             // TODO: handle property differences
 
             if (logger.isWarnEnabled()) {
                 logger.warn("Unparseable line: '" + line + "'");
             }
             patch.append(line).append("\n");
             // skip to next file
             currentFile = null;
             currentDifference = null;
         }
     }
 
     public List<ScmFile> getChangedFiles() {
         return changedFiles;
     }
 
     public Map<String, CharSequence> getDifferences() {
         return differences;
     }
 
     public String getPatch() {
         return patch.toString();
     }
 }