/*
    * 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.svnexe.command.changelog;
  
  import java.util.ArrayList;
  import java.util.Date;
  import java.util.List;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import org.apache.maven.scm.ChangeFile;
  import org.apache.maven.scm.ChangeSet;
  import org.apache.maven.scm.ScmFileStatus;
  import org.apache.maven.scm.provider.svn.SvnChangeSet;
  import org.apache.maven.scm.util.AbstractConsumer;
  
  /**
   * @author <a href="mailto:evenisse@apache.org">Emmanuel Venisse</a>
   *
   */
  public class SvnChangeLogConsumer extends AbstractConsumer {
      /**
       * Date formatter for svn timestamp (after a little massaging)
       */
      private static final String SVN_TIMESTAMP_PATTERN = "yyyy-MM-dd HH:mm:ss zzzzzzzzz";
  
      /**
       * State machine constant: expecting header
       */
      private static final int GET_HEADER = 1;
  
      /**
       * State machine constant: expecting file information
       */
      private static final int GET_FILE = 2;
  
      /**
       * State machine constant: expecting comments
       */
      private static final int GET_COMMENT = 3;
  
      /**
       * There is always action and affected path; when copying/moving, recognize also original path and revision
       */
      private static final Pattern FILE_PATTERN = Pattern.compile("^\\s\\s\\s([A-Z])\\s(.+)$");
  
      /**
       * This matches the 'original file info' part of the complete file line.
       * Note the use of [:alpha:] instead of literal 'from' - this is meant to allow non-English localizations.
       */
      private static final Pattern ORIG_FILE_PATTERN = Pattern.compile("\\([A-Za-z]+ (.+):(\\d+)\\)");
  
      /**
       * The file section ends with a blank line
       */
      private static final String FILE_END_TOKEN = "";
  
      /**
       * The comment section ends with a dashed line
       */
      private static final String COMMENT_END_TOKEN =
              "------------------------------------" + "------------------------------------";
  
      /**
       * Current status of the parser
       */
      private int status = GET_HEADER;
  
      /**
       * List of change log entries
       */
      private final List<ChangeSet> entries = new ArrayList<>();
  
      /**
       * The current log entry being processed by the parser
       */
      private SvnChangeSet currentChange;
  
      /**
       * The current revision of the entry being processed by the parser
       */
      private String currentRevision;
  
     /**
      * The current comment of the entry being processed by the parser
      */
     private StringBuilder currentComment;
 
     /**
      * The regular expression used to match header lines
      */
     private static final Pattern HEADER_REG_EXP = Pattern.compile("^(.+) \\| (.+) \\| (.+) \\|.*$");
 
     private static final int REVISION_GROUP = 1;
 
     private static final int AUTHOR_GROUP = 2;
 
     private static final int DATE_GROUP = 3;
 
     private static final Pattern REVISION_REG_EXP1 = Pattern.compile("rev (\\d+):");
 
     private static final Pattern REVISION_REG_EXP2 = Pattern.compile("r(\\d+)");
 
     private static final Pattern DATE_REG_EXP = Pattern.compile("(\\d+-\\d+-\\d+ " + // date 2002-08-24
             "\\d+:\\d+:\\d+) "
             + // time 16:01:00
             "([\\-+])(\\d\\d)(\\d\\d)"); // gmt offset -0400);)
 
     private final String userDateFormat;
 
     /**
      * Default constructor.
      */
     public SvnChangeLogConsumer(String userDateFormat) {
         this.userDateFormat = userDateFormat;
     }
 
     public List<ChangeSet> getModifications() {
         return entries;
     }
 
     // ----------------------------------------------------------------------
     // StreamConsumer Implementation
     // ----------------------------------------------------------------------
 
     /**
      * {@inheritDoc}
      */
     public void consumeLine(String line) {
         if (logger.isDebugEnabled()) {
             logger.debug(line);
         }
         switch (status) {
             case GET_HEADER:
                 processGetHeader(line);
                 break;
             case GET_FILE:
                 processGetFile(line);
                 break;
             case GET_COMMENT:
                 processGetComment(line);
                 break;
             default:
                 throw new IllegalStateException("Unknown state: " + status);
         }
     }
 
     // ----------------------------------------------------------------------
     //
     // ----------------------------------------------------------------------
 
     /**
      * Process the current input line in the GET_HEADER state.  The
      * author, date, and the revision of the entry are gathered.  Note,
      * Subversion does not have per-file revisions, instead, the entire
      * repository is given a single revision number, which is used for
      * the revision number of each file.
      *
      * @param line A line of text from the svn log output
      */
     private void processGetHeader(String line) {
         Matcher matcher = HEADER_REG_EXP.matcher(line);
         if (!matcher.matches()) {
             // The header line is not found. Intentionally do nothing.
             return;
         }
 
         currentRevision = getRevision(matcher.group(REVISION_GROUP));
 
         currentChange = new SvnChangeSet();
 
         currentChange.setAuthor(matcher.group(AUTHOR_GROUP));
 
         currentChange.setDate(getDate(matcher.group(DATE_GROUP)));
 
         currentChange.setRevision(currentRevision);
 
         status = GET_FILE;
     }
 
     /**
      * Gets the svn revision, from the svn log revision output.
      *
      * @param revisionOutput
      * @return the svn revision
      */
     private String getRevision(final String revisionOutput) {
         Matcher matcher;
         if ((matcher = REVISION_REG_EXP1.matcher(revisionOutput)).matches()) {
             return matcher.group(1);
         } else if ((matcher = REVISION_REG_EXP2.matcher(revisionOutput)).matches()) {
             return matcher.group(1);
         } else {
             throw new IllegalOutputException(revisionOutput);
         }
     }
 
     /**
      * Process the current input line in the GET_FILE state.  This state
      * adds each file entry line to the current change log entry.  Note,
      * the revision number for the entire entry is used for the revision
      * number of each file.
      *
      * @param line A line of text from the svn log output
      */
     private void processGetFile(String line) {
         Matcher matcher = FILE_PATTERN.matcher(line);
         if (matcher.matches()) {
             final String fileinfo = matcher.group(2);
             String name = fileinfo;
             String originalName = null;
             String originalRev = null;
             final int n = fileinfo.indexOf(" (");
             if (n > 1 && fileinfo.endsWith(")")) {
                 final String origFileInfo = fileinfo.substring(n);
                 Matcher matcher2 = ORIG_FILE_PATTERN.matcher(origFileInfo);
                 if (matcher2.find()) {
                     // if original file is present, we must extract the affected one from the beginning
                     name = fileinfo.substring(0, n);
                     originalName = matcher2.group(1);
                     originalRev = matcher2.group(2);
                 }
             }
             final String actionStr = matcher.group(1);
             final ScmFileStatus action;
             if ("A".equals(actionStr)) {
                 // TODO: this may even change to MOVED if we later explore whole changeset and find matching DELETED
                 action = originalRev == null ? ScmFileStatus.ADDED : ScmFileStatus.COPIED;
             } else if ("D".equals(actionStr)) {
                 action = ScmFileStatus.DELETED;
             } else if ("M".equals(actionStr)) {
                 action = ScmFileStatus.MODIFIED;
             } else if ("R".equals(actionStr)) {
                 action = ScmFileStatus.UPDATED; // == REPLACED in svn terms
             } else {
                 action = ScmFileStatus.UNKNOWN;
             }
             if (logger.isDebugEnabled()) {
                 logger.debug(actionStr + " : " + name);
             }
             final ChangeFile changeFile = new ChangeFile(name, currentRevision);
             changeFile.setAction(action);
             changeFile.setOriginalName(originalName);
             changeFile.setOriginalRevision(originalRev);
             currentChange.addFile(changeFile);
 
             status = GET_FILE;
         } else if (line.equals(FILE_END_TOKEN)) {
             // Create a buffer for the collection of the comment now
             // that we are leaving the GET_FILE state.
             currentComment = new StringBuilder();
 
             status = GET_COMMENT;
         }
     }
 
     /**
      * Process the current input line in the GET_COMMENT state.  This
      * state gathers all of the comments that are part of a log entry.
      *
      * @param line a line of text from the svn log output
      */
     private void processGetComment(String line) {
         if (line.equals(COMMENT_END_TOKEN)) {
             currentChange.setComment(currentComment.toString());
 
             entries.add(currentChange);
 
             status = GET_HEADER;
         } else {
             currentComment.append(line).append('\n');
         }
     }
 
     /**
      * Converts the date time stamp from the svn output into a date
      * object.
      *
      * @param dateOutput The date output from an svn log command.
      * @return A date representing the time stamp of the log entry.
      */
     private Date getDate(final String dateOutput) {
         Matcher matcher = DATE_REG_EXP.matcher(dateOutput);
         if (!matcher.find()) {
             throw new IllegalOutputException(dateOutput);
         }
 
         final StringBuilder date = new StringBuilder();
         date.append(matcher.group(1));
         date.append(" GMT");
         date.append(matcher.group(2));
         date.append(matcher.group(3));
         date.append(':');
         date.append(matcher.group(4));
 
         return parseDate(date.toString(), userDateFormat, SVN_TIMESTAMP_PATTERN);
     }
 }