/**************************************************************************
/* This class implements the simple ant-task "VersionManager".
/*
/* Copyright (c) 2004 by Bernhard Bablok (mail@bablokb.de)
/*
/* This program is free software; you can redistribute it and/or modify
/* it under the terms of the GNU General Public License as published
/* by  the Free Software Foundation; either version 2 of the License or
/* (at your option) any later version.
/*
/* This program is distributed in the hope that it will be useful, but
/* WITHOUT ANY WARRANTY; without even the implied warranty of
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
/* GNU General Public License for more details.
/*
/* You should have received a copy of the GNU General Public License
/* along with this program; see the file COPYING.  If not, write to
/* the Free Software Foundation Inc., 59 Temple Place - Suite 330,
/* Boston, MA  02111-1307 USA
/**************************************************************************/

import java.io.*;
import java.util.*;
import org.apache.tools.ant.*;

/**
   This class implements the ant-task "VersionManager". The tasks manages
   major-version, minor-version and patch-level of a project. If you increment
   the major-version, both minor-version and patch-level are set to zero.
   If you increment the minor-version, the patch-level is set to zero.

   <p>Basically, the version is an ant-property: version=a.b.c in a file
   (default: version.properties). The VersionManager task reads the file,
   updates the corresponding values, and rewrites it.

   @version $Revision: 1.5 $
   @author  $Author: bablokb $
*/

public class VersionManager extends Task {

  /**
     The File with the version-information.
  */

  private File iVersionFile = new File("version.properties");

  /**
     The increment-type.
  */

  private String iInc;


  /**
     Increment-type constant.
  */

  private final String TYPE_MAJOR = "major",
                       TYPE_MINOR = "minor",
                       TYPE_PL    = "patchlevel";

  /**
     Version variable.
  */

  private int iMajorVersion, iMinorVersion, iPatchLevel;

  //////////////////////////////////////////////////////////////////////////////

  /**
     Set the File with the version-information.
  */

  public void setFile(File versionFile) {
    iVersionFile = versionFile;
  }

  //////////////////////////////////////////////////////////////////////////////

  /**
     Set the increment-type.
  */

  public void setInc(String inc) {
    iInc = inc;
    validateInc();
  }

  //////////////////////////////////////////////////////////////////////////////

  /**
     Validate the increment-type.
  */

  private void validateInc() {
    if (! iInc.equals(TYPE_MAJOR) &&
        ! iInc.equals(TYPE_MINOR) &&
        ! iInc.equals(TYPE_PL))
      throw new BuildException("Invalid value of inc: " + iInc);
  }

  //////////////////////////////////////////////////////////////////////////////

  /**
     Increment the type (major, minor or patch-level) - this executes the task.
  */

  public void execute() {
    try {
      readFile();
      if (iInc.equals(TYPE_MAJOR)) {
        log("incrementing major-version");
        iMajorVersion += 1;
        iMinorVersion  = 0;
        iPatchLevel    = 0;
      } else if (iInc.equals(TYPE_MINOR)) {
        log("incrementing minor-version");
        iMinorVersion += 1;
        iPatchLevel    = 0;
      } else {
        log("incrementing patch-level");
        iPatchLevel += 1;
      }
      writeFile();
      log("new version is: " + 
          iMajorVersion + "." + iMinorVersion + "." +
          iPatchLevel);
    } catch (IOException e) {
      throw new BuildException("Failed with IOException: " + e.toString());
    }
  }

  //////////////////////////////////////////////////////////////////////////////

  /**
     Read the version-file and set variables. If it does not exist,
     set default-values.
  */

  private void readFile() throws IOException {
    if (!iVersionFile.exists()) {
      log("Version-File " + iVersionFile.toString() + " does not exist.");
      iMajorVersion = 0;
      iMinorVersion = 0;
      iPatchLevel   = 0;
      return;
    }

    BufferedReader reader = 
      new BufferedReader(new FileReader(iVersionFile));
    String line;
    while ((line = reader.readLine()) != null) {
      if (line.startsWith("app.version")) {
        StringTokenizer tok = new StringTokenizer(line," =");
        tok.nextToken();   // skip app.version = 
	iMajorVersion = Integer.parseInt(tok.nextToken(".= "));
        iMinorVersion = Integer.parseInt(tok.nextToken());
        iPatchLevel   = Integer.parseInt(tok.nextToken());
        break;
      }
    }
    reader.close();
  }

  //////////////////////////////////////////////////////////////////////////////

  /**
     Save the version-file after update.
  */

  private void writeFile() throws IOException {
    PrintWriter writer =
      new PrintWriter(new FileWriter(iVersionFile));
    writer.println("# created by VersionManager " + (new Date()).toString());
    writer.println("#\n# modify at your own risk!\n");
    writer.println("app.version = " + iMajorVersion + "." + 
      iMinorVersion + "." +
      iPatchLevel);
    writer.close();
  }
}