/*--
  This file is a part of ZetaGrid, a simple and secure Grid Computing
  kernel.

  Copyright (c) 2001-2004 Sebastian Wedeniwski.  All rights reserved.

  Use in source and binary forms, with or without modification,
  are permitted provided that the following conditions are met:

  1. The source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.

  2. The origin of this software must not be misrepresented; you must 
     not claim that you wrote the original software.  If you plan to
     use this software in a product, please contact the author.

  3. Altered source versions must be plainly marked as such, and must
     not be misrepresented as being the original software. The author
     must be informed about these changes.

  4. The name of the author may not be used to endorse or promote 
     products derived from this software without specific prior written 
     permission.

  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.

  Version 1.5.6, September 24, 2002

  This program is based on the work of:
     R. Auberger
     H. Haddorp
     S. Wedeniwski
--*/

package zeta;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;

/**
 *  The <code>ZetaProperties</code> class represents a persistent set of properties.
 *  The Properties are loaded from the file "zeta.cfg."
 *  Each key and its corresponding value in the property list is a string.
 *  If the property key is not found in the original property list then the
 *  second property list "default.cfg" is searched.
 *  The default property file has the following content:
 *  <code>
<p># host identification via HTTP
<br>host.name=www.zetagrid.net
<br>host.port=80
<br>downloadURL=/servlet/service/getClient
<br>requestURL=/servlet/service/requestWorkUnit
<br>resultURL=/servlet/service/result
<br>
<br># executes the specified method
<br>exec.class=zeta.ZetaCalc
<br>exec.method=run
<br>
<br># size of the packages (Pentium III 800 MHz):
<br># t: tiny package ~  60 minutes
<br># s: small package ~  90 minutes
<br># m: medium package ~ 3 hours
<br># l: large package ~  4 hours
<br># h: huge package ~  6 hours
<br>package_size=m
<br>
<br># max. number of packages is 5
<br>packages=1
<br>
<br># number of packages must be greater or equal than the number of processors
<br># please contact Sebastian Wedeniwski (wedeniws@de.ibm.com) if you want to use more than 5 processors
<br># the value 0 sequentially completes all local packages and terminates the process
<br>processors=1
<br>
<br># usage of the processor power
<br># the value 0 means the usage of the complete CPU power
<br># a small value (>0) reduce the intensity, e.g. 5000
<br>sleepN=0
<br>
<br># set the task which should be computed
<br># the default is 'zeta-zeros': Computation of the zeros of the Riemann zeta function
<br>task=zeta-zeros
<br>
<br># port number which is used to avoid conflicts
<br># this port number must be changed if it is used by other applications, e.g. www.webmin.com
<br>port=10000
<br>
<br># the folowing two parameters are used by the screen saver
<br>prio=low
<br>call=java.exe -Xmx128m -cp zeta.jar;zeta_client.jar zeta.ZetaClient
<br></code>
**/
public class ZetaProperties {
  /**
   *  Creates a property list with the keys of the property files "zeta.cfg" and "default.cfg."
  **/
  public ZetaProperties() {
    load();
  }

  /**
   *  Reloads the property files "zeta.cfg" and "default.cfg."
  **/
  public void reload() {
    props = propsDefault = null;
    load();
  }

  /**
   *  Loads the property files "zeta.cfg" and "default.cfg."
  **/
  public void load() {
    File propsDefaultFile = new File("default.cfg");
    if (propsDefault == null && propsDefaultFile.canRead()) {
      try {
        propsDefault = new Properties();
        propsDefault.load(new FileInputStream(propsDefaultFile));
      } catch (IOException e) {
        System.out.println(e.getMessage());
      }
    }
    try {
      File propsFile = new File("zeta.cfg");
      if (props == null && propsFile.canRead()) {
        props = new Properties(propsDefault);
        props.load(new FileInputStream(propsFile));
      }
    } catch (IOException e) {
      System.out.println(e.getMessage());
    }
  }

  /**
   * Searches for the property with the specified key in this property list.
   * If the key is not found in this property list, the default property list,
   * and its defaults, recursively, are then checked. The method returns
   * <code>null</code> if the property is not found.
   *
   * @param   key   the property key.
  **/
  public String get(String key) {
    if (propsDefault == null || props == null) load();
    String s = (props != null)? (String)props.get(key) : null;
    if (s != null || propsDefault == null) return s;
    return (String)propsDefault.get(key);
  }

  /**
   *  Searches for the property with the specified key in this property list.
   *  If the key is not found in this property list, the default property list, and its defaults,
   *  recursively, are then checked. The method returns the default value argument if the property is not found.
   *
   *  @param   key   the property key.
   *  @param   defaultValue   a default value.
   *
   *  @return the value in this property list with the specified key value.
  **/
  public String get(String key, String defaultValue) {
    String s = get(key);
    return (s != null)? s : defaultValue;
  }

  /**
   *  Searches for the property with the specified key in this property list.
   *  If the key is not found in this property list, the default property list, and its defaults,
   *  recursively, are then checked. The method returns the default value argument if the property is not found
   *  or not an integer.
   *
   *  @param   key   the property key.
   *  @param   defaultValue   a default value.
   *
   *  @return the value in this property list with the specified key value.
  **/
  public int get(String key, int defaultValue) {
    try {
      String s = get(key);
      if (s != null) return Integer.parseInt(s);
    } catch (NumberFormatException e) {
    }
    return defaultValue;
  }

  /**
   *  A property list that contains default values for any keys not
   *  found in the main property list.
  **/
  private Properties propsDefault = null;

  /**
   *  The main property list.
  **/
  private Properties props = null;
}