FlatFilePredicateManager.java

/*
 * 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. You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

package org.aitools.programd.predicates;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Map;
import java.util.Properties;

import org.aitools.programd.Core;
import org.aitools.util.resource.Filesystem;
import org.aitools.util.runtime.DeveloperError;
import org.aitools.util.runtime.UserError;

/**
 * Uses "flat-file" Java properties files to store predicate data.
 * 
 * @author <a href="mailto:noel@aitools.org">Noel Bush</a>
 */
public class FlatFilePredicateManager extends PredicateManager {

  /** The name of the subdirectory for the predicate files. */
  private String _dirname;

  /** The suffix for a predicates storage file. */
  private static final String PREDICATES_SUFFIX = ".predicates";

  /** The string "{@value} ". */
  private static final String FILE_LABEL = "FlatFilePredicateManager predicates file";

  /**
   * Creates a new FlatFilePredicateManager with the given Core as owner.
   * 
   * @param core the Core that owns this FlatFilePredicateManager
   */
  public FlatFilePredicateManager(Core core) {
    super(core);
    this._dirname = this._core.getSettings().getFfpmDirectory().getPath();
  }

  /**
   * Composes a filename for storing/retrieving predicates.
   * 
   * @param user
   * @param bot
   * @return a filename
   */
  @SuppressWarnings("boxing")
  protected String composeFilename(String user, String bot) {
    return String.format("%s%c%s%c%s%s", this._dirname, File.separatorChar, bot, File.separatorChar, user,
        PREDICATES_SUFFIX);
  }

  /**
   * @see org.aitools.programd.predicates.PredicateManager#dumpPredicates()
   */
  @Override
  public void dumpPredicates() {
    {
      for (String bot : this._bots.keySet()) {
        Map<String, PredicateMap> predicateCache = this._bots.get(bot).getPredicateCache();
        for (String user : predicateCache.keySet()) {
          Properties predicates = this.loadPredicates(user, bot);
          PredicateMap predicateMap = predicateCache.get(user);
          for (String name : predicateMap.keySet()) {
            PredicateValue value = predicateMap.get(name);
            if (value.size() == 1) {
              predicates.setProperty(name, value.getFirstValue());
            }
            else {
              for (int index = 1; index <= value.size(); index++) {
                predicates.setProperty(name + '.' + index, value.get(index));
              }
            }
          }
          predicateMap.clear();
          String fileName = this.composeFilename(user, bot);
          Filesystem.checkOrCreate(fileName, FILE_LABEL);
          FileOutputStream outputStream;
          try {
            outputStream = Filesystem.getFileOutputStream(fileName);
          }
          catch (FileNotFoundException e) {
            throw new DeveloperError(String.format("Could not locate just-created file: \"%s\".", fileName), e);
          }

          try {
            predicates.store(outputStream, null);
          }
          catch (IOException e) {
            throw new UserError("Error trying to save predicates.", e);
          }
        }
      }
    }
  }

  /**
   * @see org.aitools.programd.predicates.PredicateManager#initialize()
   */
  @Override
  public void initialize() {
    // No initialization necessary.
  }

  /**
   * @see org.aitools.programd.predicates.PredicateManager#loadPredicate(java.lang.String, java.lang.String,
   *      java.lang.String)
   */
  @Override
  public String loadPredicate(String name, String user, String bot) throws NoSuchPredicateException {
    Properties predicates = this.loadPredicates(user, bot);

    // Try to get the predicate value.
    String result = predicates.getProperty(name);

    if (result == null) {
      throw new NoSuchPredicateException(name);
    }
    return result;
  }

  /**
   * Loads the predicates file for a given user. Ensures that the directory exists.
   * 
   * @param user the user to look for
   * @param bot the bot with which to associate the user in the search
   * @return the predicates for the user
   */
  protected Properties loadPredicates(String user, String bot) {
    Properties predicates = new Properties();

    File predicateFile = Filesystem.checkOrCreate(this.composeFilename(bot, user), FILE_LABEL);
    if (predicateFile.canRead()) {
      try {
        predicates.load(new FileInputStream(predicateFile));
      }
      catch (IOException e) {
        throw new UserError("Error trying to load predicates.", e);
      }
    }
    return predicates;
  }
}