package org.jactr.core.chunk.six;

/*
 * default logging
 */
import javolution.util.FastList;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jactr.core.chunk.IChunk;
import org.jactr.core.chunk.four.Link4;
import org.jactr.core.chunk.link.IAssociativeLink;
import org.jactr.core.chunk.link.IAssociativeLinkEquation;
import org.jactr.core.model.IModel;
import org.jactr.core.module.declarative.associative.IAssociativeLinkContainer;
import org.jactr.core.module.declarative.six.learning.IDeclarativeLearningModule6;

public class AssociativeLinkEquation6 implements IAssociativeLinkEquation
{
  /**
   * Logger definition
   */
  static private final transient Log  LOGGER = LogFactory
                                                 .getLog(AssociativeLinkEquation6.class);

  private IDeclarativeLearningModule6 _declarativeLearningModule;

  public AssociativeLinkEquation6(IDeclarativeLearningModule6 decLM)
  {
    _declarativeLearningModule = decLM;
  }

  public double computeLearnedStrength(IAssociativeLink link)
  {
    return computeDefaultStrength(link);
  }

  public double computeDefaultStrength(IAssociativeLink link)
  {
    if (Double.isNaN(_declarativeLearningModule.getMaximumStrength()))
      return 0;

    double max = _declarativeLearningModule.getMaximumStrength();

    /**
     * In theory, this is Sji = Smax - ln(fanj). However, the lisp manual
     * mentions fanj = fanj+1 / count
     */
    double fanj = link.getJChunk().getAdapter(IAssociativeLinkContainer.class)
        .getNumberOfOutboundLinks();

    // fanj++;
    fanj = fanj / ((Link4) link).getCount();

    double ln = Math.log(fanj);
    double strength = max - ln;

    if (LOGGER.isDebugEnabled())
      LOGGER.debug(String.format(
                  "Sji j:%s i:%s fanj = %.2f, ln(fanj) = %.2f, max = %.2f yields Sji %.2f",
                  link.getJChunk(), link.getIChunk(), fanj, ln, max, strength));

    return strength;
  }

  public void resetStrengths(IModel model)
  {
    try
    {
      FastList<IAssociativeLink> links = FastList.newInstance();
      for (IChunk chunk : model.getDeclarativeModule().getChunks().get())
      {
        IAssociativeLinkContainer alc = chunk
            .getAdapter(IAssociativeLinkContainer.class);
        links.clear();
        alc.getOutboundLinks(links);
        for (IAssociativeLink link : links)
        {
          if (LOGGER.isDebugEnabled())
            LOGGER.debug("Reseting strength of " + link);
          ((Link4) link).setStrength(computeDefaultStrength(link));
        }
      }
    }
    catch (Exception e)
    {
      LOGGER.error("Could not reset links because of an exception ", e);
    }
  }

}