/*
 *    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; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    MergeTwoValues.java
 *    Copyright (C) 1999 University of Waikato, Hamilton, New Zealand
 *
 */


package weka.filters.unsupervised.attribute;

import weka.core.Attribute;
import weka.core.Capabilities;
import weka.core.FastVector;
import weka.core.Instance; 
import weka.core.DenseInstance;
import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.RevisionUtils;
import weka.core.SingleIndex;
import weka.core.UnsupportedAttributeTypeException;
import weka.core.Utils;
import weka.core.WekaException;
import weka.core.Capabilities.Capability;
import weka.filters.Filter;
import weka.filters.StreamableFilter;
import weka.filters.UnsupervisedFilter;

import java.util.Enumeration;
import java.util.Vector;

/** 
 <!-- globalinfo-start -->
 * Merges two values of a nominal attribute into one value.
 * <p/>
 <!-- globalinfo-end -->
 * 
 <!-- options-start -->
 * Valid options are: <p/>
 * 
 * <pre> -C &lt;col&gt;
 *  Sets the attribute index (default last).</pre>
 * 
 * <pre> -F &lt;value index&gt;
 *  Sets the first value's index (default first).</pre>
 * 
 * <pre> -S &lt;value index&gt;
 *  Sets the second value's index (default last).</pre>
 * 
 <!-- options-end -->
 *
 * @author Eibe Frank (eibe@cs.waikato.ac.nz) 
 * @version $Revision: 5987 $
 */
public class MergeTwoValues 
  extends Filter
  implements UnsupervisedFilter, StreamableFilter, OptionHandler {

  /** for serialization */
  static final long serialVersionUID = 2925048980504034018L;
  
  /** The attribute's index setting. */
  private SingleIndex m_AttIndex = new SingleIndex("last"); 

  /** The first value's index setting. */
  private SingleIndex m_FirstIndex = new SingleIndex("first");

  /** The second value's index setting. */
  private SingleIndex m_SecondIndex = new SingleIndex("last");

  /**
   * Returns a string describing this filter
   *
   * @return a description of the filter suitable for
   * displaying in the explorer/experimenter gui
   */
  public String globalInfo() {

    return  "Merges two values of a nominal attribute into one value.";
  }

  /** 
   * Returns the Capabilities of this filter.
   *
   * @return            the capabilities of this object
   * @see               Capabilities
   */
  public Capabilities getCapabilities() {
    Capabilities result = super.getCapabilities();
    result.disableAll();

    // attributes
    result.enableAllAttributes();
    result.enable(Capability.MISSING_VALUES);
    
    // class
    result.enableAllClasses();
    result.enable(Capability.MISSING_CLASS_VALUES);
    result.enable(Capability.NO_CLASS);
    
    return result;
  }

  /**
   * Sets the format of the input instances.
   *
   * @param instanceInfo an Instances object containing the input 
   * instance structure (any instances contained in the object are 
   * ignored - only the structure is required).
   * @return true if the outputFormat may be collected immediately
   * @throws Exception if the input format can't be set 
   * successfully
   */
  public boolean setInputFormat(Instances instanceInfo) 
       throws Exception {

    super.setInputFormat(instanceInfo);
    m_AttIndex.setUpper(instanceInfo.numAttributes() - 1);
    m_FirstIndex.setUpper(instanceInfo.
			  attribute(m_AttIndex.getIndex()).numValues() - 1);
    m_SecondIndex.setUpper(instanceInfo.
			   attribute(m_AttIndex.getIndex()).numValues() - 1);
    if ((instanceInfo.classIndex() > -1) && (instanceInfo.classIndex() == m_AttIndex.getIndex())) {
      throw new Exception("Cannot process class attribute.");
    }
    if (!instanceInfo.attribute(m_AttIndex.getIndex()).isNominal()) {
      throw new UnsupportedAttributeTypeException("Chosen attribute not nominal.");
    }
    if (instanceInfo.attribute(m_AttIndex.getIndex()).numValues() < 2) {
      throw new UnsupportedAttributeTypeException("Chosen attribute has less than " +
						  "two values.");
    }
    if (m_SecondIndex.getIndex() <= m_FirstIndex.getIndex()) {
      // XXX Maybe we should just swap the values??
      throw new Exception("The second index has to be greater "+
			  "than the first.");
    }
    setOutputFormat();
    return true;
  }

  /**
   * Input an instance for filtering. The instance is processed
   * and made available for output immediately.
   *
   * @param instance the input instance
   * @return true if the filtered instance may now be
   * collected with output().
   * @throws IllegalStateException if no input format has been set.
   */
  public boolean input(Instance instance) {

    if (getInputFormat() == null) {
      throw new IllegalStateException("No input instance format defined");
    }
    if (m_NewBatch) {
      resetQueue();
      m_NewBatch = false;
    }
    Instance newInstance = (Instance)instance.copy();
    if ((int)newInstance.value(m_AttIndex.getIndex()) == m_SecondIndex.getIndex()) {
      newInstance.setValue(m_AttIndex.getIndex(), (double)m_FirstIndex.getIndex());
    }
    else if ((int)newInstance.value(m_AttIndex.getIndex()) > m_SecondIndex.getIndex()) {
      newInstance.setValue(m_AttIndex.getIndex(),
			   newInstance.value(m_AttIndex.getIndex()) - 1);
    }
    push(newInstance);
    return true;
  }

  /**
   * Returns an enumeration describing the available options.
   *
   * @return an enumeration of all the available options.
   */
  public Enumeration listOptions() {

    Vector newVector = new Vector(3);

    newVector.addElement(new Option(
              "\tSets the attribute index (default last).",
              "C", 1, "-C <col>"));

    newVector.addElement(new Option(
              "\tSets the first value's index (default first).",
              "F", 1, "-F <value index>"));

    newVector.addElement(new Option(
              "\tSets the second value's index (default last).",
              "S", 1, "-S <value index>"));

    return newVector.elements();
  }


  /**
   * Parses a given list of options. <p/>
   * 
   <!-- options-start -->
   * Valid options are: <p/>
   * 
   * <pre> -C &lt;col&gt;
   *  Sets the attribute index (default last).</pre>
   * 
   * <pre> -F &lt;value index&gt;
   *  Sets the first value's index (default first).</pre>
   * 
   * <pre> -S &lt;value index&gt;
   *  Sets the second value's index (default last).</pre>
   * 
   <!-- options-end -->
   *
   * @param options the list of options as an array of strings
   * @throws Exception if an option is not supported
   */
  public void setOptions(String[] options) throws Exception {
    
    String attIndex = Utils.getOption('C', options);
    if (attIndex.length() != 0) {
      setAttributeIndex(attIndex);
    } else {
      setAttributeIndex("last");
    }

    String firstValIndex = Utils.getOption('F', options);
    if (firstValIndex.length() != 0) {
      setFirstValueIndex(firstValIndex);
    } else {
      setFirstValueIndex("first");
    }

    String secondValIndex = Utils.getOption('S', options);
    if (secondValIndex.length() != 0) {
      setSecondValueIndex(secondValIndex);
    } else {
      setSecondValueIndex("last");
    }
   
    if (getInputFormat() != null) {
      setInputFormat(getInputFormat());
    }
  }

  /**
   * Gets the current settings of the filter.
   *
   * @return an array of strings suitable for passing to setOptions
   */
  public String [] getOptions() {

    String [] options = new String [6];
    int current = 0;

    options[current++] = "-C";
    options[current++] = "" + getAttributeIndex();
    options[current++] = "-F"; 
    options[current++] = "" + getFirstValueIndex();
    options[current++] = "-S"; 
    options[current++] = "" + getSecondValueIndex();
    while (current < options.length) {
      options[current++] = "";
    }
    return options;
  }

  /**
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String attributeIndexTipText() {

    return "Sets which attribute to process. This "
      + "attribute must be nominal (\"first\" and \"last\" are valid values)";
  }

  /**
   * Get the index of the attribute used.
   *
   * @return the index of the attribute
   */
  public String getAttributeIndex() {

    return m_AttIndex.getSingleIndex();
  }

  /**
   * Sets index of the attribute used.
   *
   * @param attIndex the index of the attribute
   */
  public void setAttributeIndex(String attIndex) {
    
    m_AttIndex.setSingleIndex(attIndex);
  }

  /**
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String firstValueIndexTipText() {

    return "Sets the first value to be merged. "
      + "(\"first\" and \"last\" are valid values)";
  }

  /**
   * Get the index of the first value used.
   *
   * @return the index of the first value
   */
  public String getFirstValueIndex() {

    return m_FirstIndex.getSingleIndex();
  }

  /**
   * Sets index of the first value used.
   *
   * @param firstIndex the index of the first value
   */
  public void setFirstValueIndex(String firstIndex) {
    
    m_FirstIndex.setSingleIndex(firstIndex);
  }

  /**
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String secondValueIndexTipText() {

    return "Sets the second value to be merged. "
      + "(\"first\" and \"last\" are valid values)";
  }

  /**
   * Get the index of the second value used.
   *
   * @return the index of the second value
   */
  public String getSecondValueIndex() {

    return m_SecondIndex.getSingleIndex();
  }

  /**
   * Sets index of the second value used.
   *
   * @param secondIndex the index of the second value
   */
  public void setSecondValueIndex(String secondIndex) {
    
    m_SecondIndex.setSingleIndex(secondIndex);
  }

  /**
   * Set the output format. Takes the current average class values
   * and m_InputFormat and calls setOutputFormat(Instances) 
   * appropriately.
   */
  private void setOutputFormat() {
    
    Instances newData;
    FastVector newAtts, newVals;
    boolean firstEndsWithPrime = false, 
      secondEndsWithPrime = false;
    StringBuffer text = new StringBuffer();
      
    // Compute new attributes
      
    newAtts = new FastVector(getInputFormat().numAttributes());
    for (int j = 0; j < getInputFormat().numAttributes(); j++) {
      Attribute att = getInputFormat().attribute(j);
      if (j != m_AttIndex.getIndex()) {
	newAtts.addElement(att.copy());
      } else {
	  
	// Compute new value
	  
	if (att.value(m_FirstIndex.getIndex()).endsWith("'")) {
	  firstEndsWithPrime = true;
	}
	if (att.value(m_SecondIndex.getIndex()).endsWith("'")) {
	  secondEndsWithPrime = true;
	}
	if (firstEndsWithPrime || secondEndsWithPrime) {
	  text.append("'");
	}
	if (firstEndsWithPrime) {
	  text.append(((String)att.value(m_FirstIndex.getIndex())).
		      substring(1, ((String)att.value(m_FirstIndex.getIndex())).
				length() - 1));
	} else {
	  text.append((String)att.value(m_FirstIndex.getIndex()));
	}
	text.append('_');
	if (secondEndsWithPrime) {
	  text.append(((String)att.value(m_SecondIndex.getIndex())).
		      substring(1, ((String)att.value(m_SecondIndex.getIndex())).
				length() - 1));
	} else {
	  text.append((String)att.value(m_SecondIndex.getIndex()));
	}
	if (firstEndsWithPrime || secondEndsWithPrime) {
	  text.append("'");
	}
	  
	// Compute list of attribute values
	  
	newVals = new FastVector(att.numValues() - 1);
	for (int i = 0; i < att.numValues(); i++) {
	  if (i == m_FirstIndex.getIndex()) {
	    newVals.addElement(text.toString());
	  } else if (i != m_SecondIndex.getIndex()) {
	    newVals.addElement(att.value(i));
	  }
	}
	newAtts.addElement(new Attribute(att.name(), newVals));
      }
    }
      
    // Construct new header
      
    newData = new Instances(getInputFormat().relationName(), newAtts,
			    0);
    newData.setClassIndex(getInputFormat().classIndex());
    setOutputFormat(newData);
  }
  
  /**
   * Returns the revision string.
   * 
   * @return		the revision
   */
  public String getRevision() {
    return RevisionUtils.extract("$Revision: 5987 $");
  }
  
  /**
   * Main method for testing this class.
   *
   * @param argv should contain arguments to the filter: 
   * use -h for help
   */
  public static void main(String [] argv) {
    runFilter(new MergeTwoValues(), argv);
  }
}
