/*
 *    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.
 */

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

package weka.core;

import java.io.Serializable;
import java.util.Enumeration;
import java.util.Vector;

/** 
 * Class representing a range of cardinal numbers. The range is set by a 
 * string representation such as: <P>
 *
 * <code>
 *   first-last
 *   1,2,3,4
 * </code> <P>
 * or combinations thereof. The range is internally converted from
 * 1-based to 0-based (so methods that set or get numbers not in string
 * format should use 0-based numbers).
 *
 * @author Len Trigg (trigg@cs.waikato.ac.nz)
 * @version $Revision: 5953 $
 */
public class Range
  implements Serializable, RevisionHandler {
  
  /** for serialization */
  static final long serialVersionUID = 3667337062176835900L;

  /** Record the string representations of the columns to delete */
  /*@non_null spec_public@*/Vector m_RangeStrings = new Vector();

  /** Whether matching should be inverted */
  /*@spec_public@*/ boolean m_Invert;

  /** The array of flags for whether an column is selected */
  /*@spec_public@*/boolean [] m_SelectFlags;

  /** Store the maximum value permitted in the range. -1 indicates that
      no upper value has been set */
  /*@spec_public@*/ int m_Upper = -1;

  /** Default constructor. */
  //@assignable this.*;
    public Range() {
  }

  /**
   * Constructor to set initial range.
   *
   * @param rangeList the initial range
   * @throws IllegalArgumentException if the range list is invalid
   */
  public Range(/*@non_null@*/ String rangeList) {

    setRanges(rangeList);
  }

  /**
   * Sets the value of "last".
   *
   * @param newUpper the value of "last"
   */
  public void setUpper(int newUpper) {

    if (newUpper >= 0) {
      m_Upper = newUpper;
      setFlags();
    }
  }
  
  /**
   * Gets whether the range sense is inverted, i.e. all <i>except</i>
   * the values included by the range string are selected.
   * 
   * @return whether the matching sense is inverted
   */
  //@ensures \result <==> m_Invert;
  public /*@pure@*/boolean getInvert() {

    return m_Invert;
  }

  /**
   * Sets whether the range sense is inverted, i.e. all <i>except</i>
   * the values included by the range string are selected.
   * 
   * @param newSetting true if the matching sense is inverted
   */
  public void setInvert(boolean newSetting) {

    m_Invert = newSetting;
  }

  /**
   * Gets the string representing the selected range of values
   *
   * @return the range selection string
   */
  public /*@non_null pure@*/String getRanges() {

    StringBuffer result = new StringBuffer(m_RangeStrings.size()*4);
    boolean first = true;
    char sep = ',';
    for (int i = 0; i < m_RangeStrings.size(); i++) {
      if (first) {
        result.append((String)m_RangeStrings.elementAt(i));
        first = false;
      } else {
        result.append(sep + (String)m_RangeStrings.elementAt(i));
      }
    }
    return result.toString();
  }

  /**
   * Sets the ranges from a string representation. Note that setUpper()
   * must be called afterwards for ranges to be actually set internally.
   *
   * @param rangeList the comma separated list of ranges. The empty
   * string sets the range to empty.
   * @throws IllegalArgumentException if the rangeList was not well formed
   */
  //@requires rangeList != null;
  //@assignable m_RangeStrings,m_SelectFlags;
  public void setRanges(String rangeList) {

    Vector<String> ranges = new Vector<String> (10);

    // Split the rangeList up into the vector
    while (!rangeList.equals("")) {
      String range = rangeList.trim();
      int commaLoc = rangeList.indexOf(',');
      if (commaLoc != -1) {
	range = rangeList.substring(0, commaLoc).trim();
	rangeList = rangeList.substring(commaLoc + 1).trim();
      } else {
	rangeList = "";
      }
      if (!range.equals("")) {
	ranges.addElement(range);
      }
    }
    m_RangeStrings = ranges;
    m_SelectFlags = null;
  }

  /**
   * Gets whether the supplied cardinal number is included in the current
   * range.
   *
   * @param index the number of interest
   * @return true if index is in the current range
   * @throws RuntimeException if the upper limit of the range hasn't been defined
   */
  //@requires m_Upper >= 0;
  //@requires 0 <= index && index < m_SelectFlags.length;
  public /*@pure@*/ boolean isInRange(int index) {

    if (m_Upper == -1) {
      throw new RuntimeException("No upper limit has been specified for range");
    }
    if (m_Invert) {
      return !m_SelectFlags[index];
    } else {
      return m_SelectFlags[index];
    }
  }

  /**
   * Constructs a representation of the current range. Being a string
   * representation, the numbers are based from 1.
   * 
   * @return the string representation of the current range
   */
  public /*@non_null pure@*/ String toString() {

    if (m_RangeStrings.size() == 0) {
      return "Empty";
    }
    String result ="Strings: ";
    Enumeration enu = m_RangeStrings.elements();
    while (enu.hasMoreElements()) {
      result += (String)enu.nextElement() + " ";
    }
    result += "\n";

    result += "Invert: " + m_Invert + "\n";

    try {
      if (m_Upper == -1) {
	throw new RuntimeException("Upper limit has not been specified");
      }
      String cols = null;
      for (int i = 0; i < m_SelectFlags.length; i++) {
	if (isInRange(i)) {
	  if (cols == null) {
	    cols = "Cols: " + (i + 1);
	  } else {
	    cols += "," + (i + 1);
	  }
	}
      }
      if (cols != null) {
	result += cols + "\n";
      }
    } catch (Exception ex) {
      result += ex.getMessage();
    }
    return result;
  }

  /**
   * Gets an array containing all the selected values, in the order
   * that they were selected (or ascending order if range inversion is on)
   *
   * @return the array of selected values
   * @throws RuntimeException if the upper limit of the range hasn't been defined
   */
  //@requires m_Upper >= 0;
  public /*@non_null@*/ int [] getSelection() {

    if (m_Upper == -1) {
      throw new RuntimeException("No upper limit has been specified for range");
    }
    int [] selectIndices = new int [m_Upper + 1];
    int numSelected = 0;
    if (m_Invert)
    {
      for (int i = 0; i <= m_Upper; i++) {
	if (!m_SelectFlags[i]) {
	  selectIndices[numSelected++] = i;
	}
      }
    }
    else
    {
      Enumeration enu = m_RangeStrings.elements();
      while (enu.hasMoreElements()) {
	String currentRange = (String)enu.nextElement();
	int start = rangeLower(currentRange);
	int end = rangeUpper(currentRange);
	for (int i = start; (i <= m_Upper) && (i <= end); i++) {
	  if (m_SelectFlags[i]) {
	    selectIndices[numSelected++] = i;
	  }
	}
      }
    }
    int [] result = new int [numSelected];
    System.arraycopy(selectIndices, 0, result, 0, numSelected);
    return result;
  }

  /**
   * Creates a string representation of the indices in the supplied array.
   *
   * @param indices an array containing indices to select.
   * Since the array will typically come from a program, indices are assumed
   * from 0, and thus will have 1 added in the String representation.
   * @return the string representation of the indices
   */
  public static /*@non_null pure@*/String indicesToRangeList(/*@non_null@*/ int []indices) {

    StringBuffer rl = new StringBuffer();
    int last = -2;
    boolean range = false;
    for(int i = 0; i < indices.length; i++) {
      if (i == 0) {
	rl.append(indices[i] + 1);
      } else if (indices[i] == last) {
        range = true;
      } else {
        if (range) {
          rl.append('-').append(last);
          range = false;
        }
	rl.append(',').append(indices[i] + 1);
      }
      last = indices[i] + 1;
    }
    if (range) {
      rl.append('-').append(last);
    }
    return rl.toString();
  }

  /** Sets the flags array. */
  protected void setFlags() {

    m_SelectFlags = new boolean [m_Upper + 1];
    Enumeration enu = m_RangeStrings.elements();
    while (enu.hasMoreElements()) {
      String currentRange = (String)enu.nextElement();
      if (!isValidRange(currentRange)) {
	throw new IllegalArgumentException("Invalid range list at " + currentRange);
      }
      int start = rangeLower(currentRange);
      int end = rangeUpper(currentRange);
      for (int i = start; (i <= m_Upper) && (i <= end); i++) {
	m_SelectFlags[i] = true;
      }
    }
  }


  /**
   * Translates a single string selection into it's internal 0-based equivalent
   *
   * @param single the string representing the selection (eg: 1 first last)
   * @return the number corresponding to the selected value
   */
  protected /*@pure@*/ int rangeSingle(/*@non_null@*/ String single) {

    if (single.toLowerCase().equals("first")) {
      return 0;
    }
    if (single.toLowerCase().equals("last")) {
      return m_Upper;
    }
    int index = Integer.parseInt(single) - 1;
    if (index < 0) {
      index = 0;
    }
    if (index > m_Upper) {
      index = m_Upper;
    }
    return index;
  }

  /**
   * Translates a range into it's lower index.
   *
   * @param range the string representation of the range
   * @return the lower index of the range
   */ 
  protected int rangeLower(/*@non_null@*/ String range) {

    int hyphenIndex;
    if ((hyphenIndex = range.indexOf('-')) >= 0) {
      return Math.min(rangeLower(range.substring(0, hyphenIndex)),
		       rangeLower(range.substring(hyphenIndex + 1)));
    }
    return rangeSingle(range);
  }

  /**
   * Translates a range into it's upper index. Must only be called once
   * setUpper has been called.
   *
   * @param range the string representation of the range
   * @return the upper index of the range
   */
  protected int rangeUpper(/*@non_null@*/ String range) {

    int hyphenIndex;
    if ((hyphenIndex = range.indexOf('-')) >= 0) {
      return Math.max(rangeUpper(range.substring(0, hyphenIndex)),
		       rangeUpper(range.substring(hyphenIndex + 1)));
    }
    return rangeSingle(range);
  }

  /**
   * Determines if a string represents a valid index or simple range.
   * Examples: <code>first  last   2   first-last  first-4  4-last</code>
   * Doesn't check that a < b for a-b
   *
   * @param range the string to check
   * @return true if the range is valid
   */
  protected boolean isValidRange(String range) {

    if (range == null) {
      return false;
    }
    int hyphenIndex;
    if ((hyphenIndex = range.indexOf('-')) >= 0) {
      if (isValidRange(range.substring(0, hyphenIndex)) &&
	  isValidRange(range.substring(hyphenIndex + 1))) {
	return true;
      }
      return false;
    }
    if (range.toLowerCase().equals("first")) {
      return true;
    }
    if (range.toLowerCase().equals("last")) {
      return true;
    }
    try {
      int index = Integer.parseInt(range);
      if ((index > 0) && (index <= m_Upper + 1)){
	return true;
      }
      return false;
    } catch (NumberFormatException ex) {
      return false;
    }
  }
  
  /**
   * Returns the revision string.
   * 
   * @return		the revision
   */
  public String getRevision() {
    return RevisionUtils.extract("$Revision: 5953 $");
  }

  /**
   * Main method for testing this class.
   *
   * @param argv one parameter: a test range specification
   */
  public static void main(String [] argv) {

    try {
      if (argv.length == 0) {
	throw new Exception("Usage: Range <rangespec>");
      }
      Range range = new Range();
      range.setRanges(argv[0]);
      range.setUpper(9);
      range.setInvert(false);
      System.out.println("Input: " + argv[0] + "\n"
			 + range.toString());
      int [] rangeIndices = range.getSelection();
      for (int i = 0; i < rangeIndices.length; i++)
	System.out.print(" " + (rangeIndices[i] + 1));
      System.out.println("");
    } catch (Exception ex) {
      System.out.println(ex.getMessage());
    }
  }
}