package Roommates;

import java.io.*;

/**
 * The class Pelt is used to build a Person's preference list. 
 * Each object of the class Pelt comprises three data elements: 
 * a preference list element i.e. the id of a Person, 
 * a pointer to the next Pelt and 
 * a pointer to the preceding Pelt.
 */
public class Pelt implements Cloneable
{
  /** Array for Pelt */ 
  private int a[] = new int[3];

  /*--------------------------------------------------------------------*/

  /**
   * Initialises preference list element and sets predecessor
   * and successor pointers to point to relevant Pelts.
   * @param i position of Pelt in preference list
   * @param j preference list element i.e. Woman's id
   */
  public Pelt(int i,int j)
  {
    a[0] = i-1;      // predeccessor
    a[1] = j;        // entry
    a[2] = i+1;      // successor
  }

  /*--------------------------------------------------------------------*/

  /**
   * Clone method for Pelt.
   */
  public Object clone()
  {
    Pelt pObj = new Pelt(0,0);
    for (int i=0; i<=2; i++)
      pObj.a[i]=a[i];   // assignment ok here as a[i] is a variable
    return pObj;
  } 

  /*--------------------------------------------------------------------*/

  /**
   * Returns pointer to preceding Pelt.
   * @return position in preference list of preceding Pelt.
   */
  public int getPred()
  {
    return a[0];
  }

  /*--------------------------------------------------------------------*/

  /**
   * Returns preference list element.
   * @return id of a Person
   */
  public int getEntry()
  {
    return a[1];
  }

  /*--------------------------------------------------------------------*/

  /**
   * Returns pointer to succeeding Pelt.
   * @return position in preference list of succeeding Pelt
   */
  public int getSucc()
  {
    return a[2];
  }

  /*--------------------------------------------------------------------*/

  /**
  * Changes predeccessor pointer to point to 
  * Pelt at position i in preference list.
  * @param i position in preference list of preceding Pelt
  */
  public void changePred(int i)
  {
    a[0] = i;
  }
 
  /*--------------------------------------------------------------------*/

  /**
  * Changes Entry entry of Pelt to have value i.
  * @param i an integer representing new value of Entry
  */
  public void changeEntry(int i)
  {
    a[1] = i;
  }

  /*--------------------------------------------------------------------*/

  /**
  * Changes successor pointer to point to 
  * Pelt at position i in preference list.
  * @param i position in preference list of succeeding Pelt
  */
  public void changeSucc(int i)
  {
    a[2] = i;
  }

  /*--------------------------------------------------------------------*/

  /**
  * Prints preference list element
  * @param annotateMatching a boolean indicating whether we are to super-
  *        impose the stable matching onto the preference lists
  * @param partner an integer (this Person's partner id)
  * @param size an integer (number of persons)
  */
  public void print(boolean annotateMatching, int partner, int size, 
                    BufferedWriter fo) throws IOException
  {
    int j = String.valueOf(a[1]).length();  // Number of digits in id
    int k = String.valueOf(size).length();  // Number of digits in size
    for (; k>j; j++)
      fo.write(" ");
    fo.write(String.valueOf(a[1]));
    if ((annotateMatching) && (a[1]==partner))
      fo.write("*");
    else
      fo.write(" ");
  }
}