package org.paneris.bibliomania.fti;

 import org.melati.util.BugException;

 import org.melati.poem.util.Order;

 import org.melati.poem.util.SortUtils;

 import com.sleepycat.db.DatabaseException;

 public class Score {

   public static class Hit {

     public double score;

     public long textID;

     public Hit(SearchResults results) {

       if ((textID = results.currentTextID()) == -1)

         throw new BugException("Tried to score an empty hit.");

       score = 1.;

       int i = results.currentWordIndex();

       for (;;) {

         results.skipToNextHit();

         int j = results.currentWordIndex();

         if (j == -1) break;

         score += 0.2 + Math.exp((i - j) * (j - i) / 100.);

         i = j;

       }

     }

   }

   private static final Order highScoreFirst =

       new Order() {

         public boolean lessOrEqual(Object a, Object b) {

           return ((Hit)a).score >= ((Hit)b).score;

         }

       };

   /**

    * FIXME should be implemented with "select the N smallest" rather than a

    * full "sort"

    */

   public static Hit[] scoredHits(

       SearchResults r, long startTextID, long limitTextID, int max)

           throws DatabaseException {

     Hit[] them = new Hit[512];

     int n = 0;

     for (r.gotoText(startTextID);

          n < max && r.currentTextID() != -1 && r.currentTextID() < limitTextID;

          r.gotoText(r.currentTextID() + 1)) {

       if (n >= them.length) {

         Hit[] old = them;

         them = new Hit[old.length * 2];

         System.arraycopy(old, 0, them, 0, old.length);

       }

       them[n++] = new Hit(r);

     }

     Hit[] sorted = new Hit[n];

     System.arraycopy(them, 0, sorted, 0, n);

     SortUtils.qsort(highScoreFirst, sorted);

     return sorted;

   }

 }