package org.paneris.bibliomania.fti;
   
   import java.io.BufferedInputStream;
   import java.io.File;
   import java.io.FileInputStream;
   import java.io.IOException;
   import java.io.InputStream;
   
   import org.melati.poem.NoSuchRowPoemException;
  
  import com.sleepycat.db.DatabaseException;
  
  public class ContextSearchResults implements SearchResults {
  
    private static byte[] skipBuffer = new byte[5000];
  
    public static final String contextUnavailable = "(context not available)";
  
    public static final int contextWordsAfterHit = 5;
  
    public static final int wordsGapBetweenAreas = 6;
  
    private Library library;
  
    private Text currentText = null;
  
    private SearchResults results;
  
    private AnchorFinder blockmarks;
  
    // we don't want to use a Reader for this because then skip is implemented
    // using repeated reads ...
  
    private InputStream body = null;
  
    private long bodyPosition;
  
    public ContextSearchResults(Library library, SearchResults results,
        IndexOther fti) {
      this.library = library;
      this.results = results;
      blockmarks = new AnchorFinder(fti, true);
    }
  
    public int frequency() {
      return results.frequency();
    }
  
    public int hitWordsCount() {
      return results.hitWordsCount();
    }
  
    public void init() {
      closeBody();
      results.init();
    }
  
    public void skipToNextHit() {
      results.skipToNextHit();
    }
  
    public void skipToWordIndex(int wordIndex) {
      results.skipToWordIndex(wordIndex);
    }
  
    public int currentWordIndex() {
      return results.currentWordIndex();
    }
  
    public int currentOffset() {
      return results.currentOffset();
    }
  
    public void gotoText(long textID) throws DatabaseException {
      closeBody();
      results.gotoText(textID);
      long it = results.currentTextID();
      currentText = it == -1 ? null : library.text(it);
    }
  
    public void gotoPosition(long position) throws DatabaseException {
      gotoText(position >> 32);
      if (currentTextID() != -1)
        skipToWordIndex((int) position);
    }
  
    public long getPosition() {
      int wi = currentWordIndex();
      return wi == -1 ? -1 : (currentTextID() << 32 | wi);
    }
  
    public long currentTextID() {
      return results.currentTextID();
    }
  
    public Text currentText() {
      return currentText;
    }
  
   public String currentAnchor() throws DatabaseException {
     // FIXME not necessarily very optimal
     // could exploit forward-moving definition of these cursors
     int index = currentWordIndex();
     return index == -1 ? null : blockmarks
         .anchorOfIndex(currentTextID(), index);
   }
 
   private synchronized void closeBody() {
     if (body != null) {
       try {
         body.close();
       } catch (IOException e) {
       }
       body = null;
     }
   }
 
   public synchronized String nextArea() {
     try {
       long target = results.currentOffset();
       if (target == -1) {
         closeBody();
         return null;
       }
 
       if (body == null) {
         if (currentText == null)
           return null;
         try { 
           body = new BufferedInputStream(currentText.bodyForFragment());
           bodyPosition = 0;
         } catch (NoSuchRowPoemException e) { 
           // This should not happen in a coherent database, but 
           // the one on my machine isn't coherent
           return null;
         }
       }
 
       if (bodyPosition > target)
         throw new IOException("tried to skip backwards");
 
       // FIXME BufferedInputStream seems genuinely not to work well
       // wrt to skipping ... so we use skip for the first move and dummy
       // reads thereafter
 
       if (bodyPosition == 0)
         bodyPosition += body.skip(target - bodyPosition);
       else {
         long read;
         do {
           bodyPosition += (read = body.read(skipBuffer, 0, (int) Math.min(
               target - bodyPosition, skipBuffer.length)));
         } while (read > 0);
       }
 
       if (bodyPosition < target)
         throw new IOException("skipped only to " + bodyPosition + " not "
             + target);
 
       StringBuffer buf = new StringBuffer();
       IndexTokenizer words = new IndexTokenizer(body, true);
       int baseIndex = Math.max(results.currentWordIndex()
           - IndexOther.contextWordsBeforeHit, 0);
       // int lastIndex = -1;
       do {
         int limitIndex = results.currentWordIndex() + results.hitWordsCount()
             + contextWordsAfterHit - baseIndex;
 
         while (words.hasMoreWords() && words.wordIndex() < limitIndex) {
           String word = words.nextWord();
           if (!word.startsWith("#")) {
             if (words.hadBreak() && buf.length() > 0)
               buf.append(' ');
             buf.append(word);
           }
         }
 
         // lastIndex = results.currentWordIndex() + results.hitWordsCount();
 
         results.skipToNextHit();
       } while (results.currentWordIndex() != -1
           && (results.currentWordIndex() - baseIndex) - words.wordIndex() < wordsGapBetweenAreas);
 
       bodyPosition += words.bytesReadFromUnderlyingStream();
 
       return buf.toString();
     } catch (IOException e) {
       System.err.println(e);
 
       try {
         body.close();
       } catch (Exception ee) {
       }
 
       return null;
     }
   }
 
   public static void main(String[] args) throws Exception {
     IndexOther fti = new IndexOther(new File("/tmp"));
 
     SearchResults rawResults;
     if (args[0].charAt(0) == '_') {
       args[0] = args[0].substring(1);
       rawResults = fti.groupSearchResults(args);
       System.out.println("phrase");
     } else if (args[0].equals("-query")) {
       rawResults = fti.querySearchResults(args[1]);
     } else {
       rawResults = fti.andSearchResults(args);
       System.out.println("and");
     }
 
     ContextSearchResults results = new ContextSearchResults(new Library() {
       public Text text(final long textID) {
         return new Text() {
           public InputStream body() throws IOException {
             return new FileInputStream(
                 "/usr/doc/HOWTO/other-formats/html/CDROM-HOWTO-3.html");
           }
 
           public InputStream bodyForFragment() throws IOException {
             return body();
           }
 
           public long ftiTextID() {
             return textID;
           }
         };
       }
     }, rawResults, fti);
 
     for (results.gotoText(0); results.currentTextID() != -1;
     // FIXME this isn't very clever! (maybe?)
     results.gotoText(results.currentTextID() + 1)) {
       System.out.println("== " + results.currentTextID());
       for (;;) {
         String anchor = results.currentAnchor();
         String area = results.nextArea();
         if (area == null)
           break;
         System.out.println("-- A HREF=http://doc#" + anchor);
         System.out.println(area);
       }
     }
   }
 
   public void close() {
     results.close();
     blockmarks.close();
     closeBody();
   }
 }