package net.sourceforge.phpeclipse.wiki.editor;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import net.sourceforge.phpeclipse.wiki.editor.model.WikipediaText;
import net.sourceforge.phpeclipse.wiki.editor.model.WikipediaSection;

import org.eclipse.core.runtime.IProgressMonitor;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.Position;
import org.eclipse.jface.text.source.Annotation;
import org.eclipse.jface.text.source.projection.ProjectionAnnotation;
import org.eclipse.jface.text.source.projection.ProjectionAnnotationModel;

public class WikiFoldingStructureProvider {

  private WikiEditor fEditor;

  private IDocument fDocument;

  private IProgressMonitor fProgressMonitor;

  public WikiFoldingStructureProvider(WikiEditor editor) {
    fEditor = editor;
  }

  public void setProgressMonitor(IProgressMonitor progressMonitor) {
    fProgressMonitor = progressMonitor;
  }

  public void setDocument(IDocument document) {
    fDocument = document;
  }

  public void updateFoldingRegions(WikipediaSection section) {
    try {

      ProjectionAnnotationModel model = (ProjectionAnnotationModel) fEditor.getAdapter(ProjectionAnnotationModel.class);
      if (model == null)
        return;

      Set currentRegions = new HashSet();
      addFoldingRegions(currentRegions, section.getChildren());
      updateFoldingRegions(model, currentRegions);
    } catch (BadLocationException e) {
      e.printStackTrace();
    }
  }

  private void updateFoldingRegions(ProjectionAnnotationModel model, Set currentRegions) {
    Annotation[] deletions = computeDifferences(model, currentRegions);

    Map additionsMap = new HashMap();
    for (Iterator iter = currentRegions.iterator(); iter.hasNext();)
      additionsMap.put(new ProjectionAnnotation(), iter.next());

    if ((deletions.length != 0 || additionsMap.size() != 0) && (fProgressMonitor == null || !fProgressMonitor.isCanceled()))
      model.modifyAnnotations(deletions, additionsMap, new Annotation[] {});
  }

  private Annotation[] computeDifferences(ProjectionAnnotationModel model, Set current) {
    List deletions = new ArrayList();
    for (Iterator iter = model.getAnnotationIterator(); iter.hasNext();) {
      Object annotation = iter.next();
      if (annotation instanceof ProjectionAnnotation) {
        Position position = model.getPosition((Annotation) annotation);
        if (current.contains(position))
          current.remove(position);
        else
          deletions.add(annotation);
      }
    }
    return (Annotation[]) deletions.toArray(new Annotation[deletions.size()]);
  }

  private void addFoldingRegions(Set regions, Object[] elements) throws BadLocationException {
    for (int i = 0; i < elements.length; i++) {
      WikipediaSection element = (WikipediaSection) elements[i];
      if (element.getOffset() >= 0) {
        int startLine = fDocument.getLineOfOffset(element.getOffset());
        int endLine = fDocument.getLineOfOffset(element.getOffset() + element.getLength());
        if (startLine < endLine) {
          int start = fDocument.getLineOffset(startLine);
          int end = fDocument.getLineOffset(endLine) + fDocument.getLineLength(endLine);
          Position position = new Position(start, end - start);
          regions.add(position);
        }

        Object[] children = element.getChildren();
        if (children != null) {
          addFoldingRegions(regions, children);
        }
      }
    }
  }
}