/***********************************************************************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others. All rights reserved. This program and the accompanying materials are made
 * available under the terms of the Common Public License v1.0 which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors: IBM Corporation - initial API and implementation
 **********************************************************************************************************************************/
package net.sourceforge.phpeclipse.wiki.editor;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

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

import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.jface.resource.ImageRegistry;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITextSelection;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.TextUtilities;
import org.eclipse.jface.text.contentassist.CompletionProposal;
import org.eclipse.jface.text.contentassist.ICompletionProposal;
import org.eclipse.jface.text.contentassist.IContentAssistProcessor;
import org.eclipse.jface.text.contentassist.IContextInformation;
import org.eclipse.jface.text.contentassist.IContextInformationValidator;
import org.eclipse.jface.text.templates.DocumentTemplateContext;
import org.eclipse.jface.text.templates.Template;
import org.eclipse.jface.text.templates.TemplateContext;
import org.eclipse.jface.text.templates.TemplateContextType;
import org.eclipse.jface.text.templates.TemplateException;
import org.eclipse.jface.text.templates.TemplateProposal;
import org.eclipse.swt.graphics.Image;

public class WikiCompletionProcessor implements IContentAssistProcessor {

  static class StringComparator implements Comparator {
    public int compare(Object o1, Object o2) {
      String s1 = (String) o1;
      String s2 = (String) o2;
      return s1.compareTo(s2);
      //	return s1.toUpperCase().compareTo(s2.toUpperCase());
    }

    public boolean equals(Object o) {
      //      String s = (String) o;
      return compare(this, o) == 0;
    }
  }

  private static final String TEMPLATE_ICON = "icons/template.gif";

  //  private static TreeSet TITLES_SET = null;
  private static final String WIKIPEDIA_TEMPLATE_CTX = "net.sourceforge.phpeclipse.wiki.editor.templates";

  private static final class ProposalComparator implements Comparator {
    public int compare(Object o1, Object o2) {
      return ((TemplateProposal) o2).getRelevance() - ((TemplateProposal) o1).getRelevance();
    }
  }

  private static final Comparator fgProposalComparator = new ProposalComparator();

  private final WikiEditor fEditor;

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

  //  private static void readFile(String filename) {
  //    TITLES_SET = new TreeSet(new StringComparator());
  //    FileReader fileReader;
  //    try {
  //      fileReader = new FileReader(filename);
  //      BufferedReader bufferedReader = new BufferedReader(fileReader);
  //      LineTokenizer lineTokenizer = new LineTokenizer();
  //      StringBuffer line = new StringBuffer(1024);
  //      while (lineTokenizer.getToken(line, bufferedReader)) {
  //        if (line.length() == 0) {
  //          // this should not happen
  //        } else {
  //          TITLES_SET.add(line.toString());
  //          line.delete(0, line.length());
  //        }
  //      }
  //      bufferedReader.close();
  //    } catch (FileNotFoundException e) {
  //      // ignore this
  //      // TODO DialogBox which asks the user if she/he likes to build new index?
  //    } catch (IOException e) {
  //      // TODO Auto-generated catch block
  //      e.printStackTrace();
  //    }
  //  }

  public ICompletionProposal[] computeCompletionProposals(ITextViewer viewer, int offset) {
    WikipediaSection section = fEditor.getSection();
    if (section == null)
      return null;

    ITextSelection selection = (ITextSelection) viewer.getSelectionProvider().getSelection();
    // adjust offset to start of normalized selection:
    if (selection.getOffset() != offset)
      offset = selection.getOffset();

    String prefix = getPrefix(viewer, offset);
    Region region = new Region(offset - prefix.length(), prefix.length() + selection.getLength());
    List result = new ArrayList();

    if (prefix.length() > 2) {
      if (WikiEditorPlugin.fWikiDB == null) {
        try {
          WikiEditorPlugin.fWikiDB = new WikipediaDB();
        } catch (Exception ex1) {
          //        ex1.printStackTrace(); // could not start db
          WikiEditorPlugin.fWikiDB = null;
        }
      }
      if (WikiEditorPlugin.fWikiDB != null) {
        try {
          ArrayList list = WikiEditorPlugin.fWikiDB.queryPrefixTitle(prefix);
          ICompletionProposal[] titleProposals = computeTitleProposals(list, region, viewer);
          result.addAll(Arrays.asList(titleProposals));
        } catch (Exception ex1) {
          //    ex1.printStackTrace(); // could not start db
          WikiEditorPlugin.fWikiDB = null;
        }
      }
    }
    //    if (TITLES_SET==null) {
    // TODO make this a preference
    //      readFile("c:\\temp\\titles.txt");
    //    }
    //    if (TITLES_SET.size()>0 && prefix.length()>3) {
    //      SortedSet subSet = TITLES_SET.subSet(prefix, prefix + '\255');
    //      Iterator iter = subSet.iterator();
    //      ArrayList list;
    //      String title;
    //      int maxProposals = 200;
    //      while (iter.hasNext()) {
    //        title = (String) iter.next();
    //        if (title.toLowerCase().startsWith(prefix.toLowerCase())) {
    //          result.add(title);
    //        }
    //        if (maxProposals-- < 0) {
    //          break;
    //        }
    //      }
    //    }

    ICompletionProposal[] templateProposals = computeTemplateProposals(viewer, region, section, prefix);
    //    ICompletionProposal[] ingredientProposals = computeIngredientsProposals(viewer, region, recipe, prefix);
    //    ICompletionProposal[] titleProposals = computeTitleProposals(viewer, region, recipe, prefix);

    //    result.addAll(Arrays.asList(ingredientProposals));
    result.addAll(Arrays.asList(templateProposals));
    //    result.addAll(Arrays.asList(titleProposals));

    return (ICompletionProposal[]) result.toArray(new ICompletionProposal[result.size()]);
  }

  private ICompletionProposal[] computeTitleProposals(ArrayList list, IRegion region, ITextViewer viewer) {
    ICompletionProposal[] arr = new ICompletionProposal[list.size()];
    //    String lineDelimiter = TextUtilities.getDefaultLineDelimiter(viewer.getDocument());
    String temp;
    for (int i = 0; i < arr.length; i++) {
      temp = (String) list.get(i);
      arr[i] = new CompletionProposal(temp, region.getOffset(), region.getLength(), temp.length(), null, temp,
          null, null);
    }
    return arr;
  }

  private TemplateContextType getContextType(WikipediaSection section, int offset) {
    return WikiEditorPlugin.getDefault().getContextTypeRegistry().getContextType(WIKIPEDIA_TEMPLATE_CTX);
  }

  /**
   * Creates a concrete template context for the given region in the document. This involves finding out which context fType is
   * valid at the given location, and then creating a context of this fType. The default implementation returns a
   * <code>DocumentTemplateContext</code> for the context fType at the given location.
   * 
   * @param viewer
   *          the viewer for which the context is created
   * @param region
   *          the region into <code>document</code> for which the context is created
   * @return a template context that can handle template insertion at the given location, or <code>null</code>
   */
  private TemplateContext createContext(ITextViewer viewer, IRegion region, WikipediaSection recipe) {
    TemplateContextType contextType = getContextType(recipe, region.getOffset());
    if (contextType != null) {
      IDocument document = viewer.getDocument();
      return new DocumentTemplateContext(contextType, document, region.getOffset(), region.getLength());
    }
    return null;
  }

  private ICompletionProposal[] computeTemplateProposals(ITextViewer viewer, IRegion region, WikipediaSection recipe, String prefix) {
    TemplateContext context = createContext(viewer, region, recipe);
    if (context == null)
      return new ICompletionProposal[0];

    ITextSelection selection = (ITextSelection) viewer.getSelectionProvider().getSelection();
    context.setVariable("selection", selection.getText()); // name of the selection variables {line, word}_selection

    String id = context.getContextType().getId();
    Template[] templates = WikiEditorPlugin.getDefault().getTemplateStore().getTemplates(id);

    List matches = new ArrayList();
    for (int i = 0; i < templates.length; i++) {
      Template template = templates[i];
      try {
        context.getContextType().validate(template.getPattern());
      } catch (TemplateException e) {
        continue;
      }
      //      int relevance = getRelevance(template, prefix);
      //      if (relevance > 0) {
      matches.add(new TemplateProposal(template, context, region, getImage(template), 1));
      //      }
    }

    Collections.sort(matches, fgProposalComparator);

    return (ICompletionProposal[]) matches.toArray(new ICompletionProposal[matches.size()]);
  }

  /**
   * Returns the relevance of a template given a prefix. The default implementation returns a number greater than zero if the
   * template name starts with the prefix, and zero otherwise.
   * 
   * @param template
   *          the template to compute the relevance for
   * @param prefix
   *          the prefix after which content assist was requested
   * @return the relevance of <code>template</code>
   * @see #getPrefix(ITextViewer, int)
   */
  private int getRelevance(Template template, String prefix) {
    if (template.getName().startsWith(prefix))
      return 90;
    return 0;
  }

  private String getPrefix(ITextViewer viewer, int offset) {
    int i = offset;
    IDocument document = viewer.getDocument();
    if (i > document.getLength())
      return "";

    try {
      while (i > 0) {
        char ch = document.getChar(i - 1);
        if (!Character.isLetterOrDigit(ch) && (ch != ':') && (ch != '_'))
          break;
        i--;
      }

      return document.get(i, offset - i);
    } catch (BadLocationException e) {
      return "";
    }
  }

  /**
   * Always return the default image.
   */
  private Image getImage(Template template) {
    ImageRegistry registry = WikiEditorPlugin.getDefault().getImageRegistry();
    Image image = registry.get(TEMPLATE_ICON);
    if (image == null) {
      ImageDescriptor desc = WikiEditorPlugin.imageDescriptorFromPlugin("net.sourceforge.phpeclipse.wiki.editor", TEMPLATE_ICON);
      registry.put(TEMPLATE_ICON, desc);
      image = registry.get(TEMPLATE_ICON);
    }
    return image;
  }

  public IContextInformation[] computeContextInformation(ITextViewer viewer, int offset) {
    return null;
  }

  public char[] getCompletionProposalAutoActivationCharacters() {
    return null;
  }

  public char[] getContextInformationAutoActivationCharacters() {
    return null;
  }

  public String getErrorMessage() {
    return null;
  }

  public IContextInformationValidator getContextInformationValidator() {
    return null;
  }
}