package org.simantics.browsing.ui.swt;

import java.util.regex.Pattern;

import org.eclipse.swt.events.KeyAdapter;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeItem;
import org.simantics.browsing.ui.GraphExplorer;

/**
 * Selects tree items based on pressed key events.<p>
 * 
 * The default implementation of SWT.Tree (Windows?) uses only the the first column when matching the items.<p>
 * 
 * This implementation checks all columns. Override <pre>matches(), matchesColumn()</pre> for customized behavior.<p>
 * 
 * @author Marko Luukkainen <marko.luukkainen@vtt.fi>
 *
 */
public class KeyToSelectionAdapter extends KeyAdapter {

	private static final int KEY_INPUT_DELAY = 500;
	
    private final GraphExplorer          explorer;

    private String matcher = "";
    private int prevEvent = 0;
    private int columns = 0;
        
    protected Pattern alphaNum;
    
    /**
     * @param contextProvider
     * @param explorer
     */
    public KeyToSelectionAdapter(GraphExplorer explorer) {
        assert explorer != null;

        this.explorer = explorer;
        this.alphaNum = Pattern.compile("\\p{Alnum}");
    }

    @Override
    public void keyPressed(KeyEvent e) {
    	if (explorer.isDisposed())
            return;

         
         if (!alphaNum.matcher(Character.toString(e.character)).matches())
        	 return;
         // concatenate / replace matcher.
         if ((e.time - prevEvent) > KEY_INPUT_DELAY )
    		 matcher = "";
    	 prevEvent = e.time;
    	 matcher = matcher += Character.toString(e.character);

    	 TreeItem item = null;
    	 Tree tree = explorer.getControl();
    	 columns = tree.getColumnCount();
    	 TreeItem[] selected = tree.getSelection();
    	
    	 item = find(tree, selected);
    	 
    	 if (item == null && matcher.length() > 1) {
    		 matcher = matcher.substring(matcher.length()-1);
    		 item = find(tree, selected);
    	 }
    	 
    	 if (item != null) {
			 tree.select(item);
			 tree.showItem(item);
			
		 } 
    	 // without this the default handling would take over.
    	 e.doit = false;
    }
    
    private TreeItem previous = null;
    private boolean foundPrev = false;
    
	private TreeItem find(Tree tree, TreeItem[] selected) {
		TreeItem item = null;

		TreeItem items[] = tree.getItems();
		if (selected.length == 0) {
			previous = null;
			foundPrev = true;
			item = findItem(items, 0);

		} else {
			previous = selected[0];
			foundPrev = false;
			item = findItem(items, 0);
			if (item == null) {
				previous = null;
				foundPrev = true;
				item = findItem(items, 0);
			}
		}
		return item;
	}
    
    private TreeItem findItem(TreeItem items[], int depth) {
    	for (int i = 0; i < items.length; i++) {
    		TreeItem item = items[i];
    		if (item != previous) {
    			if (foundPrev && matches(item, depth, columns, matcher))
    				return item;
	    		
    		} else {
    			foundPrev = true;
    		}
    		TreeItem childItem = findItem(item.getItems(),depth+1);	
    		if (childItem != null)
    			return childItem;
    	}
    	return null;
    }
    
    
    /**
     * 
     * @param item
     * @param depth Depth of the item in the tree.
     * @param columns Number of columns.
     * @param string Matching string.
     * @return
     */
    protected boolean matches(TreeItem item, int depth, int columns, String matcher) {
    	for (int c = 0; c < columns; c++) {	
			if (matchesColumn(item, c, matcher)) {
				return true;
			}
		}
    	return false;
    }
    
    /**
     * 
     * @param item
     * @param column
     * @param matcher
     * @return
     */
    protected boolean matchesColumn(TreeItem item, int column, String matcher) {
    	String text = item.getText(column);
		if (text.toLowerCase().startsWith(matcher)) {
			return true;
		}
		return false;
    }


}