/**
 * 
 */
package ie.dcu.apps.ist.actions;

import java.io.*;

/**
 * Jump to previous file in current directory.
 * 
 * @author Kevin McGuinness
 */
public class PreviousAction extends AppAction {
	private final java.io.FileFilter imageFilter;


	public PreviousAction(ActionManager m) {
		super(m);
		
		// Create an image file filter
		imageFilter = new SimpleFileFilter(NextAction.EXTENSIONS);
	}
	
	
	@Override 
	public void run() {
		if (window.hasContext()) {
			// Get currently opened file
			File file = window.getContext().getFile();
			
			// Find the one before & open it
			File next = findPrevious(file);
			if (next != null) {
				manager.get(OpenAction.class).open(next);
			}
		}
	}
	

	
	private File findPrevious(File file) {
		File dir = file.getParentFile();
		
		if (dir != null) {
			
			// List the images
			File[] files = dir.listFiles(imageFilter);
			
			// Need at least one
			if (files.length > 1) {
				
				// Search for ourself...
				for (int i = 0; i < files.length; i++) {
					
					if (files[i].equals(file)) {
						
						// Use previous file (wrap back to last)
						return files[(i > 0) ? i - 1 : files.length - 1];
					}
				}
			}
		}
		
		return null;
	}

}