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

import java.io.*;
import java.util.*;

/**
 * Jump to the next image in the directory
 * 
 * @author Kevin McGuinness
 */
public class NextAction extends AppAction {
	// Supported file extensions
	static final String EXTENSIONS = "jpg;jpeg;png;gif;bmp;ctx";
	
	private final java.io.FileFilter imageFilter;

	
	public NextAction(ActionManager m) {
		super(m);
		
		// Create an image file filter
		imageFilter = new SimpleFileFilter(EXTENSIONS);
	}

	
	@Override 
	public void run() {
		if (window.hasContext()) {
			// Get currently opened file
			File file = window.getContext().getFile();
			
			// Find the one after & open it
			File next = findNext(file);
			if (next != null) {
				manager.get(OpenAction.class).open(next);
			}
		}
	}
	
	
	private File findNext(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 next file (wrap back to first)
						return files[(i+1)%files.length];
					}
				}
			}
		}
		
		return null;
	}
	
}

class SimpleFileFilter implements java.io.FileFilter {
	
	/**
	 * Holds the list of extensions. It is expected it will be quite
	 * short, so we use an ArrayList.
	 */
	private final ArrayList<String> extensions;
	
	
	/**
	 * Construct a simple file extension filter based on a semicolon separated
	 * list of file extensions.
	 * 
	 * @param extensions
	 *          A list of file extensions (ex. jpeg;jpg;png)
	 */
	public SimpleFileFilter(String extensions) {
		String[] exts = extensions.split(";");
		this.extensions = new ArrayList<String>(exts.length);
		
		for (String s : exts) {
			if ((s = s.trim()).length() != 0) {
				if (s.startsWith("*")) {
					s = s.substring(1);
				}
				
				if (!s.startsWith(".")) {
					s = "." + s;
				}
				
				this.extensions.add(s);
			}
		}
	}
	

	public boolean accept(File pathname) {
		if (pathname.isFile()) {
			String name = pathname.getName();
			
			// List of extensions should be fairly short..
			for (String ext : extensions) {
				if (name.endsWith(ext)) {
					return true;
				}
			}
		}
		
		return false;
	}
}