import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;
import java.util.Calendar;

import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.UIManager;


/**
 * Continuously monitors the internet connection once a minute.  Once it detects that the 
 * internet is down, then it will shut down the computer.
 * @author Jia
 *
 */
public class InternetConnectionChecker {

	String [] urls = {
			"http://www.yahoo.com/",
			"http://www.google.com/",
			"http://www.aol.com/"
	};
	
	String[] commands = {"cmd /c shutdown.exe -t 00 -s -f"};
	
	public InternetConnectionChecker()throws Exception{
		
		File f = new File("C:\\Internet Log.txt");
		BufferedWriter bw;
		if (!f.exists())
			f.createNewFile();
		boolean connected = false; 
		boolean append = true;
		FileWriter fw = new FileWriter(f, append);
		
		for (int i=0; i<urls.length; i++){
			URL url = new URL(urls[i]);
			try{
				URLConnection connection = url.openConnection();
				connection.connect();
			}catch(IOException e){
				continue;
			}
			connected = true;
			if (connected)
				break;
		}
		
		if (connected){

		}
		else{
			bw = new BufferedWriter(fw);
			bw.append(getTime());
			bw.newLine();
			bw.close();
			executeCommand(commands[0]);
		}
	}
	
	public void executeCommand(String s){
		Runtime rt=Runtime.getRuntime(); 
		try {
			rt.exec(s);
		} catch (IOException e1) {
			JOptionPane.showMessageDialog(null, "cannot execute " + s);
			e1.printStackTrace();
		}
	}
	
	public String getTime(){
		Calendar cal = Calendar.getInstance();
		int hour12 = cal.get(Calendar.HOUR);            // 0..11
	    int min = cal.get(Calendar.MINUTE);             // 0..59
	    int sec = cal.get(Calendar.SECOND);             // 0..59
	    int ampm = cal.get(Calendar.AM_PM);             // 0=AM, 1=PM
	    
	    int year = cal.get(Calendar.YEAR);
	    int month = cal.get(Calendar.MONTH) + 1;
	    int day = cal.get(Calendar.DAY_OF_MONTH);
	    
	    String time = month + "/" + day + "/" + year + "||" +hour12 + ":" + min + ":" + sec;
	    if (ampm == 0)
	    	time +=  " AM";
	    else
	    	time +=  " PM";
	    System.out.println(time);
	    return time;
	}
	
	public static void main(String[] args)throws Exception{
		UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());	
		JFrame frame = new JFrame("Internet monitor");
		frame.setVisible(true);
		frame.setSize(300,100);
		frame.setLocationRelativeTo(null);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		while (true){
			new InternetConnectionChecker();
			Thread.sleep(60000);
		}
		
	}
}