import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Timer;
import java.util.TimerTask;


public class CachedReadOnlyFile{
	private	long 			refreshDelay = 0;
	private	File			originalFile = null;
	private	File 			cachedFile = null;
	private	FileInputStream	cachedStream = null;
	private boolean			errorFlag = false;
	private Timer			timer = null;
	
	public CachedReadOnlyFile(File file, long msDelay) throws Exception{
		 //call update() and all the other crap necessary for it
		originalFile = file;
		update();
		if(errorFlag){
			throw new IOException("Failure in creation of cached file or reading of original file.  Check permissions and try again.");
		}
		
		// create the timer and set it to run every msDelay milliseconds
		timer = new Timer();
		timer.schedule(new MyTask(), 10000, msDelay);
	}
	private synchronized void update(){
		errorFlag = true;
		
		if(cachedStream != null){
			try{
				cachedStream.close();
			} catch(Exception ex){
				ex.printStackTrace();
				return;
			} finally{
				cachedStream = null;
				Runtime.getRuntime().gc();
			}
		}
		
		if(cachedFile != null){
			try{
				cachedFile.delete();
			} catch(Exception ex){
				ex.printStackTrace();
				return;
			} finally{
				cachedFile = null;
				Runtime.getRuntime().gc();
			}
		}
		
		cachedFile = new File("cached" + originalFile.getName());
		try{
			cachedFile.createNewFile();
		} catch(Exception ex){
			ex.printStackTrace();
			return;
		}
		
		FileInputStream		reader = null;
		FileOutputStream	writer = null;
		try{
			reader = new FileInputStream(originalFile);
			writer = new FileOutputStream(cachedFile);
		} catch(Exception ex){
			ex.printStackTrace();
			return;
		}
		
		try{
			while(reader.available() != 0){
				writer.write(reader.read());
			}
		} catch(Exception ex){
			ex.printStackTrace();
			return;
		}
		
		try{
			cachedStream = new FileInputStream(cachedFile);
		} catch(Exception ex){
			ex.printStackTrace();
			return;
		}
		
		errorFlag = false;
	}
	
	public synchronized int available(){
		try{
			return cachedStream.available();
		} catch(Exception ex){
			ex.printStackTrace();
		}
		return 0;
	}
	public synchronized int read(){
		try{
			return cachedStream.read();
		} catch(Exception ex){
			ex.printStackTrace();
		}
		return 0;
	}
	public synchronized int read(byte[] b){
		try{
			return cachedStream.read(b);
		} catch(Exception ex){
			ex.printStackTrace();
		}
		return 0;
	}
	public synchronized int read(byte[] b, int off, int len){
		try{
			return cachedStream.read(b, off, len);
		} catch(Exception ex){
			ex.printStackTrace();
		}
		return 0;
	}
	public synchronized long skip(long n){
		try{
			return cachedStream.skip(n);
		} catch(Exception ex){
			ex.printStackTrace();
		}
		return 0;
	}
	
	protected void finalize() throws Throwable{
		try {
			cachedStream.close();
			cachedFile.delete();
		} catch(Exception ex){
			ex.printStackTrace();
		} finally{
			super.finalize();
		}
	}

	
	
	
	
	private class MyTask extends TimerTask{
		public MyTask(){
			super();
		}
		public void run(){
			update();
		}
	}
}