
package nfs;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
import java.util.HashMap;

public class NfsServer {

	public static final int port = 23232; 
	public static int key=0;
	private HashMap handles = null; 

	public NfsServer() {
		handles = new HashMap();
	}

	public DatagramPacket open(RemotePacket rp) {
		DatagramPacket dp = null; 
		int mapkey=key++;
		String strkey=null;
		boolean err=false;
		InputStream is=null;
		OutputStream os=null;
		
		try {
			is = new FileInputStream(rp.getArgs()[0]);
			os = new FileOutputStream(rp.getArgs()[0], true); // in appending mode
		} catch (FileNotFoundException e) {
			err=true;
		}
		// a fresh handle is needed for avoiding double entries
		strkey = new String(rp.getArgs()[0]+"_"+mapkey);
		if (err){
			dp = RemotePacket.RemotePacket("ERROR","FILENOTFOUNDEXCEPTION",strkey);
		}else{
			handles.put(strkey, new StreamRef(is,os));
			dp = RemotePacket.RemotePacket("HANDLE", strkey);
		}
		dp.setAddress(rp.dp.getAddress());
		dp.setPort(rp.dp.getPort());
		return dp;
	}

	public DatagramPacket read(RemotePacket rp) {
		DatagramPacket dp = null; 
		String handleref = rp.getArgs()[0];
		System.out.println("handle:"+handleref);
		StreamRef  sr = handles.get(handleref);
		if(sr == null) {
			dp = RemotePacket.RemotePacket("ERROR", "HANDLE NOT IN CACHE", handleref);
		} else {			
			InputStream is = sr.getIn();
			int len = Integer.parseInt(rp.getArgs()[1]);	
			byte [] buffer = new byte[len];
			try {
				int letti = is.read(buffer,0,len);
				if (letti==-1)
					// the file is empty
					letti=0;
				byte [] buf = new byte[letti];
				for(int i=0; i