// Ftpserver.java
// Mike Dricken
// Bridget Waltz
// This program is run on port 5180 of the server machine.
// The program is run by typing "java Ftpserver"

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

public class Ftpserver extends Thread{

DatagramSocket	dataSock;					// the UDP socket on this program
public static	String	filename;

public static void main(String argv[]) throws Exception{
	int availableBytes = 1;	
	String	responseline = null;	// raw string of what the client actually sent the server
	String	code = null;					// stores 4 letter command requested by the user on the client side
	String	passwd, user = null;			// password and username of user on the client side

	ServerSocket	welcome=null;			// the TCP socket that listens for other clients wanting to connect
	Socket connectionSocket = null;			// the TCP socket that is created when a client connects
	BufferedReader	inFromClient=null;		// buffered TCP data from the client
	DataOutputStream	outToClient=null;	// buffered TCP data waiting to be sent to the client

	int	loggedin = 0;						//0 = not logged in, 1 = logged in
	
	//variables for LIST
	String fileName = "Ftpserver.java";
	File name = new File(fileName);
	String path, directory = "", completeList = "";
	String directory_2 = "", completeList_2 = "";
	String [] fileList;
	String [] fileList_2;
	int tokenNumber, tokenNumber_2;
	String [] tokenElement, tokenElement_2;


//--------------------------------------------------
// Begin program 



try{
welcome = new ServerSocket(5180);
}
catch (IOException e) {
System.out.println(e);
}

try{
connectionSocket = welcome.accept();
System.out.println("TCP Connection with client established...\n");
inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
outToClient = new DataOutputStream(connectionSocket.getOutputStream());
}
catch (IOException e) {
System.out.println(e);
}


DatagramSocket dataSock = null;

outToClient.writeBytes("220\n");


// after server has established a connection, stay in a while loop until client sends the 'QUIT' command.
while(true) {
responseline = inFromClient.readLine();
code = new String(responseline.substring(0, 4));

if (responseline.compareTo("QUIT") == 0) {
	break;}	// quit the while loop


// user name entry - this must be done before other commands can be done
else if (code.compareTo("USER") == 0) {
	user = new String(responseline.substring(5,responseline.length()));
	if (user.compareTo("bwaltz") == 0){
		outToClient.writeBytes("331\n");
		loggedin = 0;}
	else {outToClient.writeBytes("230\n");
		loggedin = 1;}
}

// password entry - 'bwaltz' is the only user that must enter a password, the password is 'letmein'

else if (code.compareTo("PASS") == 0) {
	passwd = new String(responseline.substring(5,responseline.length()));
	if (user.compareTo("bwaltz") == 0) {
		if (passwd.compareTo("letmein") == 0){
			outToClient.writeBytes("230\n");
			loggedin = 1;
		}						// correct password for 'bwaltz'
		else { outToClient.writeBytes("331\n");
		}						// incorrect password for 'bwaltz'
	}
	else {outToClient.writeBytes("230\n");
	}	// normal users don't need passwords
}


else if (loggedin == 0){
	outToClient.writeBytes("530\n");
	}


// ----------- RETR (retrieve a file) command ------------------
else if ((code.compareTo("RETR") == 0) && (loggedin == 0)) {
	outToClient.writeBytes("530\n");
	}
else if ((code.compareTo("RETR") == 0) && (loggedin == 1)) {
	outToClient.writeBytes("150\n");
	filename = new String(responseline.substring(5, responseline.length()));
	try
	{
			InetAddress addr = connectionSocket.getInetAddress();
			DatagramSocket outNet = new DatagramSocket();
			//Open The File And Send it
			FileInputStream iStream = new FileInputStream(filename);
			System.out.println("Now Sending: " + filename);
			availableBytes = iStream.available();
			Thread.sleep(500); // pause program for 1/2 second to allow the program receiving datagrams to get ready
					
	while(availableBytes > 0) {

	// the packet size is limited to 16kB.	
	if(availableBytes <= 16000) 
	{
		byte [] bytes = new byte [availableBytes]; 
		int i = iStream.read(bytes);
		DatagramPacket message = new DatagramPacket(bytes, bytes.length, addr, 3500);
		Thread.sleep(10);
		outNet.send(message);
	}
	else
	{
		byte [] bytes = new byte [16000];
		int i = iStream.read(bytes);
		DatagramPacket message = new DatagramPacket(bytes, bytes.length, addr, 3500);
		Thread.sleep(10);
		outNet.send(message);
	}
	availableBytes = iStream.available();
	}

	outToClient.writeBytes("DONE\n");
	outToClient.writeBytes("250\n");
	}
	catch (IOException e){  // send appropritate message to the client if an error occured.
		outToClient.writeBytes("DONE\n");
		String err = new String(e.toString());
		if (err.startsWith("java.io.FileNotFound")) {
			outToClient.writeBytes("450\n");
		}
		else if (err.startsWith("java.net")) {
			outToClient.writeBytes("425\n");
		}
	}

}// end of RETRIEVE 



// ----------- STOR (store a file) command ------------------
else if ((code.compareTo("STOR") == 0) && (loggedin == 1)) {
		outToClient.writeBytes("150\n");
	    filename = new String(responseline.substring(5,responseline.length()));
		dataSock = new DatagramSocket(3500);
		Ftpserver udpin = new Ftpserver(dataSock);
        udpin.start();
		// the run thread is now sending packets to the client
		responseline = inFromClient.readLine(); // wait for a TCP 'DONE' signal from client
		udpin.stop();
		dataSock.close();
		if (responseline.compareTo("NE") == 0) { // the file is non existant. send 450
			outToClient.writeBytes("450\n");
			File deleteFile = new File(filename);
			deleteFile.delete();	// delete the created nonexistant filename on the local hard drive
			}
		else{
		outToClient.writeBytes("250\n");	// file transferred succesfully
		}
}



// --------- PRWD (print working directory) --------------------
// this sends the current working directory out to the client.
else if ((code.compareTo("PRWD") == 0) && (loggedin == 1)){
		directory = "";
		completeList = "";
		directory_2 = "";
		completeList_2 = "";
		
		path = name.getAbsolutePath();
		
		if (path.substring(0,1).equals("/"))
		{
		StringTokenizer tokens = new StringTokenizer( path, "/");
		tokenNumber = tokens.countTokens();
		tokenElement = new String[tokenNumber];
		for(int j = 0; j < tokenNumber - 1; j++)
		{
			tokenElement[j] = tokens.nextToken();
			
			if (directory != "")
			{
				directory = directory + "/" + tokenElement[j];
			}
			else
			{
				directory = directory + tokenElement[j];
			}
		}
	
		directory = "/" + directory + "/";
		
		outToClient.writeBytes("998 " + directory + "\n" );
		}
		else
		{
		StringTokenizer tokens_2 = new StringTokenizer( path, "\\");
		tokenNumber_2 = tokens_2.countTokens();
		tokenElement_2 = new String[tokenNumber_2];
		
		for(int j = 0; j < tokenNumber_2 - 1; j++)
		{
			tokenElement_2[j] = tokens_2.nextToken();
			
			if (directory_2 != "")
			{
				directory_2 = directory_2 + "\\" + tokenElement_2[j];
			}
			else
			{
				directory_2 = directory_2 + tokenElement_2[j];
			}
		}
		
		
		outToClient.writeBytes("998 " + directory_2 + "\n" );
		
		}
		
		
}

else if ((code.compareTo("LIST") == 0) && (loggedin == 1)){
		directory = "";
		completeList = "";
		directory_2 = "";
		completeList_2 = "";
		
		path = name.getAbsolutePath();
				
		if (path.substring(0,1).equals("/"))
		{
		StringTokenizer tokens = new StringTokenizer( path, "/");
		tokenNumber = tokens.countTokens();
		tokenElement = new String[tokenNumber];
		
		for(int j = 0; j < tokenNumber - 1; j++)
		{
			tokenElement[j] = tokens.nextToken();
			
			if (directory != "")
			{
				directory = directory + "/" + tokenElement[j];
			}
			else
			{
				directory = directory + tokenElement[j];
			}
		}
		
		directory = "/" + directory + "/";
		
		
		File fileDirectory = new File(directory);
		
		fileList = fileDirectory.list();
		
		for(int i = 0; i < fileList.length; i++)
		{
			completeList = completeList + " " + fileList[i];
		}
		
		outToClient.writeBytes("999 " + completeList + "\n" );
		}
		else
		{
		StringTokenizer tokens_2 = new StringTokenizer( path, "\\");
		tokenNumber_2 = tokens_2.countTokens();
		tokenElement_2 = new String[tokenNumber_2];
		for(int j = 0; j < tokenNumber_2 - 1; j++)
		{
			tokenElement_2[j] = tokens_2.nextToken();
			if (directory_2 != "")
			{
				directory_2 = directory_2 + "\\" + tokenElement_2[j];
			}
			else
			{
				directory_2 = directory_2 + tokenElement_2[j];
			}
		}
		
		File fileDirectory_2 = new File(directory_2);
		fileList_2 = fileDirectory_2.list();
		for(int i = 0; i < fileList_2.length; i++)
		{
			completeList_2 = completeList_2 + " " + fileList_2[i];
	
		}
		
		outToClient.writeBytes("999 " + completeList_2 + "\n" );
		
		}
		
		
	
}



//---------- DELE (delete a command on this (the server's) hard drive) -----------
else if ((code.compareTo("DELE") == 0) && (loggedin == 1)){
	String fileName_2 = new String(responseline.substring(5,responseline.length()));
	File deleteFile = new File(fileName_2);
	
	if (deleteFile.exists() == true)
	{
		if (deleteFile.delete() == true)
		{
			outToClient.writeBytes("250\n");

		}
		else
		{
			outToClient.writeBytes("450\n");

		}
	}
	else
	{
		outToClient.writeBytes("450\n");
		System.out.println("File does not exist!");
	}

}

} // while

}//main



public	Ftpserver(DatagramSocket dataSock) {
	this.dataSock = dataSock;
	}



// The run command is used to send datagrams from this program. It is only used in the 'RETR' command
public void run() {
	int datalength = 9;
    DatagramPacket packet = new DatagramPacket(new byte[16000], 16000);
	try {
		FileOutputStream outtoFile = new FileOutputStream(filename);
		datalength = 9;
		System.out.println("Retrieving " + filename);
        while(true) {
	       	dataSock.receive(packet);
   			datalength = packet.getLength();
   			byte [] theData = new byte [datalength];
   			byte [] packetBuf = new byte [16000];
   			packetBuf = packet.getData(); 
  			if (datalength == 16000){ 
				outtoFile.write(packetBuf);
                }
       		else { 
       			for(int i=0;i<datalength;i++){
					theData[i] = packetBuf[i];
                }
           outtoFile.write(theData);
		   } 
		}
	}
    catch (UnknownHostException e){
	System.out.println(e);
	}
    catch (IOException e){
	System.out.println(e);
	}
}// run method


}//class Ftpserver