package de.tudarmstadt.informatik.hostage.protocol;

import java.util.ArrayList;
import java.util.List;

/**
 * FTP protocol
 * @author Wulf Pfeiffer
 */
public final class FTP implements Protocol<String> {
	/**
	 * Represents the states of the protocol
	 */
	private static enum STATE {
		NONE, OPEN, CLOSED, USER, LOGGED_IN
	};

	/**
	 * Denotes in which state the protocol is right now
	 */
	private STATE state = STATE.NONE;
	
	private String lastMessage;

	@Override
	public int getPort() {
		return 21;
	}

	@Override
	public TALK_FIRST whoTalksFirst() {
		return TALK_FIRST.SERVER;
	}

	@Override
	public List<String> processMessage(String message) {
		if(message != null)
			lastMessage = message;
		List<String> response = new ArrayList<String>();
		switch (state) {
		case NONE:
			if (message == null) {
				state = STATE.OPEN;
				response.add(c220);
			} else {
				state = STATE.CLOSED;
				response.add(c421);
			}
			break;
		case OPEN:
			if (message.contains("QUIT")) {
				state = STATE.CLOSED;
				return null;
			} else if (message.equals("USER \r\n")) {
				response.add(c501);
			} else if (message.contains("USER")) {
				state = STATE.USER;
				response.add(c331);
			} else {
				response.add(c332);
			}
			break;
		case USER:
			if (message.equals("PASS \r\n")) {
				state = STATE.OPEN;
				response.add(c501);
			} else if (message.contains("PASS")) {
				state = STATE.LOGGED_IN;
				response.add(c230);
			} else {
				state = STATE.CLOSED;
				response.add(c221);
			}
			break;
		case LOGGED_IN:
			if (message != null && !message.contains("QUIT")) {
				response.add(c500);
			} else {
				state = STATE.CLOSED;
				response.add(c221);
			}
			break;
		default:
			state = STATE.CLOSED;
			response.add(c421);
		}
		return response;
	}
	
	private String c220 = "220 Service ready for new user.";
	private String c221 = "221 Service closing control connection.";
	private String c230 = "230 User logged in.";
	private String c331 = "331 User name ok, need password.";
	private String c332 = "332 Need account for login.";
	private String c421 = "421 Service not available, closing control connection.";
	private String c500 = "500 Syntax error, command unrecognized.";
	private String c501 = "501 Syntax error in parameters or arguments";

	@Override
	public boolean isClosed() {
		return state == STATE.CLOSED;
	}

	@Override
	public boolean isSecure() {
		return false;
	}

	@Override
	public Class<String> getType() {
		return String.class;
	}

	@Override
	public String toString() {
		return "FTP";
	}

}