package davmail.smtp;

import davmail.AbstractConnection;
import davmail.DavGatewayTray;
import davmail.exchange.ExchangeSession;
import sun.misc.BASE64Decoder;

import java.io.IOException;
import java.net.Socket;
import java.util.Date;
import java.util.StringTokenizer;

/**
 * Dav Gateway smtp connection implementation
 */
public class SmtpConnection extends AbstractConnection {
    protected static final int INITIAL = 0;
    protected static final int AUTHENTICATED = 1;
    protected static final int STARTMAIL = 2;
    protected static final int RECIPIENT = 3;
    protected static final int MAILDATA = 4;

    // Initialize the streams and start the thread
    public SmtpConnection(Socket clientSocket) {
        super(clientSocket);
    }

    public void run() {
        String line;
        StringTokenizer tokens;


        try {
            sendClient("220 DavMail SMTP ready at " + new Date());
            for (; ;) {
                line = readClient();
                // unable to read line, connection closed ?
                if (line == null) {
                    break;
                }

                tokens = new StringTokenizer(line);
                if (tokens.hasMoreTokens()) {
                    String command = tokens.nextToken();

                    if ("QUIT".equalsIgnoreCase(command)) {
                        sendClient("221 Closing connection");
                        break;
                    } else if ("EHLO".equals(command)) {
                        // inform server that AUTH is supported
                        // actually it is mandatory (only way to get credentials)
                        sendClient("250-AUTH LOGIN PLAIN");
                        sendClient("250 Hello");
                    } else if ("HELO".equals(command)) {
                        sendClient("250 Hello");
                    } else if ("AUTH".equals(command)) {
                        if (tokens.hasMoreElements()) {
                            String authType = tokens.nextToken();
                            if ("PLAIN".equals(authType) && tokens.hasMoreElements()) {
                                decodeCredentials(tokens.nextToken());
                                session = new ExchangeSession();
                                try {
                                    session.login(userName, password);
                                    sendClient("235 OK Authenticated");
                                    state = AUTHENTICATED;
                                } catch (Exception e) {
                                    DavGatewayTray.warn("Authentication failed",e);
                                    sendClient("554 Authenticated failed");
                                    state = INITIAL;
                                }
                            } else {
                                sendClient("451 Error : unknown authentication type");
                            }
                        } else {
                            sendClient("451 Error : authentication type not specified");
                        }
                    } else if ("MAIL".equals(command)) {
                        if (state == AUTHENTICATED) {
                            state = STARTMAIL;
                            sendClient("250 Sender OK");
                        } else {
                            state = INITIAL;
                            sendClient("503 Bad sequence of commands");
                        }
                    } else if ("RCPT".equals(command)) {
                        if (state == STARTMAIL || state == RECIPIENT) {
                            state = RECIPIENT;
                            sendClient("250 Recipient OK");
                        } else {
                            state = AUTHENTICATED;
                            sendClient("503 Bad sequence of commands");
                        }
                    } else if ("DATA".equals(command)) {
                        if (state == RECIPIENT) {
                            state = MAILDATA;
                            sendClient("354 Start mail input; end with <CRLF>.<CRLF>");

                            try {
                                session.sendMessage(in);
                                state = AUTHENTICATED;
                                sendClient("250 Queued mail for delivery");
                            } catch (Exception e) {
                                DavGatewayTray.error("Authentication failed",e);
                                state = AUTHENTICATED;
                                sendClient("451 Error : " + e.getMessage());
                            }

                        } else {
                            state = AUTHENTICATED;
                            sendClient("503 Bad sequence of commands");
                        }
                    }

                } else {
                    sendClient("500 Unrecognized command");
                }

                os.flush();
            }
        } catch (IOException e) {
            DavGatewayTray.error("Exception handling client",e);
        } finally {
            try {
                client.close();
            } catch (IOException e2) {
                DavGatewayTray.debug("Exception closing client",e2);
            }
            try {
                if (session != null) {
                    session.close();
                }
            } catch (IOException e3) {
                DavGatewayTray.debug("Exception closing gateway",e3);
            }
        }
        DavGatewayTray.resetIcon();
    }

    /**
     * Decode SMTP credentials
     *
     * @param encodedCredentials smtp encoded credentials
     * @throws java.io.IOException
     */
    protected void decodeCredentials(String encodedCredentials) throws IOException {
        BASE64Decoder decoder = new BASE64Decoder();
        String decodedCredentials = new String(decoder.decodeBuffer(encodedCredentials));
        int index = decodedCredentials.indexOf((char) 0, 1);
        if (index > 0) {
            userName = decodedCredentials.substring(1, index);
            password = decodedCredentials.substring(index + 1);
        } else {
            throw new IOException("Invalid credentials");
        }
    }

}