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package handler;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PushbackInputStream;
import java.util.Arrays;
import javax.security.auth.callback.Callback;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.callback.NameCallback;
import javax.security.auth.callback.PasswordCallback;
import javax.security.auth.callback.UnsupportedCallbackException;

/**
 *  Username/Password Callbackhandler
 * @author MartinH
 */
public class UserNameHandler implements CallbackHandler {

    static String user;
    static String pwd;

    static {
        setUser("okbtester");
        setPassword("okbtester");
    }

    public static void setUser(String userName) {
        user = userName;
    }

    public static void setPassword(String passwd) {
        pwd = passwd;
    }

    /**
     * Invoke an array of Callbacks.
     *
     * <p>
     *
     * @param callbacks an array of <code>Callback</code> objects which contain
     *			the information requested by an underlying security
     *			service to be retrieved or displayed.
     *
     * @exception java.io.IOException if an input or output error occurs. <p>
     *
     * @exception UnsupportedCallbackException if the implementation of this
     *			method does not support one or more of the Callbacks
     *			specified in the <code>callbacks</code> parameter.
     */
    public void handle(Callback[] callbacks)
            throws IOException, UnsupportedCallbackException {

        for (int i = 0; i < callbacks.length; i++) {
            if (callbacks[i] instanceof NameCallback) {

                // prompt the user for a username
                NameCallback nc = (NameCallback) callbacks[i];

                System.err.print(nc.getPrompt());
                System.err.flush();
                nc.setName(user);
                //nc.setName((new BufferedReader(new InputStreamReader(System.in))).readLine());

            } else if (callbacks[i] instanceof PasswordCallback) {

                // prompt the user for sensitive information
                PasswordCallback pc = (PasswordCallback) callbacks[i];
                System.err.print(pc.getPrompt());
                System.err.flush();

                pc.setPassword(pwd.toCharArray());
                //pc.setPassword(readPassword(System.in));

            } else {
                throw new UnsupportedCallbackException(callbacks[i], "Unrecognized Callback");
            }
        }
    }

    // Reads user password from given input stream.
    private char[] readPassword(InputStream in) throws IOException {

        char[] lineBuffer;
        char[] buf;
        int i;

        buf = lineBuffer = new char[128];

        int room = buf.length;
        int offset = 0;
        int c;

        loop:
        while (true) {
            switch (c = in.read()) {
                case -1:
                case '\n':
                    break loop;

                case '\r':
                    int c2 = in.read();
                    if ((c2 != '\n') && (c2 != -1)) {
                        if (!(in instanceof PushbackInputStream)) {
                            in = new PushbackInputStream(in);
                        }
                        ((PushbackInputStream) in).unread(c2);
                    } else {
                        break loop;
                    }

                default:
                    if (--room < 0) {
                        buf = new char[offset + 128];
                        room = buf.length - offset - 1;
                        System.arraycopy(lineBuffer, 0, buf, 0, offset);
                        Arrays.fill(lineBuffer, ' ');
                        lineBuffer = buf;
                    }
                    buf[offset++] = (char) c;
                    break;
            }
        }

        if (offset == 0) {
            return null;
        }

        char[] ret = new char[offset];
        System.arraycopy(buf, 0, ret, 0, offset);
        Arrays.fill(buf, ' ');

        return ret;
    }
}