package sample.module;

import java.util.*;
import java.io.IOException;
import javax.security.auth.*;
import javax.security.auth.callback.*;
import javax.security.auth.login.*;
import javax.security.auth.spi.*;
import sample.principal.SamplePrincipal;

public class SampleLoginModule implements LoginModule {

    // initial state
    private Subject subject;
    private CallbackHandler callbackHandler;
    private Map sharedState;
    private Map options;

    // configurable option
    private boolean debug = false;

    // the authentication status
    private boolean succeeded = false;
    private boolean commitSucceeded = false;

    // username and password
    private String username;
    private char[] password;

    // testUser's SamplePrincipal
    private SamplePrincipal userPrincipal;

    public void initialize(Subject subject, CallbackHandler callbackHandler,
			Map sharedState, Map options) {
 
	this.subject = subject;
	this.callbackHandler = callbackHandler;
	this.sharedState = sharedState;
	this.options = options;

	// initialize any configured options
	debug = "true".equalsIgnoreCase((String)options.get("debug"));
    }

    public boolean login() throws LoginException {

	// prompt for a user name and password
	if (callbackHandler == null)
	    throw new LoginException("Error: no CallbackHandler available " +
			"to garner authentication information from the user");

	Callback[] callbacks = new Callback[2];
	callbacks[0] = new NameCallback("user name: ");
	callbacks[1] = new PasswordCallback("password: ", false);
 
	try {
	    callbackHandler.handle(callbacks);
	    username = ((NameCallback)callbacks[0]).getName();
	    char[] tmpPassword = ((PasswordCallback)callbacks[1]).getPassword();
	    if (tmpPassword == null) {
		// treat a NULL password as an empty password
		tmpPassword = new char[0];
	    }
	    password = new char[tmpPassword.length];
	    System.arraycopy(tmpPassword, 0,
			password, 0, tmpPassword.length);
	    ((PasswordCallback)callbacks[1]).clearPassword();
 
	} catch (java.io.IOException ioe) {
	    throw new LoginException(ioe.toString());
	} catch (UnsupportedCallbackException uce) {
	    throw new LoginException("Error: " + uce.getCallback().toString() +
		" not available to garner authentication information " +
		"from the user");
	}

	// print debugging information
	if (debug) {
	    System.out.println("\t\t[SampleLoginModule] " +
				"user entered user name: " +
				username);
	    System.out.print("\t\t[SampleLoginModule] " +
				"user entered password: ");
	    for (int i = 0; i < password.length; i++)
		System.out.print(password[i]);
	    System.out.println();
	}

	// verify the username/password
	boolean usernameCorrect = false;
	boolean passwordCorrect = false;
	if (username.equals("testUser"))
	    usernameCorrect = true;
	if (usernameCorrect &&
	    password.length == 12 &&
	    password[0] == 't' &&
	    password[1] == 'e' &&
	    password[2] == 's' &&
	    password[3] == 't' &&
	    password[4] == 'P' &&
	    password[5] == 'a' &&
	    password[6] == 's' &&
	    password[7] == 's' &&
	    password[8] == 'w' &&
	    password[9] == 'o' &&
	    password[10] == 'r' &&
	    password[11] == 'd') {

	    // authentication succeeded!!!
	    passwordCorrect = true;
	    if (debug)
		System.out.println("\t\t[SampleLoginModule] " +
				"authentication succeeded");
	    succeeded = true;
	    return true;
	} else {

	    // authentication failed -- clean out state
	    if (debug)
		System.out.println("\t\t[SampleLoginModule] " +
				"authentication failed");
	    succeeded = false;
	    username = null;
	    for (int i = 0; i < password.length; i++)
		password[i] = ' ';
	    password = null;
	    if (!usernameCorrect) {
		throw new FailedLoginException("User Name Incorrect");
	    } else {
		throw new FailedLoginException("Password Incorrect");
	    }
	}
    }

    public boolean commit() throws LoginException {
	if (succeeded == false) {
	    return false;
	} else {
	    // add a Principal (authenticated identity)
	    // to the Subject

	    // assume the user we authenticated is the SamplePrincipal
	    userPrincipal = new SamplePrincipal(username);
	    if (!subject.getPrincipals().contains(userPrincipal))
		subject.getPrincipals().add(userPrincipal);

	    if (debug) {
		System.out.println("\t\t[SampleLoginModule] " +
				"added SamplePrincipal to Subject");
	    }

	    // in any case, clean out state
	    username = null;
	    for (int i = 0; i < password.length; i++)
		password[i] = ' ';
	    password = null;

	    commitSucceeded = true;
	    return true;
	}
    }

    public boolean abort() throws LoginException {
	if (succeeded == false) {
	    return false;
	} else if (succeeded == true && commitSucceeded == false) {
	    // login succeeded but overall authentication failed
	    succeeded = false;
	    username = null;
	    if (password != null) {
		for (int i = 0; i < password.length; i++)
		    password[i] = ' ';
		password = null;
	    }
	    userPrincipal = null;
	} else {
	    // overall authentication succeeded and commit succeeded,
	    // but someone else's commit failed
	    logout();
	}
	return true;
    }

    public boolean logout() throws LoginException {

	subject.getPrincipals().remove(userPrincipal);
	succeeded = false;
	succeeded = commitSucceeded;
	username = null;
	if (password != null) {
	    for (int i = 0; i < password.length; i++)
		password[i] = ' ';
	    password = null;
	}
	userPrincipal = null;
	return true;
    }
}