/*
 * Copyright (c) 2004, 2015, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

import java.security.Principal;
import java.util.Arrays;
import java.util.Map;
import javax.security.auth.Subject;
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;
import javax.security.auth.login.FailedLoginException;
import javax.security.auth.login.LoginException;
import javax.security.auth.spi.LoginModule;

/**
 * This code was based on JAAS demo code, small modification is made for testing
 * purpose.
 */
public class SmartLoginModule implements LoginModule {

    // initial state
    private Subject subject;
    private CallbackHandler callbackHandler;

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

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

    // Default values for this login module. In real world,
    // don't do it in this way!
    private String myUsername;
    private char[] myPassword;
    private String header;

    // testUser's SamplePrincipal
    private SamplePrincipal userPrincipal;

    public SmartLoginModule() {
        this("testUser",
                new char[]{'t', 'e', 's', 't', 'P', 'a', 's', 's',
                    'w', 'o', 'r', 'd', '1'},
                "SmartLoginModule1: ");
    }

    public SmartLoginModule(String userName, char[] password, String header) {
        myUsername = userName;
        myPassword = password;
        this.header = header;
    }

    @Override
    public boolean abort() throws LoginException {
        if (!succeeded) {
            return false;
        } else if (succeeded && !commitSucceeded) {
            // login succeeded but overall authentication failed
            succeeded = false;
            username = null;
            password = null;
            userPrincipal = null;
        } else {
            // overall authentication succeeded and commit succeeded,
            // but someone else's commit failed
            logout();
        }
        return true;
    }

    @Override
    public boolean commit() throws LoginException {
        if (!succeeded) {
            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);
            }
            // in any case, clean out state
            username = null;
            password = null;
            commitSucceeded = true;
            return true;
        }
    }

    @Override
    public void initialize(Subject subject, CallbackHandler callbackHandler,
            Map<String, ?> sharedState, Map<String, ?> options) {
        this.subject = subject;
        this.callbackHandler = callbackHandler;
    }

    @Override
    public boolean login() throws LoginException {
        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(header + "user name: ");
        callbacks[1] = new PasswordCallback(header + "password: ", false);

        try {
            callbackHandler.handle(callbacks);
            username = ((NameCallback) callbacks[0]).getName();
            char[] tmpPassword
                    = ((PasswordCallback) callbacks[1]).getPassword();
            if (tmpPassword == null) {
                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 (LoginException) new LoginException().initCause(ioe);
        } catch (UnsupportedCallbackException uce) {
            throw new LoginException("Error: " + header
                    + uce.getCallback().toString()
                    + " not available to garner authentication information "
                    + "from the user");
        }

        // verify the username/password
        if (username.equals(myUsername)
                && Arrays.equals(password, myPassword)) {
            System.out.println("\t\t" + header + " authentication succeeded");
            succeeded = true;
            return true;
        } else {
            // authentication failed -- clean out state
            System.out.println("\t\t" + header + " authentication failed");
            printDebugInfo();
            succeeded = false;
            username = null;
            password = null;
            throw new FailedLoginException("User Name or Password Incorrect");
        }
    }

    @Override
    public boolean logout() throws LoginException {
        subject.getPrincipals().remove(userPrincipal);
        succeeded = false;
        succeeded = commitSucceeded;
        username = null;
        password = null;
        userPrincipal = null;
        return true;
    }

    // print debugging information
    private void printDebugInfo() {
        System.out.println("\t\t" + header + " correct user name: "
                + myUsername);
        System.out.println("\t\t" + header + " user entered user name: "
                + username);
        System.out.print("\t\t" + header + " correct password: ");
        for (char c : myPassword) {
            System.out.print(c);
        }
        System.out.println();
        System.out.print("\t\t" + header + " user entered password: ");
        for (char c : password) {
            System.out.print(c);
        }
        System.out.println();
    }
}

class SamplePrincipal implements Principal, java.io.Serializable {

    /**
     * @serial
     */
    private String name;

    /**
     * Create a SamplePrincipal with a Sample username.
     *
     * @param name the Sample username for this user.
     * @exception NullPointerException if the <code>name</code> is
     * <code>null</code>.
     */
    public SamplePrincipal(String name) {
        if (name == null) {
            throw new NullPointerException("illegal null input");
        }

        this.name = name;
    }

    @Override
    public String getName() {
        return name;
    }

    @Override
    public String toString() {
        return "SamplePrincipal:  " + name;
    }

    @Override
    public boolean equals(Object o) {
        if (o == null) {
            return false;
        }

        if (this == o) {
            return true;
        }

        if (!(o instanceof SamplePrincipal)) {
            return false;
        }
        SamplePrincipal that = (SamplePrincipal) o;

        return this.getName().equals(that.getName());
    }

    @Override
    public int hashCode() {
        return name.hashCode();
    }
}