/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.nifi.security.krb;

import org.apache.commons.lang3.Validate;

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 java.io.IOException;

/**
 * CallbackHandler that provides the given username and password.
 */
public class UsernamePasswordCallbackHandler implements CallbackHandler {

    private final String username;
    private final String password;

    public UsernamePasswordCallbackHandler(final String username, final String password) {
        this.username = username;
        this.password = password;
        Validate.notBlank(this.username);
        Validate.notBlank(this.password);
    }

    @Override
    public void handle(Callback[] callbacks) throws IOException, UnsupportedCallbackException {
        for (final Callback callback : callbacks) {
            if (callback instanceof NameCallback) {
                final NameCallback nameCallback = (NameCallback) callback;
                nameCallback.setName(username);
            } else if (callback instanceof PasswordCallback) {
                final PasswordCallback passwordCallback = (PasswordCallback) callback;
                passwordCallback.setPassword(password.toCharArray());
            } else {
                throw new IllegalStateException("Unexpected callback type: " + callback.getClass().getCanonicalName());
            }
        }
    }

}
