/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Licensed 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.neo4j.driver;

import static java.util.Collections.singletonMap;
import static org.neo4j.driver.Values.value;
import static org.neo4j.driver.internal.security.InternalAuthToken.CREDENTIALS_KEY;
import static org.neo4j.driver.internal.security.InternalAuthToken.PARAMETERS_KEY;
import static org.neo4j.driver.internal.security.InternalAuthToken.PRINCIPAL_KEY;
import static org.neo4j.driver.internal.security.InternalAuthToken.REALM_KEY;
import static org.neo4j.driver.internal.security.InternalAuthToken.SCHEME_KEY;
import static org.neo4j.driver.internal.util.Iterables.newHashMapWithSize;

import java.util.Map;
import java.util.Objects;
import org.neo4j.driver.internal.security.InternalAuthToken;

/**
 * This is a listing of the various methods of authentication supported by this
 * driver. The scheme used must be supported by the Neo4j Instance you are connecting
 * to.
 * @see GraphDatabase#driver(String, AuthToken)
 * @since 1.0
 */
public final class AuthTokens {
    private AuthTokens() {}

    /**
     * The basic authentication scheme, using a username and a password.
     * @param username this is the "principal", identifying who this token represents
     * @param password this is the "credential", proving the identity of the user
     * @return an authentication token that can be used to connect to Neo4j
     * @see GraphDatabase#driver(String, AuthToken)
     * @throws NullPointerException when either username or password is {@code null}
     */
    public static AuthToken basic(String username, String password) {
        return basic(username, password, null);
    }

    /**
     * The basic authentication scheme, using a username and a password.
     * @param username this is the "principal", identifying who this token represents
     * @param password this is the "credential", proving the identity of the user
     * @param realm this is the "realm", specifies the authentication provider
     * @return an authentication token that can be used to connect to Neo4j
     * @see GraphDatabase#driver(String, AuthToken)
     * @throws NullPointerException when either username or password is {@code null}
     */
    public static AuthToken basic(String username, String password, String realm) {
        Objects.requireNonNull(username, "Username can't be null");
        Objects.requireNonNull(password, "Password can't be null");

        Map<String, Value> map = newHashMapWithSize(4);
        map.put(SCHEME_KEY, value("basic"));
        map.put(PRINCIPAL_KEY, value(username));
        map.put(CREDENTIALS_KEY, value(password));
        if (realm != null) {
            map.put(REALM_KEY, value(realm));
        }
        return new InternalAuthToken(map);
    }

    /**
     * The bearer authentication scheme, using a base64 encoded token.
     *
     * @param token base64 encoded token
     * @return an authentication token that can be used to connect to Neo4j
     * @throws NullPointerException when token is {@code null}
     * @see GraphDatabase#driver(String, AuthToken)
     */
    public static AuthToken bearer(String token) {
        Objects.requireNonNull(token, "Token can't be null");

        Map<String, Value> map = newHashMapWithSize(2);
        map.put(SCHEME_KEY, value("bearer"));
        map.put(CREDENTIALS_KEY, value(token));
        return new InternalAuthToken(map);
    }

    /**
     * The kerberos authentication scheme, using a base64 encoded ticket
     *
     * @param base64EncodedTicket a base64 encoded service ticket
     * @return an authentication token that can be used to connect to Neo4j
     * @throws NullPointerException when ticket is {@code null}
     * @see GraphDatabase#driver(String, AuthToken)
     * @since 1.3
     */
    public static AuthToken kerberos(String base64EncodedTicket) {
        Objects.requireNonNull(base64EncodedTicket, "Ticket can't be null");

        Map<String, Value> map = newHashMapWithSize(3);
        map.put(SCHEME_KEY, value("kerberos"));
        map.put(PRINCIPAL_KEY, value("")); // This empty string is required for backwards compatibility.
        map.put(CREDENTIALS_KEY, value(base64EncodedTicket));
        return new InternalAuthToken(map);
    }

    /**
     * A custom authentication token used for doing custom authentication on the server side.
     * @param principal this used to identify who this token represents
     * @param credentials this is credentials authenticating the principal
     * @param realm this is the "realm:", specifying the authentication provider.
     * @param scheme this it the authentication scheme, specifying what kind of authentication that should be used
     * @return an authentication token that can be used to connect to Neo4j
     * @see GraphDatabase#driver(String, AuthToken)
     * @throws NullPointerException when either principal, credentials or scheme is {@code null}
     */
    public static AuthToken custom(String principal, String credentials, String realm, String scheme) {
        return custom(principal, credentials, realm, scheme, null);
    }

    /**
     * A custom authentication token used for doing custom authentication on the server side.
     * @param principal this used to identify who this token represents
     * @param credentials this is credentials authenticating the principal
     * @param realm this is the "realm:", specifying the authentication provider.
     * @param scheme this it the authentication scheme, specifying what kind of authentication that should be used
     * @param parameters extra parameters to be sent along the authentication provider.
     * @return an authentication token that can be used to connect to Neo4j
     * @see GraphDatabase#driver(String, AuthToken)
     * @throws NullPointerException when either principal, credentials or scheme is {@code null}
     */
    public static AuthToken custom(
            String principal, String credentials, String realm, String scheme, Map<String, Object> parameters) {
        Objects.requireNonNull(principal, "Principal can't be null");
        Objects.requireNonNull(credentials, "Credentials can't be null");
        Objects.requireNonNull(scheme, "Scheme can't be null");

        Map<String, Value> map = newHashMapWithSize(5);
        map.put(SCHEME_KEY, value(scheme));
        map.put(PRINCIPAL_KEY, value(principal));
        map.put(CREDENTIALS_KEY, value(credentials));
        if (realm != null) {
            map.put(REALM_KEY, value(realm));
        }
        if (parameters != null) {
            map.put(PARAMETERS_KEY, value(parameters));
        }
        return new InternalAuthToken(map);
    }

    /**
     * No authentication scheme. This will only work if authentication is disabled
     * on the Neo4j Instance we are connecting to.
     * @return an authentication token that can be used to connect to Neo4j instances with auth disabled
     * @see GraphDatabase#driver(String, AuthToken)
     */
    public static AuthToken none() {
        return new InternalAuthToken(singletonMap(SCHEME_KEY, value("none")));
    }
}
