/*
 * Copyright 2002-2020 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.security.oauth2.server.resource.authentication;

import reactor.core.publisher.Mono;

import org.springframework.core.convert.converter.Converter;
import org.springframework.security.authentication.AbstractAuthenticationToken;
import org.springframework.security.authentication.AuthenticationServiceException;
import org.springframework.security.authentication.ReactiveAuthenticationManager;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.oauth2.jwt.BadJwtException;
import org.springframework.security.oauth2.jwt.Jwt;
import org.springframework.security.oauth2.jwt.JwtException;
import org.springframework.security.oauth2.jwt.ReactiveJwtDecoder;
import org.springframework.security.oauth2.server.resource.InvalidBearerTokenException;
import org.springframework.util.Assert;

/**
 * A {@link ReactiveAuthenticationManager} for Jwt tokens.
 *
 * @author Rob Winch
 * @since 5.1
 */
public final class JwtReactiveAuthenticationManager implements ReactiveAuthenticationManager {

	private final ReactiveJwtDecoder jwtDecoder;

	private Converter<Jwt, ? extends Mono<? extends AbstractAuthenticationToken>> jwtAuthenticationConverter = new ReactiveJwtAuthenticationConverterAdapter(
			new JwtAuthenticationConverter());

	public JwtReactiveAuthenticationManager(ReactiveJwtDecoder jwtDecoder) {
		Assert.notNull(jwtDecoder, "jwtDecoder cannot be null");
		this.jwtDecoder = jwtDecoder;
	}

	@Override
	public Mono<Authentication> authenticate(Authentication authentication) {
		// @formatter:off
		return Mono.justOrEmpty(authentication)
				.filter((a) -> a instanceof BearerTokenAuthenticationToken)
				.cast(BearerTokenAuthenticationToken.class)
				.map(BearerTokenAuthenticationToken::getToken)
				.flatMap(this.jwtDecoder::decode)
				.flatMap(this.jwtAuthenticationConverter::convert)
				.cast(Authentication.class)
				.onErrorMap(JwtException.class, this::onError);
		// @formatter:on
	}

	/**
	 * Use the given {@link Converter} for converting a {@link Jwt} into an
	 * {@link AbstractAuthenticationToken}.
	 * @param jwtAuthenticationConverter the {@link Converter} to use
	 */
	public void setJwtAuthenticationConverter(
			Converter<Jwt, ? extends Mono<? extends AbstractAuthenticationToken>> jwtAuthenticationConverter) {
		Assert.notNull(jwtAuthenticationConverter, "jwtAuthenticationConverter cannot be null");
		this.jwtAuthenticationConverter = jwtAuthenticationConverter;
	}

	private AuthenticationException onError(JwtException ex) {
		if (ex instanceof BadJwtException) {
			return new InvalidBearerTokenException(ex.getMessage(), ex);
		}
		return new AuthenticationServiceException(ex.getMessage(), ex);
	}

}
