/*
 * Copyright 2020-2021 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 example;

import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;

import com.nimbusds.jose.jwk.JWK;
import com.nimbusds.jose.jwk.JWKSet;
import com.nimbusds.jose.jwk.RSAKey;
import com.nimbusds.jose.jwk.source.ImmutableJWKSet;
import com.nimbusds.jose.jwk.source.JWKSource;
import com.nimbusds.jose.proc.SecurityContext;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.Customizer;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configurers.oauth2.server.resource.OAuth2ResourceServerConfigurer;
import org.springframework.security.config.http.SessionCreationPolicy;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.oauth2.jwt.JwtDecoder;
import org.springframework.security.oauth2.jwt.JwtEncoder;
import org.springframework.security.oauth2.jwt.NimbusJwtDecoder;
import org.springframework.security.oauth2.jwt.NimbusJwtEncoder;
import org.springframework.security.oauth2.server.resource.web.BearerTokenAuthenticationEntryPoint;
import org.springframework.security.oauth2.server.resource.web.access.BearerTokenAccessDeniedHandler;
import org.springframework.security.provisioning.InMemoryUserDetailsManager;
import org.springframework.security.web.SecurityFilterChain;

/**
 * Security configuration for the main application.
 *
 * @author Josh Cummings
 */
@Configuration
public class RestConfig {

	@Value("${jwt.public.key}")
	RSAPublicKey key;

	@Value("${jwt.private.key}")
	RSAPrivateKey priv;

	@Bean
	public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
		// @formatter:off
		http
				.authorizeHttpRequests((authorize) -> authorize
						.anyRequest().authenticated()
				)
				.csrf((csrf) -> csrf.ignoringRequestMatchers("/token"))
				.httpBasic(Customizer.withDefaults())
				.oauth2ResourceServer(OAuth2ResourceServerConfigurer::jwt)
				.sessionManagement((session) -> session.sessionCreationPolicy(SessionCreationPolicy.STATELESS))
				.exceptionHandling((exceptions) -> exceptions
						.authenticationEntryPoint(new BearerTokenAuthenticationEntryPoint())
						.accessDeniedHandler(new BearerTokenAccessDeniedHandler())
				);
		// @formatter:on
		return http.build();
	}

	@Bean
	UserDetailsService users() {
		// @formatter:off
		return new InMemoryUserDetailsManager(
			User.withUsername("user")
				.password("{noop}password")
				.authorities("app")
				.build()
		);
		// @formatter:on
	}

	@Bean
	JwtDecoder jwtDecoder() {
		return NimbusJwtDecoder.withPublicKey(this.key).build();
	}

	@Bean
	JwtEncoder jwtEncoder() {
		JWK jwk = new RSAKey.Builder(this.key).privateKey(this.priv).build();
		JWKSource<SecurityContext> jwks = new ImmutableJWKSet<>(new JWKSet(jwk));
		return new NimbusJwtEncoder(jwks);
	}

}
