/*
 * Copyright 2002-2024 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.config.annotation.authentication.configuration;

import java.util.ArrayList;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.context.ApplicationContext;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.core.log.LogMessage;
import org.springframework.security.authentication.dao.DaoAuthenticationProvider;
import org.springframework.security.authentication.password.CompromisedPasswordChecker;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
import org.springframework.security.core.userdetails.UserDetailsPasswordService;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.crypto.password.PasswordEncoder;

/**
 * Lazily initializes the global authentication with a {@link UserDetailsService} if it is
 * not yet configured and there is only a single Bean of that type. Optionally, if a
 * {@link PasswordEncoder} is defined will wire this up too.
 *
 * @author Rob Winch
 * @since 4.1
 */
@Order(InitializeUserDetailsBeanManagerConfigurer.DEFAULT_ORDER)
class InitializeUserDetailsBeanManagerConfigurer extends GlobalAuthenticationConfigurerAdapter {

	static final int DEFAULT_ORDER = Ordered.LOWEST_PRECEDENCE - 5000;

	private final ApplicationContext context;

	/**
	 * @param context
	 */
	InitializeUserDetailsBeanManagerConfigurer(ApplicationContext context) {
		this.context = context;
	}

	@Override
	public void init(AuthenticationManagerBuilder auth) throws Exception {
		auth.apply(new InitializeUserDetailsManagerConfigurer());
	}

	class InitializeUserDetailsManagerConfigurer extends GlobalAuthenticationConfigurerAdapter {

		private final Log logger = LogFactory.getLog(getClass());

		@Override
		public void configure(AuthenticationManagerBuilder auth) throws Exception {
			List<BeanWithName<UserDetailsService>> userDetailsServices = getBeansWithName(UserDetailsService.class);
			if (auth.isConfigured()) {
				if (!userDetailsServices.isEmpty()) {
					this.logger.warn("Global AuthenticationManager configured with an AuthenticationProvider bean. "
							+ "UserDetailsService beans will not be used for username/password login. "
							+ "Consider removing the AuthenticationProvider bean. "
							+ "Alternatively, consider using the UserDetailsService in a manually instantiated "
							+ "DaoAuthenticationProvider.");
				}
				return;
			}

			if (userDetailsServices.isEmpty()) {
				return;
			}
			else if (userDetailsServices.size() > 1) {
				List<String> beanNames = userDetailsServices.stream().map(BeanWithName::getName).toList();
				this.logger.warn(LogMessage.format("Found %s UserDetailsService beans, with names %s. "
						+ "Global Authentication Manager will not use a UserDetailsService for username/password login. "
						+ "Consider publishing a single UserDetailsService bean.", userDetailsServices.size(),
						beanNames));
				return;
			}
			var userDetailsService = userDetailsServices.get(0).getBean();
			var userDetailsServiceBeanName = userDetailsServices.get(0).getName();
			PasswordEncoder passwordEncoder = getBeanOrNull(PasswordEncoder.class);
			UserDetailsPasswordService passwordManager = getBeanOrNull(UserDetailsPasswordService.class);
			CompromisedPasswordChecker passwordChecker = getBeanOrNull(CompromisedPasswordChecker.class);
			DaoAuthenticationProvider provider;
			if (passwordEncoder != null) {
				provider = new DaoAuthenticationProvider(passwordEncoder);
			}
			else {
				provider = new DaoAuthenticationProvider();
			}
			provider.setUserDetailsService(userDetailsService);
			if (passwordManager != null) {
				provider.setUserDetailsPasswordService(passwordManager);
			}
			if (passwordChecker != null) {
				provider.setCompromisedPasswordChecker(passwordChecker);
			}
			provider.afterPropertiesSet();
			auth.authenticationProvider(provider);
			this.logger.info(LogMessage.format(
					"Global AuthenticationManager configured with UserDetailsService bean with name %s",
					userDetailsServiceBeanName));
		}

		/**
		 * @return a bean of the requested class if there's just a single registered
		 * component, null otherwise.
		 */
		private <T> T getBeanOrNull(Class<T> type) {
			String[] beanNames = InitializeUserDetailsBeanManagerConfigurer.this.context.getBeanNamesForType(type);
			if (beanNames.length != 1) {
				return null;
			}
			return InitializeUserDetailsBeanManagerConfigurer.this.context.getBean(beanNames[0], type);
		}

		/**
		 * @return a list of beans of the requested class, along with their names. If
		 * there are no registered beans of that type, the list is empty.
		 */
		private <T> List<BeanWithName<T>> getBeansWithName(Class<T> type) {
			List<BeanWithName<T>> beanWithNames = new ArrayList<>();
			String[] beanNames = InitializeUserDetailsBeanManagerConfigurer.this.context.getBeanNamesForType(type);
			for (String beanName : beanNames) {
				T bean = InitializeUserDetailsBeanManagerConfigurer.this.context.getBean(beanNames[0], type);
				beanWithNames.add(new BeanWithName<T>(bean, beanName));
			}
			return beanWithNames;
		}

		static class BeanWithName<T> {

			private final T bean;

			private final String name;

			BeanWithName(T bean, String name) {
				this.bean = bean;
				this.name = name;
			}

			T getBean() {
				return this.bean;
			}

			String getName() {
				return this.name;
			}

		}

	}

}
