/*
 * Copyright 2012-2020 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.boot.autoconfigure.web.reactive.error;

import java.util.stream.Collectors;

import org.springframework.beans.factory.ObjectProvider;
import org.springframework.boot.autoconfigure.AutoConfigureBefore;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
import org.springframework.boot.autoconfigure.condition.SearchStrategy;
import org.springframework.boot.autoconfigure.web.ResourceProperties;
import org.springframework.boot.autoconfigure.web.ServerProperties;
import org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.boot.web.reactive.error.DefaultErrorAttributes;
import org.springframework.boot.web.reactive.error.ErrorAttributes;
import org.springframework.boot.web.reactive.error.ErrorWebExceptionHandler;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;
import org.springframework.http.codec.ServerCodecConfigurer;
import org.springframework.web.reactive.config.WebFluxConfigurer;
import org.springframework.web.reactive.result.view.ViewResolver;

/**
 * {@link EnableAutoConfiguration Auto-configuration} to render errors via a WebFlux
 * {@link org.springframework.web.server.WebExceptionHandler}.
 *
 * @author Brian Clozel
 * @author Scott Frederick
 * @since 2.0.0
 */
@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.REACTIVE)
@ConditionalOnClass(WebFluxConfigurer.class)
@AutoConfigureBefore(WebFluxAutoConfiguration.class)
@EnableConfigurationProperties({ ServerProperties.class, ResourceProperties.class })
public class ErrorWebFluxAutoConfiguration {

	private final ServerProperties serverProperties;

	public ErrorWebFluxAutoConfiguration(ServerProperties serverProperties) {
		this.serverProperties = serverProperties;
	}

	@Bean
	@ConditionalOnMissingBean(value = ErrorWebExceptionHandler.class, search = SearchStrategy.CURRENT)
	@Order(-1)
	public ErrorWebExceptionHandler errorWebExceptionHandler(ErrorAttributes errorAttributes,
			ResourceProperties resourceProperties, ObjectProvider<ViewResolver> viewResolvers,
			ServerCodecConfigurer serverCodecConfigurer, ApplicationContext applicationContext) {
		DefaultErrorWebExceptionHandler exceptionHandler = new DefaultErrorWebExceptionHandler(errorAttributes,
				resourceProperties, this.serverProperties.getError(), applicationContext);
		exceptionHandler.setViewResolvers(viewResolvers.orderedStream().collect(Collectors.toList()));
		exceptionHandler.setMessageWriters(serverCodecConfigurer.getWriters());
		exceptionHandler.setMessageReaders(serverCodecConfigurer.getReaders());
		return exceptionHandler;
	}

	@Bean
	@ConditionalOnMissingBean(value = ErrorAttributes.class, search = SearchStrategy.CURRENT)
	public DefaultErrorAttributes errorAttributes() {
		return new DefaultErrorAttributes();
	}

}
