/*
 * Copyright 2002-2018 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
 *
 *      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.springframework.web.client;

import java.io.IOException;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.springframework.http.HttpStatus;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.lang.Nullable;
import org.springframework.util.CollectionUtils;

Implementation of ResponseErrorHandler that uses 
HttpMessageConverters to convert HTTP error responses to 
RestClientExceptions. 
To use this error handler, you must specify a status mapping and/or a series mapping. If either of these mappings has a match for the status code of a given ClientHttpResponse, DefaultResponseErrorHandler.hasError(ClientHttpResponse) will return true, and DefaultResponseErrorHandler.handleError(ClientHttpResponse) will attempt to use the configured message converters to convert the response into the mapped subclass of RestClientException. Note that the status mapping takes precedence over series mapping. 
If there is no match, this error handler will default to the behavior of DefaultResponseErrorHandler. Note that you can override this default behavior by specifying a series mapping from HttpStatus.Series#CLIENT_ERROR and/or HttpStatus.Series#SERVER_ERROR to null. 
Author:
Simon Galperin, Arjen Poutsma
See Also:
RestTemplate.setErrorHandler(ResponseErrorHandler)
Since:
5.0/**
 * Implementation of {@link ResponseErrorHandler} that uses {@link HttpMessageConverter
 * HttpMessageConverters} to convert HTTP error responses to {@link RestClientException
 * RestClientExceptions}.
 *
 * <p>To use this error handler, you must specify a
 * {@linkplain #setStatusMapping(Map) status mapping} and/or a
 * {@linkplain #setSeriesMapping(Map) series mapping}. If either of these mappings has a match
 * for the {@linkplain ClientHttpResponse#getStatusCode() status code} of a given
 * {@code ClientHttpResponse}, {@link #hasError(ClientHttpResponse)} will return
 * {@code true}, and {@link #handleError(ClientHttpResponse)} will attempt to use the
 * {@linkplain #setMessageConverters(List) configured message converters} to convert the response
 * into the mapped subclass of {@link RestClientException}. Note that the
 * {@linkplain #setStatusMapping(Map) status mapping} takes precedence over
 * {@linkplain #setSeriesMapping(Map) series mapping}.
 *
 * <p>If there is no match, this error handler will default to the behavior of
 * {@link DefaultResponseErrorHandler}. Note that you can override this default behavior
 * by specifying a {@linkplain #setSeriesMapping(Map) series mapping} from
 * {@code HttpStatus.Series#CLIENT_ERROR} and/or {@code HttpStatus.Series#SERVER_ERROR}
 * to {@code null}.
 *
 * @author Simon Galperin
 * @author Arjen Poutsma
 * @since 5.0
 * @see RestTemplate#setErrorHandler(ResponseErrorHandler)
 */
public class ExtractingResponseErrorHandler extends DefaultResponseErrorHandler {

	private List<HttpMessageConverter<?>> messageConverters = Collections.emptyList();

	private final Map<HttpStatus, Class<? extends RestClientException>> statusMapping = new LinkedHashMap<>();

	private final Map<HttpStatus.Series, Class<? extends RestClientException>> seriesMapping = new LinkedHashMap<>();


	
Create a new, empty ExtractingResponseErrorHandler. 
Note that setMessageConverters(List<HttpMessageConverter<?>>) must be called when using this constructor. /**
	 * Create a new, empty {@code ExtractingResponseErrorHandler}.
	 * <p>Note that {@link #setMessageConverters(List)} must be called when using this constructor.
	 */
	public ExtractingResponseErrorHandler() {
	}

	
Create a new ExtractingResponseErrorHandler with the given HttpMessageConverter instances. 
Params:
messageConverters – the message converters to use/**
	 * Create a new {@code ExtractingResponseErrorHandler} with the given
	 * {@link HttpMessageConverter} instances.
	 * @param messageConverters the message converters to use
	 */
	public ExtractingResponseErrorHandler(List<HttpMessageConverter<?>> messageConverters) {
		this.messageConverters = messageConverters;
	}


	
Set the message converters to use by this extractor.
/**
	 * Set the message converters to use by this extractor.
	 */
	public void setMessageConverters(List<HttpMessageConverter<?>> messageConverters) {
		this.messageConverters = messageConverters;
	}

	
Set the mapping from HTTP status code to RestClientException subclass. If this mapping has a match for the status code of a given ClientHttpResponse, DefaultResponseErrorHandler.hasError(ClientHttpResponse) will return true and DefaultResponseErrorHandler.handleError(ClientHttpResponse) will attempt to use the configured message converters to convert the response into the mapped subclass of RestClientException. /**
	 * Set the mapping from HTTP status code to {@code RestClientException} subclass.
	 * If this mapping has a match
	 * for the {@linkplain ClientHttpResponse#getStatusCode() status code} of a given
	 * {@code ClientHttpResponse}, {@link #hasError(ClientHttpResponse)} will return
	 * {@code true} and {@link #handleError(ClientHttpResponse)} will attempt to use the
	 * {@linkplain #setMessageConverters(List) configured message converters} to convert the
	 * response into the mapped subclass of {@link RestClientException}.
	 */
	public void setStatusMapping(Map<HttpStatus, Class<? extends RestClientException>> statusMapping) {
		if (!CollectionUtils.isEmpty(statusMapping)) {
			this.statusMapping.putAll(statusMapping);
		}
	}

	
Set the mapping from HTTP status series to RestClientException subclass. If this mapping has a match for the status code of a given ClientHttpResponse, DefaultResponseErrorHandler.hasError(ClientHttpResponse) will return true and DefaultResponseErrorHandler.handleError(ClientHttpResponse) will attempt to use the configured message converters to convert the response into the mapped subclass of RestClientException. /**
	 * Set the mapping from HTTP status series to {@code RestClientException} subclass.
	 * If this mapping has a match
	 * for the {@linkplain ClientHttpResponse#getStatusCode() status code} of a given
	 * {@code ClientHttpResponse}, {@link #hasError(ClientHttpResponse)} will return
	 * {@code true} and {@link #handleError(ClientHttpResponse)} will attempt to use the
	 * {@linkplain #setMessageConverters(List) configured message converters} to convert the
	 * response into the mapped subclass of {@link RestClientException}.
	 */
	public void setSeriesMapping(Map<HttpStatus.Series, Class<? extends RestClientException>> seriesMapping) {
		if (!CollectionUtils.isEmpty(seriesMapping)) {
			this.seriesMapping.putAll(seriesMapping);
		}
	}


	@Override
	protected boolean hasError(HttpStatus statusCode) {
		if (this.statusMapping.containsKey(statusCode)) {
			return this.statusMapping.get(statusCode) != null;
		}
		else if (this.seriesMapping.containsKey(statusCode.series())) {
			return this.seriesMapping.get(statusCode.series()) != null;
		}
		else {
			return super.hasError(statusCode);
		}
	}

	@Override
	public void handleError(ClientHttpResponse response, HttpStatus statusCode) throws IOException {
		if (this.statusMapping.containsKey(statusCode)) {
			extract(this.statusMapping.get(statusCode), response);
		}
		else if (this.seriesMapping.containsKey(statusCode.series())) {
			extract(this.seriesMapping.get(statusCode.series()), response);
		}
		else {
			super.handleError(response, statusCode);
		}
	}

	private void extract(@Nullable Class<? extends RestClientException> exceptionClass,
			ClientHttpResponse response) throws IOException {

		if (exceptionClass == null) {
			return;
		}

		HttpMessageConverterExtractor<? extends RestClientException> extractor =
				new HttpMessageConverterExtractor<>(exceptionClass, this.messageConverters);
		RestClientException exception = extractor.extractData(response);
		if (exception != null) {
			throw exception;
		}
	}

}