/*
 * 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.web.client;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.lang.Nullable;
import org.springframework.util.FileCopyUtils;
import org.springframework.util.ObjectUtils;

Spring's default implementation of the ResponseErrorHandler interface. 
This error handler checks for the status code on the ClientHttpResponse. Any code in the 4xx or 5xx series is considered to be an error. This behavior can be changed by overriding hasError(HttpStatus). Unknown status codes will be ignored by hasError(ClientHttpResponse). 
See handleError(ClientHttpResponse) for more details on specific exception types. 
Author:
Arjen Poutsma, Rossen Stoyanchev, Juergen Hoeller
See Also:
RestTemplate.setErrorHandler
Since:
3.0/**
 * Spring's default implementation of the {@link ResponseErrorHandler} interface.
 *
 * <p>This error handler checks for the status code on the
 * {@link ClientHttpResponse}. Any code in the 4xx or 5xx series is considered
 * to be an error. This behavior can be changed by overriding
 * {@link #hasError(HttpStatus)}. Unknown status codes will be ignored by
 * {@link #hasError(ClientHttpResponse)}.
 *
 * <p>See {@link #handleError(ClientHttpResponse)} for more details on specific
 * exception types.
 *
 * @author Arjen Poutsma
 * @author Rossen Stoyanchev
 * @author Juergen Hoeller
 * @since 3.0
 * @see RestTemplate#setErrorHandler
 */
public class DefaultResponseErrorHandler implements ResponseErrorHandler {

	
Delegates to hasError(HttpStatus) (for a standard status enum value) or hasError(int) (for an unknown status code) with the response status code. 
See Also:
ClientHttpResponse.getRawStatusCode()
hasError(HttpStatus)
hasError(int)/**
	 * Delegates to {@link #hasError(HttpStatus)} (for a standard status enum value) or
	 * {@link #hasError(int)} (for an unknown status code) with the response status code.
	 * @see ClientHttpResponse#getRawStatusCode()
	 * @see #hasError(HttpStatus)
	 * @see #hasError(int)
	 */
	@Override
	public boolean hasError(ClientHttpResponse response) throws IOException {
		int rawStatusCode = response.getRawStatusCode();
		HttpStatus statusCode = HttpStatus.resolve(rawStatusCode);
		return (statusCode != null ? hasError(statusCode) : hasError(rawStatusCode));
	}

	
Template method called from hasError(ClientHttpResponse). 
The default implementation checks HttpStatus.isError(). Can be overridden in subclasses. 
Params:
statusCode – the HTTP status code as enum value
See Also:
HttpStatus.isError()
Returns:
true if the response indicates an error; false otherwise/**
	 * Template method called from {@link #hasError(ClientHttpResponse)}.
	 * <p>The default implementation checks {@link HttpStatus#isError()}.
	 * Can be overridden in subclasses.
	 * @param statusCode the HTTP status code as enum value
	 * @return {@code true} if the response indicates an error; {@code false} otherwise
	 * @see HttpStatus#isError()
	 */
	protected boolean hasError(HttpStatus statusCode) {
		return statusCode.isError();
	}

	
Template method called from hasError(ClientHttpResponse). 
The default implementation checks if the given status code is CLIENT_ERROR or SERVER_ERROR. Can be overridden in subclasses. 
Params:
unknownStatusCode – the HTTP status code as raw value
See Also:
Series.CLIENT_ERROR
Series.SERVER_ERROR
Returns:
true if the response indicates an error; false otherwise
Since:
4.3.21/**
	 * Template method called from {@link #hasError(ClientHttpResponse)}.
	 * <p>The default implementation checks if the given status code is
	 * {@link org.springframework.http.HttpStatus.Series#CLIENT_ERROR CLIENT_ERROR} or
	 * {@link org.springframework.http.HttpStatus.Series#SERVER_ERROR SERVER_ERROR}.
	 * Can be overridden in subclasses.
	 * @param unknownStatusCode the HTTP status code as raw value
	 * @return {@code true} if the response indicates an error; {@code false} otherwise
	 * @since 4.3.21
	 * @see org.springframework.http.HttpStatus.Series#CLIENT_ERROR
	 * @see org.springframework.http.HttpStatus.Series#SERVER_ERROR
	 */
	protected boolean hasError(int unknownStatusCode) {
		HttpStatus.Series series = HttpStatus.Series.resolve(unknownStatusCode);
		return (series == HttpStatus.Series.CLIENT_ERROR || series == HttpStatus.Series.SERVER_ERROR);
	}

	
Handle the error in the given response with the given resolved status code.
The default implementation throws:

HttpClientErrorException if the status code is in the 4xx series, or one of its sub-classes such as BadRequest and others. 
HttpServerErrorException if the status code is in the 5xx series, or one of its sub-classes such as InternalServerError and others. 
UnknownHttpStatusCodeException for error status codes not in the HttpStatus enum range. 
Throws:
UnknownHttpStatusCodeException – in case of an unresolvable status code
See Also:
handleError(ClientHttpResponse, HttpStatus)/**
	 * Handle the error in the given response with the given resolved status code.
	 * <p>The default implementation throws:
	 * <ul>
	 * <li>{@link HttpClientErrorException} if the status code is in the 4xx
	 * series, or one of its sub-classes such as
	 * {@link HttpClientErrorException.BadRequest} and others.
	 * <li>{@link HttpServerErrorException} if the status code is in the 5xx
	 * series, or one of its sub-classes such as
	 * {@link HttpServerErrorException.InternalServerError} and others.
	 * <li>{@link UnknownHttpStatusCodeException} for error status codes not in the
	 * {@link HttpStatus} enum range.
	 * </ul>
	 * @throws UnknownHttpStatusCodeException in case of an unresolvable status code
	 * @see #handleError(ClientHttpResponse, HttpStatus)
	 */
	@Override
	public void handleError(ClientHttpResponse response) throws IOException {
		HttpStatus statusCode = HttpStatus.resolve(response.getRawStatusCode());
		if (statusCode == null) {
			byte[] body = getResponseBody(response);
			String message = getErrorMessage(response.getRawStatusCode(),
					response.getStatusText(), body, getCharset(response));
			throw new UnknownHttpStatusCodeException(message,
					response.getRawStatusCode(), response.getStatusText(),
					response.getHeaders(), body, getCharset(response));
		}
		handleError(response, statusCode);
	}

	
Return error message with details from the response body, possibly truncated:
404 Not Found: [{'id': 123, 'message': 'my very long... (500 bytes)]

/**
	 * Return error message with details from the response body, possibly truncated:
	 * <pre>
	 * 404 Not Found: [{'id': 123, 'message': 'my very long... (500 bytes)]
	 * </pre>
	 */
	private String getErrorMessage(
			int rawStatusCode, String statusText, @Nullable byte[] responseBody, @Nullable Charset charset) {

		String preface = rawStatusCode + " " + statusText + ": ";
		if (ObjectUtils.isEmpty(responseBody)) {
			return preface + "[no body]";
		}

		if (charset == null) {
			charset = StandardCharsets.UTF_8;
		}
		int maxChars = 200;

		if (responseBody.length < maxChars * 2) {
			return preface + "[" + new String(responseBody, charset) + "]";
		}

		try {
			Reader reader = new InputStreamReader(new ByteArrayInputStream(responseBody), charset);
			CharBuffer buffer = CharBuffer.allocate(maxChars);
			reader.read(buffer);
			reader.close();
			buffer.flip();
			return preface + "[" + buffer.toString() + "... (" + responseBody.length + " bytes)]";
		}
		catch (IOException ex) {
			// should never happen
			throw new IllegalStateException(ex);
		}
	}

	
Handle the error based on the resolved status code.
The default implementation delegates to HttpClientErrorException.create for errors in the 4xx range, to HttpServerErrorException.create for errors in the 5xx range, or otherwise raises UnknownHttpStatusCodeException. 
See Also:
HttpClientErrorException.create
HttpServerErrorException.create
Since:
5.0/**
	 * Handle the error based on the resolved status code.
	 *
	 * <p>The default implementation delegates to
	 * {@link HttpClientErrorException#create} for errors in the 4xx range, to
	 * {@link HttpServerErrorException#create} for errors in the 5xx range,
	 * or otherwise raises {@link UnknownHttpStatusCodeException}.
	 *
	 * @since 5.0
	 * @see HttpClientErrorException#create
	 * @see HttpServerErrorException#create
	 */
	protected void handleError(ClientHttpResponse response, HttpStatus statusCode) throws IOException {
		String statusText = response.getStatusText();
		HttpHeaders headers = response.getHeaders();
		byte[] body = getResponseBody(response);
		Charset charset = getCharset(response);
		String message = getErrorMessage(statusCode.value(), statusText, body, charset);

		switch (statusCode.series()) {
			case CLIENT_ERROR:
				throw HttpClientErrorException.create(message, statusCode, statusText, headers, body, charset);
			case SERVER_ERROR:
				throw HttpServerErrorException.create(message, statusCode, statusText, headers, body, charset);
			default:
				throw new UnknownHttpStatusCodeException(message, statusCode.value(), statusText, headers, body, charset);
		}
	}

	
Determine the HTTP status of the given response.
Params:
response – the response to inspect
Throws:
IOException – in case of I/O errors
UnknownHttpStatusCodeException – in case of an unknown status code that cannot be represented with the HttpStatus enum
Returns:
the associated HTTP status
Since:
4.3.8
Deprecated:
as of 5.0, in favor of handleError(ClientHttpResponse, HttpStatus)/**
	 * Determine the HTTP status of the given response.
	 * @param response the response to inspect
	 * @return the associated HTTP status
	 * @throws IOException in case of I/O errors
	 * @throws UnknownHttpStatusCodeException in case of an unknown status code
	 * that cannot be represented with the {@link HttpStatus} enum
	 * @since 4.3.8
	 * @deprecated as of 5.0, in favor of {@link #handleError(ClientHttpResponse, HttpStatus)}
	 */
	@Deprecated
	protected HttpStatus getHttpStatusCode(ClientHttpResponse response) throws IOException {
		HttpStatus statusCode = HttpStatus.resolve(response.getRawStatusCode());
		if (statusCode == null) {
			throw new UnknownHttpStatusCodeException(response.getRawStatusCode(), response.getStatusText(),
					response.getHeaders(), getResponseBody(response), getCharset(response));
		}
		return statusCode;
	}

	
Read the body of the given response (for inclusion in a status exception).
Params:
response – the response to inspect
Returns:
the response body as a byte array,
or an empty byte array if the body could not be read
Since:
4.3.8/**
	 * Read the body of the given response (for inclusion in a status exception).
	 * @param response the response to inspect
	 * @return the response body as a byte array,
	 * or an empty byte array if the body could not be read
	 * @since 4.3.8
	 */
	protected byte[] getResponseBody(ClientHttpResponse response) {
		try {
			return FileCopyUtils.copyToByteArray(response.getBody());
		}
		catch (IOException ex) {
			// ignore
		}
		return new byte[0];
	}

	
Determine the charset of the response (for inclusion in a status exception).
Params:
response – the response to inspect
Returns:
the associated charset, or null if none
Since:
4.3.8/**
	 * Determine the charset of the response (for inclusion in a status exception).
	 * @param response the response to inspect
	 * @return the associated charset, or {@code null} if none
	 * @since 4.3.8
	 */
	@Nullable
	protected Charset getCharset(ClientHttpResponse response) {
		HttpHeaders headers = response.getHeaders();
		MediaType contentType = headers.getContentType();
		return (contentType != null ? contentType.getCharset() : null);
	}

}