/*
    * Copyright 2011 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.oauth2.http.converter;
  
  import java.io.IOException;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  
  import org.springframework.http.HttpInputMessage;
  import org.springframework.http.HttpOutputMessage;
  import org.springframework.http.MediaType;
  import org.springframework.http.converter.FormHttpMessageConverter;
  import org.springframework.http.converter.HttpMessageConverter;
  import org.springframework.http.converter.HttpMessageNotReadableException;
  import org.springframework.http.converter.HttpMessageNotWritableException;
  import org.springframework.security.oauth2.common.exceptions.OAuth2Exception;
  import org.springframework.util.LinkedMultiValueMap;
  import org.springframework.util.MultiValueMap;
  
  /**
   * Converter that can handle inbound form data and convert it to an OAuth2 exception. Needed to support external servers,
   * like Facebook that might not send JSON data.
   * 
  @author Rob Winch
   * @author Dave Syer
   *
   */
  public final class FormOAuth2ExceptionHttpMessageConverter implements HttpMessageConverter<OAuth2Exception> {
  
  	private static final List<MediaType> SUPPORTED_MEDIA = Collections.singletonList(MediaType.APPLICATION_FORM_URLENCODED);
  
  	private final FormHttpMessageConverter delegateMessageConverter = new FormHttpMessageConverter();
  
  	public boolean canRead(Class<?> clazz, MediaType mediaType) {
  		return OAuth2Exception.class.equals(clazz) && MediaType.APPLICATION_FORM_URLENCODED.equals(mediaType);
  	}
  
  	public boolean canWrite(Class<?> clazz, MediaType mediaType) {
  		return OAuth2Exception.class.equals(clazz) && MediaType.APPLICATION_FORM_URLENCODED.equals(mediaType);
  	}
  
  	public List<MediaType> getSupportedMediaTypes() {
  		return SUPPORTED_MEDIA;
  	}
  
  	public OAuth2Exception read(Class<? extends OAuth2Exception> clazz, HttpInputMessage inputMessage)
  			throws IOException, HttpMessageNotReadableException {
  		MultiValueMap<String, String> data = delegateMessageConverter.read(null, inputMessage);
  		Map<String,String> flattenedData = data.toSingleValueMap();
  		return OAuth2Exception.valueOf(flattenedData);
  	}
  
  	public void write(OAuth2Exception t, MediaType contentType, HttpOutputMessage outputMessage) throws IOException,
  			HttpMessageNotWritableException {
  		MultiValueMap<String, String> data = new LinkedMultiValueMap<String, String>();
  		data.add(OAuth2Exception.ERROR, t.getOAuth2ErrorCode());
  		data.add(OAuth2Exception.DESCRIPTION, t.getMessage());
  		Map<String, String> additionalInformation = t.getAdditionalInformation();
  		if(additionalInformation != null) {
  			for(Map.Entry<String,String> entry : additionalInformation.entrySet()) {
  				data.add(entry.getKey(), entry.getValue());
  			}
  		}
  		delegateMessageConverter.write(data, contentType, outputMessage);
  	}
  
  }