/*
    * 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 org.springframework.http.HttpInputMessage;
  import org.springframework.http.HttpOutputMessage;
  import org.springframework.http.MediaType;
  import org.springframework.http.converter.AbstractHttpMessageConverter;
  import org.springframework.http.converter.FormHttpMessageConverter;
  import org.springframework.http.converter.HttpMessageNotReadableException;
  import org.springframework.http.converter.HttpMessageNotWritableException;
  import org.springframework.security.oauth2.common.DefaultOAuth2AccessToken;
  import org.springframework.security.oauth2.common.OAuth2AccessToken;
  import org.springframework.util.MultiValueMap;
  
  /**
   * Converter that can handle inbound form data and convert it to an access token. Needed to support external servers,
   * like Facebook that might not send JSON token data.
   * 
   * @author Rob Winch
   * @author Dave Syer
   * 
   */
  public class FormOAuth2AccessTokenMessageConverter extends AbstractHttpMessageConverter<OAuth2AccessToken> {
  
  	private final FormHttpMessageConverter delegateMessageConverter;
  
  	public FormOAuth2AccessTokenMessageConverter() {
  		super(MediaType.APPLICATION_FORM_URLENCODED, MediaType.TEXT_PLAIN);
  		this.delegateMessageConverter = new FormHttpMessageConverter();
  	}
  
  	@Override
  	protected boolean supports(Class<?> clazz) {
  		return OAuth2AccessToken.class.equals(clazz);
  	}
  
  	@Override
  	protected OAuth2AccessToken readInternal(Class<? extends OAuth2AccessToken> clazz, HttpInputMessage inputMessage)
  			throws IOException, HttpMessageNotReadableException {
  		MultiValueMap<String, String> data = delegateMessageConverter.read(null, inputMessage);
  		return DefaultOAuth2AccessToken.valueOf(data.toSingleValueMap());
  	}
  
  	@Override
  	protected void writeInternal(OAuth2AccessToken accessToken, HttpOutputMessage outputMessage) throws IOException,
  			HttpMessageNotWritableException {
  		throw new UnsupportedOperationException(
  				"This converter is only used for converting from externally aqcuired form data");
  	}
  }