/*
    * Copyright 2006-2011 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.provider.client;
  
  import java.io.IOException;
  
  import javax.servlet.FilterChain;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.springframework.security.authentication.BadCredentialsException;
  import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
  import org.springframework.security.core.Authentication;
  import org.springframework.security.core.AuthenticationException;
  import org.springframework.security.core.context.SecurityContextHolder;
  import org.springframework.security.oauth2.common.exceptions.BadClientCredentialsException;
  import org.springframework.security.oauth2.provider.error.OAuth2AuthenticationEntryPoint;
  import org.springframework.security.web.AuthenticationEntryPoint;
  import org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter;
  import org.springframework.security.web.authentication.AuthenticationFailureHandler;
  import org.springframework.security.web.authentication.AuthenticationSuccessHandler;
  import org.springframework.security.web.util.matcher.RequestMatcher;
  import org.springframework.web.HttpRequestMethodNotSupportedException;
  
  /**
   * A filter and authentication endpoint for the OAuth2 Token Endpoint. Allows clients to authenticate using request
   * parameters if included as a security filter, as permitted by the specification (but not recommended). It is
   * recommended by the specification that you permit HTTP basic authentication for clients, and not use this filter at
   * all.
   * 
   * @author Dave Syer
   * 
   */
  public class ClientCredentialsTokenEndpointFilter extends AbstractAuthenticationProcessingFilter {
  
  	private AuthenticationEntryPoint authenticationEntryPoint = new OAuth2AuthenticationEntryPoint();
  
  	private boolean allowOnlyPost = false;
  
  	public ClientCredentialsTokenEndpointFilter() {
  		this("/oauth/token");
  	}
  
  	public ClientCredentialsTokenEndpointFilter(String path) {
  		super(path);
  		setRequiresAuthenticationRequestMatcher(new ClientCredentialsRequestMatcher(path));
  		// If authentication fails the type is "Form"
  		((OAuth2AuthenticationEntryPoint) authenticationEntryPoint).setTypeName("Form");
  	}
  
  	public void setAllowOnlyPost(boolean allowOnlyPost) {
  		this.allowOnlyPost = allowOnlyPost;
  	}
  
  	/**
  	 * @param authenticationEntryPoint the authentication entry point to set
  	 */
  	public void setAuthenticationEntryPoint(AuthenticationEntryPoint authenticationEntryPoint) {
  		this.authenticationEntryPoint = authenticationEntryPoint;
  	}
  
  	@Override
  	public void afterPropertiesSet() {
  		super.afterPropertiesSet();
  		setAuthenticationFailureHandler(new AuthenticationFailureHandler() {
  			public void onAuthenticationFailure(HttpServletRequest request, HttpServletResponse response,
  					AuthenticationException exception) throws IOException, ServletException {
  				if (exception instanceof BadCredentialsException) {
  					exception = new BadCredentialsException(exception.getMessage(), new BadClientCredentialsException());
  				}
  				authenticationEntryPoint.commence(request, response, exception);
  			}
  		});
  		setAuthenticationSuccessHandler(new AuthenticationSuccessHandler() {
  			public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response,
  					Authentication authentication) throws IOException, ServletException {
  				// no-op - just allow filter chain to continue to token endpoint
  			}
  		});
  	}
  
  	@Override
  	public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response)
  			throws AuthenticationException, IOException, ServletException {
  
  		if (allowOnlyPost && !"POST".equalsIgnoreCase(request.getMethod())) {
  			throw new HttpRequestMethodNotSupportedException(request.getMethod(), new String[] { "POST" });
  		}
 
 		String clientId = request.getParameter("client_id");
 		String clientSecret = request.getParameter("client_secret");
 
 		// If the request is already authenticated we can assume that this
 		// filter is not needed
 		Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
 		if (authentication != null && authentication.isAuthenticated()) {
 			return authentication;
 		}
 
 		if (clientId == null) {
 			throw new BadCredentialsException("No client credentials presented");
 		}
 
 		if (clientSecret == null) {
 			clientSecret = "";
 		}
 
 		clientId = clientId.trim();
 		UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken(clientId,
 				clientSecret);
 
 		return this.getAuthenticationManager().authenticate(authRequest);
 
 	}
 
 	@Override
 	protected void successfulAuthentication(HttpServletRequest request, HttpServletResponse response,
 			FilterChain chain, Authentication authResult) throws IOException, ServletException {
 		super.successfulAuthentication(request, response, chain, authResult);
 		chain.doFilter(request, response);
 	}
 
 	protected static class ClientCredentialsRequestMatcher implements RequestMatcher {
 
 		private String path;
 
 		public ClientCredentialsRequestMatcher(String path) {
 			this.path = path;
 
 		}
 
 		@Override
 		public boolean matches(HttpServletRequest request) {
 			String uri = request.getRequestURI();
 			int pathParamIndex = uri.indexOf(';');
 
 			if (pathParamIndex > 0) {
 				// strip everything after the first semi-colon
 				uri = uri.substring(0, pathParamIndex);
 			}
 
 			String clientId = request.getParameter("client_id");
 
 			if (clientId == null) {
 				// Give basic auth a chance to work instead (it's preferred anyway)
 				return false;
 			}
 
 			if ("".equals(request.getContextPath())) {
 				return uri.endsWith(path);
 			}
 
 			return uri.endsWith(request.getContextPath() + path);
 		}
 
 	}
 
 }