content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.apache.ambari.server.api;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  
  import jakarta.servlet.Filter;
  import jakarta.servlet.FilterChain;
  import jakarta.servlet.FilterConfig;
  import jakarta.servlet.ServletException;
  import jakarta.servlet.ServletRequest;
  import jakarta.servlet.ServletResponse;
  import jakarta.servlet.http.HttpServletRequest;
  import jakarta.servlet.http.HttpServletRequestWrapper;
  import jakarta.servlet.http.HttpServletResponse;
  
  import org.springframework.http.HttpMethod;
  
  public class MethodOverrideFilter implements Filter {
    private static final String HEADER_NAME = "X-Http-Method-Override";
    //limit override to GET method only (no need for others now)
    private static final List<String> ALLOWED_METHODS = new ArrayList<String>(){{
      add("GET");
    }};
  
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
  
    }
  
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
      if (request instanceof HttpServletRequest) {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
  
        String method = httpServletRequest.getHeader(HEADER_NAME);
        if (method != null) {
          if (ALLOWED_METHODS.contains(method.toUpperCase())) {
            final HttpMethod httpMethod = HttpMethod.valueOf(method.toUpperCase());
            HttpServletRequestWrapper requestWrapper = new HttpServletRequestWrapper(httpServletRequest){
              @Override
              public String getMethod() {
                return httpMethod.toString();
              }
            };
  
            chain.doFilter(requestWrapper, response);
            return;
          } else {
            HttpServletResponse httpResponse = (HttpServletResponse) response;
            httpResponse.sendError(400, "Incorrect HTTP method for override: "+ method + ". Allowed values: "+ ALLOWED_METHODS);
          }
        }
      }
      chain.doFilter(request, response);
    }
  
    @Override
    public void destroy() {
  
    }
  }
  