content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * 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
   *
   *      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 com.alibaba.csp.sentinel.transport.command;
  
  import com.alibaba.csp.sentinel.command.CommandHandler;
  import com.alibaba.csp.sentinel.command.CommandRequest;
  import com.alibaba.csp.sentinel.command.CommandResponse;
  import com.alibaba.csp.sentinel.config.SentinelConfig;
  import com.alibaba.csp.sentinel.transport.command.http.StatusCode;
  import com.alibaba.csp.sentinel.transport.log.CommandCenterLog;
  
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import java.io.PrintWriter;
  import java.util.Map;
  
  /**
   * @author shenbaoyong
   */
  public class SentinelApiHandler {
  
      public static final String SERVER_ERROR_MESSAGE = "Command server error";
  
      private CommandHandler commandHandler;
  
      public SentinelApiHandler(CommandHandler commandHandler) {
          this.commandHandler = commandHandler;
      }
  
      public void handle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) {
          PrintWriter printWriter = null;
          try {
              long start = System.currentTimeMillis();
              printWriter = httpServletResponse.getWriter();
              CommandCenterLog.debug("[SentinelApiHandler] request income: {}", httpServletRequest.getRequestURL());
              CommandRequest request = new CommandRequest();
              Map<String, String[]> parameterMap = httpServletRequest.getParameterMap();
              for (Map.Entry<String, String[]> entry : parameterMap.entrySet()) {
                  String[] value = entry.getValue();
                  if (value != null && value.length >= 1) {
                      request.addParam(entry.getKey(), value[0]);
                  }
              }
              CommandResponse<?> response = commandHandler.handle(request);
              handleResponse(response, httpServletResponse, printWriter);
  
              long cost = System.currentTimeMillis() - start;
              CommandCenterLog.debug("[SentinelApiHandler] Deal request: {}, time cost: {} ms", httpServletRequest.getRequestURL(), cost);
          } catch (Throwable e) {
              CommandCenterLog.warn("[SentinelApiHandler] error", e);
              try {
                  if (printWriter != null) {
                      writeResponse(httpServletResponse, printWriter, StatusCode.INTERNAL_SERVER_ERROR, SERVER_ERROR_MESSAGE);
                  }
              } catch (Exception e1) {
                  CommandCenterLog.warn("Failed to write error response", e1);
              }
          }
      }
  
      private void writeResponse(HttpServletResponse httpServletResponse, PrintWriter out, StatusCode statusCode, String message) {
          httpServletResponse.setStatus(statusCode.getCode());
          if (message != null) {
              out.print(message);
          }
          out.flush();
      }
  
      private <T> void handleResponse(CommandResponse<T> response, HttpServletResponse httpServletResponse, final PrintWriter printWriter) throws Exception {
          if (response.isSuccess()) {
              if (response.getResult() == null) {
                  writeResponse(httpServletResponse, printWriter, StatusCode.OK, null);
                  return;
              }
              // Here we directly use `toString` to encode the result to plain text.
              byte[] buffer = response.getResult().toString().getBytes(SentinelConfig.charset());
              writeResponse(httpServletResponse, printWriter, StatusCode.OK, new String(buffer));
          } else {
              String msg = SERVER_ERROR_MESSAGE;
              if (response.getException() != null) {
                  msg = response.getException().getMessage();
              }
              writeResponse(httpServletResponse, printWriter, StatusCode.BAD_REQUEST, msg);
          }
      }
  
  }
  