package common.http.error;
   
   import common.http.interceptor.HttpServletBiConsumer;
   import common.http.interceptor.ServletInterceptor;
   
   import javax.servlet.ServletException;
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   import javax.validation.ConstraintViolation;
  import javax.validation.ConstraintViolationException;
  import java.io.IOException;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.List;
  import java.util.stream.Collectors;
  
  import static javax.servlet.http.HttpServletResponse.SC_BAD_REQUEST;
  
  /**
   * @see ForwardOnError
   */
  public class ForwardOnErrorInterceptor extends ServletInterceptor<ForwardOnError> {
  
      private String page;
  
      @Override
      protected void init(ForwardOnError annotation) {
          this.page = annotation.value();
      }
  
      @Override
      public void handle(HttpServletRequest req, HttpServletResponse resp, HttpServletBiConsumer next) throws ServletException, IOException {
          try{
              next.handle(req,resp);
          } catch (IllegalArgumentException e) {
              forwardErrorPage(req, resp, SC_BAD_REQUEST, e.getMessage());
          } catch (ConstraintViolationException e) {
              List<String> collect = e.getConstraintViolations().stream()
                      .map(ConstraintViolation::getMessage)
                      .collect(Collectors.toList());
              forwardErrorPage(req,resp,SC_BAD_REQUEST,collect);
          }
      }
  
      private void forwardErrorPage(HttpServletRequest req, HttpServletResponse resp,
                                    int code, Collection<String> messages) throws ServletException, IOException {
          req.setAttribute("errors", messages);
          resp.setStatus(code);
          req.getRequestDispatcher(page).forward(req, resp);
      }
  
      private void forwardErrorPage(HttpServletRequest req, HttpServletResponse resp, int code, String message) throws IOException, ServletException {
          List<String> singleton = message == null ? Collections.emptyList() : List.of(message);
          forwardErrorPage(req, resp, code, singleton);
      }
  
      @Override
      public int priority() {
          return 1;
      }
  }