package cn.home1.oss.lib.errorhandle.internal;
   
   import static cn.home1.oss.lib.errorhandle.api.ExceptionResolver.COMPOSITE_EXCEPTION_RESOLVER;
   
   import com.google.common.collect.ImmutableMap;
   
   import cn.home1.oss.lib.errorhandle.api.ExceptionResolver;
   import cn.home1.oss.lib.errorhandle.api.ResolvedError;
   import cn.home1.oss.lib.errorhandle.api.ResolvedErrorException;
  
  import lombok.Setter;
  
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.beans.factory.annotation.Qualifier;
  import org.springframework.boot.autoconfigure.web.ErrorAttributes;
  import org.springframework.core.Ordered;
  import org.springframework.core.annotation.Order;
  import org.springframework.web.context.request.RequestAttributes;
  import org.springframework.web.servlet.HandlerExceptionResolver;
  import org.springframework.web.servlet.ModelAndView;
  
  import java.util.Map;
  
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  /**
   * {@link org.springframework.boot.autoconfigure.web.DefaultErrorAttributes}
   *
   * <p>
   * Created by zhanghaolun on 16/8/9.
   * </p>
   */
  @Order(Ordered.HIGHEST_PRECEDENCE)
  public class ExtendedErrorAttributes //
    implements ErrorAttributes, HandlerExceptionResolver, Ordered {
  
    private static final String ERROR_ATTRIBUTE = ExtendedErrorAttributes.class.getName() + ".ERROR";
  
    @Qualifier(COMPOSITE_EXCEPTION_RESOLVER)
    @Autowired
    @Setter
    private ExceptionResolver<Throwable> resolver;
  
    @Override
    public Map<String, Object> getErrorAttributes( //
      final RequestAttributes requestAttributes, //
      final boolean includeStackTrace //
    ) {
      final Throwable error = getError(requestAttributes);
      final ResolvedError resolved = ResolvedErrorException.isResolvedError(error) ? //
        ((ResolvedErrorException) error).getError() : //
        this.resolver.resolve(requestAttributes, error);
      return resolved != null ? resolved.toErrorAttributes() : ImmutableMap.of();
    }
  
    @Override
    public int getOrder() {
      return Ordered.HIGHEST_PRECEDENCE;
    }
  
    @Override
    public ModelAndView resolveException( //
      final HttpServletRequest request, //
      final HttpServletResponse response, //
      final Object handler, //
      final Exception ex //
    ) {
      final ResolvedError resolved = this.resolver.resolve(request, ex);
      this.storeErrorAttributes(request, resolved != null ? new ResolvedErrorException(resolved) : ex);
      return null;
    }
  
    private void storeErrorAttributes(final HttpServletRequest request, final Exception ex) {
      request.setAttribute(ERROR_ATTRIBUTE, ex);
    }
  
    @Override
    public Throwable getError(final RequestAttributes requestAttributes) {
      final Throwable found = getAttribute(requestAttributes, ERROR_ATTRIBUTE);
      return found != null ? found : getAttribute(requestAttributes, "javax.servlet.error.exception");
    }
  
    @SuppressWarnings("unchecked")
    private <T> T getAttribute(final RequestAttributes requestAttributes, final String name) {
      return (T) requestAttributes.getAttribute(name, RequestAttributes.SCOPE_REQUEST);
    }
  }