func handleRequest()

in proxy/protocol/http/sidecar.go [236:298]
56 lines of code
14 McCabe index (conditional complexity)

func handleRequest(w http.ResponseWriter, inv *invocation.Invocation, ir *invocation.Response) (*http.Response, error) {
	if ir != nil {
		if ir.Err != nil {
			//handler only mesher errors, ignore http response err
			switch ir.Err.(type) {
			case hystrix.FallbackNullError:
				handleErrorResponse(inv, w, http.StatusOK, nil)
			case loadbalancer.LBError:
				handleErrorResponse(inv, w, http.StatusBadGateway, ir.Err)
			case hystrix.CircuitError:
				handleErrorResponse(inv, w, http.StatusServiceUnavailable, ir.Err)
			case fault.Fault:
				handleErrorResponse(inv, w, ir.Status, ir.Err)
			default: //for other error, check response and response body, if there is body, just transparent response
				resp, ok := inv.Reply.(*http.Response)

				if ok { // return raw transport error
					if resp != nil {
						if resp.Body == nil {
							//resp.Resp can be nil, for example network error, must handle it
							handleErrorResponse(inv, w, http.StatusBadGateway, ir.Err)
							return nil, ir.Err
						}
						copyChassisResp2HttpResp(w, resp)
						RecordStatus(inv, resp.StatusCode)
					} else {
						// unknown error, resp is nil, e.g. connection refused
						handleErrorResponse(inv, w, http.StatusBadGateway, ir.Err)
					}
				} else { // unknown err in handler chain
					handleErrorResponse(inv, w, http.StatusInternalServerError, ir.Err)
				}
			}
			return nil, ir.Err
		}
		if inv.Endpoint == "" {
			handleErrorResponse(inv, w, http.StatusBadGateway, protocol.ErrUnknown)
			return nil, protocol.ErrUnknown
		}
		if ir.Result == nil {
			if ir.Err != nil {
				handleErrorResponse(inv, w, http.StatusBadGateway, ir.Err)
				return nil, ir.Err
			}
			handleErrorResponse(inv, w, http.StatusBadGateway, ErrNilResponse)
			return nil, protocol.ErrUnknown
		}
		resp, ok := ir.Result.(*http.Response)
		if !ok {
			err := errors.New("invocationResponse result is not type *rest.Response")
			handleErrorResponse(inv, w, http.StatusBadGateway, err)
			return nil, err
		}
		//transparent proxy
		copyChassisResp2HttpResp(w, resp)

		return resp, nil
	} else {
		handleErrorResponse(inv, w, http.StatusBadGateway, protocol.ErrUnExpectedHandlerChainResponse)
		return nil, protocol.ErrUnExpectedHandlerChainResponse
	}

}