From f37dd841f32683a4397ec1c7dd17504517a48c2e Mon Sep 17 00:00:00 2001
From: Calvin Lobo <calvin.lobo@hootsuite.com>
Date: Thu, 14 Sep 2023 13:27:55 -0400
Subject: [PATCH] Added a RoundTripper to simplehttp that wraps around another
 RoundTripper and converts 4XX and 5XX series errors to SimpleError with the
 corresponding code set, as defined in the inverse mapping

---
 ecosystem/http/roundtripper.go      | 55 ++++++++++++++++++++
 ecosystem/http/roundtripper_test.go | 79 +++++++++++++++++++++++++++++
 2 files changed, 134 insertions(+)
 create mode 100644 ecosystem/http/roundtripper.go
 create mode 100644 ecosystem/http/roundtripper_test.go

diff --git a/ecosystem/http/roundtripper.go b/ecosystem/http/roundtripper.go
new file mode 100644
index 0000000..7eb4dce
--- /dev/null
+++ b/ecosystem/http/roundtripper.go
@@ -0,0 +1,55 @@
+package simplehttp
+
+import (
+	"github.com/lobocv/simplerr"
+	"net/http"
+)
+
+type attr int
+
+const (
+	attrHTTPResponse = attr(1)
+)
+
+// roundTripper is a wrapper around the given http.RoundTripper that converts 4XX and 5XX series errors to SimpleErrors
+type roundTripper struct {
+	rt http.RoundTripper
+}
+
+func (s roundTripper) RoundTrip(request *http.Request) (*http.Response, error) {
+	resp, err := s.rt.RoundTrip(request)
+	if err != nil {
+		return resp, err
+	}
+
+	if resp.StatusCode >= 400 && resp.StatusCode < 600 {
+		code, _ := GetCode(resp.StatusCode)
+		serr := simplerr.New("%s", resp.Status).
+			Code(code).
+			Attr(attrHTTPResponse, resp)
+		return nil, serr
+	}
+
+	return resp, nil
+}
+
+// EnableHTTPStatusErrors wraps the http.RoundTripper in middleware that converts 4XX and 5XX series errors to SimpleErrors
+// with the code defined in the inverse mapping.
+func EnableHTTPStatusErrors(rt http.RoundTripper) http.RoundTripper {
+	return roundTripper{rt: rt}
+}
+
+// GetHTTPResponseAttr gets the *http.Response attached to the error, if it exists.
+func GetHTTPResponseAttr(err error) *http.Response {
+	v, ok := simplerr.GetAttribute(err, attrHTTPResponse)
+	if !ok {
+		return nil
+	}
+
+	resp, ok := v.(*http.Response)
+	if !ok {
+		return nil
+	}
+
+	return resp
+}
diff --git a/ecosystem/http/roundtripper_test.go b/ecosystem/http/roundtripper_test.go
new file mode 100644
index 0000000..257c74d
--- /dev/null
+++ b/ecosystem/http/roundtripper_test.go
@@ -0,0 +1,79 @@
+package simplehttp
+
+import (
+	"fmt"
+	"github.com/lobocv/simplerr"
+	"github.com/stretchr/testify/require"
+	"net/http"
+	"testing"
+)
+
+type dummyTransport struct {
+	response *http.Response
+	err      error
+}
+
+func (d dummyTransport) RoundTrip(_ *http.Request) (*http.Response, error) {
+	return d.response, d.err
+}
+
+func TestRoundTripperConvertCode(t *testing.T) {
+
+	for status, expectedCode := range inverseMapping {
+		originalResponse := &http.Response{}
+		originalResponse.StatusCode = status
+
+		rt := EnableHTTPStatusErrors(dummyTransport{
+			response: originalResponse,
+		})
+		resp, err := rt.RoundTrip(nil)
+
+		require.NotNil(t, simplerr.As(err), fmt.Sprintf("'%s' failed: simplerr not returned", http.StatusText(status)))
+		require.True(t, simplerr.HasErrorCode(err, expectedCode), fmt.Sprintf("'%s' failed: unexpected code", http.StatusText(status)))
+		require.Nil(t, resp)
+	}
+}
+
+func TestRoundTripperNoConversionFound(t *testing.T) {
+	originalResponse := &http.Response{}
+	originalResponse.StatusCode = http.StatusOK
+
+	rt := EnableHTTPStatusErrors(dummyTransport{
+		response: originalResponse,
+	})
+	resp, err := rt.RoundTrip(nil)
+	require.NoError(t, err)
+	require.Equal(t, originalResponse, resp)
+}
+
+func TestRoundTripperAttrResponse(t *testing.T) {
+
+	originalResponse := &http.Response{StatusCode: http.StatusTeapot}
+
+	rt := EnableHTTPStatusErrors(dummyTransport{
+		response: originalResponse,
+	})
+
+	resp, err := rt.RoundTrip(nil)
+	expectedCode := simplerr.CodeUnknown
+	require.True(t, simplerr.HasErrorCode(err, expectedCode), "failed to convert error code")
+	require.Nil(t, resp)
+
+	gotOriginalResponse := GetHTTPResponseAttr(err)
+	require.Equal(t, originalResponse, gotOriginalResponse)
+
+	require.Nil(t, GetHTTPResponseAttr(nil))
+	require.Nil(t, GetHTTPResponseAttr(simplerr.New("something").Attr(attrHTTPResponse, "not an *http.Response")))
+}
+
+func TestRoundTripperErrorOnUnderlyingRoundTripper(t *testing.T) {
+
+	rt := EnableHTTPStatusErrors(dummyTransport{
+		err: fmt.Errorf("some error"),
+	})
+	resp, err := rt.RoundTrip(nil)
+
+	require.Nil(t, resp)
+	require.Errorf(t, err, "some error")
+
+}