messaging: introduce transforms with initial one for normalizing emoji reactions

Author: jeffyanta

messaging/server.go

@@ -432,7 +432,7 @@ func (s *Server) SendMessage(ctx context.Context, req *messagingpb.SendMessageRe
 
 	msg := &messagingpb.Message{
 		SenderId:          userID,
-		Content:           req.Content,
+		Content:           []*messagingpb.Content{ApplyTransforms(req.Content[0])},
 		WasSenderOffStage: wasSenderOffStage,
 	}
 

messaging/transform.go

@@ -0,0 +1,42 @@
+package messaging
+
+import (
+	"unicode"
+
+	"google.golang.org/protobuf/proto"
+
+	messagingpb "github.com/code-payments/flipchat-protobuf-api/generated/go/messaging/v1"
+)
+
+var (
+	AllTransforms = []Transform{
+		RemoveEmojiVariationModifiersTransform,
+	}
+)
+
+type Transform func(*messagingpb.Content) *messagingpb.Content
+
+func RemoveEmojiVariationModifiersTransform(content *messagingpb.Content) *messagingpb.Content {
+	if content.GetReaction() == nil {
+		return content
+	}
+
+	cloned := proto.Clone(content).(*messagingpb.Content)
+
+	var transformed []rune
+	for _, r := range cloned.GetReaction().Emoji {
+		if !unicode.In(r, unicode.Variation_Selector) {
+			transformed = append(transformed, r)
+		}
+	}
+	cloned.GetReaction().Emoji = string(transformed)
+
+	return cloned
+}
+
+func ApplyTransforms(content *messagingpb.Content) *messagingpb.Content {
+	for _, transform := range AllTransforms {
+		content = transform(content)
+	}
+	return content
+}

messaging/transform_test.go

@@ -0,0 +1,39 @@
+package messaging
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	messagingpb "github.com/code-payments/flipchat-protobuf-api/generated/go/messaging/v1"
+)
+
+func TestRemoveEmojiVariationModifiersTransform(t *testing.T) {
+	for _, tc := range []struct {
+		in  string
+		out string
+	}{
+		{
+			in:  "",
+			out: "",
+		},
+		{
+			in:  "👍",
+			out: "👍",
+		},
+		{
+			in:  "\u2764\uFE0F",
+			out: "\u2764",
+		},
+	} {
+		in := &messagingpb.Content{
+			Type: &messagingpb.Content_Reaction{
+				Reaction: &messagingpb.ReactionContent{
+					Emoji: tc.in,
+				},
+			},
+		}
+		out := RemoveEmojiVariationModifiersTransform(in)
+		require.Equal(t, tc.out, out.GetReaction().Emoji)
+	}
+}