feat: added API gateway

internal/gw/utils/http.go

@@ -0,0 +1,35 @@
+package utils
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"datarush/internal/gw/domain"
+)
+
+func RespondJSON(w http.ResponseWriter, statusCode int, data interface{}) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(statusCode)
+
+	if data != nil {
+		if err := json.NewEncoder(w).Encode(data); err != nil {
+			http.Error(w, "internal server error", http.StatusInternalServerError)
+		}
+	}
+}
+
+func RespondError(w http.ResponseWriter, err error) {
+	if appErr, ok := err.(*domain.AppError); ok {
+		RespondJSON(w, appErr.StatusCode, domain.NewErrorResponse(appErr.Err, appErr.Message))
+		return
+	}
+
+	RespondJSON(w, http.StatusInternalServerError, domain.NewErrorResponse(err, "internal server error"))
+}
+
+func DecodeJSON(r *http.Request, v interface{}) error {
+	if err := json.NewDecoder(r.Body).Decode(v); err != nil {
+		return domain.NewBadRequestError("invalid JSON body")
+	}
+	return nil
+}