Added a new layer: engine (equivalent to use cases in Clean Architecture). Should make testing things easier

utils/time.go

@@ -0,0 +1,11 @@
+package utils
+
+import "time"
+
+func ToTime(millis int64) time.Time {
+	return time.Unix(0, millis*int64(time.Millisecond))
+}
+
+func ToMillis(t time.Time) int64 {
+	return t.UnixNano() / int64(time.Millisecond)
+}