commit 3fcae4eba159b91c3fa7db4e5e83a7d657222a5c
Author: Tobias Berger <tobi.berger13@gmail.com>
Date:   Fri Jan 7 17:43:05 2022 +0100

    Initial commit

diff --git a/types/ServerMessage.ts b/types/ServerMessage.ts
new file mode 100644
index 0000000..ab0cadd
--- /dev/null
+++ b/types/ServerMessage.ts
@@ -0,0 +1,59 @@
+export enum MessageType {
+  ACK = "0",
+  TEXT = "1",
+}
+
+export type ServerMessage = {
+  type: string;
+  date: number;
+};
+export function isServerMessage(obj: unknown): obj is ServerMessage {
+  if (typeof obj !== "object") return false;
+  if (obj === null) return false;
+  if (
+    !Object.hasOwnProperty.call(obj, "type") ||
+    typeof (obj as { type: unknown }).type !== "string"
+  ) {
+    return false;
+  }
+  if (
+    !Object.hasOwnProperty.call(obj, "date") ||
+    typeof (obj as { date: unknown }).date !== "number"
+  ) {
+    return false;
+  }
+
+  return true;
+}
+
+export type TextMessage = ServerMessage & {
+  type: MessageType.TEXT;
+  author: string;
+  content: string;
+};
+export function isTextMessage(obj: unknown): obj is TextMessage {
+  if (!isServerMessage(obj)) return false;
+  if (obj.type !== MessageType.TEXT) return false;
+  if (
+    !Object.hasOwnProperty.call(obj, "author") ||
+    typeof (obj as ServerMessage & { author: unknown }).author !== "string"
+  ) {
+    return false;
+  }
+  if (
+    !Object.hasOwnProperty.call(obj, "author") ||
+    typeof (obj as ServerMessage & { content: unknown }).content !== "string"
+  ) {
+    return false;
+  }
+  return true;
+}
+
+export type AckMessage = ServerMessage & {
+  type: MessageType.ACK;
+};
+export function isAckMessage(obj: unknown): obj is AckMessage {
+  if (!isServerMessage(obj)) return false;
+  if (obj.type !== MessageType.ACK) return false;
+  return true;
+}