Add basic `Message` type definition

ts/types/Message.ts

@@ -0,0 +1,47 @@
+import { Attachment } from './Attachment';
+
+
+export type Message = IncomingMessage | OutgoingMessage;
+
+export type IncomingMessage = {
+  type: 'incoming';
+  attachments: Array<Attachment>;
+  body?: string;
+  conversationId: string;
+  decrypted_at?: number;
+  errors?: Array<any>;
+  flags?: number;
+  id: string;
+  received_at: number;
+  sent_at: number;
+  source?: string;
+  sourceDevice?: number;
+  timestamp: number;
+} & Message4
+
+export type OutgoingMessage = {
+  type: 'outgoing';
+  attachments: Array<Attachment>;
+  body?: string;
+  conversationId: string;
+  delivered: number;
+  delivered_to: Array<string>;
+  destination: string; // PhoneNumber
+  expirationStartTimestamp: number;
+  expires_at?: number;
+  expireTimer?: number;
+  id: string;
+  received_at: number;
+  recipients?: Array<string>; // Array<PhoneNumber>
+  sent: boolean;
+  sent_at: number;
+  sent_to: Array<string>; // Array<PhoneNumber>
+  synced: boolean;
+  timestamp: number;
+} & Message4
+
+interface Message4 {
+  numAttachments?: number;
+  numVisualMediaAttachments?: number;
+  numFileAttachments?: number;
+}