From 0f6053ce08e58e4b0d7f2de2a6e245555877cfbb Mon Sep 17 00:00:00 2001
From: Mikunj <mikunj@live.com.au>
Date: Wed, 27 May 2020 11:05:30 +1000
Subject: [PATCH] Add events to MessageQueueInterface. Added strict typings for
 events.

---
 ts/session/sending/MessageQueue.ts          | 10 +++-
 ts/session/sending/MessageQueueInterface.ts | 12 +++--
 ts/session/sending/index.ts                 |  7 +--
 ts/session/utils/TypedEmitter.ts            | 53 +++++++++++++++++++++
 ts/session/utils/index.ts                   |  2 +
 5 files changed, 76 insertions(+), 8 deletions(-)
 create mode 100644 ts/session/utils/TypedEmitter.ts
 create mode 100644 ts/session/utils/index.ts

diff --git a/ts/session/sending/MessageQueue.ts b/ts/session/sending/MessageQueue.ts
index 5eeaa2426..274640ac4 100644
--- a/ts/session/sending/MessageQueue.ts
+++ b/ts/session/sending/MessageQueue.ts
@@ -1,13 +1,19 @@
-import { MessageQueueInterface } from './MessageQueueInterface';
+import { EventEmitter } from 'events';
+import {
+  MessageQueueInterface,
+  MessageQueueInterfaceEvents,
+} from './MessageQueueInterface';
 import { OpenGroupMessage, OutgoingContentMessage } from '../messages/outgoing';
-import { JobQueue } from '../utils/JobQueue';
 import { PendingMessageCache } from './PendingMessageCache';
+import { JobQueue, TypedEventEmitter } from '../utils';
 
 export class MessageQueue implements MessageQueueInterface {
+  public readonly events: TypedEventEmitter<MessageQueueInterfaceEvents>;
   private readonly jobQueues: Map<string, JobQueue> = new Map();
   private readonly cache: PendingMessageCache;
 
   constructor() {
+    this.events = new EventEmitter();
     this.cache = new PendingMessageCache();
     this.processAllPending();
   }
diff --git a/ts/session/sending/MessageQueueInterface.ts b/ts/session/sending/MessageQueueInterface.ts
index a231ad02c..553b25ed0 100644
--- a/ts/session/sending/MessageQueueInterface.ts
+++ b/ts/session/sending/MessageQueueInterface.ts
@@ -1,13 +1,19 @@
 import { OpenGroupMessage, OutgoingContentMessage } from '../messages/outgoing';
+import { RawMessage } from '../types/RawMessage';
+import { TypedEventEmitter } from '../utils';
 
 // TODO: add all group messages here, replace OutgoingContentMessage with them
 type GroupMessageType = OpenGroupMessage | OutgoingContentMessage;
+
+export interface MessageQueueInterfaceEvents {
+  success: (message: RawMessage) => void;
+  fail: (message: RawMessage, error: Error) => void;
+}
+
 export interface MessageQueueInterface {
+  events: TypedEventEmitter<MessageQueueInterfaceEvents>;
   sendUsingMultiDevice(user: string, message: OutgoingContentMessage): void;
   send(device: string, message: OutgoingContentMessage): void;
   sendToGroup(message: GroupMessageType): void;
   sendSyncMessage(message: OutgoingContentMessage): void;
-  // TODO: Find a good way to handle events in this
-  // E.g if we do queue.onMessageSent() we want to also be able to stop listening to the event
-  // TODO: implement events here
 }
diff --git a/ts/session/sending/index.ts b/ts/session/sending/index.ts
index 69ca9153b..f6cf299b6 100644
--- a/ts/session/sending/index.ts
+++ b/ts/session/sending/index.ts
@@ -1,5 +1,6 @@
+// TS 3.8 supports export * as X from 'Y'
 import * as MessageSender from './MessageSender';
-import { MessageQueue } from './MessageQueue';
-import { MessageQueueInterface } from './MessageQueueInterface';
+export { MessageSender };
 
-export { MessageSender, MessageQueue, MessageQueueInterface };
+export * from './MessageQueue';
+export * from './MessageQueueInterface';
diff --git a/ts/session/utils/TypedEmitter.ts b/ts/session/utils/TypedEmitter.ts
new file mode 100644
index 000000000..a6a27f200
--- /dev/null
+++ b/ts/session/utils/TypedEmitter.ts
@@ -0,0 +1,53 @@
+// Code from https://github.com/andywer/typed-emitter
+
+type Arguments<T> = [T] extends [(...args: infer U) => any]
+  ? U
+  : [T] extends [void] ? [] : [T];
+
+/**
+ * Type-safe event emitter.
+ *
+ * Use it like this:
+ *
+ * interface MyEvents {
+ *   error: (error: Error) => void
+ *   message: (from: string, content: string) => void
+ * }
+ *
+ * const myEmitter = new EventEmitter() as TypedEmitter<MyEvents>
+ *
+ * myEmitter.on("message", (from, content) => {
+ *   // ...
+ * })
+ *
+ * myEmitter.emit("error", "x")  // <- Will catch this type error
+ *
+ * or
+ *
+ * class MyEmitter extends EventEmitter implements TypedEventEmitter<MyEvents>
+ */
+export interface TypedEventEmitter<Events> {
+  addListener<E extends keyof Events>(event: E, listener: Events[E]): this;
+  on<E extends keyof Events>(event: E, listener: Events[E]): this;
+  once<E extends keyof Events>(event: E, listener: Events[E]): this;
+  prependListener<E extends keyof Events>(event: E, listener: Events[E]): this;
+  prependOnceListener<E extends keyof Events>(
+    event: E,
+    listener: Events[E]
+  ): this;
+
+  off<E extends keyof Events>(event: E, listener: Events[E]): this;
+  removeAllListeners<E extends keyof Events>(event?: E): this;
+  removeListener<E extends keyof Events>(event: E, listener: Events[E]): this;
+
+  emit<E extends keyof Events>(
+    event: E,
+    ...args: Arguments<Events[E]>
+  ): boolean;
+  eventNames(): Array<keyof Events | string | symbol>;
+  listeners<E extends keyof Events>(event: E): Array<Function>;
+  listenerCount<E extends keyof Events>(event: E): number;
+
+  getMaxListeners(): number;
+  setMaxListeners(maxListeners: number): this;
+}
diff --git a/ts/session/utils/index.ts b/ts/session/utils/index.ts
new file mode 100644
index 000000000..a33d528ba
--- /dev/null
+++ b/ts/session/utils/index.ts
@@ -0,0 +1,2 @@
+export * from './TypedEmitter';
+export * from './JobQueue';