From 5579d40c24d15f69e44246f788fb93beb367f994 Mon Sep 17 00:00:00 2001
From: Damien Arrachequesne <damien.arrachequesne@gmail.com>
Date: Mon, 10 May 2021 09:35:33 +0200
Subject: [PATCH] feat: add support for the "wsPreEncoded" writing option

A few notes:

- only the first element is pre-encoded, because the other elements are
buffers and will be sent as is over the WebSocket connection

- using `socket.packet()` was unexpectedly working, we will now use
`socket.client.writeToEngine()` (see [1])

See also: https://github.com/socketio/engine.io/commit/7706b123df914777d19c8179b45ab6932f82916c

[1]: https://github.com/socketio/socket.io/issues/3775
---
 lib/index.ts  | 10 +++++++++-
 test/index.js | 20 ++++++++++++++------
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/lib/index.ts b/lib/index.ts
index a8a7675..5147ae7 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -135,8 +135,16 @@ export class Adapter extends EventEmitter {
     packet.nsp = this.nsp.name;
     const encodedPackets = this.encoder.encode(packet);
 
+    const firstPacketOpts = {
+      wsPreEncoded: "4" + encodedPackets[0], // "4" being the "message" packet type in Engine.IO
+      ...packetOpts
+    };
+
     this.apply(opts, socket => {
-      socket.packet(encodedPackets, packetOpts);
+      socket.client.writeToEngine(encodedPackets[0], firstPacketOpts);
+      for (let i = 1; i < encodedPackets.length; i++) {
+        socket.client.writeToEngine(encodedPackets[i], packetOpts);
+      }
     });
   }
 
diff --git a/test/index.js b/test/index.js
index d976771..8e2bbe5 100644
--- a/test/index.js
+++ b/test/index.js
@@ -65,8 +65,10 @@ describe("socket.io-adapter", () => {
         id,
         {
           id,
-          packet() {
-            ids.push(id);
+          client: {
+            writeToEngine() {
+              ids.push(id);
+            }
           }
         }
       ];
@@ -74,7 +76,9 @@ describe("socket.io-adapter", () => {
     const nsp = {
       server: {
         encoder: {
-          encode() {}
+          encode() {
+            return [];
+          }
         }
       },
       sockets: new Map([socket("s1"), socket("s2"), socket("s3")])
@@ -98,8 +102,10 @@ describe("socket.io-adapter", () => {
         id,
         {
           id,
-          packet() {
-            ids.push(id);
+          client: {
+            writeToEngine() {
+              ids.push(id);
+            }
           }
         }
       ];
@@ -107,7 +113,9 @@ describe("socket.io-adapter", () => {
     const nsp = {
       server: {
         encoder: {
-          encode() {}
+          encode() {
+            return [];
+          }
         }
       },
       sockets: new Map([socket("s1"), socket("s2"), socket("s3")])