From 356370db2653aaf29d27794a47cca696ebe48b7a Mon Sep 17 00:00:00 2001
From: Kevin Jahns <kevin.jahns@pm.me>
Date: Wed, 3 Feb 2021 15:04:18 +0100
Subject: [PATCH] Extendable messageHanlers

---
 src/y-websocket.js | 55 +++++++++++++++++++++++++++-------------------
 1 file changed, 33 insertions(+), 22 deletions(-)

diff --git a/src/y-websocket.js b/src/y-websocket.js
index e6be557..c307fe3 100644
--- a/src/y-websocket.js
+++ b/src/y-websocket.js
@@ -26,6 +26,33 @@ const messageQueryAwareness = 3
 const messageAwareness = 1
 const messageAuth = 2
 
+/**
+ *                       encoder,          decoder,          provider,          emitSynced, messageType
+ * @type {Array<function(encoding.Encoder, decoding.Decoder, WebsocketProvider, boolean,    number):void>}
+ */
+const messageHandlers = []
+
+messageHandlers[messageSync] = (encoder, decoder, provider, emitSynced, messageType) => {
+  encoding.writeVarUint(encoder, messageSync)
+  const syncMessageType = syncProtocol.readSyncMessage(decoder, encoder, provider.doc, provider)
+  if (emitSynced && syncMessageType === syncProtocol.messageYjsSyncStep2 && !provider.synced) {
+    provider.synced = true
+  }
+}
+
+messageHandlers[messageQueryAwareness] = (encoder, decoder, provider, emitSynced, messageType) => {
+  encoding.writeVarUint(encoder, messageAwareness)
+  encoding.writeVarUint8Array(encoder, awarenessProtocol.encodeAwarenessUpdate(provider.awareness, Array.from(provider.awareness.getStates().keys())))
+}
+
+messageHandlers[messageAwareness] = (encoder, decoder, provider, emitSynced, messageType) => {
+  awarenessProtocol.applyAwarenessUpdate(provider.awareness, decoding.readVarUint8Array(decoder), provider)
+}
+
+messageHandlers[messageAuth] = (encoder, decoder, provider, emitSynced, messageType) => {
+  authProtocol.readAuthMessage(decoder, provider.doc, permissionDeniedHandler)
+}
+
 const reconnectTimeoutBase = 1200
 const maxReconnectTimeout = 2500
 // @todo - this should depend on awareness.outdatedTime
@@ -47,28 +74,11 @@ const readMessage = (provider, buf, emitSynced) => {
   const decoder = decoding.createDecoder(buf)
   const encoder = encoding.createEncoder()
   const messageType = decoding.readVarUint(decoder)
-  switch (messageType) {
-    case messageSync: {
-      encoding.writeVarUint(encoder, messageSync)
-      const syncMessageType = syncProtocol.readSyncMessage(decoder, encoder, provider.doc, provider)
-      if (emitSynced && syncMessageType === syncProtocol.messageYjsSyncStep2 && !provider.synced) {
-        provider.synced = true
-      }
-      break
-    }
-    case messageQueryAwareness:
-      encoding.writeVarUint(encoder, messageAwareness)
-      encoding.writeVarUint8Array(encoder, awarenessProtocol.encodeAwarenessUpdate(provider.awareness, Array.from(provider.awareness.getStates().keys())))
-      break
-    case messageAwareness:
-      awarenessProtocol.applyAwarenessUpdate(provider.awareness, decoding.readVarUint8Array(decoder), provider)
-      break
-    case messageAuth:
-      authProtocol.readAuthMessage(decoder, provider.doc, permissionDeniedHandler)
-      break
-    default:
-      console.error('Unable to compute message')
-      return encoder
+  const messageHandler = provider.messageHandlers[messageType]
+  if (/** @type {any} */ (messageHandler)) {
+    messageHandler(encoder, decoder, provider, emitSynced, messageType)
+  } else {
+    console.error('Unable to compute message')
   }
   return encoder
 }
@@ -198,6 +208,7 @@ export class WebsocketProvider extends Observable {
     this.wsconnecting = false
     this.bcconnected = false
     this.wsUnsuccessfulReconnects = 0
+    this.messageHandlers = messageHandlers.slice()
     this.mux = mutex.createMutex()
     /**
      * @type {boolean}