Add plugin websocket hooks (#18151)

* Add plugin websocket hooks

* Improve sending message mechanism and filter out of the router plugin specific messages

* Return and manage error if the request clone fails

* Wording change to avoid repetition

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

plugin/hooks.go

@@ -15,28 +15,31 @@ import (
 // Feel free to add more, but do not change existing assignments. Follow the naming convention of
 // <HookName>ID as the autogenerated glue code depends on that.
 const (
-	OnActivateID             = 0
-	OnDeactivateID           = 1
-	ServeHTTPID              = 2
-	OnConfigurationChangeID  = 3
-	ExecuteCommandID         = 4
-	MessageWillBePostedID    = 5
-	MessageWillBeUpdatedID   = 6
-	MessageHasBeenPostedID   = 7
-	MessageHasBeenUpdatedID  = 8
-	UserHasJoinedChannelID   = 9
-	UserHasLeftChannelID     = 10
-	UserHasJoinedTeamID      = 11
-	UserHasLeftTeamID        = 12
-	ChannelHasBeenCreatedID  = 13
-	FileWillBeUploadedID     = 14
-	UserWillLogInID          = 15
-	UserHasLoggedInID        = 16
-	UserHasBeenCreatedID     = 17
-	ReactionHasBeenAddedID   = 18
-	ReactionHasBeenRemovedID = 19
-	OnPluginClusterEventID   = 20
-	TotalHooksID             = iota
+	OnActivateID                    = 0
+	OnDeactivateID                  = 1
+	ServeHTTPID                     = 2
+	OnConfigurationChangeID         = 3
+	ExecuteCommandID                = 4
+	MessageWillBePostedID           = 5
+	MessageWillBeUpdatedID          = 6
+	MessageHasBeenPostedID          = 7
+	MessageHasBeenUpdatedID         = 8
+	UserHasJoinedChannelID          = 9
+	UserHasLeftChannelID            = 10
+	UserHasJoinedTeamID             = 11
+	UserHasLeftTeamID               = 12
+	ChannelHasBeenCreatedID         = 13
+	FileWillBeUploadedID            = 14
+	UserWillLogInID                 = 15
+	UserHasLoggedInID               = 16
+	UserHasBeenCreatedID            = 17
+	ReactionHasBeenAddedID          = 18
+	ReactionHasBeenRemovedID        = 19
+	OnPluginClusterEventID          = 20
+	OnWebSocketConnectID            = 21
+	OnWebSocketDisconnectID         = 22
+	WebSocketMessageHasBeenPostedID = 23
+	TotalHooksID                    = iota
 )
 
 const (
@@ -219,4 +222,25 @@ type Hooks interface {
 	//
 	// Minimum server version: 5.36
 	OnPluginClusterEvent(c *Context, ev model.PluginClusterEvent)
+
+	// OnWebSocketConnect is invoked when a new websocket connection is opened.
+	//
+	// This is used to track which users have connections opened with the Mattermost
+	// websocket.
+	//
+	// Minimum server version: 6.0
+	OnWebSocketConnect(webConnID, userID string)
+
+	// OnWebSocketDisconnect is invoked when a websocket connection is closed.
+	//
+	// This is used to track which users have connections opened with the Mattermost
+	// websocket.
+	//
+	// Minimum server version: 6.0
+	OnWebSocketDisconnect(webConnID, userID string)
+
+	// WebSocketMessageHasBeenPosted is invoked when a websocket message is received.
+	//
+	// Minimum server version: 6.0
+	WebSocketMessageHasBeenPosted(webConnID, userID string, req *model.WebSocketRequest)
 }