feat(chat): add support for chat part messages. Closes #3201 (#3291)

core/chat/events/eventtype.go

@@ -8,6 +8,8 @@ const (
 	MessageSent EventType = "CHAT"
 	// UserJoined is the event sent when a chat user join action takes place.
 	UserJoined EventType = "USER_JOINED"
+	// UserParted is the event sent when a chat user part action takes place.
+	UserParted EventType = "USER_PARTED"
 	// UserNameChanged is the event sent when a chat username change takes place.
 	UserNameChanged EventType = "NAME_CHANGE"
 	// UserColorChanged is the event sent when a chat user color change takes place.

core/chat/events/userPartEvent.go

@@ -0,0 +1,17 @@
+package events
+
+// UserPartEvent is the event fired when a user leaves chat.
+type UserPartEvent struct {
+	Event
+	UserEvent
+}
+
+// GetBroadcastPayload will return the object to send to all chat users.
+func (e *UserPartEvent) GetBroadcastPayload() EventPayload {
+	return EventPayload{
+		"type":      UserParted,
+		"id":        e.ID,
+		"timestamp": e.Timestamp,
+		"user":      e.User,
+	}
+}