From cd5bd51a028d110232586fc70590e72aa7016a99 Mon Sep 17 00:00:00 2001
From: Cyberarm <matthewlikesrobots@gmail.com>
Date: Thu, 23 Apr 2026 19:39:36 -0500
Subject: [PATCH] Added EventBus, a simple global pub-sub event system.

---
 lib/cyberarm_engine.rb           |  1 +
 lib/cyberarm_engine/event_bus.rb | 39 ++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 lib/cyberarm_engine/event_bus.rb

diff --git a/lib/cyberarm_engine.rb b/lib/cyberarm_engine.rb
index 44c8339..1adecbf 100644
--- a/lib/cyberarm_engine.rb
+++ b/lib/cyberarm_engine.rb
@@ -10,6 +10,7 @@ require "json"
 require_relative "cyberarm_engine/version"
 require_relative "cyberarm_engine/stats"
 require_relative "cyberarm_engine/result"
+require_relative "cyberarm_engine/event_bus"
 
 require_relative "cyberarm_engine/common"
 
diff --git a/lib/cyberarm_engine/event_bus.rb b/lib/cyberarm_engine/event_bus.rb
new file mode 100644
index 0000000..35768e7
--- /dev/null
+++ b/lib/cyberarm_engine/event_bus.rb
@@ -0,0 +1,39 @@
+module CyberarmEngine
+  class EventBus
+    Subscriber = Data.define(:event, :listener, :method, :callback)
+    @subscribers = []
+
+    def self.subscribe(event, listener = nil, method = nil, &block)
+      raise "Subscriber cannot have both a method AND a callback block" if method && block_given?
+
+      subscriber = Subscriber.new(event, listener, method, block)
+      @subscribers << subscriber
+
+      subscriber
+    end
+
+    def self.unsubscribe(event, listener_or_subscriber)
+      @subscribers.delete_if { |s| s.event == event && (s == listener_or_subscriber || s.listener == listener_or_subscriber) }
+    end
+
+    def self.unsubscribe!(event)
+      @subscribers.delete_if { |s| s.event == event }
+    end
+
+    def self.announce(event, *payload)
+      subscribers = @subscribers.select { |s| s.event == event }
+
+      subscribers.each do |subscriber|
+        subscriber&.listener&.send(subscriber.method, *payload) if subscriber&.method
+        subscriber.callback&.call(*payload)
+      rescue StandardError => e
+        # TODO
+        warn "Failed to deliver event (#{event}) to listener (#{subscriber.inspect}): #{e}"
+      end
+    end
+
+    def self.publish(*args)
+      announce(*args)
+    end
+  end
+end