using System; using System.Collections.Generic; using UnityEngine; namespace Unity.VisualScripting { ///

/// A global container that maps Event names and Component references to actions for registered listeners. ///

/// /// It is the EventMachine base class for ScriptMachine and StateMachine that triggers events. /// This overrides almost all Unity callbacks (such as Awake, OnEnable, Update, etc.) and triggers an event /// on the EventBus. /// /// /// The following example shows how to use the EventBus to send a custom event from a script to a node in /// a graph. It also shows how to use the EventBus as a global event manager by executing a callback in a /// script, not just a node. /// /// For more information on how to create custom event nodes refer to the /// User Manual. /// /// In this example we've added some code to a GameObject. This code checks for when the user presses a sequence of /// keys to enable a cheat code, then triggers the CheatCodeActivated event. We register the /// CheatCodeActivated event in the Start method. The Update method triggers the event twice /// with 2 different targets: one for the CheatCodeActivated callback and the other to trigger the /// CheatCodeEnabled Node. /// ///


    ///
    /// The CheatCodeEnabled Node:
    ///
    /// 
    ///


    public static class EventBus
    {
        static EventBus()
        {
            events = new Dictionary>(new EventHookComparer());
        }

        private static readonly Dictionary> events;
        internal static Dictionary> testAccessEvents => events;

        public static void Register(EventHook hook, Action handler)
        {
            if (!events.TryGetValue(hook, out var handlers))
            {
                handlers = new HashSet();
                events.Add(hook, handlers);
            }

            handlers.Add(handler);
        }

        public static void Unregister(EventHook hook, Delegate handler)
        {
            if (events.TryGetValue(hook, out var handlers))
            {
                if (handlers.Remove(handler))
                {
                    // Free the key references for GC collection
                    if (handlers.Count == 0)
                    {
                        events.Remove(hook);
                    }
                }
            }
        }

        public static void Trigger(EventHook hook, TArgs args)
        {
            HashSet> handlers = null;

            if (events.TryGetValue(hook, out var potentialHandlers))
            {
                foreach (var potentialHandler in potentialHandlers)
                {
                    if (potentialHandler is Action handler)
                    {
                        if (handlers == null)
                        {
                            handlers = HashSetPool>.New();
                        }

                        handlers.Add(handler);
                    }
                }
            }

            if (handlers != null)
            {
                foreach (var handler in handlers)
                {
                    if (!potentialHandlers.Contains(handler))
                    {
                        continue;
                    }

                    handler.Invoke(args);
                }

                handlers.Free();
            }
        }

        public static void Trigger(string name, GameObject target, TArgs args)
        {
            Trigger(new EventHook(name, target), args);
        }

        public static void Trigger(EventHook hook)
        {
            Trigger(hook, new EmptyEventArgs());
        }

        public static void Trigger(string name, GameObject target)
        {
            Trigger(new EventHook(name, target));
        }
    }
}