#nullable enable

using System;
using UnityEngine;

namespace ShrinkEventBus
{
    /// <summary>
    /// Optional Unity lifecycle host for generated event bindings. It does not require
    /// the target component to inherit from an SDK base class.
    /// </summary>
    [DisallowMultipleComponent]
    public sealed class ShrinkMonoEventScope : MonoBehaviour
    {
        [SerializeField] private string bus = "game";
        [SerializeField] private bool includeChildren;
        private IDisposable? _binding;
        private ShrinkEventBinding? _bindingGroup;

        public string BusId
        {
            get => bus;
            set => bus = value ?? string.Empty;
        }

        private void OnEnable()
        {
            RefreshBindings();
        }

        private void OnDisable()
        {
            ReleaseBindings();
        }

        public void RefreshBindings()
        {
            ReleaseBindings();
            var key = ShrinkBusKey.Parse(bus);
            if (!EventBus.TryGetBus(key, out var targetBus))
                targetBus = EventBus.GetOrCreateBus(key, ShrinkBusOptions.MainThread());

            var components = includeChildren
                ? GetComponentsInChildren<MonoBehaviour>(true)
                : GetComponents<MonoBehaviour>();
            for (var i = 0; i < components.Length; i++)
                TryAttach(components[i], targetBus);
        }

        public void ReleaseBindings()
        {
            _binding?.Dispose();
            _binding = null;
            _bindingGroup = null;
        }

        private void TryAttach(MonoBehaviour target, IShrinkEventBus targetBus)
        {
            if (target == null || ReferenceEquals(target, this))
                return;
            if (target is not IShrinkGeneratedSubscriber)
                return;

            var binding = targetBus.Attach(target);
            if (_bindingGroup == null)
                _bindingGroup = new ShrinkEventBinding();
            _bindingGroup.Add(binding);
            _binding = _bindingGroup;
        }
    }
}