using System;
using Chernobyl.Collections.Generic;
using Chernobyl.Destruction;
using UnityEngine;

namespace Chernobyl.Unity.Event
{
    /// <summary>
    /// Toggles the enable state of an <see cref="GameObject"/> on and off based on events.
    /// </summary>
    public class EnableToggle : MonoBehaviour
    {
        /// <summary>
        /// The event that causes the attached to object to be enabled.
        /// </summary>
        [Tooltip("The event that causes the attached to object to be enabled.")]
        public EventSource Enable;

        /// <summary>
        /// The event that causes the attached to object to be disabled.
        /// </summary>
        [Tooltip("The event that causes the attached to object to be disabled.")]
        public EventSource Disable;

        /// <summary>
        /// The <see cref="Behaviour"/> instances that are to be toggled.
        /// </summary>
        [Tooltip("The Behaviours that are to be toggled.")]
        public Behaviour[] Toggleables;

        /// <summary>See Unity docs for more info.</summary>
        public void Start()
        {
            if (Enable == null && Disable == null)
                throw new ArgumentNullException($"The {nameof(Enable)} and {nameof(Disable)} are " +
                                                "null. At least one must be set.");

            Toggleables.ThrowIfEmptyOrNull(nameof(Toggleables));

            if (Enable != null) _enableSubscription = Enable.Observable.Subscribe(OnEventEnable);
            if (Disable != null) _disableSubscription = Disable.Observable.Subscribe(OnEventDisable);
        }

        /// <summary>See Unity docs for more info.</summary>
        public void OnDestroy()
        {
            _enableSubscription.Dispose();
            _disableSubscription.Dispose();
        }

        void OnEventEnable(object obj) => Toggleables.For(t => t.enabled = true);
        void OnEventDisable(object obj) => Toggleables.For(t => t.enabled = false);

        IDisposable _enableSubscription = Disposable.Empty;
        IDisposable _disableSubscription = Disposable.Empty;
    }
}