using System;
using System.Collections.Generic;
using UnityEngine;

namespace AibisDream.Framework
{
    /// <summary>
    /// 单播事件系统
    /// 特点：通过枚举索引事件，多处可触发，但仅有一个方法能被注册（后注册覆盖先注册）
    /// 用途：用于解耦项目中的单例依赖
    /// </summary>
    public class SingleCastEventSystem
    {
        public static readonly SingleCastEventSystem Global = new();

        // 内部接口：用于统一存储不同类型的事件
        private interface IEventEntry
        {
        }

        // 类型化的条目存储
        private class Entry<T> : IEventEntry where T : Delegate
        {
            public T Handler;
        }

        // 按枚举类型分组的存储
        // Key: 枚举类型, Value: 该枚举所有值的条目数组
        private readonly Dictionary<Type, IEventEntry[]> _entries = new(50);

        #region 无参数

        public void Register<T>(T key, Action handler) where T : IConvertible
        {
            var entry = GetEntry<T, Action>(key);

#if DEBUG
            if (entry.Handler != null)
            {
                Debug.LogWarning($"[SingleCastEvent] {typeof(T).Name}.{key} 已被注册，正在覆盖");
            }
#endif

            entry.Handler = handler;
        }

        public void Trigger<T>(T key) where T : IConvertible
        {
            var entry = GetEntryOrNull<T, Action>(key);
            entry?.Handler?.Invoke();
        }

        #endregion

        #region 1个参数

        public void Register<T, T1>(T key, Action<T1> handler) where T : IConvertible
        {
            var entry = GetEntry<T, Action<T1>>(key);

#if DEBUG
            if (entry.Handler != null)
            {
                Debug.LogWarning($"[SingleCastEvent] {typeof(T).Name}.{key} 已被注册，正在覆盖");
            }
#endif

            entry.Handler = handler;
        }

        public void Trigger<T, T1>(T key, T1 arg1) where T : IConvertible
        {
            var entry = GetEntryOrNull<T, Action<T1>>(key);
            entry?.Handler?.Invoke(arg1);
        }

        #endregion

        #region 2个参数

        public void Register<T, T1, T2>(T key, Action<T1, T2> handler) where T : IConvertible
        {
            var entry = GetEntry<T, Action<T1, T2>>(key);

#if DEBUG
            if (entry.Handler != null)
            {
                Debug.LogWarning($"[SingleCastEvent] {typeof(T).Name}.{key} 已被注册，正在覆盖");
            }
#endif

            entry.Handler = handler;
        }

        public void Trigger<T, T1, T2>(T key, T1 arg1, T2 arg2) where T : IConvertible
        {
            var entry = GetEntryOrNull<T, Action<T1, T2>>(key);
            entry?.Handler?.Invoke(arg1, arg2);
        }

        #endregion

        #region 注销

        public void Unregister<T>(T key) where T : IConvertible
        {
            var index = key.ToInt32(null);
            var enumType = typeof(T);

            if (_entries.TryGetValue(enumType, out var arr) && index < arr.Length)
            {
                arr[index] = null;
            }
        }

        public void UnregisterAll()
        {
            _entries.Clear();
        }

        #endregion

        #region 内部辅助方法

        private Entry<TDelegate> GetEntry<TEnum, TDelegate>(TEnum key)
            where TEnum : IConvertible
            where TDelegate : Delegate
        {
            var index = key.ToInt32(null);
            var enumType = typeof(TEnum);

            if (!_entries.TryGetValue(enumType, out var arr))
            {
                // 首次使用该枚举类型，创建条目数组
                var valueCount = Enum.GetValues(enumType).Length;
                arr = new IEventEntry[valueCount];
                _entries[enumType] = arr;
            }

            if (arr[index] == null)
            {
                arr[index] = new Entry<TDelegate>();
            }

            return (Entry<TDelegate>)arr[index];
        }

        private Entry<TDelegate> GetEntryOrNull<TEnum, TDelegate>(TEnum key)
            where TEnum : IConvertible
            where TDelegate : Delegate
        {
            var index = key.ToInt32(null);
            var enumType = typeof(TEnum);

            if (!_entries.TryGetValue(enumType, out var arr)) return null;
            if (index >= arr.Length) return null;

            return arr[index] as Entry<TDelegate>;
        }

        #endregion
    }
}