using System;
using System.Collections.Generic;
using System.Reflection;
using Cysharp.Threading.Tasks;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace BITKit
{
    public class ReflectionHelper
    {
        public static InitializationState state = InitializationState.None;
        static Type[] types = new Type[0];
        static IEnumerable<MethodInfo> methods = new List<MethodInfo>();
        static IEnumerable<FieldInfo> fields = new List<FieldInfo>();
        static Dictionary<Type, MethodInfo[]> methodsCache = new();
        static Dictionary<Type, FieldInfo[]> fieldsCache = new();
        static Dictionary<Attribute, Attribute[]> attributes = new();
        public static async Task<IEnumerable<MethodInfo>> GetMethods<Att>() where Att : Attribute
        {
            await EnsureConfig();
            var type = typeof(Att);
            if (methodsCache.TryGetValue(type, out var _methods))
            {

            }
            else
            {
                _methods = methods.ToArray()
                .Where(x => x.GetCustomAttribute<Att>() is not null
                ).ToArray();
                methodsCache.Add(type, _methods);
            }
            return _methods;
        }
        public static async Task<IEnumerable<FieldInfo>> GetFields<Att>() where Att : Attribute
        {
            await EnsureConfig();
            var type = typeof(Att);
            if (fieldsCache.TryGetValue(type, out var _fields))
            {

            }
            else
            {
                _fields = fields
                .Where(x => x.GetCustomAttribute<Att>() is not null
                ).ToArray();
                fieldsCache.Add(type, _fields);
            }
            return _fields;
        }
        public static async Task<IEnumerable<Type>> GetTypes()
        {
            await EnsureConfig();
            return types;
        }
        public static async Task<IEnumerable<Type>> GetTypes<T>()
        {
            var type = typeof(T);
            await EnsureConfig();
            var currentTheadID = Thread.CurrentThread.ManagedThreadId.ToString();
            BIT4Log.Log<ReflectionHelper>($"GetTypes运行于线程:{currentTheadID}");
            return types
            .Where(x => x.IsAbstract is false)
            .Where(x => type.IsAssignableFrom(x));
        }
        public static async Task<IEnumerable<Att>> GetAttributes<Att>() where Att : Attribute
        {
            await EnsureConfig();
            List<Att> atts = new();
            var _atts = types
            .Where(x => x.IsAbstract is false)
            .Where(x => x.GetCustomAttribute<Att>() is not null)
            .Select(x => x.GetCustomAttribute<Att>());
            foreach (var att in _atts)
            {
                if (att is not null)
                {
                    atts.Add(att);
                }
            }
            return atts;
        }
        public static async Task<IEnumerable<T>> GetInstances<T>() where T : class
        {
            await EnsureConfig();
            var results = new List<T>();
            var instances = (await GetTypes<T>())
            .Where(x => x.IsClass)
            .Where(x => x.IsAbstract is false)
#if UNITY
             //.Where(x=>x.IsAssignableFrom(typeof(UnityEngine.Object))is false)
             .Where(x=>typeof(UnityEngine.Object).IsAssignableFrom(x) is false)
#endif
            .Where(x => x.ContainsGenericParameters is false)
            .Select(x =>
            {
                try
                {
                    var instance = System.Activator.CreateInstance(x) as T;
                    DI.Inject(instance);
                    return instance;
                }
                catch (Exception e)
                {
                    BIT4Log.LogException(e);
                }
                return null;
            });

            foreach (var instance in instances)
            {
                if (instance is not null)
                {
                    results.Add(instance);
                }
            }
            return results;
        }
        static async Task EnsureConfig()
        {
            await TaskHelper.WaitUntil(() => state == InitializationState.Initialized);
            await UniTask.SwitchToThreadPool();
        }
        internal  static void Init()
        {
            try
            {
                state = InitializationState.Initializing;
                lock (types)
                {
                    Stopwatch stopWatch = new Stopwatch();
                    stopWatch.Start();
                    var loadedAssemblies = BITApp.Assemblies.IsValid() ? BITApp.Assemblies : AppDomain.CurrentDomain.GetAssemblies();
                    BIT4Log.Log<ReflectionHelper>($"已加载程序集:{loadedAssemblies.Length}个");
                    var result = new List<Type>();
                    for (var i = 0; i < loadedAssemblies.Length; i++)
                    {
                        var asm = loadedAssemblies[i];
                        try
                        {
                            foreach (var x in asm.GetExportedTypes())
                            {
                                var rootNamespace = x.Namespace;
                                if(string.IsNullOrEmpty(rootNamespace))
                                {
                                    rootNamespace = Constant.System.Internal;
                                }
                                else
                                {
                                    rootNamespace = rootNamespace.Split(@".").First();
                                }
                                if(BITApp.Settings.whiteList.Count > 0)
                                {
                                     if(BITApp.Settings.whiteList.Contains(rootNamespace))
                                    {
                                        result.Add(x);
                                    }
                                }
                                else
                                {
                                    if(BITApp.Settings.blackList.Contains(rootNamespace) is false) {
                                        result.Add(x);
                                    }
                                }
                            }
                        }
                        catch { continue; }
                        try
                        {
                            BITApp.CancellationTokenSource.Token.ThrowIfCancellationRequested();
                        }
                        catch (System.Exception)
                        {
                            Reload();
                            return;
                        }

                    }

                    Stopwatch ignoreWatch = new Stopwatch();
                    var allTypesCount = result.Count;
                    ignoreWatch.Start();
                    types = result
                    .ToArray();
    
                    ignoreWatch.Stop();

                    StringBuilder allNamespaceBuilder = new();
                    foreach (var x in types.Select(x => x.Namespace).Distinct())
                    {
                        allNamespaceBuilder.AppendLine(x);
                    }
                    BIT4Log.Log<ReflectionHelper>($"已加载的命名空间:\n{allNamespaceBuilder}");
                    BIT4Log.Log<ReflectionHelper>($"忽略部分Types:{ignoreWatch.ElapsedMilliseconds}ms");
                    methods = types.SelectMany(x => x.GetMethods());
                    fields = types.SelectMany(x => x.GetFields());
                    stopWatch.Stop();
                    BIT4Log.Log<ReflectionHelper>($"获取所有Types:{stopWatch.ElapsedMilliseconds}ms");
                }
            }
            catch (System.Exception e)
            {
                BIT4Log.LogException(e);
            }
            state = InitializationState.Initialized;
            BIT4Log.Log<ReflectionHelper>("已完成初始化");
        }
        [ExcuteOnStop]
        public static void Reload()
        {
            state = InitializationState.None;
            types = new Type[0];
            methods = new MethodInfo[0];
            fields = new FieldInfo[0];
            fieldsCache.Clear();
            methodsCache.Clear();
        }
    }
}