using System;
using System.Buffers;
using System.Collections.Generic;

namespace AlicizaX
{
    public static class ModuleSystem
    {
        internal const int DesignModuleCount = 32;

        private static readonly Dictionary<Type, IModule> _moduleMaps = new Dictionary<Type, IModule>(DesignModuleCount);
        private static readonly GameFrameworkLinkedList<IModule> _modules = new GameFrameworkLinkedList<IModule>();

        // Update systems
        private static readonly GameFrameworkLinkedList<IModuleUpdate> _updateModules = new GameFrameworkLinkedList<IModuleUpdate>();
        private static readonly IModuleUpdate[] _updateExecuteArray = new IModuleUpdate[DesignModuleCount];
        private static int _updateExecuteCount;

        // LateUpdate systems
        private static readonly GameFrameworkLinkedList<IModuleLateUpdate> _lateUpdateModules = new GameFrameworkLinkedList<IModuleLateUpdate>();
        private static readonly IModuleLateUpdate[] _lateUpdateExecuteArray = new IModuleLateUpdate[DesignModuleCount];
        private static int _lateUpdateExecuteCount;

        // FixedUpdate systems
        private static readonly GameFrameworkLinkedList<IModuleFixedUpdate> _fixedUpdateModules = new GameFrameworkLinkedList<IModuleFixedUpdate>();
        private static readonly IModuleFixedUpdate[] _fixedUpdateExecuteArray = new IModuleFixedUpdate[DesignModuleCount];
        private static int _fixedUpdateExecuteCount;

        // Gizmos systems
        private static readonly GameFrameworkLinkedList<IModuleDrawGizmos> _gizmosUpdateModules = new GameFrameworkLinkedList<IModuleDrawGizmos>();
        private static readonly IModuleDrawGizmos[] _gizmosUpdateExecuteArray = new IModuleDrawGizmos[DesignModuleCount];
        private static int _gizmosExecuteCount;

        // GUI systems
        private static readonly GameFrameworkLinkedList<IModuleGUI> _guiUpdateModules = new GameFrameworkLinkedList<IModuleGUI>();
        private static readonly IModuleGUI[] _guiUpdateExecuteArray = new IModuleGUI[DesignModuleCount];
        private static int _guiExecuteCount;

        // Dirty flags
        private static bool _isExecuteListDirty;
        private static bool _isLateExecuteListDirty;
        private static bool _isFixedExecuteListDirty;
        private static bool _isGizmosExecuteListDirty;
        private static bool _isGUIExecuteListDirty;

        internal static void Dispose()
        {
            // Clear all modules and execute arrays
            _updateModules.Clear();
            Array.Clear(_updateExecuteArray, 0, _updateExecuteArray.Length);
            _updateExecuteCount = 0;

            _lateUpdateModules.Clear();
            Array.Clear(_lateUpdateExecuteArray, 0, _lateUpdateExecuteArray.Length);
            _lateUpdateExecuteCount = 0;

            _fixedUpdateModules.Clear();
            Array.Clear(_fixedUpdateExecuteArray, 0, _fixedUpdateExecuteArray.Length);
            _fixedUpdateExecuteCount = 0;

            _gizmosUpdateModules.Clear();
            Array.Clear(_gizmosUpdateExecuteArray, 0, _gizmosUpdateExecuteArray.Length);
            _gizmosExecuteCount = 0;

            _guiUpdateModules.Clear();
            Array.Clear(_guiUpdateExecuteArray, 0, _guiUpdateExecuteArray.Length);
            _guiExecuteCount = 0;

            // Dispose all modules
            for (var current = _modules.Last; current != null; current = current.Previous)
            {
                current.Value.Dispose();
            }

            _modules.Clear();
            _moduleMaps.Clear();
        }

        #region Public Manager

        public static T RegisterManager<T>() where T : AManager, new()
        {
            T manager = new T();
            if (manager is IModuleAwake awakeManager)
            {
                awakeManager.Awake();
            }

            AddManager(manager);
            return manager;
        }

        private static void AddManager(AManager manager)
        {
            Type type = manager.GetType();
            _moduleMaps[type] = manager;
            _modules.AddLast(manager);
            manager.Register();
            CheckSystemLife(manager);
        }

        #endregion

        #region Public System

        public static T RegisterModule<T, TImple>() where T : IModule where TImple : class, T, new()
        {
            Type interfaceType = typeof(T);
            Type implType = typeof(TImple);
            if (!interfaceType.IsInterface)
            {
                throw new GameFrameworkException(Utility.Text.Format("You must register module by interface, but '{0}' is not.", interfaceType.FullName));
            }

            if (!implType.IsClass || implType.IsInterface || implType.IsAbstract)
            {
                throw new GameFrameworkException(Utility.Text.Format("You must register module by Class and not Interface and Abstract, but '{0}' is not.", implType.FullName));
            }

            if (!typeof(IModule).IsAssignableFrom(interfaceType))
            {
                throw new GameFrameworkException(Utility.Text.Format("Module must implement IModule.", interfaceType.FullName));
            }

            if (GetModule(interfaceType) != null)
            {
                Log.Error("Already Register {0}", interfaceType.FullName);
                return default;
            }

            TImple impl = new TImple();
            return (T)SetModuleInstance(interfaceType, impl);
        }

        public static T GetModule<T>() where T : class
        {
            Type interfaceType = typeof(T);
            if (!interfaceType.IsInterface)
            {
                throw new GameFrameworkException(Utility.Text.Format("You must get module by interface, but '{0}' is not.", interfaceType.FullName));
            }

            return GetModule(interfaceType) as T;
        }

        public static IModule GetModule(Type moduleType)
        {
            return _moduleMaps.TryGetValue(moduleType, out var ret) ? ret : default;
        }

        private static IModule SetModuleInstance<TImpl>(Type interfaceType, TImpl impl) where TImpl : class, IModule
        {
            _moduleMaps[interfaceType] = impl;
            _modules.AddLast(impl);

            if (impl is IModuleAwake awakeSystem)
            {
                awakeSystem.Awake();
            }

            CheckSystemLife(impl);
            return impl;
        }

        #endregion

        private static void CheckSystemLife(IModule module)
        {
            if (module is IModuleUpdate updateSystem)
            {
                BindSystemLife(updateSystem, _updateModules, ref _isExecuteListDirty);
            }

            if (module is IModuleLateUpdate lateUpdate)
            {
                BindSystemLife(lateUpdate, _lateUpdateModules, ref _isLateExecuteListDirty);
            }

            if (module is IModuleFixedUpdate fixedUpdate)
            {
                BindSystemLife(fixedUpdate, _fixedUpdateModules, ref _isFixedExecuteListDirty);
            }

            if (module is IModuleDrawGizmos drawGizmosUpdate)
            {
                BindSystemLife(drawGizmosUpdate, _gizmosUpdateModules, ref _isGizmosExecuteListDirty);
            }

            if (module is IModuleGUI guiUpdate)
            {
                BindSystemLife(guiUpdate, _guiUpdateModules, ref _isGUIExecuteListDirty);
            }
        }

        private static void BindSystemLife<T>(T system, GameFrameworkLinkedList<T> updateModule, ref bool executeDirty) where T : IExecuteSystem
        {
            var current = updateModule.First;
            while (current != null && system.Priority <= current.Value.Priority)
            {
                current = current.Next;
            }

            if (current != null)
            {
                updateModule.AddBefore(current, system);
            }
            else
            {
                updateModule.AddLast(system);
            }

            executeDirty = true;
        }

        #region BuildExecuteList

        private static void BuildExecuteList()
        {
            if (!_isExecuteListDirty) return;
            _isExecuteListDirty = false;
            _updateExecuteCount = 0;
            foreach (var module in _updateModules)
            {
                if (_updateExecuteCount >= _updateExecuteArray.Length) break;
                _updateExecuteArray[_updateExecuteCount++] = module;
            }
        }

        private static void BuildLateExecuteList()
        {
            if (!_isLateExecuteListDirty) return;
            _isLateExecuteListDirty = false;
            _lateUpdateExecuteCount = 0;
            foreach (var module in _lateUpdateModules)
            {
                if (_lateUpdateExecuteCount >= _lateUpdateExecuteArray.Length) break;
                _lateUpdateExecuteArray[_lateUpdateExecuteCount++] = module;
            }
        }

        private static void BuildFixedExecuteList()
        {
            if (!_isFixedExecuteListDirty) return;
            _isFixedExecuteListDirty = false;
            _fixedUpdateExecuteCount = 0;
            foreach (var module in _fixedUpdateModules)
            {
                if (_fixedUpdateExecuteCount >= _fixedUpdateExecuteArray.Length) break;
                _fixedUpdateExecuteArray[_fixedUpdateExecuteCount++] = module;
            }
        }

        private static void BuildGizmosExecuteList()
        {
            if (!_isGizmosExecuteListDirty) return;
            _isGizmosExecuteListDirty = false;
            _gizmosExecuteCount = 0;
            foreach (var module in _gizmosUpdateModules)
            {
                if (_gizmosExecuteCount >= _gizmosUpdateExecuteArray.Length) break;
                _gizmosUpdateExecuteArray[_gizmosExecuteCount++] = module;
            }
        }

        private static void BuildGUIExecuteList()
        {
            if (!_isGUIExecuteListDirty) return;
            _isGUIExecuteListDirty = false;
            _guiExecuteCount = 0;
            foreach (var module in _guiUpdateModules)
            {
                if (_guiExecuteCount >= _guiUpdateExecuteArray.Length) break;
                _guiUpdateExecuteArray[_guiExecuteCount++] = module;
            }
        }

        #endregion

        #region RunExecuteList

        internal static void UpdateExecuteList(float elapseSeconds, float realElapseSeconds)
        {
            BuildExecuteList();
            for (int i = 0; i < _updateExecuteCount; i++)
            {
                _updateExecuteArray[i].Update(elapseSeconds, realElapseSeconds);
            }
        }

        internal static void UpdateLateExecuteList()
        {
            BuildLateExecuteList();
            for (int i = 0; i < _lateUpdateExecuteCount; i++)
            {
                _lateUpdateExecuteArray[i].LateUpdate();
            }
        }

        internal static void UpdateFixedExecuteList()
        {
            BuildFixedExecuteList();
            for (int i = 0; i < _fixedUpdateExecuteCount; i++)
            {
                _fixedUpdateExecuteArray[i].FixedUpdate();
            }
        }

        internal static void UpdateGizmosExecuteList()
        {
            BuildGizmosExecuteList();
            for (int i = 0; i < _gizmosExecuteCount; i++)
            {
                _gizmosUpdateExecuteArray[i].DrawGizmos();
            }
        }

        internal static void UpdateGUIExecuteList()
        {
            BuildGUIExecuteList();
            for (int i = 0; i < _guiExecuteCount; i++)
            {
                _guiUpdateExecuteArray[i].OnGUI();
            }
        }

        #endregion
    }
}