using Basler.Pylon;
using Prism.Commands;
using Prism.Events;
using Prism.Ioc;
using Prism.Mvvm;
using Prism.Regions;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Threading.Tasks;
using TeamAAS_VP.Core;
using TeamAAS_VP.Core.Lights;
using TeamAAS_VP.Data;
using TeamAAS_VP.Events;
using TeamAAS_VP.Interfaces;
using TeamAAS_VP.Models.Lights;
using TeamAAS_VP.Resources.Languages;

namespace TeamAAS_VP.ViewModels.DebugMod
{
    public class LightManualViewModel : BindableBase, INavigationAware
    {
        IContainerProvider _container;
        IEventAggregator _eventAggregator;
        ILightManagerService _light_manager_service; // fallback
        ILightManagerService _lightManagerService;
        IConfigService _configService;
        ISystemDatabaseService _systemDatabaseService;

        #region 属性
        private ObservableCollection<ChannelItem> _Channels = new ObservableCollection<ChannelItem>();
        public ObservableCollection<ChannelItem> Channels
        {
            get => _Channels; set => SetProperty(ref _Channels, value);
        }
        #endregion

        #region 命令
        private DelegateCommand _LoadedCommand;
        public DelegateCommand LoadedCommand =>
            _LoadedCommand ?? (_LoadedCommand = new DelegateCommand(ExecuteLoadedCommand));

        #endregion

        #region 事件

        #endregion

        public LightManualViewModel(IContainerProvider container, IEventAggregator ea, ILightManagerService lightManagerService, IConfigService configService, ISystemDatabaseService systemDatabaseService)
        {
            _container = container;
            _eventAggregator = ea;
            _light_manager_service = lightManagerService;
            _lightManagerService = lightManagerService;
            _configService = configService;
            _systemDatabaseService = systemDatabaseService;
            //订阅权限登录事件
            _eventAggregator.GetEvent<UserLoginNotification>().Subscribe(LoginChange);
        }

        #region 方法
        void ExecuteLoadedCommand()
        {
            if (_systemDatabaseService.GetCurrentUser().userPart == Enums.UserPart.Operator)
            {
                IsAllowEdit = false;
            }
            else
            {
                IsAllowEdit = true;
            }
        }
        #endregion

        #region 继承
        public void ConfirmNavigationRequest(NavigationContext navigationContext, Action<bool> continuationCallback)
        {
            continuationCallback(true);
        }

        public async void OnNavigatedTo(NavigationContext navigationContext)
        {
            // load channels from light manager service
            Channels.Clear();
            try
            {
                var globals = _lightManagerService.GlobalChannels.ToList();
                foreach (var kv in globals)
                {
                    var item = new ChannelItem(kv.Key, (ILightChannel)kv.Value, _lightManagerService, _configService, _eventAggregator);
                    Channels.Add(item);
                    await item.InitializeAsync();
                }
            }
            catch (Exception ex)
            {
                // ignore or notify
            }
        }

        public bool IsNavigationTarget(NavigationContext navigationContext)
        {
            return true;
        }

        public void OnNavigatedFrom(NavigationContext navigationContext)
        {
            // nothing
        }
        #endregion

        private bool _IsAllowEdit = false;

        public bool IsAllowEdit
        {
            get { return _IsAllowEdit; }
            set { SetProperty(ref _IsAllowEdit, value); }
        }

        private void LoginChange(Models.User user)
        {
            if (user.userPart == Enums.UserPart.Operator)
            {
                IsAllowEdit = false;
            }
            else
            {
                IsAllowEdit = true;
            }
        }

        public class ChannelItem : BindableBase
        {
            private readonly int _globalId;
            private readonly ILightChannel _channel;
            private readonly ILightManagerService _lightManagerService;
            private readonly IConfigService _configService;
            private readonly IEventAggregator _eventAggregator;

            public int GlobalId => _globalId;

            private string _Name;
            public string Name { get => _Name; set => SetProperty(ref _Name, value); }

            private int _PendingBrightness;
            public int PendingBrightness { get => _PendingBrightness; set => SetProperty(ref _PendingBrightness, value); }

            private int _CurrentBrightness;
            public int CurrentBrightness { get => _CurrentBrightness; set => SetProperty(ref _CurrentBrightness, value); }

            private bool _IsOn;
            public bool IsOn { get => _IsOn; set => SetProperty(ref _IsOn, value); }

            public DelegateCommand SaveCommand { get; }
            public DelegateCommand TurnOnCommand { get; }
            public DelegateCommand TurnOffCommand { get; }

            private DelegateCommand<object> _BrightnessChangedCommand;
            public DelegateCommand<object> BrightnessChangedCommand =>
                _BrightnessChangedCommand ?? (_BrightnessChangedCommand = new DelegateCommand<object>(ExecuteBrightnessChangedCommand));

            // 去抖与写入控制字段
            private readonly object _writeLock = new object();
            private int? _latestQueuedBrightness = null;
            private bool _isWriting = false;
            private System.Threading.CancellationTokenSource _debounceCts;

            public ChannelItem(int globalId, ILightChannel channel, ILightManagerService lightManagerService, IConfigService configService, IEventAggregator eventAggregator)
            {
                _globalId = globalId;
                _channel = channel;
                _lightManagerService = lightManagerService;
                _configService = configService;
                _eventAggregator = eventAggregator;
                Name = channel?.ChannelName ?? $"Channel {_globalId}";
                PendingBrightness = 0;
                CurrentBrightness = 0;
                IsOn = false;

                SaveCommand = new DelegateCommand(async () => await SaveAsync());
                TurnOnCommand = new DelegateCommand(async () => await TurnOnAsync());
                TurnOffCommand = new DelegateCommand(async () => await TurnOffAsync());
            }

            public async Task InitializeAsync()
            {
                try
                {
                    if (_channel != null)
                    {
                        var b = await _channel.GetBrightnessAsync();
                        CurrentBrightness = b;
                        PendingBrightness = b;
                        IsOn = await _channel.GetStatusAsync();
                    }
                }
                catch
                {
                }
            }

            // 当滑块变化时调用：采用去抖 + 只写最新值的策略
            async void ExecuteBrightnessChangedCommand(object obj)
            {
                try
                {
                    var parameter = obj as Tuple<object, double, double>;
                    if (parameter == null) return;

                    int newValue = (int)parameter.Item2;
                    // 更新 PendingBrightness 可即时反映到 UI（根据需要）
                    PendingBrightness = newValue;

                    QueueBrightnessChange(newValue);
                }
                catch (Exception)
                {
                    // ignore
                }
            }

            // 将新的亮度值入队（覆盖之前未写入的值），并启动去抖延迟任务
            private void QueueBrightnessChange(int brightness)
            {
                lock (_writeLock)
                {
                    _latestQueuedBrightness = brightness;
                    // 取消之前的去抖任务
                    try
                    {
                        _debounceCts?.Cancel();
                        _debounceCts?.Dispose();
                    }
                    catch { }
                    _debounceCts = new System.Threading.CancellationTokenSource();
                    var token = _debounceCts.Token;

                    // 启动去抖后处理（不等待）
                    System.Threading.Tasks.Task.Run(async () =>
                    {
                        try
                        {
                            // 去抖延迟，可调整为 150-300ms
                            await System.Threading.Tasks.Task.Delay(200, token);
                            await ProcessWritesAsync();
                        }
                        catch (System.OperationCanceledException)
                        {
                            // 被取消，忽略
                        }
                        catch
                        {
                            // 忽略其它异常防止未观测异常
                        }
                    }, System.Threading.CancellationToken.None);
                }
            }

            // 串行化写入循环：写入当前最新值，若在写入过程中又有新值则继续写入，直到没有新值
            private async System.Threading.Tasks.Task ProcessWritesAsync()
            {
                // 快速检查与设置写入标志，保证只有一个写入循环执行
                lock (_writeLock)
                {
                    if (_isWriting) return;
                    _isWriting = true;
                }

                try
                {
                    while (true)
                    {
                        int? toWrite = null;
                        lock (_writeLock)
                        {
                            if (_latestQueuedBrightness.HasValue)
                            {
                                toWrite = _latestQueuedBrightness.Value;
                                _latestQueuedBrightness = null;
                            }
                        }

                        if (!toWrite.HasValue)
                        {
                            // 没有需要写入的值，退出循环
                            break;
                        }

                        try
                        {
                            // 实际写入（底层方法可能不支持取消）
                            var success = await _lightManagerService.SetGlobalChannelBrightnessAsync(_globalId, toWrite.Value);
                            if (success)
                            {
                                CurrentBrightness = toWrite.Value;
                                PendingBrightness = toWrite.Value;
                                IsOn = toWrite.Value > 0;
                            }
                        }
                        catch
                        {
                            // 忽略写入异常，继续检查是否有新值需要写入
                        }
                    }
                }
                finally
                {
                    lock (_writeLock)
                    {
                        _isWriting = false;
                    }
                }
            }

            private async Task SaveAsync()
            {
                try
                {
                    var success = await _lightManagerService.SetGlobalChannelBrightnessAsync(_globalId, PendingBrightness);
                    if (success)
                    {
                        CurrentBrightness = PendingBrightness;
                        IsOn = PendingBrightness > 0;
                        // also save as default in config
                        _configService.UpdateChannelDefaultBrightness(_globalId, PendingBrightness);
                        _eventAggregator.GetEvent<SnackbarMessageNotification>().Publish(new MessageParameter() { Msg = string.Format(Lang.保存完成01, Name, PendingBrightness), Duration = 1 });
                    }
                    else
                    {
                        _eventAggregator.GetEvent<SnackbarMessageNotification>().Publish(new MessageParameter() { Msg = string.Format(Lang.保存失败0, Name), Duration = 1 });
                    }
                }
                catch (Exception ex)
                {
                    _eventAggregator.GetEvent<SnackbarMessageNotification>().Publish(new MessageParameter() { Msg = string.Format(Lang.保存异常0, ex.Message), Duration = 1 });
                }
            }

            private async Task TurnOnAsync()
            {
                try
                {
                    var success = await _lightManagerService.TurnOnGlobalChannelAsync(_globalId);
                    if (success)
                    {
                        IsOn = true;
                        // refresh brightness
                        var b = await _channel.GetBrightnessAsync();
                        PendingBrightness = b;
                        CurrentBrightness = b;
                        _eventAggregator.GetEvent<SnackbarMessageNotification>().Publish(new MessageParameter() { Msg = string.Format(Lang.打开通道0, Name), Duration = 1 });
                    }
                }
                catch (Exception ex)
                {
                    _eventAggregator.GetEvent<SnackbarMessageNotification>().Publish(new MessageParameter() { Msg = string.Format(Lang.打开异常0,ex.Message), Duration = 1 });
                }
            }

            private async Task TurnOffAsync()
            {
                try
                {
                    var success = await _lightManagerService.TurnOffGlobalChannelAsync(_globalId);
                    if (success)
                    {
                        IsOn = false;
                        PendingBrightness = 0;
                        CurrentBrightness = 0;
                        _eventAggregator.GetEvent<SnackbarMessageNotification>().Publish(new MessageParameter() { Msg = string.Format(Lang.关闭通道0,Name), Duration = 1 });
                    }
                }
                catch (Exception ex)
                {
                    _eventAggregator.GetEvent<SnackbarMessageNotification>().Publish(new MessageParameter() { Msg = string.Format(Lang.关闭异常0, ex.Message), Duration = 1 });
                }
            }
        }
    }
}