using MDM.Services.Plant;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using RIZO.Admin.WebApi.PLC.Model;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace RIZO.Admin.WebApi.PLC.Service
{
    public class PlcHostedService : BackgroundService, IDisposable
    {
        private readonly ILogger<PlcHostedService> _logger;
        private readonly PlcService _plcService;
        private Timer _timer;
        private bool _isRunning;
        private readonly object _timerLock = new object();

        // 1. 按IP隔离信号量（避免单PLC故障阻塞所有）
        private readonly ConcurrentDictionary<string, SemaphoreSlim> _plcSemaphores = new();

        // 2. 连接状态增强（分级+失败次数+最后请求时间）
        private readonly ConcurrentDictionary<string, PlcConnectionStatus> _connectionStatusCache = new();

        // 3. 配置刷新
        private Timer _configRefreshTimer;
        private readonly SemaphoreSlim _configRefreshLock = new(1, 1);

        // 基础配置（配置驱动+热更新）
        private readonly IOptionsMonitor<PlcPollingSettings> _pollingSettingsMonitor;
        private PlcPollingSettings _currentSettings;
        private SemaphoreSlim _globalSemaphore;
        private readonly SemaphoreSlim _timerAsyncLock = new(1, 1);

        // PLC配置列表（支持动态刷新）
        private List<PlcConfig> _plcConfigs = new();
        private PlantWorkstationService _plantWorkstationService;

        /// <summary>
        /// 增强版PLC连接状态
        /// </summary>
        private class PlcConnectionStatus
        {
            public bool IsConnected { get; set; }
            public DateTime LastCheckTime { get; set; }
            public int FailCount { get; set; } // 连续失败次数
            public DateTime LastRequestTime { get; set; } // 最后有数据请求的时间
            public ConnectionLevel Level { get; set; } = ConnectionLevel.Disconnected;
        }

        /// <summary>
        /// 连接状态分级
        /// </summary>
        private enum ConnectionLevel
        {
            Disconnected = 0, // 断开
            Weak = 1,         // 弱连接（偶尔失败）
            Normal = 2        // 正常连接
        }

        public PlcHostedService(
            ILogger<PlcHostedService> logger,
            PlcService plcService,
            IOptionsMonitor<PlcPollingSettings> pollingSettingsMonitor = null)
        {
            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
            _plcService = plcService ?? throw new ArgumentNullException(nameof(plcService));
            _plantWorkstationService = new PlantWorkstationService();

            // 配置初始化（支持热更新，无配置时用默认值）
            _pollingSettingsMonitor = pollingSettingsMonitor;
            _currentSettings = pollingSettingsMonitor?.CurrentValue ?? new PlcPollingSettings();

            // 监听配置热更新
            if (_pollingSettingsMonitor != null)
            {
                _pollingSettingsMonitor.OnChange(newSettings =>
                {
                    _currentSettings = newSettings;
                    _logger.LogInformation("PLC轮询配置已热更新，新配置：{Settings}",
                        Newtonsoft.Json.JsonConvert.SerializeObject(newSettings));
                    // 配置变更后立即调整定时器频率
                    AdjustTimerInterval();
                    // 重新初始化全局信号量（并行度变更时生效）
                    _globalSemaphore?.Dispose();
                    _globalSemaphore = new SemaphoreSlim(
                        _currentSettings.GlobalParallelDegree,
                        _currentSettings.GlobalParallelDegree);
                });
            }

            // 初始化全局信号量
            _globalSemaphore = new SemaphoreSlim(
                _currentSettings.GlobalParallelDegree,
                _currentSettings.GlobalParallelDegree);

            // 初始化PLC配置
            _ = RefreshPlcConfigsAsync();
        }

        /// <summary>
        /// 动态刷新PLC配置（支持热更新）
        /// </summary>
        private async Task RefreshPlcConfigsAsync()
        {
            if (!await _configRefreshLock.WaitAsync(0)) return;

            try
            {
                var newConfigs = new List<PlcConfig>();
                try
                {
                    newConfigs = _plantWorkstationService.Queryable()
                        .Where(it => it.Status == 1)
                        .Select(it => new PlcConfig
                        {
                            PlcName = it.WorkstationCode,
                            Ip = it.PlcIP,
                            Rack = (short)it.Rack, // 空值兜底
                            Slot = (short)it.Slot  // 空值兜底
                        })
                        .ToList();
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, "刷新PLC配置异常，使用旧配置");
                    return;
                }

                // 更新配置并初始化状态缓存
                if (newConfigs.Any())
                {
                    _plcConfigs = newConfigs;
                    foreach (var config in _plcConfigs)
                    {
                        // 初始化IP隔离信号量（从配置读取并发数）
                        _plcSemaphores.TryAdd(config.Ip, new SemaphoreSlim(
                            _currentSettings.MaxConcurrentPerPlc,
                            _currentSettings.MaxConcurrentPerPlc));

                        // 初始化连接状态
                        _connectionStatusCache.TryAdd(config.Ip, new PlcConnectionStatus
                        {
                            IsConnected = false,
                            LastCheckTime = DateTime.MinValue,
                            FailCount = 0,
                            LastRequestTime = DateTime.MinValue,
                            Level = ConnectionLevel.Disconnected
                        });
                    }
                    _logger.LogInformation($"刷新PLC配置完成，当前有效配置数：{_plcConfigs.Count}");
                }
            }
            finally
            {
                _configRefreshLock.Release();
            }
        }

        /// <summary>
        /// 重写BackgroundService的ExecuteAsync
        /// </summary>
        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            _logger.LogInformation("PLC后台监听服务启动中...");

            if (!_plcConfigs.Any())
            {
                _logger.LogWarning("未配置有效PLC参数，跳过PLC自动连接");
                return;
            }

            _isRunning = true;

            // 1. 启动时批量并行连接PLC
            await BatchConnectPlcAsync(stoppingToken);

            // 2. 启动配置刷新定时器（从配置读取间隔）
            _configRefreshTimer = new Timer(
                async _ => await RefreshPlcConfigsAsync(),
                null,
                TimeSpan.Zero,
                TimeSpan.FromSeconds(_currentSettings.ConfigRefreshInterval));

            // 3. 启动数据轮询定时器（初始使用空闲频率）
            _timer = new Timer(
                TimerCallback,
                null,
                TimeSpan.Zero,
                TimeSpan.FromSeconds(_currentSettings.IdlePollInterval));

            _logger.LogInformation($"PLC服务启动完成 | 全局并行度：{_currentSettings.GlobalParallelDegree} | 设备总数：{_plcConfigs.Count}");

            // 等待停止信号
            await Task.Delay(Timeout.Infinite, stoppingToken);

            // 停止所有定时器
            _timer?.Change(Timeout.Infinite, 0);
            _configRefreshTimer?.Change(Timeout.Infinite, 0);
            _logger.LogInformation("PLC后台监听服务已收到停止信号");
        }

        /// <summary>
        /// 优化版定时器回调（动态调整轮询频率）
        /// </summary>
        private async void TimerCallback(object state)
        {
            if (!_isRunning)
            {
                _logger.LogDebug("PLC服务已停止，跳过轮询");
                return;
            }

            // 异步锁防止重叠执行
            if (!await _timerAsyncLock.WaitAsync(0))
            {
                _logger.LogDebug("前一轮PLC轮询未完成，跳过本次执行");
                return;
            }

            try
            {
                await PollPlcDataAsync();

                // 动态调整定时器频率（全局自适应）
                AdjustTimerInterval();
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "PLC轮询回调异常");
            }
            finally
            {
                _timerAsyncLock.Release();
            }
        }

        /// <summary>
        /// 动态调整定时器轮询频率
        /// </summary>
        private void AdjustTimerInterval()
        {
            // 统计活跃时长内有数据请求的PLC数量
            var activePlcCount = _connectionStatusCache.Values
                .Count(s => (DateTime.Now - s.LastRequestTime).TotalSeconds <= _currentSettings.ActiveDuration);

            // 有活跃PLC则使用高频，否则使用低频
            var newInterval = activePlcCount > 0
                ? TimeSpan.FromSeconds(_currentSettings.ActivePollInterval)
                : TimeSpan.FromSeconds(_currentSettings.IdlePollInterval);

            // 仅当频率变化时更新定时器
            if (_timer != null)
            {
                try
                {
                    _timer.Change(newInterval, newInterval);
                    _logger.LogDebug($"调整轮询频率：{newInterval.TotalSeconds}s（活跃PLC数：{activePlcCount}）");
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, "调整轮询频率失败");
                }
            }
        }

        /// <summary>
        /// 启动时批量并行连接PLC（带指数退避重试）
        /// </summary>
        private async Task BatchConnectPlcAsync(CancellationToken cancellationToken)
        {
            _logger.LogInformation("开始批量连接所有PLC...");

            var validConfigs = _plcConfigs.Where(c => !string.IsNullOrWhiteSpace(c.Ip)).ToList();
            if (!validConfigs.Any())
            {
                _logger.LogWarning("无有效PLC配置，跳过批量连接");
                return;
            }

            var tasks = validConfigs.Select(async config =>
            {
                await _globalSemaphore.WaitAsync(cancellationToken);
                try
                {
                    // 指数退避重试连接
                    bool connectSuccess = false;
                    for (int retry = 0; retry < _currentSettings.MaxRetryTimes; retry++)
                    {
                        try
                        {
                            using var timeoutTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
                            timeoutTokenSource.CancelAfter(TimeSpan.FromSeconds(_currentSettings.ConnectTimeoutSeconds));

                            var result = await _plcService.TestSinglePlcAsync(config, timeoutTokenSource.Token);
                            connectSuccess = result.ConnectSuccess;

                            if (connectSuccess) break;

                            // 指数退避等待（从配置读取初始间隔）
                            var waitTime = TimeSpan.FromSeconds(_currentSettings.InitialRetryInterval * Math.Pow(2, retry));
                            await Task.Delay(waitTime, cancellationToken);
                        }
                        catch (OperationCanceledException)
                        {
                            _logger.LogWarning($"[{config.PlcName}] 连接重试{retry + 1}次超时 | IP：{config.Ip}");
                        }
                        catch (Exception ex)
                        {
                            _logger.LogError(ex, $"[{config.PlcName}] 连接重试{retry + 1}次异常 | IP：{config.Ip}");
                        }
                    }

                    // 更新连接状态
                    if (_connectionStatusCache.TryGetValue(config.Ip, out var status))
                    {
                        status.IsConnected = connectSuccess;
                        status.LastCheckTime = DateTime.Now;
                        status.FailCount = connectSuccess ? 0 : status.FailCount + 1;
                        status.Level = connectSuccess ? ConnectionLevel.Normal : ConnectionLevel.Disconnected;
                    }

                    if (connectSuccess)
                        _logger.LogInformation($"[{config.PlcName}] 连接成功 | IP：{config.Ip}");
                    else
                        _logger.LogWarning($"[{config.PlcName}] 连接失败（{_currentSettings.MaxRetryTimes}次重试） | IP：{config.Ip}");
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, $"[{config.PlcName}] 批量连接异常 | IP：{config.Ip}");
                }
                finally
                {
                    _globalSemaphore.Release();
                }
            });

            await Task.WhenAll(tasks);
        }

        /// <summary>
        /// 优化版并行轮询PLC数据（IP隔离+动态频率+异常闭环）
        /// </summary>
        private async Task PollPlcDataAsync()
        {
            var validConfigs = _plcConfigs.Where(c => !string.IsNullOrWhiteSpace(c.Ip)).ToList();
            if (!validConfigs.Any())
            {
                _logger.LogWarning("无有效PLC配置，跳过数据轮询");
                return;
            }

            // 统计本次轮询结果
            int successCount = 0, failCount = 0, skipCount = 0, activeCount = 0;

            var tasks = validConfigs.Select(async config =>
            {
                // 获取IP隔离信号量
                if (!_plcSemaphores.TryGetValue(config.Ip, out var plcSemaphore))
                {
                    _logger.LogWarning($"[{config.PlcName}] 未找到IP隔离信号量，跳过 | IP：{config.Ip}");
                    Interlocked.Increment(ref skipCount);
                    return;
                }

                await _globalSemaphore.WaitAsync();
                await plcSemaphore.WaitAsync();

                try
                {
                    if (!_connectionStatusCache.TryGetValue(config.Ip, out var status))
                    {
                        _logger.LogWarning($"[{config.PlcName}] 未找到连接状态缓存，跳过 | IP：{config.Ip}");
                        Interlocked.Increment(ref skipCount);
                        return;
                    }

                    // 1. 检查连接状态缓存是否过期
                    bool needRecheck = (DateTime.Now - status.LastCheckTime).TotalSeconds > _currentSettings.ConfigRefreshInterval;
                    bool isConnected = status.IsConnected;

                    // 2. 缓存过期则重新检查连接
                    if (needRecheck)
                    {
                        isConnected = await RecheckPlcConnectionAsync(config, status);
                    }

                    // 3. 连接断开且失败次数超阈值，触发告警
                    if (!isConnected && status.FailCount >= _currentSettings.MaxRetryTimes)
                    {
                        _logger.LogError($"[{config.PlcName}] 连续{status.FailCount}次连接失败，触发告警 | IP：{config.Ip}");
                        Interlocked.Increment(ref skipCount);
                        return;
                    }

                    // 4. 连接断开则跳过读取
                    if (!isConnected)
                    {
                        _logger.LogDebug($"[{config.PlcName}] 连接断开，跳过数据读取 | IP：{config.Ip}");
                        Interlocked.Increment(ref skipCount);
                        return;
                    }

                    // 5. 读取PLC生产数据
                    var (success, prodData, message) = await _plcService.ReadProductionDataAsync(
                        config.Ip, config.PlcName, config.Rack, config.Slot);

                    if (success)
                    {
                        // 更新最后请求时间（标记为活跃）
                        status.LastRequestTime = DateTime.Now;
                        status.Level = ConnectionLevel.Normal;
                        status.FailCount = 0;
                        Interlocked.Increment(ref successCount);

                        // 有有效数据则计数
                        if (prodData != null)
                        {
                            Interlocked.Increment(ref activeCount);
                            await ProcessPlcProductionDataAsync(config, prodData);
                        }
                    }
                    else
                    {
                        // 读取失败更新状态
                        status.FailCount++;
                        status.Level = status.FailCount <= 1 ? ConnectionLevel.Weak : ConnectionLevel.Disconnected;
                        Interlocked.Increment(ref failCount);
                    }
                }
                catch (OperationCanceledException)
                {
                    _logger.LogWarning($"[{config.PlcName}] 轮询操作超时 | IP：{config.Ip}");
                    UpdateStatusOnFailure(config.Ip);
                    Interlocked.Increment(ref failCount);
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, $"[{config.PlcName}] 轮询异常 | IP：{config.Ip}");
                    UpdateStatusOnFailure(config.Ip);
                    Interlocked.Increment(ref failCount);
                }
                finally
                {
                    plcSemaphore.Release();
                    _globalSemaphore.Release();
                }
            });

            await Task.WhenAll(tasks);

            // 输出本轮轮询统计
            //_logger.LogInformation($"PLC轮询完成 | 成功：{successCount} | 失败：{failCount} | 跳过：{skipCount} | 有数据：{activeCount}");
        }

        /// <summary>
        /// 重新检查PLC连接状态
        /// </summary>
        private async Task<bool> RecheckPlcConnectionAsync(PlcConfig config, PlcConnectionStatus status)
        {
            try
            {
                using var timeoutTokenSource = new CancellationTokenSource(TimeSpan.FromSeconds(_currentSettings.ConnectTimeoutSeconds));
                var connectResult = await _plcService.TestSinglePlcAsync(config, timeoutTokenSource.Token);

                // 更新状态
                status.IsConnected = connectResult.ConnectSuccess;
                status.LastCheckTime = DateTime.Now;
                status.FailCount = connectResult.ConnectSuccess ? 0 : status.FailCount + 1;
                status.Level = connectResult.ConnectSuccess ? ConnectionLevel.Normal : ConnectionLevel.Disconnected;

                if (!connectResult.ConnectSuccess)
                {
                    _logger.LogDebug($"[{config.PlcName}] 连接缓存过期，重新检测仍断开 | IP：{config.Ip}");
                }

                return connectResult.ConnectSuccess;
            }
            catch (OperationCanceledException)
            {
                _logger.LogWarning($"[{config.PlcName}] 连接重检超时 | IP：{config.Ip}");
                status.IsConnected = false;
                status.LastCheckTime = DateTime.Now;
                status.FailCount++;
                status.Level = ConnectionLevel.Disconnected;
                return false;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, $"[{config.PlcName}] 连接重检异常 | IP：{config.Ip}");
                status.IsConnected = false;
                status.LastCheckTime = DateTime.Now;
                status.FailCount++;
                status.Level = ConnectionLevel.Disconnected;
                return false;
            }
        }

        /// <summary>
        /// 失败时更新连接状态
        /// </summary>
        private void UpdateStatusOnFailure(string ip)
        {
            if (_connectionStatusCache.TryGetValue(ip, out var status))
            {
                status.IsConnected = false;
                status.FailCount++;
                status.Level = status.FailCount <= 1 ? ConnectionLevel.Weak : ConnectionLevel.Disconnected;
            }
        }

        /// <summary>
        /// 处理PLC生产数据（可扩展）
        /// </summary>
        private async Task ProcessPlcProductionDataAsync(PlcConfig config, PlcProductionData prodData)
        {
            try
            {
                // 业务处理逻辑：入库/推MQ/缓存等
                // 示例：await _plcDataService.SaveProductionDataAsync(prodData);
                await Task.CompletedTask;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, $"[{config.PlcName}] 生产数据处理失败 | IP：{config.Ip}");
            }
        }

        /// <summary>
        /// 重写停止逻辑
        /// </summary>
        public override async Task StopAsync(CancellationToken cancellationToken)
        {
            _logger.LogInformation("PLC后台监听服务停止中...");
            _isRunning = false;

            // 停止所有定时器
            _timer?.Change(Timeout.Infinite, 0);
            _configRefreshTimer?.Change(Timeout.Infinite, 0);

            // 等待当前轮询完成
            await Task.Delay(1000, cancellationToken);

            await base.StopAsync(cancellationToken);
            _logger.LogInformation("PLC后台监听服务已停止");
        }

        /// <summary>
        /// 完整释放资源
        /// </summary>
        public override void Dispose()
        {
            // 释放定时器
            _timer?.Dispose();
            _configRefreshTimer?.Dispose();

            // 释放信号量
            _globalSemaphore?.Dispose();
            _timerAsyncLock?.Dispose();
            _configRefreshLock?.Dispose();

            // 释放IP隔离信号量
            foreach (var semaphore in _plcSemaphores.Values)
            {
                semaphore.Dispose();
            }

            base.Dispose();
            _logger.LogInformation("PLC后台监听服务已释放所有资源");
        }
    }
}