using Xunit;
using Serilog.Events;
using YZWater.Core.Models;
using YZWater.Core.Services;

namespace YZWater.Core.Tests.Services;

/// <summary>
/// 报警内存状态的并发回归测试。
/// 背景：轮询线程（CheckAlarms）、UI 线程（ViewD 搁置/复位）、SignalR 线程（远程复位）会同时读写
/// _activeAlarms / _alarmStartTimes / _escalatedAlarms 这几个普通集合。改动前它们完全没有同步，
/// 一边枚举一边被写入就直接抛 "Collection was modified"，异常被 Avalonia 的 UI 兜底吞掉后
/// 表现为"报警列表点不开 / 复位了但还在报警"，界面上看不出任何线索。
/// 这里压两件事：并发不炸不卡，且同一个条件不会被重复触发。
/// </summary>
[Collection("Serilog minimum level")]
public class AlarmServiceConcurrencyTests : IDisposable
{
    private readonly LogEventLevel _originalLevel = LogService.MinimumLevel;
    private readonly AlarmService _service;

    public AlarmServiceConcurrencyTests()
    {
        // 状态变更会记 Warning（报警触发/泛溢），压掉以免污染测试输出
        LogService.ApplyMinimumLevel("Error");
        _service = new AlarmService(PlcPollingService.Instance);
        _service.AlarmDelaySeconds = 0; // 立即触发，让压测真正走到触发分支而不是只登记起始时间
    }

    public void Dispose()
    {
        _service.Dispose();
        LogService.ApplyMinimumLevel(_originalLevel.ToString());
    }

    /// <summary>
    /// 评估、复位、搁置、读快照四路并发：不能抛异常，也不能卡死
    /// （卡死意味着锁里做了落库/事件回调之类的外部调用，与等锁的 UI 线程互等）。
    /// </summary>
    [Fact]
    public async Task ConcurrentEvaluateResetShelveRead_DoesNotCorruptState()
    {
        var workers = new List<Task>();

        // ① 两路"轮询线程"：反复评估条件成立，偶尔让一半条件恢复（触发清除分支）
        for (var t = 0; t < 2; t++)
        {
            workers.Add(Task.Run(() =>
            {
                for (var round = 0; round < 200; round++)
                {
                    for (var i = 0; i < 20; i++)
                        _service.CheckCustomCondition($"Tank{i}_High", true, $"液位高 {i}", 2);

                    // 每 20 轮清一次：既制造"边枚举边写"的窗口，又不会把报警表灌满
                    if (round % 20 == 19)
                        for (var i = 0; i < 20; i += 2)
                            _service.CheckCustomCondition($"Tank{i}_High", false, string.Empty, 0);
                }
            }));
        }

        // ② "UI 线程"：读快照属性（内部要遍历活跃集合）
        workers.Add(Task.Run(() =>
        {
            for (var round = 0; round < 2000; round++)
            {
                _ = _service.HasActiveAlarm;
                _ = _service.ActiveAlarmCount;
                _ = _service.ActiveAlarmMessage;
            }
        }));

        // ③ "UI 线程"：搁置 / 取消搁置
        workers.Add(Task.Run(() =>
        {
            for (var round = 0; round < 300; round++)
            {
                var key = $"Shelve{round % 7}_High";
                _service.Shelve(key, 30, "Tester");
                _service.Unshelve(key, "Tester");
            }
        }));

        // ④ "远程客户端"：全部复位（清空同一批集合并回写数据库）
        workers.Add(Task.Run(async () =>
        {
            for (var round = 0; round < 30; round++)
                await _service.ResetAllAlarmsAsync("Tester");
        }));

        var all = Task.WhenAll(workers);
        var finished = await Task.WhenAny(all, Task.Delay(TimeSpan.FromSeconds(60)));
        Assert.True(finished == all, "并发压测未在 60 秒内结束，疑似锁内做外部调用导致互等");

        await all; // 任一 worker 抛出 InvalidOperationException 等异常时让测试失败

        // 状态没被压坏：清空后重新评估仍能触发，并如实反映到快照属性
        await _service.ResetAllAlarmsAsync("Tester");
        _service.CheckCustomCondition("AfterStress_High", true, "压测后仍可触发", 2);
        _service.CheckCustomCondition("AfterStress_High", true, "压测后仍可触发", 2);

        Assert.True(_service.HasActiveAlarm);
        Assert.Equal(1, _service.ActiveAlarmCount);
        Assert.Contains("AfterStress_High", _service.ActiveAlarmMessage);
    }

    /// <summary>
    /// 同一条件被多个线程同时判定成立时只能触发一次 ——
    /// "是否已在报警"的检查和"占住活跃集合"必须在同一把锁里，否则两边都能通过检查，
    /// 报警列表和声音通知会收到重复的同一条报警。
    /// </summary>
    [Fact]
    public async Task SameCondition_RaisedOnlyOnceUnderConcurrentThreads()
    {
        const string conditionId = "ConcurrentTank_High";
        var raised = new List<AlarmRecord>();
        var raisedLock = new object();
        void OnRaised(AlarmRecord alarm)
        {
            lock (raisedLock) raised.Add(alarm);
        }

        _service.AlarmRaised += OnRaised;
        try
        {
            var workers = new List<Task>();
            for (var t = 0; t < 4; t++)
            {
                workers.Add(Task.Run(() =>
                {
                    // 第一轮只登记起始时间，之后每一轮都是"条件仍成立"的重复评估
                    for (var round = 0; round < 300; round++)
                        _service.CheckCustomCondition(conditionId, true, "液位高", 2);
                }));
            }
            await Task.WhenAll(workers);
        }
        finally
        {
            _service.AlarmRaised -= OnRaised;
        }

        int duplicates;
        lock (raisedLock)
            duplicates = raised.Count(a => a.ConditionId == conditionId);

        Assert.Equal(1, duplicates);
    }

    /// <summary>
    /// 搁置期间不能因为并发而漏网触发（判定搁置与占住活跃集合在同一临界区内才成立）。
    /// </summary>
    [Fact]
    public async Task ShelvedCondition_IsNotRaisedEvenWhenEvaluatedConcurrently()
    {
        const string conditionId = "ShelvedTank_High";
        var raised = 0;
        void OnRaised(AlarmRecord alarm)
        {
            if (alarm.ConditionId == conditionId) Interlocked.Increment(ref raised);
        }

        _service.AlarmRaised += OnRaised;
        try
        {
            _service.Shelve(conditionId, 30, "Tester");

            var workers = new List<Task>();
            for (var t = 0; t < 4; t++)
            {
                workers.Add(Task.Run(() =>
                {
                    for (var round = 0; round < 300; round++)
                        _service.CheckCustomCondition(conditionId, true, "液位高", 2);
                }));
            }
            await Task.WhenAll(workers);
        }
        finally
        {
            _service.AlarmRaised -= OnRaised;
            _service.Unshelve(conditionId, "Tester");
        }

        Assert.Equal(0, raised);
    }

    /// <summary>
    /// 复位后条件仍成立时必须能重新触发，不能留下"已复位但界面仍报警"的脏状态。
    /// </summary>
    [Fact]
    public async Task ResetWhileConditionStillActive_LetsNextPollReRaise()
    {
        const string conditionId = "ResetThenRaise_High";
        _service.CheckCustomCondition(conditionId, true, "液位高", 2);
        _service.CheckCustomCondition(conditionId, true, "液位高", 2);
        Assert.True(_service.HasActiveAlarm);

        await _service.ResetAllAlarmsAsync("Tester");
        Assert.False(_service.HasActiveAlarm);

        _service.CheckCustomCondition(conditionId, true, "液位高", 2);
        _service.CheckCustomCondition(conditionId, true, "液位高", 2);
        Assert.Contains(conditionId, _service.ActiveAlarmMessage);
    }
}