using Fleet.Core;
using Fleet.Hosting;

namespace Fleet.Tests;

public sealed class RestartScheduleTests
{
    private static RestartSchedule Parse(string text)
    {
        Assert.True(RestartSchedule.TryParse(text, out RestartSchedule? schedule), text);
        return schedule!;
    }

    [Theory]
    [InlineData("04:00")]
    [InlineData("04:00Z")]
    [InlineData("04:00+08:00")]
    [InlineData("23:59-05:30")]
    [InlineData(" 00:00 ")]
    public void Parse_AcceptsTimeWithOptionalOffset(string text) => Parse(text);

    [Theory]
    [InlineData("")]
    [InlineData("4:00")]
    [InlineData("24:00")]
    [InlineData("04:60")]
    [InlineData("04:00+8:00")]
    [InlineData("04:00+15:00")]
    [InlineData("04:00 UTC")]
    [InlineData("0400")]
    [InlineData("04:00+08:60")]
    public void Parse_RejectsEverythingElse(string text) => Assert.False(RestartSchedule.TryParse(text, out _));

    [Fact]
    public void NextAfter_IsStrictlyLater_AndRollsToTomorrow()
    {
        RestartSchedule utc = Parse("04:00");
        Assert.Equal(new DateTimeOffset(2026, 10, 7, 4, 0, 0, TimeSpan.Zero), utc.NextAfter(new DateTimeOffset(2026, 10, 7, 3, 59, 59, TimeSpan.Zero)));
        Assert.Equal(new DateTimeOffset(2026, 10, 8, 4, 0, 0, TimeSpan.Zero), utc.NextAfter(new DateTimeOffset(2026, 10, 7, 4, 0, 0, TimeSpan.Zero)));
        Assert.Equal(new DateTimeOffset(2026, 10, 8, 4, 0, 0, TimeSpan.Zero), utc.NextAfter(new DateTimeOffset(2026, 10, 7, 20, 0, 0, TimeSpan.Zero)));
    }

    [Fact]
    public void NextAfter_UsesTheWrittenOffset()
    {
        // 04:00+08:00 就是 UTC 前一天 20:00
        RestartSchedule china = Parse("04:00+08:00");
        Assert.Equal(new DateTimeOffset(2026, 10, 6, 20, 0, 0, TimeSpan.Zero), china.NextAfter(new DateTimeOffset(2026, 10, 6, 19, 0, 0, TimeSpan.Zero)));
        Assert.Equal(new DateTimeOffset(2026, 10, 7, 20, 0, 0, TimeSpan.Zero), china.NextAfter(new DateTimeOffset(2026, 10, 6, 20, 0, 0, TimeSpan.Zero)));
    }

    [Fact]
    public void NextAfter_WithMinimumUptime_DoesNotRestartAgainRightAfterARestart()
    {
        RestartSchedule schedule = Parse("04:00");
        // 04:00:03 重启后启动：加上最短运行时间再算，下一次是明天，而不是几秒后
        var started = new DateTimeOffset(2026, 10, 7, 4, 0, 3, TimeSpan.Zero);
        Assert.Equal(new DateTimeOffset(2026, 10, 8, 4, 0, 0, TimeSpan.Zero), schedule.NextAfter(started + RestartSchedule.MinimumUptime));
        // 03:55 启动：离 04:00 只有 5 分钟，不够最短运行时间，顺延到明天
        var early = new DateTimeOffset(2026, 10, 7, 3, 55, 0, TimeSpan.Zero);
        Assert.Equal(new DateTimeOffset(2026, 10, 8, 4, 0, 0, TimeSpan.Zero), schedule.NextAfter(early + RestartSchedule.MinimumUptime));
    }

    [Fact]
    public void Resolve_ReportsABadValueInsteadOfIgnoringIt()
    {
        Assert.Null(RestartSchedule.Resolve(null));
        Assert.Null(RestartSchedule.Resolve("  "));
        InvalidOperationException error = Assert.Throws<InvalidOperationException>(() => RestartSchedule.Resolve("tomorrow"));
        Assert.Contains("restart_at", error.Message);
    }

    [Fact]
    public async Task ServiceShell_StopsAtTheScheduledTime()
    {
        var time = new ImmediateTimeProvider(new DateTimeOffset(2026, 10, 7, 12, 0, 0, TimeSpan.Zero));
        var log = new ListLog();
        bool stoppedByToken = false;

        // 业务循环只在被取消时返回；定时重启到点以后令牌被取消，RunAsync 正常返回
        await ServiceShell.RunAsync(async ct =>
        {
            try
            {
                await Task.Delay(Timeout.Infinite, ct);
            }
            catch (OperationCanceledException)
            {
                stoppedByToken = true;
                throw;
            }
        }, log, new RestartController(Parse("04:00")), time).WaitAsync(TimeSpan.FromSeconds(10));

        Assert.True(stoppedByToken);
        Assert.Contains(log.Lines, l => l.Contains("scheduled_restart", StringComparison.Ordinal));
        Assert.Contains(log.Lines, l => l.Contains("restart scheduled", StringComparison.Ordinal));
    }

    [Fact]
    public async Task ServiceShell_PicksUpAScheduleThePanelSendsLater()
    {
        var time = new ImmediateTimeProvider(new DateTimeOffset(2026, 10, 7, 12, 0, 0, TimeSpan.Zero));
        var log = new ListLog();
        using var controller = new RestartController();

        Task shell = ServiceShell.RunAsync(ct => Task.Delay(Timeout.Infinite, ct), log, controller, time);
        await Task.Delay(300);
        Assert.False(shell.IsCompleted, "no schedule yet: the node keeps running");

        Assert.True(controller.SetRemote("04:30+08:00"));
        await shell.WaitAsync(TimeSpan.FromSeconds(10));
        Assert.Contains(log.Lines, l => l.Contains("scheduled_restart", StringComparison.Ordinal));
        Assert.Contains(log.Lines, l => l.Contains("source=panel", StringComparison.Ordinal));
    }

    [Fact]
    public async Task ServiceShell_ClearingTheScheduleCancelsTheRestart()
    {
        var time = new ManualTimeProvider(new DateTimeOffset(2026, 10, 7, 12, 0, 0, TimeSpan.Zero));
        var log = new ListLog();
        using var controller = new RestartController();

        controller.SetRemote("04:30+08:00");

        Task shell = ServiceShell.RunAsync(ct => Task.Delay(Timeout.Infinite, ct), log, controller, time);
        await Task.Delay(300);
        controller.SetRemote(null); // 面板关掉了
        await Task.Delay(300);
        Assert.False(shell.IsCompleted);
        Assert.Contains(log.Lines, l => l.Contains("restart scheduled", StringComparison.Ordinal));
        Assert.DoesNotContain(log.Lines, l => l.Contains("scheduled_restart", StringComparison.Ordinal));
        // 清理：把进程停掉
        Assert.True(controller.SetRemote("04:30+08:00"));
        // 新的计时器是异步注册的：反复推进，直到进程退出
        for (int i = 0; i < 100 && !shell.IsCompleted; i++)
        {
            time.Advance();
            await Task.Delay(50);
        }

        await shell.WaitAsync(TimeSpan.FromSeconds(10));
    }

    [Fact]
    public void Controller_LocalSettingWinsOverThePanel_AndBadTextIsRejected()
    {
        using var controller = new RestartController(Parse("04:00"));
        Assert.True(controller.IsLocal);
        Assert.True(controller.SetRemote("05:00"));
        Assert.Equal(new DateTimeOffset(2026, 10, 7, 4, 0, 0, TimeSpan.Zero), controller.Current!.NextAfter(new DateTimeOffset(2026, 10, 7, 0, 0, 0, TimeSpan.Zero)));

        using var remoteOnly = new RestartController();
        Assert.Null(remoteOnly.Current);
        Assert.False(remoteOnly.SetRemote("whenever"));
        Assert.Null(remoteOnly.Current);
        Assert.True(remoteOnly.SetRemote("05:00"));
        Assert.NotNull(remoteOnly.Current);
        Assert.True(remoteOnly.SetRemote(null));
        Assert.Null(remoteOnly.Current);
    }

    /// <summary>计时器马上触发：用来验证「到点」之后的行为，不用真的等。</summary>
    private sealed class ImmediateTimeProvider : TimeProvider
    {
        private readonly DateTimeOffset _now;

        public ImmediateTimeProvider(DateTimeOffset now) => _now = now;

        public override DateTimeOffset GetUtcNow() => _now;

        public override ITimer CreateTimer(TimerCallback callback, object? state, TimeSpan dueTime, TimeSpan period)
        {
            // TrimHeapAsync 这类每 30 秒一次的循环也会走到这里；只让「很长」的延迟（定时重启，至少 10 分钟）马上触发
            var timer = new ImmediateTimer(callback, state);
            if (dueTime >= RestartSchedule.MinimumUptime)
            {
                ThreadPool.QueueUserWorkItem(_ => timer.Fire());
            }

            return timer;
        }
    }

    /// <summary>计时器只在 <see cref="Advance"/> 时触发：用来验证「还没到点」时不会退出。</summary>
    private sealed class ManualTimeProvider : TimeProvider
    {
        private readonly DateTimeOffset _now;
        private readonly List<ImmediateTimer> _timers = [];

        public ManualTimeProvider(DateTimeOffset now) => _now = now;

        public override DateTimeOffset GetUtcNow() => _now;

        public override ITimer CreateTimer(TimerCallback callback, object? state, TimeSpan dueTime, TimeSpan period)
        {
            var timer = new ImmediateTimer(callback, state);
            lock (_timers)
            {
                _timers.Add(timer);
            }

            return timer;
        }

        public void Advance()
        {
            ImmediateTimer[] due;
            lock (_timers)
            {
                due = [.. _timers];
                _timers.Clear();
            }

            foreach (ImmediateTimer timer in due)
            {
                timer.Fire();
            }
        }
    }

    private sealed class ImmediateTimer : ITimer
    {
        private readonly TimerCallback _callback;
        private readonly object? _state;

        public ImmediateTimer(TimerCallback callback, object? state)
        {
            _callback = callback;
            _state = state;
        }

        public void Fire() => _callback(_state);

        public bool Change(TimeSpan dueTime, TimeSpan period) => true;

        public void Dispose()
        {
        }

        public ValueTask DisposeAsync() => ValueTask.CompletedTask;
    }

    private sealed class ListLog : INodeLog
    {
        private readonly List<string> _lines = [];

        public IReadOnlyList<string> Lines
        {
            get
            {
                lock (_lines)
                {
                    return [.. _lines];
                }
            }
        }

        public void Write(NodeLogLevel level, string message, params (string Key, object? Value)[] fields)
        {
            lock (_lines)
            {
                _lines.Add(message + " " + string.Join(' ', fields.Select(f => f.Key + "=" + f.Value)));
            }
        }
    }
}