using System.Globalization;
using RioJoy.Core.Feedback;
using RioJoy.Core.Mapping;
using RioJoy.Core.Protocol;
using RioJoy.Core.Tests.Mapping;
using RioJoy.Core.Tests.Serial;
using Xunit;

namespace RioJoy.Core.Tests.Feedback;

public class CoalescingLampSchedulerTests
{
    private static readonly TimeSpan Fast = TimeSpan.FromMilliseconds(1); // pump as fast as timers allow

    private static Task WaitFor(Func<bool> condition, int timeoutMs = 5000) =>
        FeedbackWait.For(condition, timeoutMs);

    // "Lamp(0x12,0x3C)" → (0x12, 0x3C)
    private static (int Address, byte State) ParseLamp(string entry)
    {
        string[] parts = entry["Lamp(0x".Length..^1].Split(new[] { ",0x" }, StringSplitOptions.None);
        return (int.Parse(parts[0], NumberStyles.HexNumber, CultureInfo.InvariantCulture),
                byte.Parse(parts[1], NumberStyles.HexNumber, CultureInfo.InvariantCulture));
    }

    [Fact]
    public async Task Post_SameAddressRepeatedly_SendsOnlyTheLatestState()
    {
        var sink = new RecordingSink();
        var scheduler = new CoalescingLampScheduler(sink, Fast);
        for (byte s = 0; s <= 0x30; s++)
            scheduler.Post(0x12, s); // a burst of updates while nothing pumps

        using var cts = new CancellationTokenSource();
        Task pump = scheduler.RunAsync(cts.Token);
        await WaitFor(() => sink.Snapshot().Length >= 1);
        await Task.Delay(50); // give a buggy scheduler time to send the rest
        cts.Cancel();
        await pump.WithTimeout();

        string entry = Assert.Single(sink.Snapshot());
        Assert.Equal((0x12, (byte)0x30), ParseLamp(entry)); // burst collapsed to the last state
    }

    [Fact]
    public async Task Post_UnchangedState_IsNotResent()
    {
        var sink = new RecordingSink();
        var scheduler = new CoalescingLampScheduler(sink, Fast);
        using var cts = new CancellationTokenSource();
        Task pump = scheduler.RunAsync(cts.Token);

        scheduler.Post(0x05, RioLampState.SolidBright);
        await WaitFor(() => sink.Snapshot().Length >= 1);

        scheduler.Post(0x05, RioLampState.SolidBright); // same state again
        await Task.Delay(50);
        cts.Cancel();
        await pump.WithTimeout();

        Assert.Single(sink.Snapshot()); // no resend for an unchanged lamp
    }

    [Fact]
    public async Task Pump_SendsAtMostOneLampPerTick()
    {
        var sink = new RecordingSink();
        var scheduler = new CoalescingLampScheduler(sink, TimeSpan.FromMilliseconds(200));
        scheduler.Post(0x01, RioLampState.SolidBright);
        scheduler.Post(0x02, RioLampState.SolidBright);
        scheduler.Post(0x03, RioLampState.SolidBright);

        using var cts = new CancellationTokenSource();
        Task pump = scheduler.RunAsync(cts.Token);
        await WaitFor(() => sink.Snapshot().Length >= 1);

        // The next tick is ~200 ms out; three pending lamps must not burst.
        Assert.Single(sink.Snapshot());
        cts.Cancel();
        await pump.WithTimeout();
    }

    [Fact]
    public async Task PostAll_CoversExactlyTheValidAddressSet()
    {
        var sink = new RecordingSink();
        var scheduler = new CoalescingLampScheduler(sink, Fast);
        scheduler.PostAll(RioLampState.SolidOff);

        int validCount = Enumerable.Range(0, RioAddress.TableSize).Count(RioAddress.IsValid);
        Assert.Equal(104, validCount); // 72 buttons + 2×16 keypad keys; 0x48-0x4F is a gap

        using var cts = new CancellationTokenSource();
        Task pump = scheduler.RunAsync(cts.Token);
        await WaitFor(() => sink.Snapshot().Length >= validCount);
        await Task.Delay(50);
        cts.Cancel();
        await pump.WithTimeout();

        var sent = sink.Snapshot().Select(ParseLamp).ToArray();
        Assert.Equal(validCount, sent.Length); // nothing sent twice, no gap addresses
        Assert.All(sent, s => Assert.Equal(RioLampState.SolidOff, s.State));
        Assert.Equal(
            Enumerable.Range(0, RioAddress.TableSize).Where(RioAddress.IsValid),
            sent.Select(s => s.Address).OrderBy(a => a));
    }

    [Fact]
    public async Task Post_InvalidAddress_Ignored()
    {
        var sink = new RecordingSink();
        var scheduler = new CoalescingLampScheduler(sink, Fast);
        scheduler.Post(0x48, RioLampState.SolidBright); // gap address (rumble config is unvalidated)
        scheduler.Post(0x70, RioLampState.SolidBright);
        scheduler.Post(-1, RioLampState.SolidBright);

        using var cts = new CancellationTokenSource();
        Task pump = scheduler.RunAsync(cts.Token);
        await Task.Delay(100);
        cts.Cancel();
        await pump.WithTimeout();

        Assert.Empty(sink.Snapshot());
    }

    [Fact]
    public async Task Cancel_StopsThePump()
    {
        var sink = new RecordingSink();
        var scheduler = new CoalescingLampScheduler(sink, Fast);
        using var cts = new CancellationTokenSource();
        Task pump = scheduler.RunAsync(cts.Token);

        cts.Cancel();
        await pump.WithTimeout(); // exits cleanly, no OperationCanceledException

        scheduler.Post(0x01, RioLampState.SolidBright);
        await Task.Delay(50);
        Assert.Empty(sink.Snapshot()); // a stopped pump sends nothing
    }
}