using System.Diagnostics;
using ProjectQuint.Core.Judgement;

namespace ProjectQuint.Probes;

public readonly record struct JudgementSnapshot(int Score, int Combo, int MaxCombo,
    int MissCount, int KoolCount, int CoolCount, int GoodCount, int JudgedUnits, bool Finished);

public sealed record ReplayObservation(JudgementSnapshot Judgement, double SetupMilliseconds,
    double ReplayMilliseconds, long SetupAllocatedBytes, long ReplayAllocatedBytes);

public static class ReplayRunner
{
    public static ReplayObservation Run(SyntheticWorkload workload, int frameRate)
    {
        if (frameRate < 1 || frameRate > 10_000)
            throw new ArgumentOutOfRangeException(nameof(frameRate), "Use a frame rate from 1 to 10000.");
        var allocationStart = GC.GetAllocatedBytesForCurrentThread();
        var setupStart = Stopwatch.GetTimestamp();
        var engine = new RhythmJudgementEngine(workload.Notes, laneCount: 4);
        var setupEnd = Stopwatch.GetTimestamp();
        var replayAllocationStart = GC.GetAllocatedBytesForCurrentThread();

        long frame = 0;
        foreach (var input in workload.Events)
        {
            // Merge two timestamped streams; no sleeps or real-time waiting affect this trace.
            while ((double)frame / frameRate <= input.Time)
                engine.Update((double)frame++ / frameRate);
            if (input.Pressed)
                engine.Press(input.Lane, input.Time);
            else
                engine.Release(input.Lane, input.Time);
        }
        engine.Update(workload.Notes[^1].EndTime + 1);
        var replayEnd = Stopwatch.GetTimestamp();
        var allocationEnd = GC.GetAllocatedBytesForCurrentThread();
        return new ReplayObservation(new JudgementSnapshot(engine.Score, engine.Combo, engine.MaxCombo,
                engine.MissCount, engine.KoolCount, engine.CoolCount, engine.GoodCount,
                engine.JudgedNoteCount, engine.IsFinished),
            Milliseconds(setupStart, setupEnd), Milliseconds(setupEnd, replayEnd),
            replayAllocationStart - allocationStart, allocationEnd - replayAllocationStart);
    }

    private static double Milliseconds(long start, long end) =>
        (end - start) * 1000.0 / Stopwatch.Frequency;
}