using System.Collections.Generic;
using System.Reflection;
using NUnit.Framework;
using ProjectM.Simulation;

namespace ProjectM.Tests
{
    /// <summary>
    /// Invariants over the tuning surface, from the 2026-08-06 audit.
    ///
    /// 1. THE SIX-SITE KNOB DRIFT. Adding a knob means touching six places (the struct field, Defaults(), the
    ///    TuningKnob byte const, and the ClampKnob / Apply / Get switches). Nothing in the build caught a knob
    ///    wired into Apply but forgotten in ClampKnob — which matters because the clamp is the only thing
    ///    stopping a 0 reaching the i-frame divide, documented in TuningConfig's own header as "NaNs the
    ///    kinematic body permanently".
    ///
    /// 2. MELEE TESTS PINNED THE WRONG NUMBERS. MeleeComboTests pins fixture values that differ from the SHIPPED
    ///    defaults on nine of ten knobs, and MeleeTiming — which produces the locked 20/12/25 contact ticks — had
    ///    zero test references. These assert RELATIONSHIPS against Defaults(), so a deliberate retune stays green
    ///    and only a broken coupling fails.
    /// </summary>
    public class TuningInvariantTests
    {
        /// <summary>Knob indices that actually exist, read off the TuningKnob consts rather than assumed to be
        /// 0..Count. CLAUDE.md's rule is that a RETIRED knob's byte value stays reserved and is never renumbered
        /// (20-23 today), so the index space is deliberately full of holes.</summary>
        static byte[] LiveKnobIndices()
        {
            var list = new List<byte>();
            foreach (var f in typeof(TuningKnob).GetFields(BindingFlags.Public | BindingFlags.Static))
            {
                if (f.FieldType != typeof(byte) || f.Name == "Count") continue;
                list.Add((byte)f.GetRawConstantValue());
            }
            return list.ToArray();
        }

        [Test]
        public void EveryLiveKnob_RoundTrips_Through_Apply_And_Get()
        {
            var knobs = LiveKnobIndices();
            Assert.Greater(knobs.Length, 20, "reflection should have found the whole live knob set");

            foreach (byte knob in knobs)
            {
                var c = TuningConfig.Defaults();
                const float probe = 7f;                 // inside every knob's clamp band
                float expected = TuningConfig.ClampKnob(knob, probe);
                TuningConfig.Apply(ref c, knob, probe);
                float actual = TuningConfig.Get(in c, knob);

                Assert.AreEqual(expected, actual, 1e-4f,
                    $"knob {knob} does not round-trip: Apply/Get disagree with ClampKnob. A knob added to one " +
                    "switch and forgotten in another silently reads 0 in the overlay or bypasses its safety floor.");
            }
        }

        [Test]
        public void RetiredKnobIndices_StayReserved()
        {
            var live = new HashSet<byte>(LiveKnobIndices());
            foreach (byte retired in new byte[] { 20, 21, 22, 23 })
                Assert.IsFalse(live.Contains(retired),
                    $"knob index {retired} is RETIRED and reserved (CLAUDE.md): re-using it would silently re-mean " +
                    "a value in saved feel profiles and in the DebugOp wire payload.");
        }

        [Test]
        public void IFrameWindow_ClampsAboveZero()
        {
            Assert.Greater(TuningConfig.ClampKnob(TuningKnob.IFrameWindowTicks, 0f), 0f,
                "IFrameWindowTicks must clamp above zero — a zero reaches a divide and NaNs the character body.");
        }

        [Test]
        public void ShippedMeleeCadence_ContactLandsInsideTheCastAndRecoverWindows()
        {
            var d = TuningConfig.Defaults();
            uint step2 = MeleeTiming.ContactTicks(2, d.MeleeContactTicks);
            uint step3 = MeleeTiming.ContactTicks(3, d.MeleeContactTicks);

            // MeleeTiming's header states this coupling as documented-but-unclamped; it is otherwise enforced only
            // by a [MenuItem] audit tool a human has to remember to run. This is the mechanical version.
            Assert.Less(step3, (uint)PlayerAimSystem.CastFacingTicks,
                "finisher contact must land INSIDE the cast-facing window — at the 07-21 feel lock it sits one " +
                "tick under, so raising contact without raising the window silently breaks aim-at-contact.");
            Assert.Less(step3, (uint)d.MeleeRecoverTicks,
                "finisher contact must land before recover ends, or the hit resolves after the swing is over.");
            Assert.Less(step2, step3,
                "step 2 is the quick contact (x0.625) and step 3 the finisher (x1.25) — never the other way round.");
        }

        [Test]
        public void ContactTicks_ZeroKnob_MeansImmediate()
        {
            Assert.AreEqual(0u, MeleeTiming.ContactTicks(1, 0f));
            Assert.AreEqual(0u, MeleeTiming.ContactTicks(3, 0f),
                "0 is the IMMEDIATE sentinel at every step — the legacy same-tick resolve the mechanics tests use.");
        }

        [Test]
        public void ContactTicks_ScalePerStep_FromTheOneKnob()
        {
            const float knob = 16f;
            Assert.AreEqual(16u, MeleeTiming.ContactTicks(1, knob), "step 1 is the knob itself (x1.0)");
            Assert.AreEqual(10u, MeleeTiming.ContactTicks(2, knob), "step 2 is the quick one (x0.625)");
            Assert.AreEqual(20u, MeleeTiming.ContactTicks(3, knob), "step 3+ is the finisher (x1.25)");
        }
    }
}