using AcDream.Core.Physics;
using DatReaderWriter;
using DatReaderWriter.DBObjs;
using DatReaderWriter.Enums;
using DatReaderWriter.Options;

namespace AcDream.Content.Tests;

/// <summary>
/// AP-152 population + behaviour proof over the installed client_portal.dat.
///
/// <para>
/// Retail dispatches a Setup's collision geometry EXCLUSIVELY, BSP first, at
/// both consumers: <c>CPhysicsObj::FindObjCollisions</c> @0x0050f050 tests
/// <c>HAS_PHYSICS_BSP_PS</c> at <c>0x0050f165</c> and leaves the BSP branch
/// through the unconditional <c>0x0050f19d jmp 0x50f2b0</c>, past both the
/// CylSphere loop (0x50f1a2) and the Sphere loop (0x50f21d); and
/// <c>CPhysicsObj::calc_cross_cells</c> @0x00515230 tests the same flag at
/// <c>0x00515285</c> and routes to <c>CPhysicsObj::find_bbox_cell_list</c>
/// @0x00510fc0 at <c>0x0051528f jne 0x515305</c>, never reaching its
/// cylsphere (0x005152d1) or sorting-sphere (0x005152fb) branches.
/// </para>
///
/// <para>
/// This sweep pins the affected population and asserts that
/// <see cref="ShadowShapeBuilder.FromSetup"/> emits NO primitive for any of
/// it. Retail derives the dispatch flag from the parts themselves
/// (<c>CPartArray::CacheHasPhysicsBSP</c> @0x00518110 ORs 0x10000 on the first
/// part whose <c>gfxobj-&gt;physics_bsp</c> is non-null), which is exactly the
/// predicate used here.
/// </para>
/// </summary>
public sealed class InstalledSetupBspPrimitiveDispatchTests
{
    // EXTERNAL constants. The four bucket controls are the ones already
    // committed by the AP-22 reachability sweep (measured by an independent
    // raw client_portal.dat B-tree parse that validated itself by byte
    // accounting); the affected counts were measured on 2026-08-06 by a
    // separate DatReaderWriter sweep that reproduced FromSetup's steps rather
    // than calling it.
    //
    // They are deliberately NOT derived from the predicates below. A broken
    // enumeration, a wrong dat path, or a silently-empty decode all satisfy
    // the affected-count claim vacuously and are caught only by the controls.
    private const int ExpectedSetups = 5935;
    private const int ExpectedWithCylinder = 678;
    private const int ExpectedSphereOnlyNoCylinder = 3605;
    private const int ExpectedWithoutAnyPrimitive = 1652;

    private const int ExpectedAffected = 172;
    private const int ExpectedAffectedCylinderBearing = 73;
    private const int ExpectedAffectedSphereBearing = 99;
    private const int ExpectedWithPhysicsBspPart = 530;

    [Fact]
    public void InstalledSetups_WithBothAPrimitiveAndAPhysicsBspPart_EmitOnlyBspShapes()
    {
        string? datDir = ContentConformanceDats.ResolveDatDir();
        if (datDir is null)
            return;

        using var dats = new DatCollection(datDir, DatAccessType.Read);

        // Production physics-BSP predicate, FlatCollisionAssetBuilder.cs:377-380.
        var physicsBspCache = new Dictionary<uint, bool>();
        bool HasPhysicsBsp(uint gfxObjId)
        {
            if (physicsBspCache.TryGetValue(gfxObjId, out bool cached))
                return cached;
            bool result =
                dats.Portal.TryGet<GfxObj>(gfxObjId, out GfxObj? gfx)
                && gfx is not null
                && gfx.Flags.HasFlag(GfxObjFlags.HasPhysics)
                && gfx.PhysicsBSP?.Root is not null
                && gfx.VertexArray is not null;
            physicsBspCache[gfxObjId] = result;
            return result;
        }

        int total = 0;
        int withCylinder = 0;
        int sphereOnly = 0;
        int withoutPrimitive = 0;
        int withPhysicsBspPart = 0;
        int affected = 0;
        int affectedCylinderBearing = 0;
        int affectedSphereBearing = 0;
        var affectedThatStillEmitAPrimitive = new List<uint>();

        foreach (uint id in dats.GetAllIdsOfType<Setup>())
        {
            if (!dats.Portal.TryGet<Setup>(id, out Setup? setup) || setup is null)
                continue;
            total++;

            bool hasCylinder = false;
            foreach (var cyl in setup.CylSpheres)
            {
                if (cyl.Radius > 0f) { hasCylinder = true; break; }
            }
            bool hasSphere = false;
            foreach (var sph in setup.Spheres)
            {
                if (sph.Radius > 0f) { hasSphere = true; break; }
            }
            // FromSetup step 2 is gated on CylSpheres.Count == 0, so a Setup
            // with both only ever emitted Cylinders.
            bool emitsSphere = setup.CylSpheres.Count == 0 && hasSphere;

            if (hasCylinder) withCylinder++;
            else if (emitsSphere) sphereOnly++;
            else withoutPrimitive++;

            bool hasBspPart = false;
            foreach (uint partId in setup.Parts)
            {
                if (HasPhysicsBsp(partId)) { hasBspPart = true; break; }
            }
            if (hasBspPart) withPhysicsBspPart++;

            if (!hasBspPart || !(hasCylinder || emitsSphere))
                continue;

            affected++;
            if (hasCylinder) affectedCylinderBearing++;
            else affectedSphereBearing++;

            // The behaviour: for every affected Setup the production builder
            // must emit BSP shapes only.
            IReadOnlyList<ShadowShape> shapes =
                ShadowShapeBuilder.FromSetup(setup, 1f, HasPhysicsBsp);
            bool clean = shapes.Count > 0;
            foreach (ShadowShape shape in shapes)
            {
                if (shape.CollisionType != ShadowCollisionType.BSP)
                {
                    clean = false;
                    break;
                }
            }
            if (!clean)
                affectedThatStillEmitAPrimitive.Add(id);
        }

        // Positive controls first — without these the claim below is
        // satisfiable by an empty enumeration.
        Assert.Equal(ExpectedSetups, total);
        Assert.Equal(ExpectedWithCylinder, withCylinder);
        Assert.Equal(ExpectedSphereOnlyNoCylinder, sphereOnly);
        Assert.Equal(ExpectedWithoutAnyPrimitive, withoutPrimitive);
        Assert.Equal(ExpectedWithPhysicsBspPart, withPhysicsBspPart);

        Assert.Equal(ExpectedAffected, affected);
        Assert.Equal(ExpectedAffectedCylinderBearing, affectedCylinderBearing);
        Assert.Equal(ExpectedAffectedSphereBearing, affectedSphereBearing);

        Assert.Empty(affectedThatStillEmitAPrimitive);
    }
}