using System.Collections.Generic;
using AcDream.Core.Physics;
using DatReaderWriter;
using DatReaderWriter.DBObjs;
using DatReaderWriter.Enums;
using DatReaderWriter.Options;

namespace AcDream.Content.Tests;

/// <summary>
/// AP-155 population MEASUREMENT ONLY (contract
/// <c>docs/research/2026-08-07-s2-static-sphere-contract.md</c>, "Measurement"
/// section) — not a gate. Counts, over the installed <c>client_portal.dat</c>
/// Setups (the same <c>dats.GetAllIdsOfType&lt;Setup&gt;()</c> enumeration
/// <see cref="InstalledSetupCollisionReachabilityTests"/> and
/// <see cref="InstalledSetupBspPrimitiveDispatchTests"/> already sweep), how
/// many actually REACH the fixed static-publication Sphere emission — i.e.
/// <see cref="ShadowShapeBuilder.FromSetup"/>'s production dispatch, at
/// scale 1, emits ONLY <see cref="ShadowCollisionType.Sphere"/> shapes for
/// them. That dispatch (not a raw "has Spheres, no CylSpheres" field read) is
/// the correct population: a Setup can carry authored Spheres and STILL never
/// reach the sphere branch if a physics-BSP part suppresses it (AP-152) — 99
/// of the 3,605 "sphere-only, no cylinder" Setups the reachability sweep
/// already counted fall into exactly that trap.
/// </summary>
public sealed class Ap155StaticSpherePopulationMeasurementTests
{
    [Fact]
    public void InstalledSetups_SphereOnlyStaticPopulation_Measured()
    {
        string? datDir = ContentConformanceDats.ResolveDatDir();
        if (datDir is null)
        {
            Console.WriteLine("SKIP: installed retail DAT directory is unavailable.");
            return;
        }

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

        // Production physics-BSP predicate — same as
        // InstalledSetupBspPrimitiveDispatchTests / 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 totalSetups = 0;
        int sphereOnlyReachable = 0;
        var samples = new List<uint>();

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

            // The classifier: production FromSetup output, not raw Setup
            // fields — this is what a landblock static entity built from
            // this Setup actually registers.
            var shapes = ShadowShapeBuilder.FromSetup(setup, 1f, HasPhysicsBsp);
            if (shapes.Count == 0)
                continue;

            bool sphereOnly = true;
            foreach (var shape in shapes)
            {
                if (shape.CollisionType != ShadowCollisionType.Sphere)
                {
                    sphereOnly = false;
                    break;
                }
            }
            if (!sphereOnly)
                continue;

            sphereOnlyReachable++;
            if (samples.Count < 3)
                samples.Add(id);
        }

        Console.WriteLine("===== AP-155 static-sphere population measurement =====");
        Console.WriteLine($"Total installed Setups:                                {totalSetups}");
        Console.WriteLine($"Reach the static Sphere emission (post-fix, production dispatch): {sphereOnlyReachable}");
        Console.WriteLine("Three example object ids:");
        foreach (uint sample in samples)
            Console.WriteLine($"  0x{sample:X8}");
        Console.WriteLine("=========================================================");

        // Structural sanity only — this is a measurement, not a gate.
        Assert.True(totalSetups > 0, "Expected the installed DAT to enumerate at least one Setup.");
        Assert.True(
            sphereOnlyReachable > 0,
            "Expected at least one Setup to reach the static Sphere emission in the installed DAT.");
    }
}