// Export a creature Setup's geometry (per part, with UVs + normals + the
// ClothingBase texture substitutions applied) to JSON so an offline rasterizer
// can render it. Uses acdream's own tested GfxObjMesh/SetupMesh port rather than
// re-deriving the dat mesh format.
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Text;
using AcDream.Core.Content;
using AcDream.Core.Meshing;
using DatReaderWriter;
using DatReaderWriter.DBObjs;
using DatReaderWriter.Lib.IO;

namespace MosswartArt;

internal sealed class DatSource(DatCollection dats) : IDatObjectSource
{
    [return: MaybeNull]
    public T Get<T>(uint fileId) where T : IDBObj
        => dats.TryGet<T>(fileId, out var v) ? v : default;

    public bool TryGet<T>(uint fileId, [MaybeNullWhen(false)] out T value) where T : IDBObj
        => dats.TryGet(fileId, out value!);
}

internal sealed class AnimLoader(DatCollection dats) : AcDream.Core.Physics.IAnimationLoader
{
    public Animation? LoadAnimation(uint id)
        => dats.TryGet<Animation>(id, out var a) ? a : null;
}

internal static class Export
{
    private static string F(float v) => v.ToString("R", CultureInfo.InvariantCulture);

    public static int Run(DatCollection dats, uint setupId, uint clothingId, string outPath, uint motionTableId = 0)
    {
        if (!dats.TryGet<Setup>(setupId, out var setup) || setup is null)
        {
            Console.Error.WriteLine($"Setup 0x{setupId:X8} not found");
            return 1;
        }

        // ClothingBase substitution map, at SurfaceTexture (0x05) level.
        var texSwap = new Dictionary<uint, uint>();
        if (clothingId != 0 && dats.TryGet<ClothingTable>(clothingId, out var ct) && ct is not null)
        {
            foreach (var baseEffect in ct.ClothingBaseEffects.Values)
                foreach (var objEffect in baseEffect.CloObjectEffects)
                    foreach (var te in objEffect.CloTextureEffects)
                        texSwap[(uint)te.OldTexture] = (uint)te.NewTexture;
        }

        var referencedTextures = new HashSet<uint>();
        var src = new DatSource(dats);

        // Creatures do not define an upright pose in Setup.PlacementFrames --
        // the idle frame has to come from the MotionTable, or every part lands
        // stacked on the origin.
        var idle = MotionResolver.GetIdleFrame(setup, src, new AnimLoader(dats),
            motionTableId == 0 ? null : motionTableId);
        Console.WriteLine(idle is null ? "idle frame: NONE (falling back to placement frame)"
                                       : $"idle frame: {idle.Frames.Count} part frames");
        var refs = SetupMesh.Flatten(setup, idle);

        var sb = new StringBuilder();
        sb.Append("{\"setup\":\"0x").Append(setupId.ToString("X8")).Append("\",\"parts\":[");

        for (int i = 0; i < refs.Count; i++)
        {
            var mr = refs[i];
            if (!dats.TryGet<GfxObj>(mr.GfxObjId, out var gfx) || gfx is null) continue;
            var subs = GfxObjMesh.Build(gfx, src);

            var m = mr.PartTransform;
            if (i > 0) sb.Append(',');
            sb.Append("{\"index\":").Append(i)
              .Append(",\"gfx\":\"0x").Append(mr.GfxObjId.ToString("X8")).Append('"')
              .Append(",\"m\":[")
              .Append(F(m.M11)).Append(',').Append(F(m.M12)).Append(',').Append(F(m.M13)).Append(',').Append(F(m.M14)).Append(',')
              .Append(F(m.M21)).Append(',').Append(F(m.M22)).Append(',').Append(F(m.M23)).Append(',').Append(F(m.M24)).Append(',')
              .Append(F(m.M31)).Append(',').Append(F(m.M32)).Append(',').Append(F(m.M33)).Append(',').Append(F(m.M34)).Append(',')
              .Append(F(m.M41)).Append(',').Append(F(m.M42)).Append(',').Append(F(m.M43)).Append(',').Append(F(m.M44))
              .Append("],\"sub\":[");

            for (int s = 0; s < subs.Count; s++)
            {
                var sm = subs[s];

                // Surface (0x08) -> OrigTextureId (0x05) -> ClothingBase swap.
                uint texId = sm.SurfaceId;
                if ((texId >> 24) == 0x08 && dats.TryGet<Surface>(texId, out var surf) && surf is not null)
                    texId = (uint)surf.OrigTextureId;
                if (texSwap.TryGetValue(texId, out var swapped)) texId = swapped;
                referencedTextures.Add(texId);

                if (s > 0) sb.Append(',');
                sb.Append("{\"surface\":\"0x").Append(sm.SurfaceId.ToString("X8")).Append('"')
                  .Append(",\"tex\":\"0x").Append(texId.ToString("X8")).Append('"')
                  .Append(",\"v\":[");
                for (int v = 0; v < sm.Vertices.Length; v++)
                {
                    var vert = sm.Vertices[v];
                    if (v > 0) sb.Append(',');
                    sb.Append('[').Append(F(vert.Position.X)).Append(',').Append(F(vert.Position.Y)).Append(',').Append(F(vert.Position.Z))
                      .Append(',').Append(F(vert.Normal.X)).Append(',').Append(F(vert.Normal.Y)).Append(',').Append(F(vert.Normal.Z))
                      .Append(',').Append(F(vert.TexCoord.X)).Append(',').Append(F(vert.TexCoord.Y)).Append(']');
                }
                sb.Append("],\"i\":[");
                for (int k = 0; k < sm.Indices.Length; k++)
                {
                    if (k > 0) sb.Append(',');
                    sb.Append(sm.Indices[k]);
                }
                sb.Append("]}");
            }
            sb.Append("]}");
        }
        sb.Append("]}");

        // The documented destination (tools/IconForge/work/) does not exist in a
        // fresh checkout, so create it rather than making the caller mkdir first.
        string outFull = Path.GetFullPath(outPath);
        Directory.CreateDirectory(Path.GetDirectoryName(outFull) ?? ".");

        File.WriteAllText(outFull, sb.ToString());
        Console.WriteLine($"wrote {outPath} ({new FileInfo(outFull).Length / 1024} KB), {refs.Count} parts");

        // Dump the surfaces alongside the geometry. Keeping both halves in one
        // command means the render pipeline has a single documented input step
        // and cannot be handed geometry whose textures were never extracted.
        string textureDir = Path.Combine(Path.GetDirectoryName(outFull) ?? ".", "textures");
        Console.WriteLine($"dumping {referencedTextures.Count} referenced surfaces -> {textureDir}");
        int written = Textures.Dump(dats, referencedTextures, textureDir);
        if (written != referencedTextures.Count)
        {
            Console.Error.WriteLine(
                $"WARNING: {referencedTextures.Count - written} surface(s) did not resolve; "
                + "the render will fall back to flat grey for those.");
        }
        return 0;
    }
}