using System;
using System.Runtime.InteropServices;
using AOT;
using UnityEngine;

public partial class RenderModule: CallbackHandler<RenderModule>
{
    private const int MaxAliasFrames = 256; // Should match MAXALIASFRAMES
    
    private void BuildCallbacks()
    {
        var callbacks = new Callbacks
        {
            target = TargetPtr,

            UploadAliasModel = CreateCallback<UploadAliasModelCallback>(Callback_UploadAliasModel),
        };

        RegisterCallbacks(callbacks);
    }
    
    /// <summary>
    /// This matches unity_modcalls_t from mod_uniquake.c in native code.
    /// </summary>
    [StructLayout(LayoutKind.Sequential, Pack = 0)]
    private class Callbacks
    {
        public IntPtr target;

        public IntPtr UploadAliasModel;
    }

    [UnmanagedFunctionPointer(CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
    private delegate int UploadAliasModelCallback(IntPtr target, 
        [MarshalAs(UnmanagedType.LPStr)] string name, QVec3 boundsMin, QVec3 boundsMax,
        QAliasHeader header, IntPtr frames, [MarshalAs(UnmanagedType.LPArray, SizeConst = MaxAliasFrames)]
        IntPtr[] poseVerts, IntPtr triangles, IntPtr stVerts);

    [MonoPInvokeCallback(typeof(UploadAliasModelCallback))]
    private static int Callback_UploadAliasModel(IntPtr target, 
        string name, QVec3 boundsMin, QVec3 boundsMax, 
        QAliasHeader header, IntPtr frames,
        IntPtr[] poseVerts, IntPtr triangles, IntPtr stVerts)
    {
        if (header == null)
        {
            Debug.LogWarning($"Uploading invalid alias model, name = {name}");
            return 0;
        }

        if (frames != IntPtr.Zero)
            header.frames = frames.ToStructArray<QAliasFrameDesc>(header.numFrames);

        var poseVertices = new QTriVertex[header.numFrames][];
        for (int i = 0; i < header.numFrames && i < MaxAliasFrames; ++i)
        {
            poseVertices[i] = poseVerts[i].ToStructArray<QTriVertex>(header.numVerts);
        }

        return GetSelf(target).UploadAliasModel(
            name, boundsMin, boundsMax, header, poseVertices,
            triangles.ToStructArray<QTriangle>(header.numTriangles),
            stVerts.ToStructArray<QSTVert>(header.numVerts));
    }
}