BUTR/Bannerlord.BLSE

using System;
using System.Collections.Generic;
using System.IO;

namespace Bannerlord.LauncherEx.TPac;

internal class TexturePixelData : ExternalData
{
    public static readonly Guid TYPE_GUID = Guid.Parse("70ee4e2c-79e4-4b2d-8d54-d53ecd2a559c");

    public const string KEY_WIDTH = "width";

    public const string KEY_HEIGHT = "height";

    public const string KEY_ARRAY = "array";

    public const string KEY_MIPMAP = "mipmap";

    public const string KEY_FORMAT = "format";

    /*public const string KEY_PIXELSIZE = "pixelSize";
    public const string KEY_ALIGN = "align";*/

    public byte[][][] RawImage { set; get; } = Array.Empty<byte[][]>();

    public byte[] PrimaryRawImage => RawImage[0][0];

    public TexturePixelData() : base(TYPE_GUID) { }

    public override void ReadData(BinaryReader stream, IDictionary<object, object> userdata, int totalSize)
    {
        int array = 1, mipmap = 1;
        if (userdata.TryGetValue(KEY_ARRAY, out var arrayObj))
        {
            array = (int) arrayObj;
        }

        if (userdata.TryGetValue(KEY_MIPMAP, out var mipmapObj))
        {
            mipmap = (int) mipmapObj;
        }

        if (!userdata.TryGetValue(KEY_WIDTH, out var widthObj) || !userdata.TryGetValue(KEY_HEIGHT, out var heightObj) || !userdata.TryGetValue(KEY_FORMAT, out var formatObj))
        {
            throw new ArgumentException("No enough user data for width, height and format");
        }

        var width = (int) widthObj;
        var height = (int) heightObj;
        var format = (TextureFormat) formatObj;
        var aligh = format.GetAlignSize();
        var pixelSize = format.GetBitsPerPixel();

        //var raw = stream.ReadBytes(totalSize);

        var raw = new byte[array][][];
        for (var a = 0; a < array; a++)
        {
            raw[a] = new byte[mipmap][];
            var imageWidth = width;
            var imageHeight = height;
            for (var m = 0; m < mipmap; m++)
            {
                var alignedWidth = imageWidth;
                var alignedHeight = imageHeight;
                if (alignedWidth % aligh != 0)
                {
                    alignedWidth += aligh - (alignedWidth % aligh);
                }

                if (alignedHeight % aligh != 0)
                {
                    alignedHeight += aligh - (alignedHeight % aligh);
                }

                // prevent from overflow for mega textures or underflow for very small mipmap
                // should be alignedWidth * alignedHeight * pixelSize / 8
                var readSize = alignedWidth * alignedHeight;
                // if readSize & 7 != 0, then it cannot be divided exactly
                if (readSize >= 8 && (readSize & 7) == 0)
                    readSize = readSize / 8 * pixelSize;
                else
                    readSize = readSize * pixelSize / 8;
                raw[a][m] = stream.ReadBytes(readSize);
                imageWidth = Math.Max(imageWidth >> 1, 1);
                imageHeight = Math.Max(imageHeight >> 1, 1);
            }
        }

        RawImage = raw;
    }
}