using System.Runtime.InteropServices;

namespace Voxel
{
    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    public struct FaceData
    {
        public uint _data;

        // Bit layout:
        // [31-24]: Y (8 bits) 0-255
        // [23-20]: Z (4 bits) 0-15
        // [19-16]: X (4 bits) 0-15
        // [15-10]: Texture (6 bits) 0-63
        // [9-7]:   Facing (3 bits) 0-7
        // [6-3]:   Light (4 bits) 0-15
        // [2-0]:   unused (3 bits)

        public FaceData(byte x, byte y, byte z, Orientation facing, Textures texture, byte lightLevel)
        {
            _data = (uint)(
                ((y & 0xFF) << 24) |      // 8 bits
                ((z & 0x0F) << 20) |      // 4 bits
                ((x & 0x0F) << 16) |      // 4 bits
                (((byte)texture & 0x3F) << 10) | // 6 bits (0-63)
                (((byte)facing & 0x07) << 7) |   // 3 bits
                ((lightLevel & 0x0F) << 3)       // 4 bits
            );
        }

        public byte X => (byte)((_data >> 16) & 0x0F);
        public byte Y => (byte)((_data >> 24) & 0xFF);
        public byte Z => (byte)((_data >> 20) & 0x0F);
        public Orientation Facing => (Orientation)((_data >> 7) & 0x07);
        public Textures Texture => (Textures)((_data >> 10) & 0x3F);
        public byte LightLevel => (byte)((_data >> 3) & 0x0F);

        public byte[] Pack()
        {
            return BitConverter.GetBytes(_data);
        }
    }
}