using System.Runtime.InteropServices;

namespace SabreTools.Data.Models.BSP
{
    /// <summary>
    /// The leaves lump contains the leaves of the BSP tree.
    ///
    /// The first entry of this struct is the type of the content
    /// of this leaf. It can be one of the predefined values, found
    /// in the compiler source codes, and is litte relevant for the
    /// actual rendering process. All the more important is the
    /// next integer containing the offset into the vis lump. It
    /// defines the start of the raw PVS data for this leaf. If this
    /// value equals -1, no VIS lists are available for this leaf,
    /// usually if the map has been built without the VIS compiler.
    /// The next two 16bit integer triples span the bounding box of
    /// this leaf. Furthermore, the struct contains an index pointing
    /// into the array of marksurfaces loaded from the marksufaces
    /// lump as well as the number of consecutive marksurfaces belonging
    /// to this leaf. The marksurfaces are looped through during the
    /// rendering process and point to the actual faces. The final 4 bytes
    /// specify the volume of ambient sounds in Quake, but are unused in
    /// GoldSrc.
    /// </summary>
    /// <see href="https://developer.valvesoftware.com/wiki/BSP_(GoldSrc)"/>
    [StructLayout(LayoutKind.Sequential)]
    public sealed class BspLeaf
    {
        /// <summary>
        /// Contents enumeration
        /// </summary>
        public BspContents Contents;

        /// <summary>
        /// Offset into the visibility lump
        /// </summary>
        public int VisOffset;

        /// <summary>
        /// Defines bounding box
        /// </summary>
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
        public short[] Mins = new short[3];

        /// <summary>
        /// Defines bounding box
        /// </summary>
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
        public short[] Maxs = new short[3];

        /// <summary>
        /// Index into marksurfaces array
        /// </summary>
        public ushort FirstMarkSurfaceIndex;

        /// <summary>
        /// Count of marksurfaces array
        /// </summary>
        public ushort MarkSurfacesCount;

        /// <summary>
        /// Ambient sound levels
        /// </summary>
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
        public byte[] AmbientLevels = new byte[4];
    }
}