using System.Diagnostics;
using System.Runtime.InteropServices;

namespace Djup.Native;

[StructLayout(LayoutKind.Sequential)]
public struct Vec2
{
    public float X { get; }
    public float Y { get; }

    public Vec2(float x, float y)
    {
        Debug.Assert(float.IsFinite(x));
        Debug.Assert(float.IsFinite(y));

        X = x;
        Y = y;
    }

    public override string ToString() => $"({X}, {Y})";
}

public enum EntityState : byte
{
    Inactive = 0,
    Active,
    Removed,
    Dead
}

public enum PlayerInput : byte
{
    Up = 1 << 0,
    Down = 1 << 1,
    Left = 1 << 2,
    Right = 1 << 3
}

[StructLayout(LayoutKind.Sequential)]
public struct Player
{
    public EntityState State { get; }
    private byte input;
    public Vec2 Position { get; set; }
    public Vec2 Velocity { get; set; }
}

[StructLayout(LayoutKind.Sequential)]
public struct Bullet
{
    public EntityState State { get; set; }
    public Vec2 Position { get; set; }
    public Vec2 Velocity { get; set; }
}

[StructLayout(LayoutKind.Sequential)]
public unsafe struct Snapshot
{
    private byte active;
    public uint Tick { get; }
    private int playersLength;
    private Player* players;
    private int bulletsLength;
    private Bullet* bullets;

    public ReadOnlySpan<Player> Players =>
        new ReadOnlySpan<Player>(players, playersLength);

    public ReadOnlySpan<Bullet> Bullets =>
        new ReadOnlySpan<Bullet>(bullets, bulletsLength);
}

public enum LogLevel
{
    Trace,
    Debug,
    Info,
    Warn,
    Error,
    Fatal
}

public delegate void LoggerDelegate(LogLevel level, string source, int line, string message);