using System.Numerics;
using Silk.NET.OpenGL;

namespace AcDream.App.Rendering;

public sealed class Shader : IDisposable
{
    private readonly GL _gl;
    public uint Program { get; }

    public Shader(GL gl, string vertexPath, string fragmentPath)
    {
        _gl = gl;
        uint vert = Compile(File.ReadAllText(vertexPath), ShaderType.VertexShader);
        uint frag = Compile(File.ReadAllText(fragmentPath), ShaderType.FragmentShader);

        Program = _gl.CreateProgram();
        _gl.AttachShader(Program, vert);
        _gl.AttachShader(Program, frag);
        _gl.LinkProgram(Program);
        _gl.GetProgram(Program, ProgramPropertyARB.LinkStatus, out int linked);
        if (linked == 0)
            throw new Exception("program link failed: " + _gl.GetProgramInfoLog(Program));
        _gl.DetachShader(Program, vert);
        _gl.DetachShader(Program, frag);
        _gl.DeleteShader(vert);
        _gl.DeleteShader(frag);
    }

    private uint Compile(string source, ShaderType type)
    {
        uint id = _gl.CreateShader(type);
        _gl.ShaderSource(id, source);
        _gl.CompileShader(id);
        _gl.GetShader(id, ShaderParameterName.CompileStatus, out int ok);
        if (ok == 0)
            throw new Exception($"{type} compile failed: " + _gl.GetShaderInfoLog(id));
        return id;
    }

    public void Use() => _gl.UseProgram(Program);

    public unsafe void SetMatrix4(string name, Matrix4x4 m)
    {
        int loc = _gl.GetUniformLocation(Program, name);
        _gl.UniformMatrix4(loc, 1, false, (float*)&m);
    }

    public void SetInt(string name, int value)
    {
        int loc = _gl.GetUniformLocation(Program, name);
        _gl.Uniform1(loc, value);
    }

    public void SetFloat(string name, float value)
    {
        int loc = _gl.GetUniformLocation(Program, name);
        _gl.Uniform1(loc, value);
    }

    public void SetVec3(string name, Vector3 v)
    {
        int loc = _gl.GetUniformLocation(Program, name);
        _gl.Uniform3(loc, v.X, v.Y, v.Z);
    }

    public void SetVec2(string name, Vector2 v)
    {
        int loc = _gl.GetUniformLocation(Program, name);
        _gl.Uniform2(loc, v.X, v.Y);
    }

    public void SetVec4(string name, Vector4 v)
    {
        int loc = _gl.GetUniformLocation(Program, name);
        _gl.Uniform4(loc, v.X, v.Y, v.Z, v.W);
    }

    public void Dispose() => _gl.DeleteProgram(Program);
}