using System;
using System.Collections.Generic;
using Quik;
using Quik.VertexGenerator;
using OpenTK.Graphics.OpenGL4;
using OpenTK.Mathematics;
using OpenTK.Windowing.Common;
using OpenTK.Windowing.Desktop;
using OpenTK.Windowing.GraphicsLibraryFramework;

namespace QuikTestApplication
{
    public class Program
    {
        public const string vertex =
            @"#version 140
uniform mat4 matrix;
in vec2 position;
in vec2 texcoord;
in vec4 color;
out vec2 ftexcoord;
out vec4 fcolor;

void main()
{
    fcolor = color;
    ftexcoord = texcoord;
    gl_Position = matrix * vec4(position.xy, 0, 1);
}
";

        public const string fragment =
            @"#version 140
in vec2 ftexcoord;
in vec4 fcolor;
out vec4 outcolor;

void main()
{
    outcolor = fcolor;
}
";
        
        public static void Main(string[] args)
        {
            NativeWindowSettings windowSettings = NativeWindowSettings.Default;
            windowSettings.NumberOfSamples = 4;
            NativeWindow window = new NativeWindow(windowSettings);
            
            window.Context.MakeCurrent();
            GL.LoadBindings(new GLFWBindingsContext());

            QuikContext context = new QuikContext();
            QuikVertexGenerator gen = new QuikVertexGenerator(context);
            
            GL.Enable(EnableCap.Multisample);

            int sp;
            {
                int vs, fs;

                sp = GL.CreateProgram();
                
                vs = GL.CreateShader(ShaderType.VertexShader);
                fs = GL.CreateShader(ShaderType.FragmentShader);

                GL.ShaderSource(vs, vertex);
                GL.CompileShader(vs);
                GL.ShaderSource(fs, fragment);
                GL.CompileShader(fs);
                
                GL.AttachShader(sp, vs);
                GL.AttachShader(sp, fs);
                GL.LinkProgram(sp);
                
                GL.UseProgram(sp);
            }
            
            int vbo, ebo, vao;
            vbo = GL.GenBuffer();
            ebo = GL.GenBuffer();

            vao = GL.GenVertexArray();
            GL.BindVertexArray(vao);
            
            GL.BindBuffer(BufferTarget.ArrayBuffer, vbo);
            GL.BindBuffer(BufferTarget.ElementArrayBuffer, ebo);

            int loc;
            GL.VertexAttribPointer(
                loc = GL.GetAttribLocation(sp, "position"),
                2,
                VertexAttribPointerType.Float,
                false,
                QuikVertex.Stride,
                QuikVertex.PositionOffset);
            GL.EnableVertexAttribArray(loc);
            GL.VertexAttribPointer(
                loc = GL.GetAttribLocation(sp, "texcoords"),
                2,
                VertexAttribPointerType.Float,
                false,
                QuikVertex.Stride,
                QuikVertex.TextureCoordinatesOffset);
            GL.EnableVertexAttribArray(loc);
            GL.VertexAttribPointer(
                loc = GL.GetAttribLocation(sp, "color"),
                4,
                VertexAttribPointerType.UnsignedByte,
                true,
                QuikVertex.Stride,
                QuikVertex.ColorOffset);
            GL.EnableVertexAttribArray(loc);

            loc = GL.GetUniformLocation(sp, "matrix");

            List<QuikDrawCall> calls = new List<QuikDrawCall>();

            for (;!window.IsExiting;)
            {
                NativeWindow.ProcessWindowEvents(false);

                GL.Viewport(0, 0, window.Size.X, window.Size.Y);

                GL.ClearColor(1,1,1,1);
                GL.Clear(ClearBufferMask.ColorBufferBit);
                
                Matrix4 matrix = Matrix4.CreateOrthographicOffCenter(
                    0,
                    window.Size.X,
                    0,
                    window.Size.Y,
                    1, 
                    -1);
                GL.UniformMatrix4(loc, false, ref matrix);
                
                context.Draw.Line(
                    new QuikLine()
                    {
                        Start = new QuikVec2()
                        {
                            X = 20,
                            Y = 40
                        },
                        End = new QuikVec2()
                        {
                            X=100,
                            Y=100
                        }
                    });

                QuikCommand command;
                while (context.Draw.Commands.TryDequeue(out command))
                {
                    QuikDrawCall? call = gen.ConsumeCommand(command);
                    if (call.HasValue) calls.Add(call.Value);
                }
                
                GL.BufferData(BufferTarget.ArrayBuffer, gen.VertexCount * QuikVertex.Stride, ref gen.VertexBuffer[0], BufferUsageHint.StreamDraw);
                GL.BufferData(BufferTarget.ElementArrayBuffer, gen.ElementCount * 2, ref gen.ElementBuffer[0], BufferUsageHint.StreamDraw);
                
                foreach (QuikDrawCall call in calls)
                {
                    GL.DrawElements(BeginMode.Triangles, call.Count, DrawElementsType.UnsignedShort, call.Offset);
                }
                
                gen.Clear();
                calls.Clear();

                window.Context.SwapBuffers();
            }
        }
    }
}