package main

import (
	"fmt"
	"runtime"

	"github.com/go-gl/gl/v4.1-core/gl"
	"github.com/go-gl/glfw/v3.3/glfw"
	"github.com/go-gl/mathgl/mgl32"
)

const (
	start_width  = 1920
	start_height = 1080
)

var vertices = []float32{
	960, 540, 0.0,
	1460, 540, 0.0,
	960, 1040, 0.0,
}

const vertexShaderSource = `
#version 410 core
layout(location = 0) in vec3 position;
uniform mat4 u_Projection;
void main() {
    gl_Position = u_Projection * vec4(position, 1.0);
}
`

const fragmentShaderSource = `
#version 410 core
out vec4 color;
uniform vec4 u_Color;
void main() {
    color = u_Color;
}
`

func main() {
	runtime.LockOSThread()

	if err := glfw.Init(); err != nil {
	}
	defer glfw.Terminate()
	glfw.WindowHint(glfw.Decorated, glfw.True)
	glfw.WindowHint(glfw.TransparentFramebuffer, glfw.False)
	glfw.WindowHint(glfw.Resizable, glfw.False)

	glfw.WindowHint(glfw.ContextVersionMajor, 4)
	glfw.WindowHint(glfw.ContextVersionMinor, 1)
	glfw.WindowHint(glfw.OpenGLProfile, glfw.OpenGLCoreProfile)
	// glfw.WindowHint(glfw.TransparentFramebuffer, glfw.True)

	window, err := glfw.CreateWindow(start_width, start_height, "Learning OpenGL", nil, nil)
	if err != nil {
	}
	defer window.Destroy()

	window.MakeContextCurrent()

	if err := gl.Init(); err != nil {
		glfw.Terminate()
	}

	gl.Viewport(0, 0, int32(start_width), int32(start_height))

	window.SetMouseButtonCallback(func(w *glfw.Window, button glfw.MouseButton, action glfw.Action, mods glfw.ModifierKey) {
		println("Mouse Button Event!")
	})

	window.SetSizeCallback(func(w *glfw.Window, width int, height int) {
		fmt.Printf("Window resize event - Width: %d, Height: %d\n", width, height)
	})

	shader, _ := NewShader(vertexShaderSource, fragmentShaderSource)

	projection := CreateOrthographicProjection(start_width, start_height)

	vao := NewVertexArray()
	vbo := NewVertexBuffer(vertices)
	vao.AddBuffer(vbo, []int32{3})

	gl.ClearColor(0.2, 0.3, 0.3, 1.0)

	for !window.ShouldClose() {
		shader.Use()

		shader.SetUniformM("u_Projection", projection)
		color := HLColorRGBA{255, 0, 0, 255}
		shader.SetUniform4f("u_Color", float32(color.R)/255.0, float32(color.G)/255.0, float32(color.B)/255.0, float32(color.A)/255.0)

		gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)

		// Handled by the Draw Rectangle function
		// vao.Bind()
		// gl.DrawArrays(gl.TRIANGLES, 0, 3)
		DrawRectangleWH(0, 0, 100, 200, HLColorRGBA{255, 0, 0, 255})

		window.SwapBuffers()
		glfw.PollEvents()
	}

}

func CreateOrthographicProjection(width, height int) mgl32.Mat4 {
	return mgl32.Ortho(0, float32(width), 0, float32(height), -1, 1)
}