package main

import (
	"fmt"
	"os"
	"runtime"

	"git.tek.govt.hu/dowerx/opengl-deferred/types/gbuffer"
	"git.tek.govt.hu/dowerx/opengl-deferred/types/geometry"
	"git.tek.govt.hu/dowerx/opengl-deferred/types/light"
	"git.tek.govt.hu/dowerx/opengl-deferred/types/shader"
	"git.tek.govt.hu/dowerx/opengl-deferred/types/texture"
	"git.tek.govt.hu/dowerx/opengl-deferred/utils/fpscontrols"
	"github.com/go-gl/gl/v4.6-core/gl"
	"github.com/go-gl/glfw/v3.3/glfw"
	"github.com/go-gl/mathgl/mgl32"
)

const (
	WIDTH  = 800
	HEIGHT = 600
	TITLE  = "opengl-deferred"
	FOV    = 45.0
)

func main() {

	// init glfw
	runtime.LockOSThread()
	if err := glfw.Init(); err != nil {
		panic(err)
	}
	defer glfw.Terminate()

	glfw.WindowHint(glfw.Resizable, glfw.False)
	glfw.WindowHint(glfw.ContextVersionMajor, 4)
	glfw.WindowHint(glfw.ContextVersionMinor, 6)
	glfw.WindowHint(glfw.OpenGLProfile, glfw.OpenGLCoreProfile)
	glfw.WindowHint(glfw.OpenGLForwardCompatible, glfw.True)

	window, err := glfw.CreateWindow(WIDTH, HEIGHT, TITLE, nil, nil)
	if err != nil {
		panic(err)
	}
	window.MakeContextCurrent()

	// init gl
	if err := gl.Init(); err != nil {
		panic(err)
	}

	gl.Enable(gl.DEPTH_TEST)
	gl.Enable(gl.CULL_FACE)
	gl.DepthFunc(gl.LESS)
	gl.ClearColor(0, 0, 0, 0)

	fmt.Println("OpenGL version:", gl.GoStr(gl.GetString(gl.VERSION)))

	// load assets
	// shader
	vertexSource, err := os.ReadFile("assets/shader/deferred/deferred.vs")
	if err != nil {
		panic(err)
	}
	fragmentSource, err := os.ReadFile("assets/shader/deferred/deferred.fs")
	if err != nil {
		panic(err)
	}

	deferredShader, err := shader.New(string(vertexSource), string(fragmentSource))
	if err != nil {
		panic(err)
	}
	defer deferredShader.Delete()

	vertexSource, err = os.ReadFile("assets/shader/screen/screen.vs")
	if err != nil {
		panic(err)
	}
	fragmentSource, err = os.ReadFile("assets/shader/screen/screen.fs")
	if err != nil {
		panic(err)
	}

	screenShader, err := shader.New(string(vertexSource), string(fragmentSource))
	if err != nil {
		panic(err)
	}
	defer screenShader.Delete()

	// geometry
	cube, err := geometry.LoadOBJ("assets/geometries/suzanne.obj")
	if err != nil {
		panic(err)
	}
	defer cube.Delete()

	screen, err := geometry.Screen()
	if err != nil {
		panic(err)
	}
	defer screen.Delete()

	// textures
	albedo, err := texture.Load("assets/textures/TCom_Pavement_PaintedConcrete3_512_albedo.tif")
	if err != nil {
		panic(err)
	}
	defer albedo.Delete()

	normal, err := texture.Load("assets/textures/TCom_Pavement_PaintedConcrete3_512_normal.tif")
	if err != nil {
		panic(err)
	}
	defer normal.Delete()

	specular, err := texture.Load("assets/textures/TCom_Pavement_PaintedConcrete3_512_roughness.tif")
	if err != nil {
		panic(err)
	}
	defer specular.Delete()

	roughness, err := texture.Load("assets/textures/TCom_Pavement_PaintedConcrete3_512_roughness.tif")
	if err != nil {
		panic(err)
	}
	defer roughness.Delete()

	metalic, err := texture.Load("assets/textures/TCom_Pavement_PaintedConcrete3_512_roughness.tif")
	if err != nil {
		panic(err)
	}
	defer metalic.Delete()

	// lights
	lights := []light.Light{
		{Color: [3]float32{0, 1, 0}, Position: mgl32.Vec3{3, 3, 3}, Intensity: 3, Type: light.POINT},
		{Color: [3]float32{1, 0, 1}, Position: mgl32.Vec3{3, 3, -3}, Intensity: 15, Type: light.POINT},
	}

	// gbuffer
	gbuff, err := gbuffer.New(WIDTH, HEIGHT)
	if err != nil {
		panic(err)
	}
	defer gbuff.Delete()
	gbuff.Bind()

	// transformations
	projection := mgl32.Perspective(mgl32.DegToRad(FOV), float32(WIDTH)/HEIGHT, 0.1, 1000)
	model := mgl32.Ident4()
	controls := fpscontrols.New(1, 0.1, mgl32.Vec3{0, 0, -10}, 0, 0, window)

	for !window.ShouldClose() {
		glfw.PollEvents()
		controls.Update()

		// first pass
		// bind textures
		gl.Enable(gl.DEPTH_TEST)

		gbuff.Bind()

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

		albedo.Bind(gl.TEXTURE0)
		normal.Bind(gl.TEXTURE1)
		specular.Bind(gl.TEXTURE2)
		roughness.Bind(gl.TEXTURE3)
		metalic.Bind(gl.TEXTURE4)

		// transfer uniforms
		deferredShader.Use()
		deferredShader.Mat4("projection", projection)
		deferredShader.Mat4("view", controls.ViewMatrix())
		deferredShader.Mat4("model", model)

		deferredShader.Int("s_albedo", 0)
		deferredShader.Int("s_normal", 1)
		deferredShader.Int("s_specular", 2)
		deferredShader.Int("s_roughness", 3)
		deferredShader.Int("s_metalic", 4)
		cube.Draw()

		// second pass
		gl.Disable(gl.DEPTH_TEST)
		gl.BindFramebuffer(gl.FRAMEBUFFER, 0)
		gl.Clear(gl.COLOR_BUFFER_BIT)

		gbuff.BindTextures()

		screenShader.Use()
		screenShader.Int("s_albedo", 0)
		screenShader.Int("s_depth", 1)
		screenShader.Int("s_normal", 2)
		screenShader.Int("s_material", 3)
		screenShader.Int("s_position", 4)
		pos := controls.Position()
		screenShader.Vec3("view_pos", &pos[0])

		for _, light := range lights {
			screenShader.Light(&light)
		}

		screen.Draw()

		window.SwapBuffers()
	}

	defer fmt.Println("exiting...")
}