package main

import (
	"fmt"
	"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/material"
	am "git.tek.govt.hu/dowerx/opengl-deferred/utils/assetmanager"
	"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  = 1280
	HEIGHT = 720
	TITLE  = "opengl-deferred"
	FOV    = 75.0
)

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.CULL_FACE)
	gl.DepthFunc(gl.LESS)
	gl.ClearColor(0, 0, 0, 1)

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

	// load assets
	assetManager, err := am.Init("assets")
	if err != nil {
		panic(err)
	}
	defer assetManager.Destroy()

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

	// lights
	lights := []light.Light{
		{Color: [3]float32{1, 1, 1}, Position: mgl32.Vec3{0, 10, 0}, Intensity: 40, Type: light.POINT},
		{Color: [3]float32{1, 0, 0}, Position: mgl32.Vec3{5, 5, 5}, Intensity: 30, Type: light.POINT},
		{Color: [3]float32{0, 0, 1}, Position: mgl32.Vec3{-5, 5, -5}, Intensity: 30, 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.Get(10, 10, mgl32.Vec3{0, 0, -10}, mgl32.Vec2{0, 0}, window)

	demoMaterial := am.GetAsset[material.Material]("assets/material/demo")
	screenMaterial := am.GetAsset[material.Material]("assets/material/screen-debug")

	teapot := am.GetAsset[geometry.Geometry]("assets/geometry/teapot")

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

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

		gbuff.Bind()

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

		// apply the material
		demoMaterial.Apply()
		// transfer uniforms
		demoMaterial.Shader.Mat4("projection", projection)
		demoMaterial.Shader.Mat4("view", controls.View())
		demoMaterial.Shader.Mat4("model", model)

		teapot.Draw()

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

		gbuff.BindTextures()

		screenMaterial.Apply()

		pos := controls.Position()
		screenMaterial.Shader.Vec3("view_pos", &pos[0])

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

		screen.Draw()

		window.SwapBuffers()
	}

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