package main

import (
	"flag"
	"image"
	"log"
	"os"
	"renderer1/hrend"
	"runtime/pprof" // For performance profiling (unnecessary)

	_ "image/jpeg"

	rl "github.com/gen2brain/raylib-go/raylib"
)

const (
	Width       = 640
	Height      = 480
	NearClip    = 0.1
	FarClip     = 100
	FOV         = 90.0
	ZOffset     = -1.5
	ObjectFile  = "head.obj"
	TextureFile = "../head.jpg"
)

func must(err error) {
	if err != nil {
		panic(err)
	}
}

func loadDefault() (*hrend.ObjModel, hrend.Framebuffer) {
	log.Printf("Loading obj %s, texture %s", ObjectFile, TextureFile)

	of, err := os.Open(ObjectFile)
	must(err)
	defer of.Close()
	o, err := hrend.ParseObj(of)
	must(err)

	jf, err := os.Open(TextureFile)
	must(err)
	defer jf.Close()
	timg, _, err := image.Decode(jf)
	must(err)
	texture := hrend.NewTexture(timg, 4)

	return o, texture
}

// However flag works... idk
var cpuprofile = flag.String("cpuprofile", "", "write cpu profile to file")

// var dozbuf = flag.Bool("zbuffer", false, "Write zbuffer instead of image")
// var p6file = flag.String("p6file", "", "Output binary ppm to given file instead")
// var fov = flag.Float64("fov", 90, "Horizontal FOV in degrees")
// var xofs = flag.Float64("xofs", 0, "Offset image by x")
// var zofs = flag.Float64("zofs", -1.5, "Offset image by z (should be negative)")
// var repeat = flag.Int("repeat", 60, "Amount of times to repeat render")

func main() {
	log.Printf("Program start")

	flag.Parse()
	if *cpuprofile != "" {
		log.Printf("CPU profiling requested, write to %s", *cpuprofile)
		f, err := os.Create(*cpuprofile)
		must(err)
		defer f.Close()
		err = pprof.StartCPUProfile(f)
		must(err)
		defer pprof.StopCPUProfile()
	}

	fb := NewRaylibBuffer(Width, Height)
	rb := hrend.NewRenderbuffer(fb, Width, Height)
	o, texture := loadDefault()

	light := hrend.Vec3f{0, 0, -1}

	var projection, worldToCamera, viewport hrend.Mat44f

	rl.InitWindow(Width, Height, "Simple renderer with raylib")
	defer rl.CloseWindow()

	rl.SetTargetFPS(60)

	var thing hrend.Vec2i
	log.Print(thing)

	for !rl.WindowShouldClose() {
		rl.BeginDrawing()

		screenmat := worldToCamera.Multiply(&projection)
		screenmat = screenmat.Multiply(&viewport)

		var sc [3]hrend.Vertex
		rb.ResetZBuffer()
		for _, f := range o.Faces {
			// Precompute perspective for vertices to save time. Notice Z
			// is not considered: is this orthographic projection? Yeah probably...
			var fpt [3]hrend.Vec3f
			for i := range 3 { // Triangles, bro
				sc[i] = f[i]
				sc[i].Pos = screenmat.MultiplyPoint3(f[i].Pos)
				fpt[i] = worldToCamera.MultiplyPoint3(f[i].Pos)
			}

			l1 := fpt[2].Sub(fpt[0])
			n := l1.CrossProduct(fpt[1].Sub(fpt[0]))
			n = n.Normalize()
			intensity := n.MultSimp(&light)
			if intensity > 0 {
				hrend.TriangleTextured(&rb, texture, intensity, sc[0], sc[1], sc[2])
			}
		}

		rl.ClearBackground(rl.RayWhite)
		rl.DrawText("Congrats! You created your first window!", 190, 200, 20, rl.LightGray)

		rl.EndDrawing()
	}
}