package main

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

	_ "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
	Movement    = 1.0
	Rotation    = 0.25
	LookLock    = math.Pi / 32
	Fps         = 60
	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()
	}

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

	rl.SetTargetFPS(Fps)
	rl.DisableCursor()

	fb := NewRaylibBuffer(Width, Height)
	defer rl.UnloadTexture(fb.Texture)
	defer rl.UnloadImageColors(fb.Data)
	defer rl.UnloadImage(fb.Image)

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

	var thing hrend.Vec2i
	log.Print(thing)

	var projection, viewport hrend.Mat44f

	// These don't really change
	projection.SetProjection(float32(FOV), float32(Width)/float32(Height), NearClip, FarClip)
	viewport.SetViewportSimple(int(fb.Width), int(fb.Height), 1) //65535)

	log.Printf("Starting raylib loop")

	frameSum := 0.0
	frameCount := 0
	frameAverage := 0.0

	camtrans := hrend.Vec3f{X: 0, Y: 0, Z: ZOffset}
	camup := hrend.Vec3f{X: 0, Y: 1, Z: 0}

	// In our system, 0 degree yaw is facing -Z, into the scene
	yaw := float32(0)
	pitch := float32(math.Pi / 2) // Start looking flat

	var camera, moverot hrend.Mat44f

	for !rl.WindowShouldClose() {

		start := time.Now()

		mouse := rl.GetMouseDelta()

		pitch += Rotation * mouse.Y / Fps
		yaw += Rotation * mouse.X / Fps

		// Need a clamp function or something
		if pitch < LookLock {
			pitch = LookLock
		} else if pitch > math.Pi-LookLock {
			pitch = math.Pi - LookLock
		}

		newcamtrans := hrend.Vec3f{X: 0, Y: 0, Z: 0}
		if rl.IsKeyDown(rl.KeyD) {
			newcamtrans.X += Movement / Fps
		}
		if rl.IsKeyDown(rl.KeyA) {
			newcamtrans.X -= Movement / Fps
		}
		// Moving forward moves in the negative z direction, since we FACE
		// the -z axis (the camera does anyway)
		if rl.IsKeyDown(rl.KeyW) {
			newcamtrans.Z -= Movement / Fps
		}
		if rl.IsKeyDown(rl.KeyS) {
			newcamtrans.Z += Movement / Fps
		}
		if rl.IsKeyDown(rl.KeySpace) {
			newcamtrans.Y += Movement / Fps
		}
		if rl.IsKeyDown(rl.KeyLeftShift) {
			newcamtrans.Y -= Movement / Fps
		}

		// translate the new camera movement based on the yaw
		moverot.SetRotationY(-yaw)
		newcamtrans = moverot.MultiplyPoint3(newcamtrans)
		camtrans = *camtrans.Add(&newcamtrans)

		// The camera is really just a model
		lookvec := camera.SetCamera(&camtrans, yaw, pitch, &camup)

		screenmat := camera.Inverse().Multiply(&projection)
		screenmat = screenmat.Multiply(&viewport)

		for i := 0; i < Width*Height; i++ {
			fb.Data[i].R = 0
			fb.Data[i].G = 0
			fb.Data[i].B = 0
		}

		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...
			for i := range 3 { // Triangles, bro
				sc[i] = f[i]
				sc[i].Pos = screenmat.MultiplyPoint3(f[i].Pos)
			}

			l1 := f[2].Pos.Sub(&f[0].Pos)
			n := l1.CrossProduct(f[1].Pos.Sub(&f[0].Pos))
			n = n.Normalize()
			intensity := n.MultSimp(&lookvec)
			if intensity < 0 {
				intensity = 0
			}
			hrend.TriangleTextured(&rb, texture, intensity, sc[0], sc[1], sc[2])
			//hrend.TriangleFlat(&rb, hrend.Col2Uint(byte(255*intensity), byte(255*intensity), byte(255*intensity)), sc[0].Pos, sc[1].Pos, sc[2].Pos)
		}

		rl.UpdateTexture(fb.Texture, fb.Data)

		frameSum += time.Since(start).Seconds()
		frameCount += 1
		if frameCount&0x7 == 0 {
			frameAverage = frameSum / float64(frameCount)
			frameSum = 0
			frameCount = 0
		}

		rl.BeginDrawing()
		rl.ClearBackground(rl.RayWhite)
		rl.DrawTexture(fb.Texture, 0, 0, rl.White)
		rl.DrawText(fmt.Sprintf("Frame: %fms", frameAverage*1000), 5, 5, 20, rl.Red)
		rl.EndDrawing()
	}
}