package main

import (
	"flag"
	"fmt"
	"image"
	"image/color"
	"log"
	"math"
	"os"
	"path/filepath"
	"renderer2/hrend"
	"runtime/pprof" // For performance profiling (unnecessary)
	"time"

	_ "image/jpeg"

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

const (
	NearClip = 0.0001
	FarClip  = 10
	Movement = 1.0
	Rotation = 0.25
	LookLock = math.Pi / 32
)

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

type ObjectDef struct {
	Model    *hrend.ObjModel
	Texture  hrend.Framebuffer // This needs to go somewhere else eventually!
	Pos      hrend.Vec3f
	LookVec  hrend.Vec3f
	Scale    float32
	Lighting bool
}

func NewObjectDef(model *hrend.ObjModel, texture hrend.Framebuffer) *ObjectDef {
	result := ObjectDef{
		Model:    model,
		Texture:  texture,
		LookVec:  hrend.Vec3f{X: 0, Y: 0, Z: -1},
		Scale:    1,
		Lighting: true,
	}
	return &result
}

func loadObject(name string) (*hrend.ObjModel, hrend.Framebuffer) {
	ofile := filepath.Join("../", name+".obj")
	tfile := filepath.Join("../", name+".jpg")
	log.Printf("Loading obj %s, texture %s", ofile, tfile)

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

	jf, err := os.Open(tfile)
	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 width = flag.Int("width", 640, "width of window or frame")
var height = flag.Int("height", 480, "height of window or frame")
var renderout = flag.String("renderout", "", "If set, rendering is done to a file instead of realtime")
var renderinput = flag.String("renderinput", "", "If not realtime, the inputs are taken from here.")
var xofs = flag.Float64("xofs", 0, "starting x-offset")
var zofs = flag.Float64("zofs", 0, "starting z-offset")
var yofs = flag.Float64("yofs", 0.5, "starting y-offset")
var fov = flag.Float64("fov", 90, "the horizontal fov")
var fps = flag.Int("fps", 60, "fps to run (realtime only)")
var minlight = flag.Float64("minlight", 0.5, "Minimum light level")

// var renderconfig = flag.String("renderconfig", "", "if set, rendering is written out")

func IsRealtime() bool {
	return *renderout == ""
}

// Do next inputs, whether they come from raylib or a file
func CameraInput(yaw, pitch float32) (float32, float32, hrend.Vec3f) {

	Fps := float32(*fps)
	mouse := rl.GetMouseDelta()
	pitch += Rotation * mouse.Y / Fps
	yaw += Rotation * mouse.X / Fps
	pitch = hrend.Clamp(pitch, LookLock, 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
	var moverot hrend.Mat44f
	moverot.SetRotationY(-yaw)
	newcamtrans = moverot.MultiplyPoint3(newcamtrans)

	return yaw, pitch, newcamtrans
}

// --------------------------------------------
//
//	MAIN
//
// --------------------------------------------
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()
	}

	Width := uint(*width)
	Height := uint(*height)

	var timer hrend.FrameTimer
	var fb hrend.Framebuffer
	var drawFunc func()

	if IsRealtime() {
		rl.InitWindow(int32(Width), int32(Height), "Simple renderer with raylib")
		defer rl.CloseWindow()
		rl.SetTargetFPS(int32(*fps))
		rl.DisableCursor()
		rfb := NewRaylibBuffer(Width, Height)
		defer rl.UnloadTexture(rfb.Texture)
		defer rl.UnloadImageColors(rfb.Data)
		defer rl.UnloadImage(rfb.Image)
		fb = rfb
		drawFunc = func() {
			rl.UpdateTexture(rfb.Texture, rfb.Data)
			rl.BeginDrawing()
			rl.ClearBackground(rl.RayWhite)
			rl.DrawTexture(rfb.Texture, 0, 0, rl.White)
			rl.DrawText(fmt.Sprintf("Frame: %.2fms", timer.LastAverage.Seconds()*1000), 5, 5, 20, rl.Red)
			rl.EndDrawing()
		}
	} else {
	}

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

	// Generate world
	wtexraw := Checkerboard([]color.Color{color.RGBA{R: 0, G: 255, B: 0, A: 255}, color.RGBA{R: 50, G: 150, B: 0, A: 255}}, 32)
	wtex := hrend.NewTexture(wtexraw, 1)
	world := FlatTerrain(1)

	// Generate skybox
	skyraw := Gradient1px(color.RGBA{R: 100, G: 100, B: 255, A: 255}, color.RGBA{R: 255, G: 255, B: 255, A: 255}, 32)
	skytex := hrend.NewTexture(skyraw, 1)
	sky := Skybox()

	// Some static models we could put in the scene
	modnames := []string{"head", "diablo"}
	models := make([]*hrend.ObjModel, len(modnames))
	textures := make([]hrend.Framebuffer, len(modnames))
	for i, name := range modnames {
		models[i], textures[i] = loadObject(name)
	}

	// And the actual objects for the scene. We also put the world in there
	objects := make([]*ObjectDef, 0)
	objects = append(objects, NewObjectDef(world, wtex))
	objects = append(objects, NewObjectDef(sky, skytex)) // the actual skybox
	skyobj := objects[len(objects)-1]
	skyobj.Scale = 50
	skyobj.Lighting = false
	objects = append(objects, NewObjectDef(models[1], textures[1]))
	objects[len(objects)-1].Pos.Y += 1
	objects[len(objects)-1].Pos.Z -= 2

	// These don't really change
	var projection hrend.Mat44f //, viewport hrend.Mat44f
	projection.SetProjection(float32(*fov), float32(Width)/float32(Height), NearClip, FarClip)
	//viewport.SetViewportSimple(int(Width), int(Height), 1) //65535)

	var camera hrend.Mat44f
	var newcamtrans hrend.Vec3f
	camtrans := hrend.Vec3f{X: float32(*xofs), Y: float32(*yofs), Z: float32(*zofs)}
	camup := hrend.Vec3f{X: 0, Y: 1, Z: 0}
	lightang := -math.Pi / 4 // Angle offset from "straight down"
	light := hrend.Vec3f{X: 0, Y: float32(-math.Cos(lightang)), Z: float32(math.Sin(lightang))}

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

	log.Printf("Starting render loop")
	for !rl.WindowShouldClose() {

		start := time.Now()

		yaw, pitch, newcamtrans = CameraInput(yaw, pitch)
		camtrans = *camtrans.Add(&newcamtrans)
		_ = camera.SetCamera(&camtrans, yaw, pitch, &camup)
		screenmat := camera.Inverse().Multiply(&projection)
		//screenmat = screenmat.Multiply(&viewport)

		rb.ResetZBuffer()
		for y := range Height {
			for x := range Width {
				fb.Set(x, y, 0, 0, 0)
			}
		}

		var sc [3]hrend.Vertex
		var modelmat hrend.Mat44f
		var intensity float32
		var minz = float32(math.MaxFloat32)
		var maxz = float32(-math.MaxFloat32)
		for _, o := range objects {
			// Create the final matrix
			modelmat.SetLookAt(&o.Pos, o.Pos.Add(&o.LookVec), &camup)
			modelmat.ScaleSelf(o.Scale)
			matrix3d := modelmat.Multiply(screenmat)
			for _, f := range o.Model.Faces {
				for i := range 3 {
					sc[i] = f[i]
					sc[i].Pos = matrix3d.MultiplyPoint3(f[i].Pos)
					minz = min(minz, sc[i].Pos.Z)
					maxz = max(maxz, sc[i].Pos.Z)
				}
				log.Print(o.Model.Faces[0][0].Pos, o.Model.Faces[0][1].Pos, o.Model.Faces[0][2].Pos)
				log.Print(sc[0].Pos, sc[1].Pos, sc[2].Pos)
				log.Print(matrix3d)
				for i := range 3 {
					// Perspective divide (?) and screen coord
					sc[i].Pos.ViewportSelf(*width, *height)
				}
				//log.Print(sc[0].Pos, sc[1].Pos, sc[2].Pos, matrix3d)
				if o.Lighting {
					l1 := f[2].Pos.Sub(&f[0].Pos)
					n := l1.CrossProduct(f[1].Pos.Sub(&f[0].Pos))
					n = n.Normalize()
					// light = lookvec // use this for weird things
					intensity = n.MultSimp(&light)
					if intensity < 0 {
						intensity = 0
					}
					intensity = (intensity + float32(*minlight)) / (1 + float32(*minlight))
				} else {
					intensity = 1.0
				}
				hrend.TriangleTextured(&rb, o.Texture, intensity, sc[0], sc[1], sc[2])
				break // only render one face
				//hrend.TriangleFlat(&rb, hrend.Col2Uint(byte(255*intensity), byte(255*intensity), byte(255*intensity)), sc[0].Pos, sc[1].Pos, sc[2].Pos)
			}
			break // only render one object
		}
		//log.Print(minz, maxz)

		timer.Add(time.Since(start), 10)
		drawFunc()
	}
}