package sprites

import (
	"image"

	"git.vezzani.net/ben/games/common/ux/v1"
	"github.com/hajimehoshi/ebiten/v2"
)

var (
	updateCount int
)

func Update() {
	updateCount++
}

type animation struct {
	RowNumber  uint8
	FrameCount uint8
	Scale      float32
}

type subImager interface {
	image.Image
	SubImage(r image.Rectangle) image.Image
}

type Sprite struct {
	width, height int
	imgData       subImager
	animations    map[string]animation

	baseAnim *animation
}

func (s *Sprite) baseAnimation() animation {
	if s.baseAnim != nil {
		return *s.baseAnim
	}

	for i := range s.animations {
		if s.animations[i].RowNumber == 0 {
			a := s.animations[i]
			s.baseAnim = &a
			return a
		}
	}

	return animation{}
}

func (s *Sprite) getAnimation(id string) animation {
	if id == "" {
		return s.baseAnimation()
	}

	if anim, ok := s.animations[id]; ok {
		return anim
	}

	return s.baseAnimation()
}

func (s *Sprite) Image(ops imageOptions) image.Image {
	anim := s.getAnimation(ops.animation)

	xOffset := updateCount % int(anim.FrameCount) * s.width
	yOffset := int(anim.RowNumber) * s.height

	r := image.Rect(xOffset, yOffset, s.width, s.height).Intersect(s.imgData.Bounds())

	return s.imgData.SubImage(r)
}

func (s *Sprite) Draw(screen *ebiten.Image, options ...ImageOption) {
	ops := imageOptions{
		scaleX: ux.Scale,
		scaleY: ux.Scale,
	}

	for _, o := range options {
		o(&ops)
	}

	geom := ebiten.GeoM{}
	geom.Translate(ops.x, ops.y)
	geom.Scale(ops.scaleX, ops.scaleY)
	geom.Rotate(ops.rotateTheta)

	screen.DrawImage(
		ebiten.NewImageFromImage(
			s.Image(ops),
		),
		&ebiten.DrawImageOptions{
			GeoM: geom,
		},
	)
}

type imageOptions struct {
	x, y           float64
	scaleX, scaleY float64
	rotateTheta    float64
	animation      string
}

type ImageOption func(options *imageOptions)

func ToScale(x, y float64) ImageOption {
	return func(o *imageOptions) {
		o.scaleX *= x
		o.scaleY *= y
	}
}

func Animation(name string) ImageOption {
	return func(o *imageOptions) {
		o.animation = name
	}
}

func AtPosition(x, y float64) ImageOption {
	return func(o *imageOptions) {
		o.x, o.y = x, y
	}
}

func Rotate(theta float64) ImageOption {
	return func(o *imageOptions) {
		o.rotateTheta = theta
	}
}