package internal

import (
	"image"
	"image/color"

	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/vector"
)

type ball struct {
	x      float32
	speedX float32
	y      float32
	speedY float32
	r      float32
}

const (
	ballBaseRadius = 5
	ballBaseSpeedX = 1
	ballBaseSpeedY = 1
)

func newBall(screenWidth, screenHeight int) *ball {
	fScreenWidth := float32(screenWidth)
	fScreenHeight := float32(screenHeight)
	r := ballBaseRadius * fScreenHeight / BaseHeight
	return &ball{
		x:      fScreenWidth/2.0 - r,
		speedX: ballBaseSpeedX * fScreenWidth / BaseWidth,
		y:      fScreenHeight/2.0 - r,
		speedY: ballBaseSpeedY * fScreenHeight / BaseHeight,
		r:      r,
	}
}

var ballColor = color.White

func (b *ball) draw(img *ebiten.Image) {
	vector.DrawFilledCircle(img, b.x, b.y, b.r, ballColor, false)
}

func (b *ball) update(bounds image.Rectangle) error {
	b.x, b.y, b.speedX, b.speedY = b.nextPosAndSpeed(bounds)
	return nil
}

//nolint:nonamedreturns
func (b *ball) nextPos(bounds image.Rectangle) (x, y float32) {
	x, y, _, _ = b.nextPosAndSpeed(bounds)
	return x, y
}

//nolint:nonamedreturns
func (b *ball) nextPosAndSpeed(bounds image.Rectangle) (x, y, speedX, speedY float32) {
	speedX, speedY = b.nextSpeed(bounds)
	return b.x + speedX, b.y + speedY, speedX, speedY
}

//nolint:nonamedreturns
func (b *ball) nextSpeed(bounds image.Rectangle) (speedX, speedY float32) {
	speedX = b.speedX
	if b.x+b.r >= float32(bounds.Max.X) || b.x-b.r <= float32(bounds.Min.X) {
		speedX *= -1
	}

	speedY = b.speedY
	if b.y+b.r >= float32(bounds.Max.Y) || b.y-b.r <= float32(bounds.Min.Y) {
		speedY *= -1
	}

	return speedX, speedY
}

func (b *ball) resize(x, y float32) {
	b.x *= x
	b.speedX *= x
	b.y *= y
	b.speedY *= y
	b.r *= y
}