package hero

import (
	"image/color"
	"math"

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

// Direction flags from the controls.
type Input struct {
	Left  bool
	Right bool
	Up    bool
	Down  bool
}

// Playfield limits for movement.
type Bounds struct {
	Width  float64
	Height float64
}

// Player avatar data.
type Hero struct {
	X      float64
	Y      float64
	Radius float64
	Speed  float64
	Color  color.NRGBA
}

// Spawn settings for the avatar.
type Config struct {
	StartX float64
	StartY float64
	Radius float64
	Speed  float64
	Color  color.NRGBA
}

// Builds an avatar from the config with fallbacks.
func New(cfg Config) *Hero {
	if cfg.Radius <= 0 {
		cfg.Radius = 24
	}
	if cfg.Speed <= 0 {
		cfg.Speed = 180
	}
	if cfg.Color.A == 0 {
		cfg.Color = color.NRGBA{R: 210, G: 220, B: 255, A: 255}
	}

	return &Hero{
		X:      cfg.StartX,
		Y:      cfg.StartY,
		Radius: cfg.Radius,
		Speed:  cfg.Speed,
		Color:  cfg.Color,
	}
}

// Applies movement input and clamps to the playfield.
func (h *Hero) Update(input Input, dt float64, bounds Bounds) {
	dx, dy := 0.0, 0.0

	if input.Left {
		dx -= 1
	}
	if input.Right {
		dx += 1
	}
	if input.Up {
		dy -= 1
	}
	if input.Down {
		dy += 1
	}

	if dx != 0 || dy != 0 {
		length := math.Hypot(dx, dy)
		dx /= length
		dy /= length
	}

	h.X += dx * h.Speed * dt
	h.Y += dy * h.Speed * dt

	maxX := math.Max(h.Radius, bounds.Width-h.Radius)
	maxY := math.Max(h.Radius, bounds.Height-h.Radius)

	h.X = clamp(h.X, h.Radius, maxX)
	h.Y = clamp(h.Y, h.Radius, maxY)
}

// Renders the avatar as a filled circle.
func (h *Hero) Draw(screen *ebiten.Image) {
	vector.FillCircle(
		screen,
		float32(h.X),
		float32(h.Y),
		float32(h.Radius),
		h.Color,
		false,
	)
}

func clamp(value, min, max float64) float64 {
	if value < min {
		return min
	}
	if value > max {
		return max
	}
	return value
}