//go:build example
// +build example

package system

import (
	"math"
	"time"

	"code.rocketnine.space/tslocum/gohan"
	"code.rocketnine.space/tslocum/gohan/examples/twinstick/component"
	"code.rocketnine.space/tslocum/gohan/examples/twinstick/entity"
	"github.com/hajimehoshi/ebiten/v2"
)

func angle(x1, y1, x2, y2 float64) float64 {
	return math.Atan2(y1-y2, x1-x2)
}

type fireInputSystem struct {
	player gohan.Entity
}

func NewFireInputSystem(player gohan.Entity) *fireInputSystem {
	return &fireInputSystem{
		player: player,
	}
}

func (_ *fireInputSystem) Components() []gohan.ComponentID {
	return []gohan.ComponentID{
		component.PositionComponentID,
		component.WeaponComponentID,
	}
}

func (s *fireInputSystem) fire(weapon *component.WeaponComponent, position *component.PositionComponent, fireAngle float64) {
	if time.Since(weapon.LastFire) < weapon.FireRate {
		return
	}

	weapon.Ammo--
	weapon.LastFire = time.Now()

	speedX := math.Cos(fireAngle) * -weapon.BulletSpeed
	speedY := math.Sin(fireAngle) * -weapon.BulletSpeed

	bullet := entity.NewBullet(position.X, position.Y, speedX, speedY)
	_ = bullet
}

func (s *fireInputSystem) Update(ctx *gohan.Context) error {
	position := component.Position(ctx)
	weapon := component.Weapon(ctx)

	if weapon.Ammo <= 0 {
		return nil
	}

	if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
		cursorX, cursorY := ebiten.CursorPosition()
		fireAngle := angle(position.X, position.Y, float64(cursorX), float64(cursorY))

		s.fire(weapon, position, fireAngle)
	}

	if ebiten.IsMouseButtonPressed(ebiten.MouseButtonRight) {
		cursorX, cursorY := ebiten.CursorPosition()
		fireAngle := angle(position.X, position.Y, float64(cursorX), float64(cursorY))

		const div = 5
		weapon.BulletSpeed /= div
		for i := 0.0; i < 24; i++ {
			s.fire(weapon, position, fireAngle+i*(math.Pi/12))
			weapon.LastFire = time.Time{}
		}
		weapon.BulletSpeed *= div
	}

	switch {
	case ebiten.IsKeyPressed(ebiten.KeyLeft) && ebiten.IsKeyPressed(ebiten.KeyUp):
		s.fire(weapon, position, math.Pi/4)
	case ebiten.IsKeyPressed(ebiten.KeyLeft) && ebiten.IsKeyPressed(ebiten.KeyDown):
		s.fire(weapon, position, -math.Pi/4)
	case ebiten.IsKeyPressed(ebiten.KeyRight) && ebiten.IsKeyPressed(ebiten.KeyUp):
		s.fire(weapon, position, math.Pi*.75)
	case ebiten.IsKeyPressed(ebiten.KeyRight) && ebiten.IsKeyPressed(ebiten.KeyDown):
		s.fire(weapon, position, -math.Pi*.75)
	case ebiten.IsKeyPressed(ebiten.KeyLeft):
		s.fire(weapon, position, 0)
	case ebiten.IsKeyPressed(ebiten.KeyRight):
		s.fire(weapon, position, math.Pi)
	case ebiten.IsKeyPressed(ebiten.KeyUp):
		s.fire(weapon, position, math.Pi/2)
	case ebiten.IsKeyPressed(ebiten.KeyDown):
		s.fire(weapon, position, -math.Pi/2)
	}

	return nil
}

func (_ *fireInputSystem) Draw(ctx *gohan.Context, _ *ebiten.Image) error {
	return gohan.ErrSystemWithoutDraw
}