openquell/systems/pair_system.go

package systems

import (
	"openquell/components"
	. "openquell/components"
	. "openquell/config"
	"openquell/grid"
	"openquell/observers"

	"github.com/hajimehoshi/ebiten/v2"
	"github.com/mlange-42/arche/ecs"
	"github.com/mlange-42/arche/generic"
)

type PairSystem struct {
	World          *ecs.World
	DoorSelector   *generic.Filter4[Position, Renderable, Bond, Door]
	SwitchSelector *generic.Filter4[Position, Renderable, Bond, Switch]
	GridContainer  *grid.GridContainer
	DoorMapper     generic.Map4[
		components.Position,
		components.Renderable,
		components.Bond,
		components.Door]
}

type ToggleDoor struct {
	Entity ecs.Entity
	Open   bool
}

func NewPairSystem(world *ecs.World, gridcontainer *grid.GridContainer) System {
	doormapper := generic.NewMap4[
		components.Position,
		components.Renderable,
		components.Bond,
		components.Door](world)

	system := &PairSystem{
		DoorSelector:   generic.NewFilter4[Position, Renderable, Bond, Door](),
		SwitchSelector: generic.NewFilter4[Position, Renderable, Bond, Switch](),
		World:          world,
		GridContainer:  gridcontainer,
		DoorMapper:     doormapper,
	}

	return system
}

func (system *PairSystem) Update() error {
	observer := observers.GetGameObserver(system.World)
	posID := ecs.ComponentID[components.Position](system.World)
	veloID := ecs.ComponentID[components.Velocity](system.World)

	query := system.SwitchSelector.Query(system.World)
	relID := ecs.ComponentID[Bond](system.World)

	EntitiesToSwitch := []*ToggleDoor{}

	for query.Next() {
		swpos, _, _, switcher := query.Get()

		for _, player := range observer.GetPlayers() {
			if !system.World.Alive(player) {
				continue
			}

			playerposition := (*Position)(system.World.Get(player, posID))
			playervelocity := (*Velocity)(system.World.Get(player, veloID))

			ok, newpos := swpos.Intersects(playerposition, playervelocity)
			if ok {
				// player moved on top of the switch
				switcher.Toggle()

				// open door
				door := system.World.Relations().Get(query.Entity(), relID)
				EntitiesToSwitch = append(EntitiesToSwitch,
					&ToggleDoor{Entity: door, Open: true})

				playervelocity.Change(Stop)
				playerposition.Set(newpos)

			}
		}
	}

	doorquery := system.DoorSelector.Query(system.World)
	for doorquery.Next() {
		doorpos, _, _, door := doorquery.Get()

		for _, player := range observer.GetPlayers() {
			if !system.World.Alive(player) {
				continue
			}

			playerposition := (*Position)(system.World.Get(player, posID))
			playervelocity := (*Velocity)(system.World.Get(player, veloID))

			ok, newpos := doorpos.Intersects(playerposition, playervelocity)
			if ok && !door.IsOpen {
				playervelocity.Change(Stop)
				playerposition.Set(newpos)
			}
		}
	}

	for _, toggle := range EntitiesToSwitch {
		_, _, _, door := system.DoorMapper.Get(toggle.Entity)
		door.Toggle()
	}

	return nil
}

func (system *PairSystem) Draw(screen *ebiten.Image) {
	op := &ebiten.DrawImageOptions{}
	query := system.SwitchSelector.Query(system.World)

	for query.Next() {
		pos, _, _, switcher := query.Get()

		op.GeoM.Reset()
		op.GeoM.Translate(float64(pos.X), float64(pos.Y))
		screen.DrawImage(switcher.Sprite(), op)
	}

	doorquery := system.DoorSelector.Query(system.World)

	for doorquery.Next() {
		pos, _, _, door := doorquery.Get()

		op.GeoM.Reset()
		op.GeoM.Translate(float64(pos.X), float64(pos.Y))
		screen.DrawImage(door.Sprite(), op)
	}

}