openquell/systems/obstacle_system.go

package systems

import (
	"log/slog"
	"openquell/assets"
	"openquell/components"
	. "openquell/components"
	. "openquell/config"
	"openquell/grid"
	"openquell/observers"
	"openquell/util"

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

type ObstacleSystem struct {
	World         *ecs.World
	Selector      *generic.Filter4[Position, Velocity, Obstacle, Renderable]
	GridContainer *grid.GridContainer
}

func NewObstacleSystem(world *ecs.World, gridcontainer *grid.GridContainer) System {
	system := &ObstacleSystem{
		Selector:      generic.NewFilter4[Position, Velocity, Obstacle, Renderable](),
		World:         world,
		GridContainer: gridcontainer,
	}

	return system
}

func (system *ObstacleSystem) Update() error {
	playerobserver := observers.GetPlayerObserver(system.World)
	gameobserver := observers.GetGameObserver(system.World)
	obstacleobserver := observers.GetObstacleObserver(system.World)

	if gameobserver.Lost {
		return nil
	}

	posID := ecs.ComponentID[components.Position](system.World)
	veloID := ecs.ComponentID[components.Velocity](system.World)

	EntitiesToRemove := []ecs.Entity{}

	query := system.Selector.Query(system.World)
	gameover := false

	for query.Next() {
		obsposition, obsvelocity, _, _ := query.Get()

		// check if one player has bumped into current obstacle
		for player := range playerobserver.Entities {
			playerposition := (*Position)(system.World.Get(player, posID))
			playervelocity := (*Velocity)(system.World.Get(player, veloID))

			ok, newpos := obsposition.Intersects(playerposition, playervelocity)
			if ok {
				// slog.Debug("bumped into obstacle", "obstacle", obstacle)

				if CheckObstacleSide(playervelocity, obsvelocity.Direction) {
					// player died
					EntitiesToRemove = append(EntitiesToRemove, player)
					gameover = true
				} else {
					// bumped  into nonlethal obstacle side,  stop the
					// player, set the obstacle in motion, if possible
					slog.Debug("bump not die", "originalpos", playerposition)
					obsvelocity.Set(playervelocity)
					playervelocity.Change(Stop)
					playerposition.Set(newpos)
				}
			}
		}

		// check if current obstacle bumped into another obstacle
		for foreign_obstacle := range obstacleobserver.Entities {
			if foreign_obstacle == query.Entity() {
				// don't check obstacle against itself
				continue
			}

			foreign_obstacle_position := (*Position)(system.World.Get(foreign_obstacle, posID))

			ok, newpos := foreign_obstacle_position.Intersects(obsposition, obsvelocity)
			if ok {
				//slog.Debug("bumped into foreign obstacle", "obstacle", foreign_obstacle)
				obsposition.Set(newpos)
				obsvelocity.ResetDirectionAndStop()
			}
		}

		// FIXME: this is the same loop as in player_system, unite the
		// two, just iterate over all entities with pos,vel,render, dammit
		if obsvelocity.Moving() {
			ok, tilepos := system.GridContainer.Grid.GetSolidNeighborPosition(obsposition, obsvelocity, true)
			if ok {
				intersects, newpos := tilepos.Intersects(obsposition, obsvelocity)
				if intersects {
					// slog.Debug("collision with foreign obstacle detected", "tile",
					// 	tilepos, "obs", obsposition, "new", newpos)

					obsposition.Set(newpos)
					obsvelocity.ResetDirectionAndStop()
				}
			}

			obsposition.Move(obsvelocity)
		}

	}

	for _, entity := range EntitiesToRemove {
		system.World.RemoveEntity(entity)
	}

	if gameover {
		// winner, winner,  chicken dinner!
		timer := gameobserver.StopTimer

		if !timer.Running {
			timer.Start(LEVEL_END_WAIT)
		}

		gameobserver.Gameover()
	}

	return nil
}

func (system *ObstacleSystem) Draw(screen *ebiten.Image) {
	// write the movable tiles
	op := &ebiten.DrawImageOptions{}
	query := system.Selector.Query(system.World)

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

		op.GeoM.Reset()
		op.GeoM.Translate(float64(pos.X), float64(pos.Y))

		screen.DrawImage(sprite.Image, op)
	}
}

func (system *ObstacleSystem) AddParticle(position *components.Position) {
	particleobserver := observers.GetParticleObserver(system.World)

	ptmapper := generic.NewMap3[
		components.Position,
		components.Particle,
		components.Timer,
	](system.World)

	entity := ptmapper.New()
	pos, particle, timer := ptmapper.Get(entity)
	particleobserver.AddEntity(entity)

	particle.Index = assets.Tiles['*'].Particle
	particle.Tiles = assets.Tiles['*'].Tiles

	pos.Update(
		position.X-(16), // FIXME: use global tilesize!
		position.Y-(16),
		64,
	)

	timer.Start(PARTICLE_LOOPWAIT)
}

// return true if obstacle weapon points into the direction the player is moving
func CheckObstacleSide(playervelocity *Velocity, obsdirection int) bool {
	movingdirection := playervelocity.InvertDirection()

	if movingdirection == Stop || movingdirection == obsdirection {
		slog.Debug("Damaging obstacle collision",
			"playerdirection", util.DirectionStr(playervelocity.Direction),
			"obsdirection", util.DirectionStr(obsdirection),
			"movingdirection", util.DirectionStr(movingdirection),
		)
		return true
	}

	return false
}