package coffee.liz.ecs

import kotlin.time.Duration.Companion.nanoseconds

abstract class GameLoop<Outside> {
    private var world: World<Outside>? = null
    private var lastUpdate: Long? = null

    fun load(world: World<Outside>) {
        this.world = world
        this.lastUpdate = null
    }

    abstract fun render(world: World<Outside>)

    abstract fun outsideState(): Outside

    fun loop(now: Long) {
        val world = this.world ?: error("World not loaded")
        val outsideState = outsideState()
        val dt = (now - (lastUpdate ?: now)).nanoseconds
        world.update(outsideState, dt)
        render(world)
        lastUpdate = now
    }
}