package dev.lumareth.improvedAerodynamics.flight;

import net.minecraftforge.event.TickEvent;
import net.minecraftforge.event.server.ServerStoppedEvent;
import net.minecraftforge.eventbus.api.SubscribeEvent;

import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.Set;

/**
 * Hands what the server thread collected during a tick over to the physics thread in one piece, at the end of the
 * tick. Warium pushes its forces while the physics thread is already consuming them, so without this a tick's
 * forces can end up split over several substeps or merged with the next tick's.
 */
public final class PhysicsBridge {
    /** Something that collects data on the server thread and hands it to the physics thread at the end of each tick. */
    public interface Publishable {
        void publish(long tick);
    }

    private static final Set<Publishable> TOUCHED = Collections.newSetFromMap(new IdentityHashMap<>());
    private static long tick;
    private static volatile long publishedTick;

    private PhysicsBridge() {
    }

    /** Marks a collector as having data for this tick. */
    public static synchronized void touch(Publishable publishable) {
        TOUCHED.add(publishable);
    }

    /**
     * Tick number of the latest handover. Data published at an older tick is outdated: its ship received nothing in
     * the latest tick, so nothing should be applied anymore.
     */
    public static long publishedTick() {
        return publishedTick;
    }

    @SubscribeEvent
    public static void onServerTick(TickEvent.ServerTickEvent event) {
        if (event.phase != TickEvent.Phase.END) {
            return;
        }
        synchronized (PhysicsBridge.class) {
            tick++;
            for (Publishable publishable : TOUCHED) {
                publishable.publish(tick);
            }
            TOUCHED.clear();
            publishedTick = tick;
        }
    }

    @SubscribeEvent
    public static void onServerStopped(ServerStoppedEvent event) {
        synchronized (PhysicsBridge.class) {
            TOUCHED.clear();
        }
    }
}