hytale-gravity-flip/src/main/java/com/mythlane/gravityflip/GravityFlipPlugin.java

package com.mythlane.gravityflip;

import com.hypixel.hytale.server.core.plugin.JavaPlugin;
import com.hypixel.hytale.server.core.plugin.JavaPluginInit;
import com.hypixel.hytale.server.core.universe.Universe;
import com.hypixel.hytale.server.core.universe.world.World;
import com.hypixel.hytale.server.core.util.Config;
import com.mythlane.gravityflip.config.GravityFlipConfig;
import com.mythlane.gravityflip.physics.GravityApplier;
import com.mythlane.gravityflip.region.RegionRegistry;
import com.mythlane.gravityflip.tick.RegionTickLoop;

import java.util.concurrent.ScheduledFuture;
import java.util.logging.Level;

/**
 * Entry point for the Gravity Flip plugin.
 *
 * <p>Extends {@link JavaPlugin} from the resolved Hytale Server API
 * ({@code com.hypixel.hytale:Server:2026.03.26-89796e57b}). Lifecycle hooks
 * for this version are {@code setup()} / {@code shutdown()} (not the legacy
 * {@code onEnable()} / {@code onDisable()}). See
 * {@code .planning/phases/01-scaffold-load/JAVAPLUGIN_RESOLUTION.md} for the
 * empirical resolution.
 */
public class GravityFlipPlugin extends JavaPlugin {

    /**
     * Persisted region store, materialised on disk as
     * {@code <dataDirectory>/regions.json} (i.e. {@code Plugins/GravityFlip/regions.json}).
     *
     * <p>The named {@code withConfig(name, codec)} overload is REQUIRED — the
     * 1-arg overload hardcodes the filename to {@code config.json}.
     */
    private final Config<GravityFlipConfig> configHolder =
            withConfig("regions", GravityFlipConfig.CODEC);

    private RegionRegistry registry;
    private RegionTickLoop tickLoop;
    private GravityApplier gravityApplier;

    public GravityFlipPlugin(JavaPluginInit init) {
        super(init);
    }

    @Override
    protected void setup() {
        // NOTE: do NOT call configHolder.get() here — it blocks until preLoad() completes.
        // Safe call sites are start() and any later lifecycle phase (incl. tick loop).
        //
        // World acquisition note (Phase 02-02): the plan called for a PrepareUniverseEvent
        // listener that stashes a World reference. Empirically, PrepareUniverseEvent
        // (com.hypixel.hytale.server.core.event.events.PrepareUniverseEvent) only carries
        // a WorldConfigProvider — it does NOT expose a Universe or World. We therefore use
        // a Supplier<World> that resolves Universe.get().getDefaultWorld() lazily on each
        // tick (matching the MythWorld WorldBorderManager precedent). Until the universe
        // is ready, the supplier returns null and the tick is a no-op.
        getLogger().at(Level.INFO).log("Gravity Flip enabled");
    }

    @Override
    protected void start() {
        super.start();
        GravityFlipConfig cfg = configHolder.get();
        this.registry = new RegionRegistry(cfg, configHolder);
        this.gravityApplier = new GravityApplier(th ->
                getLogger().at(Level.WARNING).withCause(th).log("gravityApply failed"));
        this.tickLoop = new RegionTickLoop(registry, gravityApplier, th ->
                getLogger().at(Level.WARNING).withCause(th).log("detectTick failed"));

        // Lazy world resolution — see setup() comment.
        this.tickLoop.startWithDelay(2_000L, () -> {
            Universe u = Universe.get();
            return u == null ? null : u.getDefaultWorld();
        });

        // TaskRegistry registration: registerTask only accepts ScheduledFuture<Void>; the
        // scheduler returns ScheduledFuture<?>. Cast via raw types per Mythlane idiom; the
        // try/catch falls back to manual shutdown() if registration fails (deterministic
        // either way because shutdown() always invokes tickLoop.stop()).
        try {
            @SuppressWarnings({"unchecked", "rawtypes"})
            ScheduledFuture<Void> vf = (ScheduledFuture) tickLoop.future();
            getTaskRegistry().registerTask(vf);
        } catch (Throwable ignored) { /* manual shutdown() fallback */ }

        getLogger().at(Level.INFO).log(
                "Gravity Flip enabled — %d region(s) loaded, detector @100ms, gravity inversion active",
                cfg.getRegions().size());
    }

    @Override
    protected void shutdown() {
        // Stop the detector BEFORE super.shutdown() so no tick races plugin teardown.
        if (tickLoop != null) tickLoop.stop();
        // No auto-save contract: any mutation made during the session must already
        // have been persisted via configHolder().save() by the command handler that
        // performed it. See configHolder() javadoc.
        getLogger().at(Level.INFO).log("Gravity Flip disabled");
        super.shutdown();
    }

    /** Exposed for Phase 3 (gravity physics) and Phase 4 (commands). */
    public RegionRegistry regions() { return registry; }

    /**
     * Accessor for the region config holder. <strong>SAVE CONTRACT:</strong> any
     * caller that mutates {@code configHolder().get().getRegions()} MUST call
     * {@code configHolder().save()} afterwards. There is no lifecycle hook that
     * auto-saves on shutdown. {@code Config.get()} returns a SHARED MUTABLE
     * reference; concurrent writers corrupt state — Phase 02-02's
     * {@code RegionRegistry} snapshots it into an {@code AtomicReference} for
     * tick-loop reads.
     */
    public Config<GravityFlipConfig> configHolder() {
        return configHolder;
    }
}