package net.minecraft.util.profiling;

import com.mojang.jtracy.TracyClient;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicInteger;
import org.jspecify.annotations.Nullable;

public final class Profiler {
	private static final ThreadLocal<TracyZoneFiller> TRACY_FILLER = ThreadLocal.withInitial(TracyZoneFiller::new);
	private static final ThreadLocal<@Nullable ProfilerFiller> ACTIVE = new ThreadLocal<>();
	private static final AtomicInteger ACTIVE_COUNT = new AtomicInteger();

	private Profiler() {
	}

	public static Profiler.Scope use(final ProfilerFiller filler) {
		startUsing(filler);
		return Profiler::stopUsing;
	}

	private static void startUsing(final ProfilerFiller filler) {
		if (ACTIVE.get() != null) {
			throw new IllegalStateException("Profiler is already active");
		}

		ProfilerFiller active = decorateFiller(filler);
		ACTIVE.set(active);
		ACTIVE_COUNT.incrementAndGet();
		active.startTick();
	}

	private static void stopUsing() {
		ProfilerFiller active = ACTIVE.get();
		if (active == null) {
			throw new IllegalStateException("Profiler was not active");
		}

		ACTIVE.remove();
		ACTIVE_COUNT.decrementAndGet();
		active.endTick();
	}

	private static ProfilerFiller decorateFiller(final ProfilerFiller filler) {
		return ProfilerFiller.combine(getDefaultFiller(), filler);
	}

	public static ProfilerFiller get() {
		return ACTIVE_COUNT.get() == 0 ? getDefaultFiller() : Objects.requireNonNullElseGet(ACTIVE.get(), Profiler::getDefaultFiller);
	}

	private static ProfilerFiller getDefaultFiller() {
		return TracyClient.isAvailable() ? TRACY_FILLER.get() : InactiveProfiler.INSTANCE;
	}

	public interface Scope extends AutoCloseable {
		@Override
		void close();
	}
}