package org.spongepowered.benchmark;

import com.google.inject.Inject;
import org.slf4j.Logger;
import org.spongepowered.api.GameState;
import org.spongepowered.api.Sponge;
import org.spongepowered.api.command.CommandResult;
import org.spongepowered.api.command.spec.CommandSpec;
import org.spongepowered.api.event.Listener;
import org.spongepowered.api.event.SpongeEventFactory;
import org.spongepowered.api.event.cause.Cause;
import org.spongepowered.api.event.cause.NamedCause;
import org.spongepowered.api.event.game.state.GameInitializationEvent;
import org.spongepowered.api.event.game.state.GameStoppedEvent;
import org.spongepowered.api.plugin.Plugin;

@Plugin(id = "benchmarks")
public class BenchmarkPlugin {

    private static final int WARMUP_ITERATIONS = 5;
    private static final int WARMUP_COUNT = 1000;

    private static final int BENCHMARK_ITERATIONS = 20;
    private static final int BENCHMARK_COUNT = 10000;

    private static final Cause scause = Cause.of(NamedCause.of("dummy", BenchmarkPlugin.class));
    private static int event_count = 0;

    private static Logger slog;

    @Inject private Logger logger;

    @Listener
    public void onStart(GameInitializationEvent event) {
        slog = this.logger;
        Sponge.getCommandManager().register(this, CommandSpec.builder().executor((src, args) -> {
            run_benchmarks();
            return CommandResult.success();
        }).build(), "benchmark");
    }

    @Listener
    public void listener1(GameStoppedEvent event) {
        event_count++;
    }

    @Listener
    public void listener2(GameStoppedEvent event) {
        event_count++;
    }

    @Listener
    public void listener3(GameStoppedEvent event) {
        event_count++;
    }

    @Listener
    public void listener4(GameStoppedEvent event) {
        event_count++;
    }

    @Listener
    public void listener5(GameStoppedEvent event) {
        event_count++;
    }

    private static void run_benchmarks() {
        slog.info("Starting event system benchmarks");

        slog.info("Running " + WARMUP_ITERATIONS + " warmup iterations of " + WARMUP_COUNT + " cycles each");
        event_count = 0;
        long start = System.nanoTime();
        for(int i = 0; i < WARMUP_ITERATIONS; i++) {
            for(int e = 0; e < WARMUP_COUNT; e++) {
                throw_event();
            }
        }
        if(event_count != WARMUP_COUNT * WARMUP_ITERATIONS * 5) {
            slog.error("Incorrect event count " + event_count + " (Expected " + (WARMUP_COUNT * WARMUP_ITERATIONS * 5) + ")");
            return;
        }
        event_count = 0;
        long delta = System.nanoTime() - start;
        slog.info("Warmup cycles took " + (delta / 1000000f) + "ms");

        slog.info("================================================================================");
        slog.info("Running " + BENCHMARK_ITERATIONS + " benchmarking iterations of " + BENCHMARK_COUNT + " cycles each");
        long[] times = new long[BENCHMARK_ITERATIONS];
        long total_time = 0;
        int expected_count = BENCHMARK_COUNT * 5;
        for(int i = 0; i < BENCHMARK_ITERATIONS; i++) {
            start = System.nanoTime();
            for(int e = 0; e < BENCHMARK_COUNT; e++) {
                throw_event();
            }
            delta = System.nanoTime() - start;
            if(event_count != expected_count) {
                slog.error("Incorrect event count " + event_count + " (Expected " + expected_count + ")");
                return;
            }
            event_count = 0;
            total_time += delta;
            times[i] = delta;
            slog.info("    Iteration " + i + ": " + (delta / 1000000f) + "ms");
        }
        slog.info("================================================================================");
        slog.info("Total Time: " + (total_time / 1000000f) + "ms");
        slog.info("Mean Time: " + ((total_time / (double) BENCHMARK_ITERATIONS) / 1000000f) + "ms");
    }

    private static void throw_event() {
        Sponge.getEventManager().post(SpongeEventFactory.createGameStoppedServerEvent(scause, GameState.GAME_STOPPED));
    }

}