package net.minecraft.server;

import it.unimi.dsi.fastutil.objects.Object2IntLinkedOpenHashMap;
import it.unimi.dsi.fastutil.objects.Object2IntMaps;
import it.unimi.dsi.fastutil.objects.Object2IntMap.Entry;
import java.util.Queue;
import net.minecraft.util.ArrayListDeque;

public class SuppressedExceptionCollector {
	private static final int LATEST_ENTRY_COUNT = 8;
	private final Queue<SuppressedExceptionCollector.LongEntry> latestEntries = new ArrayListDeque<SuppressedExceptionCollector.LongEntry>();
	private final Object2IntLinkedOpenHashMap<SuppressedExceptionCollector.ShortEntry> entryCounts = new Object2IntLinkedOpenHashMap<>();

	private static long currentTimeMs() {
		return System.currentTimeMillis();
	}

	public synchronized void addEntry(final String location, final Throwable throwable) {
		long now = currentTimeMs();
		String message = throwable.getMessage();
		this.latestEntries.add(new SuppressedExceptionCollector.LongEntry(now, location, throwable.getClass(), message));

		while (this.latestEntries.size() > 8) {
			this.latestEntries.remove();
		}

		SuppressedExceptionCollector.ShortEntry key = new SuppressedExceptionCollector.ShortEntry(location, throwable.getClass());
		int currentValue = this.entryCounts.getInt(key);
		this.entryCounts.putAndMoveToFirst(key, currentValue + 1);
	}

	public synchronized String dump() {
		long current = currentTimeMs();
		StringBuilder result = new StringBuilder();
		if (!this.latestEntries.isEmpty()) {
			result.append("\n\t\tLatest entries:\n");

			for (SuppressedExceptionCollector.LongEntry e : this.latestEntries) {
				result.append("\t\t\t")
					.append(e.location)
					.append(":")
					.append(e.cls)
					.append(": ")
					.append(e.message)
					.append(" (")
					.append(current - e.timestampMs)
					.append("ms ago)")
					.append("\n");
			}
		}

		if (!this.entryCounts.isEmpty()) {
			if (result.isEmpty()) {
				result.append("\n");
			}

			result.append("\t\tEntry counts:\n");

			for (Entry<SuppressedExceptionCollector.ShortEntry> e : Object2IntMaps.fastIterable(this.entryCounts)) {
				result.append("\t\t\t")
					.append(((SuppressedExceptionCollector.ShortEntry)e.getKey()).location)
					.append(":")
					.append(((SuppressedExceptionCollector.ShortEntry)e.getKey()).cls)
					.append(" x ")
					.append(e.getIntValue())
					.append("\n");
			}
		}

		return result.isEmpty() ? "~~NONE~~" : result.toString();
	}

	private record LongEntry(long timestampMs, String location, Class<? extends Throwable> cls, String message) {
	}

	private record ShortEntry(String location, Class<? extends Throwable> cls) {
	}
}