package com.profiler;

import java.util.HashMap;
import java.util.Map;

import com.profiler.util.NamedThreadLocal;

public class StopWatch {

	private static ThreadLocal<Map<String, Long>> local = new NamedThreadLocal<Map<String, Long>>("StopWatch");

	public static void start(int id) {
		start(String.valueOf(id));
	}

	public static long stopAndGetElapsed(int id) {
		return stopAndGetElapsed(String.valueOf(id));
	}

	public static void start(String id) {
		Map<String, Long> map = local.get();
		if (map == null) {
			map = new HashMap<String, Long>(1);
			map.put(id, System.nanoTime());
			local.set(map);
		} else {
			map.put(id, System.nanoTime());
		}
	}

	public static long stopAndGetElapsed(String id) {
		Map<String, Long> map = local.get();
		if (map == null) {
			// throw new IllegalStateException("Stopwatch is not started.");
			// TODO application 에러로 전달되는경우가 있어서 일단 0으로
			return -1;
		} else {
			Long startTime = map.get(id);

			map.remove(id);
			// TODO: if using thread pool, this is unnecessary.
			// if (map.size() == 0) {
			// local.remove();
			// }

			if (startTime != null) {
				return System.nanoTime() - startTime;
			} else {
				return -1;
			}
		}
	}
}