#region Copyright & License Information
/*
 * Copyright (c) The OpenRA Developers and Contributors
 * This file is part of OpenRA, which is free software. It is made
 * available to you under the terms of the GNU General Public License
 * as published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version. For more
 * information, see COPYING.
 */
#endregion

using System.Diagnostics;

namespace OpenRA.Support
{
	public static class PerfTickLogger
	{
		public const long TimestampDisabled = 0L;

		static float durationThresholdMs = Game.Settings.Debug.LongTickThresholdMs;
		static long durationThresholdTicks = PerfTimer.MillisToTicks(Game.Settings.Debug.LongTickThresholdMs);

		/// <summary>Retrieve the current timestamp.</summary>
		/// <returns>TimestampDisabled if performance logging is disabled.</returns>
		public static long GetTimestamp()
		{
			var settings = Game.Settings.Debug;
			if (!settings.EnableSimulationPerfLogging)
				return TimestampDisabled;

			// TODO: Let settings notify listeners on changes
			if (durationThresholdMs != settings.LongTickThresholdMs)
			{
				durationThresholdMs = Game.Settings.Debug.LongTickThresholdMs;
				durationThresholdTicks = PerfTimer.MillisToTicks(durationThresholdMs);
			}

			return Stopwatch.GetTimestamp();
		}

		/// <summary>Logs an entry in the performance log when the current time since the start tick exceeds the game debug setting `LongTickThresholdMs`.</summary>
		/// <returns>TimestampDisabled if performance logging is disabled.</returns>
		public static long LogLongTick(long startTimestamp, string name, object item)
		{
			if (startTimestamp == TimestampDisabled)
				return TimestampDisabled;

			var currentTimetamp = Stopwatch.GetTimestamp();
			if (currentTimetamp - startTimestamp > durationThresholdTicks)
				PerfTimer.LogLongTick(startTimestamp, currentTimetamp, name, item);

			return currentTimetamp;
		}
	}
}