module mutils.time;

import core.sys.windows.windows;
import core.sys.posix.sys.time;

// Replacement for deprecated std.datetime StopWatch, used mainly in benchmark tests
struct StopWatch {
	long begin;
	long end;

	void start() {
		begin = useconds();
	}

	void stop() {
		end = useconds();
	}

	long secs() {
		return (end - begin) / 1_000_000;
	}

	long msecs() {
		long endTime = (end == 0) ? useconds() : end;
		return (endTime - begin) / 1000;
	}

	long usecs() {
		long endTime = (end == 0) ? useconds() : end;
		return (endTime - begin);
	}

}

enum long ticksPerSecond = 1_000_000;

// High precison timer, might be used for relative time measurements
long useconds() {
	version (Posix) {
		timeval t;
		gettimeofday(&t, null);
		return t.tv_sec * 1_000_000 + t.tv_usec;
	} else version (Windows) {
		__gshared double mul = -1;
		if (mul < 0) {
			long frequency;
			int ok = QueryPerformanceFrequency(&frequency);
			assert(ok);
			mul = 1_000_000.0 / frequency;
		}
		long ticks;
		int ok = QueryPerformanceCounter(&ticks);
		assert(ok);
		return cast(long)(ticks * mul);
	} else {
		static assert("OS not supported.");
	}
}

unittest {
	long ticks = useconds();
	assert(ticks > 0);
}