ptth/bare_minimum_crypto/cpp/time_helpers.cpp

#include "time_helpers.h"

#include <chrono>
#include <iostream>

namespace BareMinimumCrypto {
	using namespace std;
	using namespace chrono;
	
	Instant::Instant (int64_t x): x (x) {}
	
	Instant Instant::now () {
		const auto utc_now = system_clock::now ();
		return Instant {duration_cast <seconds> (utc_now.time_since_epoch ()).count ()};
	}
	
	bool TimeRange::contains (Instant x) const {
		if (not_after < not_before) {
			return false;
		}
		
		if (x.x < not_before) {
			return false;
		}
		
		if (x.x > not_after) {
			return false;
		}
		
		return true;
	}
	
	int64_t TimeRange::duration () const {
		return not_after - not_before;
	}
	
	TimeRange TimeRange::from_start_and_dur (Instant start, int64_t dur) {
		return TimeRange {
			start.x,
			start.x + dur
		};
	}
	
	// Most tests will use a virtual clock. But just as a smoke test,
	// make sure real time is realistic.

	int test_time () {
		const auto now = Instant::now ();
		
		const auto time_of_writing = 1610844872;
		const int64_t about_100_years = (int64_t)100 * 365 * 86400;
		
		const TimeRange tr {
			time_of_writing,
			time_of_writing + about_100_years
		};
		
		if (! tr.contains (now)) {
			cerr << "System clock is acting weird" << endl;
			return 1;
		}
		
		const TimeRange bad_tr {
			time_of_writing + about_100_years,
			time_of_writing
		};
		
		if (bad_tr.contains (now)) {
			cerr << "Invalid TimeRange should not contain any Instants" << endl;
			return 1;
		}
		
		return 0;
	}
}