use std::ops::Sub;
use std::time::Duration;

#[derive(Copy, Clone, PartialEq, PartialOrd, Debug)]
pub struct Spot {
	/// Millisecond offset from the Unix Epoch - equivalent to Date.now()
	inner: f64,
}

impl Spot {
	pub fn now() -> Self {
		Spot {
			inner: js_sys::Date::now(),
		}
	}
	pub fn as_secs(&self) -> u64 {
		self.as_duration().as_secs()
	}
	pub fn as_duration(&self) -> Duration {
		Self::now() - *self
	}
	pub fn elapsed(&self) -> Duration {
		self.as_duration()
	}
}

impl Sub<Spot> for Spot {
	type Output = Duration;

	fn sub(self, rhs: Spot) -> Self::Output {
		let diff = (self.inner - rhs.inner).max(0.0);
		let secs = (diff as u64) / 1_000;
		let nanos = (((diff as u64) % 1_000) as u32) * 1_000_000;

		Duration::new(secs, nanos)
	}
}