use super::{DnsName, DnsLabelRef};

/// Iterator type for [`DnsName::labels`]
///
/// [`DnsName::labels`]: struct.DnsName.html#method.labels
#[derive(Clone)]
pub struct DnsNameIterator<'a> {
	pub(super) name: &'a DnsName,
	pub(super) front_label: u8,
	pub(super) back_label: u8,
}

impl<'a> Iterator for DnsNameIterator<'a> {
	type Item = DnsLabelRef<'a>;

	fn next(&mut self) -> Option<Self::Item> {
		if self.front_label >= self.back_label { return None }
		let label = self.name.label_ref(self.front_label);
		self.front_label += 1;
		Some(label)
	}

	fn size_hint(&self) -> (usize, Option<usize>) {
		let count = self.len();
		(count, Some(count))
	}

	fn count(self) -> usize {
		self.len()
	}
}

impl<'a> ExactSizeIterator for DnsNameIterator<'a> {
	fn len(&self) -> usize {
		(self.back_label - self.front_label) as usize
	}
}

impl<'a> DoubleEndedIterator for DnsNameIterator<'a> {
	fn next_back(&mut self) -> Option<Self::Item> {
		if self.front_label >= self.back_label { return None }
		self.back_label -= 1;
		let label = self.name.label_ref(self.back_label);
		Some(label)
	}
}