use bytes::{Buf, Bytes};
use failure;
use std::fmt;
use std::io;
use std::result;

pub type Result<T> = result::Result<T, failure::Error>;

#[derive(Debug)]
pub struct NotEnoughData {
	position: u64,
	data: Bytes,
}

impl NotEnoughData {
	pub fn check(data: &mut io::Cursor<Bytes>, need: usize) -> Result<()> {
		if data.remaining() < need {
			failure::bail!(NotEnoughData{
				position: data.position(),
				data: data.get_ref().clone(),
			})
		}
		Ok(())
	}
}

impl fmt::Display for NotEnoughData {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
		write!(f, "not enough data at position {} in {:?}", self.position, self.data)
	}
}

impl failure::Fail for NotEnoughData {}

macro_rules! check_enough_data {
	($data:ident, $n:expr, $context:expr) => {
		{
			use $crate::_failure::ResultExt;
			$crate::errors::NotEnoughData::check($data, $n).context($context)?;
		}
	};
}