use lazy_static::lazy_static;

use zeroize::Zeroize;

use crypto_bigint::{U512, U1024};

pub use crate::field;

#[derive(Clone, Copy, PartialEq, Eq, Default, Debug, Zeroize)]
pub struct Scalar(pub(crate) U512);

// 2**446 - 13818066809895115352007386748515426880336692474882178609894547503885
lazy_static! {
  pub static ref MODULUS: Scalar = Scalar(U512::from_be_hex(concat!(
    "00000000000000",
    "00",
    "3fffffffffffffffffffffffffffffffffffffffffffffffffffffff",
    "7cca23e9c44edb49aed63690216cc2728dc58f552378c292ab5844f3",
  )));
  static ref WIDE_MODULUS: U1024 = {
    let res = U1024::from((U512::ZERO, MODULUS.0));
    debug_assert_eq!(MODULUS.0.to_le_bytes()[..], res.to_le_bytes()[.. 64]);
    res
  };
}

field!(Scalar, MODULUS, WIDE_MODULUS, 446);

impl Scalar {
  pub fn wide_reduce(bytes: [u8; 114]) -> Scalar {
    Scalar(reduce(U1024::from_le_slice(&[bytes.as_ref(), &[0; 14]].concat())))
  }
}

#[test]
fn invert() {
  assert_eq!(Scalar::one().invert().unwrap(), Scalar::one());
}