use crate::ByteOrder;

/// Extension trait for [`ff::Field`], intended as a place to put optimizable arithmetic operations.

///

/// The idea is future versions of this crate can add provided methods which are useful in dense

/// field arithmetic like `primeorder`'s RCB implementation, and `primefield` can potentially

/// automatically plug in optimized implementations when available.

// TODO(tarcieri): add some methods to this trait, e.g. `add_and_mul`, `mul_and_add`

pub trait FieldExt: ff::Field {}

/// Extension trait for [`ff::PrimeField`] which enables specifying the endianness in which

/// [`ff::PrimeField::Repr`] is encoded.

// TODO(tarcieri): remove this if/whenever zkcrypto/rfcs#4 lands. See also: zkcrypto/ff#158

pub trait PrimeFieldExt: FieldExt + ff::PrimeField {

    /// Endianness used when encoding [`ff::PrimeField::Repr`].

    const REPR_ENDIANNESS: ByteOrder = ByteOrder::BigEndian;

    /// Encode `self` using a big endian representation.

    fn to_be_repr(&self) -> Self::Repr {

        let mut repr = self.to_repr();

        if Self::REPR_ENDIANNESS == ByteOrder::LittleEndian {

            repr.as_mut().reverse();

        }

        repr

    }

    /// Encode `self` using a little endian representation.

    fn to_le_repr(&self) -> Self::Repr {

        let mut repr = self.to_repr();

        if Self::REPR_ENDIANNESS == ByteOrder::BigEndian {

            repr.as_mut().reverse();

        }

        repr

    }

}