//! Implementation of Sequoia crypto API using the Nettle cryptographic library.

use crate::types::*;

use nettle::random::{Random, Yarrow};

pub mod aead;
pub mod asymmetric;
pub mod ecdh;
pub mod hash;
pub mod symmetric;

/// Returns a short, human-readable description of the backend.
pub fn backend() -> String {
    // XXX: Once we depend on nettle-rs 7.1, add cv448 feature
    // XXX: Once we depend on nettle-rs 7.2, add nettle::version
    "Nettle".to_string()
}

/// Fills the given buffer with random data.
pub fn random(buf: &mut [u8]) {
    Yarrow::default().random(buf);
}

impl PublicKeyAlgorithm {
    pub(crate) fn is_supported_by_backend(&self) -> bool {
        use PublicKeyAlgorithm::*;
        #[allow(deprecated)]
        match &self {
            RSAEncryptSign | RSAEncrypt | RSASign | DSA | ECDH | ECDSA | EdDSA
                => true,
            ElGamalEncrypt | ElGamalEncryptSign | Private(_) | Unknown(_)
                => false,
        }
    }
}

impl Curve {
    pub(crate) fn is_supported_by_backend(&self) -> bool {
        use self::Curve::*;
        match &self {
            NistP256 | NistP384 | NistP521 | Ed25519 | Cv25519
                => true,
            BrainpoolP256 | BrainpoolP512 | Unknown(_)
                => false,
        }
    }
}

impl AEADAlgorithm {
    /// Returns the best AEAD mode supported by the backend.
    ///
    /// This SHOULD return OCB, which is the mandatory-to-implement
    /// algorithm and the most performing one, but fall back to any
    /// supported algorithm.
    pub(crate) const fn const_default() -> AEADAlgorithm {
        AEADAlgorithm::EAX
    }

    pub(crate) fn is_supported_by_backend(&self) -> bool {
        use self::AEADAlgorithm::*;
        match &self {
            EAX
                => true,
            OCB | Private(_) | Unknown(_)
                => false,
        }
    }
}