// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.

// SPDX-License-Identifier: Apache-2.0 OR ISC

use crate::aws_lc::{BN_bin2bn, BN_bn2bin, BN_new, BN_num_bytes, BN_set_u64, BIGNUM};

use crate::ptr::{ConstPointer, DetachableLcPtr, LcPtr};

use core::ptr::null_mut;

impl TryFrom<&[u8]> for LcPtr<BIGNUM> {

    type Error = ();

    fn try_from(bytes: &[u8]) -> Result<Self, Self::Error> {

        unsafe { LcPtr::new(BN_bin2bn(bytes.as_ptr(), bytes.len(), null_mut())) }

    }

}

impl TryFrom<&[u8]> for DetachableLcPtr<BIGNUM> {

    type Error = ();

    fn try_from(bytes: &[u8]) -> Result<Self, Self::Error> {

        unsafe { DetachableLcPtr::new(BN_bin2bn(bytes.as_ptr(), bytes.len(), null_mut())) }

    }

}

impl TryFrom<u64> for DetachableLcPtr<BIGNUM> {

    type Error = ();

    fn try_from(value: u64) -> Result<Self, Self::Error> {

        unsafe {

            let mut bn = DetachableLcPtr::new(BN_new())?;

            if 1 != BN_set_u64(bn.as_mut_ptr(), value) {

                return Err(());

            }

            Ok(bn)

        }

    }

}

impl ConstPointer<'_, BIGNUM> {

    pub(crate) fn to_be_bytes(&self) -> Vec<u8> {

        unsafe {

            let bn_bytes = BN_num_bytes(self.as_const_ptr());

            let mut byte_vec = Vec::with_capacity(bn_bytes as usize);

            let out_bytes = BN_bn2bin(self.as_const_ptr(), byte_vec.as_mut_ptr());

            debug_assert_eq!(out_bytes, bn_bytes as usize);

            byte_vec.set_len(out_bytes);

            byte_vec

        }

    }

}