#ifndef BACKEND_OPENSSL_HPP_CRRV8DCH
#define BACKEND_OPENSSL_HPP_CRRV8DCH

#include <vanetza/security/backend.hpp>
#include <array>
#include <cstdint>

namespace vanetza
{
namespace security
{

// forward declaration
namespace openssl
{
    class Key;
    class Point;
    class Signature;
} // namespace openssl


/**
 * \brief Backend implementation based on OpenSSL
 */
class BackendOpenSsl : public Backend
{
public:
    static constexpr auto backend_name = "OpenSSL";

    BackendOpenSsl();

    /// \see Backend::sign_data
    EcdsaSignature sign_data(const ecdsa256::PrivateKey& private_key, const ByteBuffer& data_buffer) override;

    /// \see Backend::sign_digest
    Signature sign_digest(const PrivateKey&, const ByteBuffer& digest) override;

    /// \see Backend::verify_data
    bool verify_data(const ecdsa256::PublicKey& public_key, const ByteBuffer& data, const EcdsaSignature& sig) override;

    /// \see Backend::verify_digest
    bool verify_digest(const PublicKey&, const ByteBuffer& digest, const Signature&) override;

    ByteBuffer calculate_hash(HashAlgorithm, const ByteBuffer&) override;

    /// \see Backend::decompress_point
    boost::optional<Uncompressed> decompress_point(const EccPoint& ecc_point) override;

    /// \see Backend::generate_key_pair
    ecdsa256::KeyPair generate_key_pair() override;

private:
    /// calculate SHA256 digest of data buffer
    std::array<uint8_t, 32> calculate_sha256_digest(const ByteBuffer& data) const;

    /// calculate SHA384 digest of data buffer
    std::array<uint8_t, 48> calculate_sha384_digest(const ByteBuffer& data) const;

    /// convert to internal format of private key
    openssl::Key internal_private_key(const ecdsa256::PrivateKey&) const;
    openssl::Key internal_private_key(const PrivateKey&) const;

    /// convert to internal format of public key
    openssl::Key internal_public_key(const ecdsa256::PublicKey&) const;
    openssl::Key internal_public_key(const PublicKey&) const;

    /// convert to internal format of an EC point
    openssl::Point internal_ec_point(const PublicKey&) const;
};

namespace openssl
{
/// Derive the public key from a private key (pub = priv * G), on the key's own curve.
PublicKey derive_public_key(const PrivateKey& private_key);
} // namespace openssl

} // namespace security
} // namespace vanetza

#endif /* BACKEND_OPENSSL_HPP_CRRV8DCH */