#include <cstring>
#include <stdexcept>

#include <openssl/hmac.h>
#include <openssl/rand.h>
#include "openssl_wrapper.h"

std::vector<char> secure_random_bytes(int num) {
    if (num < 0) {
        throw std::invalid_argument("secure_random_bytes(): num variable out of range (num < 0)");
    }

    std::vector<char> bytes(static_cast<size_t>(num), 0);
    if (RAND_bytes(reinterpret_cast<unsigned char*>(bytes.data()), num) == 1) {
        return bytes;
    } else {
        throw OpenSSLException(ERR_get_error());
    }
}

std::array<char, 32> hmac_sha3_256(const std::vector<char>& key, const std::vector<char>& data) {
    char hmac[EVP_MAX_MD_SIZE];
    unsigned int md_len;

    if (HMAC(EVP_sha3_256(), key.data(), static_cast<int>(key.size()), reinterpret_cast<const unsigned char*>(data.data()), data.size(), reinterpret_cast<unsigned char*>(hmac), &md_len)) {
        if (md_len != 32) {
            throw std::runtime_error("hmac_sha3_256(): HMAC() returned an unexpected size");
        }

        std::array<char, 32> ret;
        memcpy(ret.data(), hmac, 32);
        return ret;
    } else {
        throw OpenSSLException(ERR_get_error());
    }
}