#include "common/Crypto.h"

#include <drogon/utils/Utilities.h>

#include <openssl/evp.h>

#include <array>
#include <iomanip>
#include <random>
#include <sstream>
#include <string>

namespace visione::crypto
{
namespace
{
constexpr int passwordIterations = 210000;
constexpr size_t passwordHashBytes = 32;

std::string toHex(const unsigned char *data, size_t size)
{
    std::ostringstream stream;
    stream << std::hex << std::uppercase << std::setfill('0');
    for (size_t i = 0; i < size; ++i)
    {
        stream << std::setw(2) << static_cast<int>(data[i]);
    }
    return stream.str();
}

std::string pbkdf2(const std::string &password,
                   const std::string &salt,
                   int iterations)
{
    std::array<unsigned char, passwordHashBytes> output{};
    PKCS5_PBKDF2_HMAC(password.c_str(),
                      static_cast<int>(password.size()),
                      reinterpret_cast<const unsigned char *>(salt.data()),
                      static_cast<int>(salt.size()),
                      iterations,
                      EVP_sha256(),
                      static_cast<int>(output.size()),
                      output.data());
    return toHex(output.data(), output.size());
}
}  // namespace

std::string sha256(const std::string &value)
{
    return drogon::utils::getSha256(value);
}

std::string randomNumericCode(int digits)
{
    std::random_device device;
    std::mt19937 generator(device());
    std::uniform_int_distribution<int> distribution(0, 9);

    std::string code;
    code.reserve(static_cast<size_t>(digits));
    for (int i = 0; i < digits; ++i)
    {
        code.push_back(static_cast<char>('0' + distribution(generator)));
    }
    return code;
}

std::string randomToken()
{
    return drogon::utils::getUuid() + drogon::utils::getUuid();
}

std::string hashPassword(const std::string &password)
{
    const auto salt = drogon::utils::getUuid() + drogon::utils::getUuid();
    return "pbkdf2_sha256$" + std::to_string(passwordIterations) + "$" + salt +
           "$" + pbkdf2(password, salt, passwordIterations);
}

bool verifyPassword(const std::string &password, const std::string &hash)
{
    constexpr std::string_view pbkdf2Prefix = "pbkdf2_sha256$";

    if (!hash.starts_with(pbkdf2Prefix))
    {
        return false;
    }

    const auto iterationsStart = pbkdf2Prefix.size();
    const auto saltStart = hash.find('$', iterationsStart);
    if (saltStart == std::string::npos)
    {
        return false;
    }
    const auto digestStart = hash.find('$', saltStart + 1);
    if (digestStart == std::string::npos)
    {
        return false;
    }

    const auto iterations =
        std::stoi(hash.substr(iterationsStart, saltStart - iterationsStart));
    const auto salt = hash.substr(saltStart + 1, digestStart - saltStart - 1);
    const auto expected = "pbkdf2_sha256$" + std::to_string(iterations) + "$" +
                          salt + "$" + pbkdf2(password, salt, iterations);
    return expected == hash;
}

std::string hashSecret(const std::string &secret)
{
    return sha256("visione:" + secret);
}
}  // namespace visione::crypto