#include <crypt.h>
#include <stdexcept>
#include "hashing.hpp"
#include <random>
#include <sstream>
#include <iomanip>

std::string hashing::GenerateSetting(unsigned long cost) {
    // "$y$" is the yescrypt prefix
    const char* setting = crypt_gensalt("$y$", cost, nullptr, 0);
    if (!setting)
        throw std::runtime_error("crypt_gensalt() failed – yescrypt may not be supported");
    return setting;
}

std::string hashing::HashPassword(const std::string& password, const std::string& setting) {
    crypt_data data{};
    const char* hash = crypt_r(password.c_str(), setting.c_str(), &data);
    if (!hash || hash[0] == '*')
        throw std::runtime_error("crypt_r() failed");
    return hash;
}

bool hashing::VerifyPassword(const std::string& password, const std::string& stored_hash) {
    crypt_data data{};
    const char* result = crypt_r(password.c_str(), stored_hash.c_str(), &data);
    if (!result || result[0] == '*')
        return false;
    return stored_hash == result;
}

std::string hashing::generate_token(size_t bytes) {
    std::random_device rd;
    std::string token;
    token.reserve(bytes * 2);

    std::uniform_int_distribution<uint8_t> dist(0, 255);
    for (size_t i = 0; i < bytes; ++i) {
        std::ostringstream ss;
        ss << std::hex << std::setw(2) << std::setfill('0') << (int)dist(rd);
        token += ss.str();
    }
    return token;
}