#include "argon2_wrapper.h"

extern "C" {
#include <argon2.h>
}

#include <random>
#include <iomanip>
#include <sstream>
#include <stdexcept>

namespace scar {

std::string Argon2Wrapper::generateSalt(size_t length) {
    std::random_device rd;
    std::mt19937 gen(rd());
    std::uniform_int_distribution<> dis(0, 255);
    
    std::vector<uint8_t> salt_bytes(length);
    for (size_t i = 0; i < length; ++i) {
        salt_bytes[i] = static_cast<uint8_t>(dis(gen));
    }
    
    // Convert to hex string
    std::ostringstream oss;
    for (uint8_t byte : salt_bytes) {
        oss << std::hex << std::setw(2) << std::setfill('0') << static_cast<int>(byte);
    }
    
    return oss.str();
}

std::string Argon2Wrapper::hashPassword(const std::string& password, const std::string& salt) {
    // Convert hex salt string back to bytes
    std::vector<uint8_t> salt_bytes;
    for (size_t i = 0; i < salt.length(); i += 2) {
        std::string byte_string = salt.substr(i, 2);
        uint8_t byte = static_cast<uint8_t>(std::stoi(byte_string, nullptr, 16));
        salt_bytes.push_back(byte);
    }
    
    // Hash buffer
    std::vector<uint8_t> hash(HASH_LENGTH);
    
    // Perform Argon2id hashing
    int result = argon2id_hash_raw(
        TIME_COST,
        MEMORY_COST,
        PARALLELISM,
        password.data(), password.size(),
        salt_bytes.data(), salt_bytes.size(),
        hash.data(), HASH_LENGTH
    );
    
    if (result != ARGON2_OK) {
        throw std::runtime_error("Argon2 hashing failed: " + 
                                 std::string(argon2_error_message(result)));
    }
    
    // Convert to hex string
    std::ostringstream oss;
    for (uint8_t byte : hash) {
        oss << std::hex << std::setw(2) << std::setfill('0') << static_cast<int>(byte);
    }
    
    return oss.str();
}

bool Argon2Wrapper::verifyPassword(const std::string& password, const std::string& salt,
                                   const std::string& hash) {
    try {
        std::string computed_hash = hashPassword(password, salt);
        return computed_hash == hash;
    } catch (const std::exception&) {
        return false;
    }
}

} // namespace scar