#include "common/uuid.hpp"
#include <openssl/rand.h>
#include <cstring>

namespace smartbotic::common {

thread_local std::mt19937_64 UUID::generator_{std::random_device{}()};

std::string UUID::generate() {
    unsigned char bytes[16];
    RAND_bytes(bytes, 16);

    // Set version 4 (random)
    bytes[6] = (bytes[6] & 0x0f) | 0x40;
    // Set variant (RFC 4122)
    bytes[8] = (bytes[8] & 0x3f) | 0x80;

    std::ostringstream ss;
    ss << std::hex << std::setfill('0');

    for (int i = 0; i < 16; ++i) {
        if (i == 4 || i == 6 || i == 8 || i == 10) {
            ss << '-';
        }
        ss << std::setw(2) << static_cast<int>(bytes[i]);
    }

    return ss.str();
}

std::string UUID::generatePrefixed(const std::string& prefix) {
    return prefix + "_" + generate();
}

bool UUID::isValid(const std::string& uuid) {
    if (uuid.length() != 36) {
        return false;
    }

    for (size_t i = 0; i < uuid.length(); ++i) {
        char c = uuid[i];
        if (i == 8 || i == 13 || i == 18 || i == 23) {
            if (c != '-') return false;
        } else {
            if (!std::isxdigit(c)) return false;
        }
    }

    return true;
}

} // namespace smartbotic::common