#pragma once

#include <cstdint>
#include <iomanip>
#include <sstream>
#include <string>

namespace {

inline uint64_t fnv1a_64(const std::string& s) {
    uint64_t hash = 14695981039346656037ULL;
    for (unsigned char c : s) {
        hash ^= c;
        hash *= 1099511628211ULL;
    }
    return hash;
}

}

namespace mce {

class UUID {

public:
    static UUID* EMPTY;
    static mce::UUID (*fromString)(mcpe::string const&);

    char filler[0x14];

    static inline mce::UUID fromText(const std::string& text) {
        uint64_t h1 = fnv1a_64(text);
        uint64_t h2 = fnv1a_64("salt:" + text);

        uint16_t version = ((h1 >> 16) & 0x0FFF) | 0x5000; // v5
        uint16_t variant = ((h2 >> 48) & 0x3FFF) | 0x8000;

        std::ostringstream oss;
        oss << std::hex << std::setfill('0')
            << std::setw(8) << (uint32_t)(h1 >> 32) << "-"
            << std::setw(4) << (uint16_t)(h1 >> 16) << "-"
            << std::setw(4) << version << "-"
            << std::setw(4) << variant << "-"
            << std::setw(12) << (h2 & 0xFFFFFFFFFFFFULL);

        mcpe::string uuidStr(oss.str().c_str());
        return fromString(uuidStr);
    }
};

}