#ifndef MEMGRAPH_UTILS_RANDOM_XORSHIFT_HPP
#define MEMGRAPH_UTILS_RANDOM_XORSHIFT_HPP

#include <cstdlib>
#include <random>

namespace xorshift
{
    static uint64_t s[2];

    uint64_t avalance(uint64_t s)
    {
        // MurmurHash3 finalizer
        s ^= s >> 33;
        s *= 0xff51afd7ed558ccd;
        s ^= s >> 33;
        s *= 0xc4ceb9fe1a85ec53;
        s ^= s >> 33;

        return s;
    }

    void init()
    {
        // TODO
        // not sure if this thread local means anything for other threads
        // fix this!!!!

        // use a slow, more complex rnd generator to initialize a fast one
        // make sure to call this before requesting any random numbers!
        std::random_device rd;
        std::mt19937_64 gen(rd());
        std::uniform_int_distribution<unsigned long long> dist;

        // the number generated by MT can be full of zeros and xorshift
        // doesn't like this so we use MurmurHash3 64bit finalizer to
        // make it less biased

        s[0] = avalance(dist(gen));
        s[1] = avalance(dist(gen));
    }

    uint64_t next()
    {
        uint64_t s1 = s[0];
        const uint64_t s0 = s[1];

        s[0] = s0;
        s1 ^= s1 << 23; 

        return (s[1] = (s1 ^ s0 ^ (s1 >> 17) ^ (s0 >> 26))) + s0; 
    }
}

#endif