#ifndef VTR_RANDOM_H
#define VTR_RANDOM_H
#include <algorithm> //For std::swap

namespace vtr {
    /*********************** Portable random number generators *******************/
    typedef unsigned RandState;

    void srandom(int seed);
    RandState get_random_state();
    int irand(int imax);
    int irand(int imax, RandState& rand_state);
    float frand();

    //Portable/invariant version of std::shuffle
    //
    //Note that std::shuffle relies on std::uniform_int_distribution
    //which can produce different sequences accross different
    //compilers/compiler versions.
    //
    //This version should be deterministic/invariant. However,  since 
    //it uses vtr::irand(), may not be as well distributed as std::shuffle.
    template<typename Iter>
    void shuffle(Iter first, Iter last, RandState& rand_state) {
        for (auto i = (last - first) - 1; i > 0; --i) {
            using std::swap;
            swap(first[i], first[irand(i, rand_state)]);
        }
    }

} //namespace
#endif