#pragma once

#include <cstdint>

namespace roro::games {

// The Games' own dice (issue #101): the same seed gives the same game, which is what lets their
// rules be tested. xorshift32; never 0.
class Rng {
   public:
    explicit Rng(uint32_t seed) : s_(seed ? seed : 0x9E3779B9u) {}
    uint32_t next() {
        s_ ^= s_ << 13;
        s_ ^= s_ >> 17;
        s_ ^= s_ << 5;
        return s_;
    }
    int below(int n) { return n <= 1 ? 0 : static_cast<int>(next() % static_cast<uint32_t>(n)); }
    float unit() { return (next() >> 8) / 16777216.0f; }  // 0 up to 1

   private:
    uint32_t s_;
};

}  // namespace roro::games