#pragma once

#include <cstdint>
#include <map>
#include <set>
#include <vector>

namespace sim {

    struct Schedulable;

    struct Scheduler {
        std::set<Schedulable *> unsorted_schedulables;
        std::vector<Schedulable *> sorted_schedulables;
        bool sort_needed = false;

        std::multimap<Schedulable *, Schedulable *> constraints;

        Schedulable *current_schedulable = nullptr;
        std::uint64_t now = 0;

        void add_schedulable(Schedulable *schedulable);
        void remove_schedulable(Schedulable *schedulable);

        void constrain(Schedulable *prior, Schedulable *later);

        void topo_sort(std::set<Schedulable *> &live, std::set<Schedulable *> &waiting, Schedulable *candidate);
        void sort();

        void clock();
    };

    struct Schedulable {
        Scheduler &scheduler;

        Schedulable(Scheduler &scheduler);
        virtual ~Schedulable();

        virtual void clock() = 0;

        std::uint64_t now();
    };

}