/* Signals/slots for OctaSTD.
 *
 * This file is part of OctaSTD. See COPYING.md for futher information.
 */

#ifndef OSTD_SIGNAL_HH
#define OSTD_SIGNAL_HH

#include "ostd/functional.hh"
#include "ostd/utility.hh"

namespace ostd {

namespace detail {
    template<typename C, typename ...A>
    struct EventBase {
        EventBase(C *cl): p_class(cl), p_funcs(nullptr), p_nfuncs(0) {}

        EventBase(const EventBase &ev): p_class(ev.p_class),
                                        p_nfuncs(ev.p_nfuncs) {
            using Func = Function<void(C &, A...)>;
            Func *nbuf = (Func *)new byte[sizeof(Func) * p_nfuncs];
            for (Size i = 0; i < p_nfuncs; ++i)
                new (&nbuf[i]) Func(ev.p_funcs[i]);
            p_funcs = nbuf;
        }

        EventBase(EventBase &&ev): p_class(ev.p_class), p_funcs(ev.p_funcs),
                                   p_nfuncs(ev.p_nfuncs) {
            ev.p_class = nullptr;
            ev.p_funcs = nullptr;
            ev.p_nfuncs = 0;
        }

        void clear() {
            for (Size i = 0; i < p_nfuncs; ++i)
                p_funcs[i].~Function<void(C &, A...)>();
            delete[] (byte *)p_funcs;
            p_funcs = nullptr;
            p_nfuncs = 0;
        }

        template<typename F>
        Size connect(F &&func) {
            using Func = Function<void(C &, A...)>;
            Func *nbuf = (Func *)new byte[sizeof(Func) * (p_nfuncs + 1)];
            for (Size i = 0; i < p_nfuncs; ++i) {
                new (&nbuf[i]) Func(move(p_funcs[i]));
                p_funcs[i].~Func();
            }
            new (&nbuf[p_nfuncs]) Func(forward<F>(func));
            delete[] (byte *)p_funcs;
            p_funcs = nbuf;
            return p_nfuncs++;
        }

        bool disconnect(Size idx) {
            if ((idx >= p_nfuncs) || !p_funcs[idx]) return false;
            p_funcs[idx] = nullptr;
            return true;
        }

        template<typename ...Args>
        void emit(Args &&...args) const {
            if (!p_class) return;
            for (Size i = 0; i < p_nfuncs; ++i)
                if (p_funcs[i]) p_funcs[i](*p_class, args...);
        }

    private:
        C *p_class;
        Function<void(C &, A...)> *p_funcs;
        Size p_nfuncs;
    };
} /* namespace detail */

template<typename C, typename ...A>
struct Event {
private:
    using Base = detail::EventBase<C, A...>;
    Base p_base;
public:
    Event(C *cl): p_base(cl) {}
    Event(const Event &ev): p_base(ev.p_base) {}
    Event(Event &&ev): p_base(move(ev.p_base)) {}

    ~Event() { clear(); }

    void clear() { p_base.clear(); }

    template<typename F>
    Size connect(F &&func) { return p_base.connect(forward<F>(func)); }

    bool disconnect(Size idx) { return p_base.disconnect(idx); }

    template<typename ...Args>
    void emit(Args &&...args) { p_base.emit(forward<Args>(args)...); }

    template<typename ...Args>
    void operator()(Args &&...args) { emit(forward<Args>(args)...); }
};

template<typename C, typename ...A>
struct Event<const C, A...> {
private:
    using Base = detail::EventBase<const C, A...>;
    Base p_base;
public:
    Event(C *cl): p_base(cl) {}
    Event(const Event &ev): p_base(ev.p_base) {}
    Event(Event &&ev): p_base(move(ev.p_base)) {}

    ~Event() { clear(); }

    void clear() { p_base.clear(); }

    template<typename F>
    Size connect(F &&func) { return p_base.connect(forward<F>(func)); }

    bool disconnect(Size idx) { return p_base.disconnect(idx); }

    template<typename ...Args>
    void emit(Args &&...args) const { p_base.emit(forward<Args>(args)...); }

    template<typename ...Args>
    void operator()(Args &&...args) const { emit(forward<Args>(args)...); }
};

} /* namespace ostd */

#endif