/* @file Reducer.hpp */

#pragma once

#include "reactor/EventTimeFn.hpp"

namespace xo {
  namespace reactor {
    /* LastReducer, HeapReducer inherit ReducerBase */
    template<typename Event, typename EventTimeFn>
    class ReducerBase {
      static_assert(EventTimeConcept<Event, EventTimeFn>);

    public:
      using utc_nanos = xo::time::utc_nanos;

    public:
      ReducerBase() = default;
      ReducerBase(EventTimeFn const & evtfn) : event_tm_fn_{evtfn} {}

      utc_nanos event_tm(Event const & ev) const { return this->event_tm_fn_(ev); }
      
    private:
      /*   Event ev = ...;
       *   .event_tm_fn(ev) -> utc_nanos
       * reports event time associated with ev
       */
      EventTimeFn event_tm_fn_;
    }; /*ReducerBase*/
  } /*namespace reactor*/
} /*namespace xo*/

/* end Reducer.hpp */