open Wonka_types;

type delayStateT = {
  mutable talkback: (.talkbackT) => unit,
  mutable active: int,
  mutable gotEndSignal: bool
};

let delay = wait => curry(source => curry(sink => {
  let state: delayStateT = {
    talkback: Wonka_helpers.talkbackPlaceholder,
    active: 0,
    gotEndSignal: false
  };

  source((.signal) => {
    switch (signal) {
    | Start(tb) => state.talkback = tb
    | _ when !state.gotEndSignal => {
      state.active = state.active + 1;
      ignore(Js.Global.setTimeout(() => {
        if (state.gotEndSignal && state.active === 0) {
          sink(.End);
        } else {
          state.active = state.active - 1;
        };

        sink(.signal);
      }, wait));
    }
    | _ => ()
    }
  });

  sink(.Start((.signal) => {
    switch (signal) {
    | Close => {
      state.gotEndSignal = true;
      if (state.active === 0) sink(.End);
    }
    | _ when !state.gotEndSignal => state.talkback(.signal)
    | _ => ()
    }
  }));
}));