using R3;
using UnityAtoms;

namespace KitsuneCafe.Extension
{
  public static class AtomExtensions
  {
    public static Observable<T> ObserveChange<T, P, C, V, E1, E2, F, VI>(this AtomReference<T, P, C, V, E1, E2, F, VI> reference)
      where C : AtomBaseVariable<T>
      where V : AtomVariable<T, P, E1, E2, F>
      where P : struct, IPair<T>
      where E1 : AtomEvent<T>
      where E2 : AtomEvent<P>
      where F : AtomFunction<T, T>
      where VI : AtomVariableInstancer<V, P, T, E1, E2, F>
    {
      return reference.Usage switch
      {
        AtomReferenceUsage.CONSTANT => Observable.Return(reference.Value),
        AtomReferenceUsage.VALUE => Observable.EveryValueChanged(reference, r => r.Value),
        AtomReferenceUsage.VARIABLE or AtomReferenceUsage.VARIABLE_INSTANCER => reference.GetEvent<E1>().Observe().ToObservable(),
        _ => throw new System.NotImplementedException(),
      };
    }
  }
}