using System.Diagnostics;

namespace SJK.Functional;

public static class OptionExtensions
{
  public static IEnumerable<TResult> Match<T, TResult>(this IEnumerable<IOption<T>> values, Func<T, TResult> onSome, Func<TResult> onNone)
  {
    foreach (var item in values)
    {
      yield return item.Match(onSome, onNone);
    }
  }
  // public static IOption<T> GetValue<Tkey, T>(this IDictionary<Tkey, T> value, Tkey key) where Tkey : notnull
  // {
  //   if (value.TryGetValue(key, out var v))
  //   {
  //     return v.ToOption();
  //   }
  //   return None<T>.Of();
  // }
  public static IOption<T> GetValue<Tkey, T>(this IReadOnlyDictionary<Tkey, T> value, Tkey key) where Tkey : notnull
  {
    if (value.TryGetValue(key, out var v))
    {
      return v.ToOption();
    }
    return None<T>.Of();
  }
  public static IOption<T> OrElse<T>(this IOption<T> option, Func<IOption<T>> fallback)
  {
    return option.Match(
        some => option,
        () => fallback()
    );
  }
  public static IOption<TResult> BindUsing<TDisposable, TResult>(
      this IOption<TDisposable> option,
      Func<TDisposable, IOption<TResult>> func)
      where TDisposable : IDisposable
  {
    return option.Match(
        some =>
        {
          using (some) return func(some);
        },
        () => None<TResult>.Of()
    );
  }

  public static IOption<T> ToOption<T>(this T? value) => value != null ? Some<T>.Of(value) : None<T>.Of();
  [StackTraceHidden]
  // [MethodImpl(MethodImplOptions.AggressiveInlining)]
  public static T OrThrow<T, TEx>(this IOption<T> option, Func<TEx> exceptionFactory) where TEx : Exception
  {
    if (option.HasValue(out var value))
      return value;

    throw exceptionFactory();
  }
  public static IEither<L, R> ToEither<Tvalue, L, R>(this Tvalue value, Func<Tvalue, bool> isSuccess, Func<R> ok, Func<Tvalue, L> err)
  {
    return isSuccess(value) ? new Right<L, R>(ok()) : new Left<L, R>(err(value));
  }
  public static IEither<L, R> ToEither<Tvalue, L, R>(this Tvalue value, Tvalue successValue, Func<R> ok, Func<Tvalue, L> err)
  {
    return value.ToEither(e => e.Equals(successValue), ok, err);
  }
  // public static IEnumerable<IOption<T>> ToOptions<T>(this IEnumerable<T> value) => value.Select(thing => thing.ToOption());
  public static Some<T> ToSome<T>(this T value) where T : notnull => Some<T>.Of(value);
  public static void IfSome<T>(this IOption<T> value, Action<T> onSome) => value.Match(onSome, () => { });
  public static void IfNone<T>(this IOption<T> value, Action onNone) => value.Match(_ => { }, onNone);

  public static T Or<T>(this IOption<T> value, Func<T> @default) => value.Or(@default());
  public static IEnumerable<T> OnlySomes<T>(this IEnumerable<IOption<T>> options)
  {
    foreach (var item in options)
    {
      if (item.HasValue(out var item2))
        yield return item2;
    }
  }
  // public static None<T> ToNone<T>(this T value) => None<T>.Of();

  public static Option<T> ToStructOption<T>(this IOption<T> option) => option.HasValue(out var value) ? Option<T>.Some(value) : Option<T>.None;
  public static IOption<T> ToClassOption<T>(this Option<T> option) => option.HasValue ? option.Value.ToOption() : None<T>.Of();
}