using System.Collections;
using System.Collections.Immutable;
using Connected.Interop;

namespace Connected.Collections.Iterators;

internal class DictionaryIterator : IIterator
{
	private readonly object _value;
	private IDictionary _result;
	public DictionaryIterator(object value)
	{
		_value = value;

		if (value is not IDictionary dictionary)
			return;

		Enumerator = dictionary.GetEnumerator();

		CreateResult();
	}

	public static bool CanHandle(object value)
	{
		var arguments = value.GetType().GetGenericArguments();
		var kvp = typeof(KeyValuePair<,>).MakeGenericType(arguments);
		var en = typeof(IEnumerable<>).MakeGenericType(kvp);

		return value.GetType() == en;
	}
	private void CreateResult()
	{
		if (_value.GetType() == typeof(IImmutableDictionary<,>))
			_result = _value.GetType().MakeGenericType(_value.GetType().GenericTypeArguments).CreateInstance<IDictionary>();
	}

	private IDictionaryEnumerator? Enumerator { get; }
	public object? Current => Enumerator?.Value;

	public object? Result
	{
		get
		{
			if (_value is null)
				return null;

			throw new NotImplementedException();
		}
	}

	public bool MoveNext()
	{
		if (Enumerator is null)
			return false;

		return Enumerator.MoveNext();
	}

	public void Reset()
	{
		if (Enumerator is null)
			return;

		Enumerator.Reset();
	}


	public void Add(object value)
	{
		if (Current is null || Enumerator is null)
			throw new InvalidOperationException(SR.ErrIteratorCurrentNull);

		_result.Add(Enumerator.Key, value);
	}
}