FormCollection to JObject extension

FormCollectionToJObjectExtension.cs

public static class FormCollectionToJObjectExtension
{
	public static JObject ToJObject(this IFormCollection form)
	{
		JObject target = new JObject();
		foreach (var element in form)
		{
			Add(target, element.Key, element.Value);
		}
		return target;

		void Add(JObject jo, string key, StringValues value)
		{
			var chars = new[] { '.', '[' };

			var x = key.IndexOfAny(chars);
			if (x == -1)
				jo[key] = value.LastOrDefault();
			else
			{
				var name = key.Substring(0, x);
				if (key[x] == '.')
				{
					var subJo = jo[name] as JObject ?? (JObject)(jo[name] = new JObject());
					Add(subJo, key.Substring(x + 1), value);
				}
				else
				{
					var subJa = jo[name] as JArray ?? (JArray)(jo[name] = new JArray());

					var closeBracketsIndex = key.IndexOf(']', x + 1);
					var itemIndex = int.Parse(key.Substring(x + 1, closeBracketsIndex - x - 1));
					while (subJa.Count < itemIndex + 1) subJa.Add(null);

					if (closeBracketsIndex == key.Length - 1)
					{
						subJa[itemIndex] = value.LastOrDefault();
						return;
					}
					if (key[closeBracketsIndex + 1] != '.') throw new Exception();
					var remainder = key.Substring(closeBracketsIndex + 2);
					var subJo = subJa[itemIndex] as JObject ?? (JObject)(subJa[itemIndex] = new JObject());
					Add(subJo, remainder, value);
				}
			}
		}
	}
}