using System;
using Stackoverflow.Utilities;

namespace SearchBox
{
	public class IdNotFoundException : Exception { public IdNotFoundException(string message) : base(message) {  } }

	public class IdMapper
	{
		private int nextId = 0;
		public BiDictionary<int, string> map = new BiDictionary<int, string>();

		public IdMapper()
		{
		}

		public int GetId(string pageName)
		{
			// Perform unicode normalization
			pageName = pageName.Normalize(System.Text.NormalizationForm.FormC);

			int result;
			if (!map.TryGetBySecond(pageName, out result)) {
				map.Add(result = nextId++, pageName);
			}
			return result;
		}

		public string GetPageName(int id)
		{
			string result;
			if (!map.TryGetByFirst(id, out result))
				throw new IdNotFoundException($"Error: Couldn't find {id} in the ID map.");
			return result;
		}

		public void MovePageName(string oldPageName, string newPageName)
		{
			int id = map.GetBySecond(oldPageName);
			map.RemoveBySecond(oldPageName);
			map.Add(id, newPageName);
		}

		public void DeletePageName(string pageName)
		{
			map.RemoveBySecond(pageName);
		}
	}
}