using System;
using System.Collections.Concurrent;
using System.Collections.Generic;

namespace SearchBox
{
	public class InvertedIndex
	{
		private ConcurrentDictionary<string, ConcurrentDictionary<int, List<int>>> invertedIndex = new ConcurrentDictionary<string, ConcurrentDictionary<int, List<int>>>();

		public InvertedIndex()
		{
		}

		public bool AddIndex(int pageId, Index newIndex)
		{
			foreach (KeyValuePair<string, List<int>> token in newIndex)
			{
				if (!invertedIndex.ContainsKey(token.Key) &&
					!invertedIndex.TryAdd(token.Key, new ConcurrentDictionary<int, List<int>>()))
					return false;

				if (!invertedIndex[token.Key].TryAdd(pageId, token.Value))
					return false;
			}
			return true;
		}

		public bool RemoveIndex(int pageId, Index newIndex)
		{
			foreach (string token in newIndex.Tokens())
			{
				if (!invertedIndex.ContainsKey(token) || !invertedIndex[token].ContainsKey(pageId)) continue;

				if (!invertedIndex[token].TryRemove(pageId, out List<int> noop))
					return false;
			}
			return false;
		}
	}
}