using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace PocketGoogle
{
    public class Indexer : IIndexer
    {
        private readonly Dictionary<string, HashSet<int>> wordWithIdDocs =
            new Dictionary<string, HashSet<int>>();
        private readonly Dictionary<int, Dictionary<string, HashSet<int>>> idDocWithWordsAndHisPos =
            new Dictionary<int, Dictionary<string, HashSet<int>>>();

        public void Add(int id, string documentText)
        {
            var words = documentText.Split(' ', '.', ',', '!', '?', ':', '-', '\r', '\n');
            idDocWithWordsAndHisPos.Add(id, new Dictionary<string, HashSet<int>>());

            var currentPosition = 0;
            var wordsLegth = words.Length;
            for (var i = 0; i < wordsLegth; i++)
            {
                if (!wordWithIdDocs.ContainsKey(words[i]))
				{
                    wordWithIdDocs.Add(words[i], new HashSet<int>());
				}
				wordWithIdDocs[words[i]].Add(id);

                if (!idDocWithWordsAndHisPos[id].ContainsKey(words[i]))
				{
                    idDocWithWordsAndHisPos[id].Add(words[i], new HashSet<int>());
				}
                idDocWithWordsAndHisPos[id][words[i]].Add(currentPosition);
                currentPosition += words[i].Length + 1;
            }
        }

        public List<int> GetIds(string word)
        {
            if (wordWithIdDocs.ContainsKey(word))
            {
                return wordWithIdDocs[word].ToList<int>();
            }
            return new List<int>();
        }

        public List<int> GetPositions(int id, string word)
        {
            if (idDocWithWordsAndHisPos.ContainsKey(id) &&
                idDocWithWordsAndHisPos[id].ContainsKey(word))
            {
                return idDocWithWordsAndHisPos[id][word].ToList<int>();
            }
            return new List<int>();
        }

        public void Remove(int id)
        {
            foreach (var word in wordWithIdDocs.Keys)
            {
                wordWithIdDocs[word].Remove(id);
            }
            idDocWithWordsAndHisPos.Remove(id);
        }
    }
}