public string Get(int id)
        {
            using (var comparerRepository = new ComparerRepository())
            {
                var comparer = comparerRepository.Find(id);

                if (comparer is null)
                {
                    throw new ArgumentNullException("Comparer not found");
                }

                if (comparer.Left.Equals(comparer.Right))
                {
                    return("Contents are the same.");
                }

                if (!comparer.Left.Length.Equals(comparer.Right.Length))
                {
                    return("Contents are not of the same size.");
                }

                string jsonLeft  = Encoding.UTF8.GetString(Convert.FromBase64String(comparer.Left));
                string jsonRight = Encoding.UTF8.GetString(Convert.FromBase64String(comparer.Right));

                int length = 0;
                int?offset = null;
                List <DiffEntry> diffEntries = new List <DiffEntry>();

                for (int i = 0; i < jsonLeft.Length; i++)
                {
                    if (jsonLeft[i] != jsonRight[i])
                    {
                        if (length == 0)
                        {
                            offset = i;
                        }

                        length++;
                    }
                    else if (length > 0)
                    {
                        diffEntries.Add(new DiffEntry((int)offset, length));
                        length = 0;
                        offset = 0;
                    }
                }

                return(Newtonsoft.Json.JsonConvert.SerializeObject(diffEntries));
            }
        }
        public string SetContent(int id, string content, Side side = Side.Left)
        {
            if (string.IsNullOrWhiteSpace(content))
            {
                throw new ArgumentException("null content");
            }

            if (!IsBase64String(content))
            {
                throw new ArgumentException("invalid content");
            }

            using (var comparerRepository = new ComparerRepository())
            {
                var comparer = comparerRepository.Find(id);

                if (comparer is null)
                {
                    comparer = new Comparer()
                    {
                        Id = id
                    };

                    comparerRepository.Add(comparer);
                }

                if (side == Side.Left)
                {
                    comparer.Left = content;
                }
                else
                {
                    comparer.Right = content;
                }

                comparerRepository.Update(comparer);

                return($"{side}-side Content was set");
            }
        }