BirdsiteLIVE/src/BirdsiteLive.Pipeline/Tools/MaxUsersNumberProvider.cs

using System.Threading.Tasks;

using BirdsiteLive.Common.Settings;
using BirdsiteLive.DAL.Contracts;

namespace BirdsiteLive.Pipeline.Tools
{
    public interface IMaxUsersNumberProvider
    {
        Task<int> GetMaxUsersNumberAsync();
    }

    public class MaxUsersNumberProvider : IMaxUsersNumberProvider
    {
        private readonly InstanceSettings _instanceSettings;
        private readonly ITwitterUserDal _twitterUserDal;

        private int _totalUsersCount = -1;
        private int _warmUpIterations;
        private const int WarmUpMaxCapacity = 200;

        #region Ctor
        public MaxUsersNumberProvider(
            InstanceSettings instanceSettings,
            ITwitterUserDal twitterUserDal
        )
        {
            _instanceSettings = instanceSettings;
            _twitterUserDal = twitterUserDal;
        }
        #endregion

        public async Task<int> GetMaxUsersNumberAsync()
        {
            // Init data
            if (_totalUsersCount == -1)
            {
                _totalUsersCount = await _twitterUserDal.GetTwitterUsersCountAsync();
                _warmUpIterations = (int)(_totalUsersCount / (float)WarmUpMaxCapacity);
            }

            // Return if warm up ended
            if (_warmUpIterations <= 0)
                return _instanceSettings.MaxUsersCapacity;

            // Calculate warm up value
            var maxUsers =
                _warmUpIterations > 0 ? WarmUpMaxCapacity : _instanceSettings.MaxUsersCapacity;
            _warmUpIterations--;
            return maxUsers;
        }
    }
}