public Participant PickWinner(Participant[] participants)
{
var odds = participants.Select(el => el.Odd).ToArray();
var totalMargin = MarginCalculator.Calculate(odds);
var participantTicketsRangeLength =
participants.Select(el => (int)Math.Round(el.Odd.ToPercentageOdds() / totalMargin * 10000D)).ToArray();
var participantTicketsBounds = new List <(int lowerBound, int upperBound)>();
var lowerBound = 0;
for (var i = 0; i < participants.Length; i++)
{
var upperBound = lowerBound + participantTicketsRangeLength[i];
participantTicketsBounds.Add((lowerBound, upperBound));
lowerBound = upperBound + 1;
}
var winnerTicket = randomizer.Next(participantTicketsBounds[participants.Length - 1].upperBound);
var winnerIndex =
participantTicketsBounds.FindIndex(el =>
el.lowerBound <= winnerTicket && el.upperBound >= winnerTicket);
return(participants[winnerIndex]);
}
public Participant DoRace()
{
var odds = _participants.Values.Select(el => el.Odd).ToArray();
var totalMargin = MarginCalculator.Calculate(odds);
if (totalMargin < 110.00D)
{
throw new TotalMarginDeficitException();
}
return(_winnerCalculator.PickWinner(_participants.Values.ToArray()));
}
public void AddParticipant(Participant participant)
{
if (_participants.ContainsKey(participant.Name))
{
throw new ParticipantAlreadyAddedException();
}
var odds = _participants.Values.Select(el => el.Odd).Append(participant.Odd).ToArray();
var totalMargin = MarginCalculator.Calculate(odds);
if (totalMargin > 140.00D)
{
throw new TotalMarginOverloadException();
}
_participants[participant.Name] = participant;
}