public async Task <IActionResult> UpdateScores(string winnerId, string loserId)
{
var winnerImage = await repository.RetrieveAsync(winnerId);
var loserImage = await repository.RetrieveAsync(loserId);
if (winnerImage is null || loserImage is null)
{
return(NotFound());
}
var expectedScoreWinner = eloRatingCalculator.ComputeExpectation(
winnerImage.Score, loserImage.Score);
var expectedScoreLoser = eloRatingCalculator.ComputeExpectation(
loserImage.Score, winnerImage.Score);
winnerImage.Score = eloRatingCalculator.ComputeRating(
winnerImage.Score, expectedScoreWinner, constants.ScoreWhenWin, constants.KFactor);
loserImage.Score = eloRatingCalculator.ComputeRating(
loserImage.Score, expectedScoreLoser, constants.ScoreWhenLose, constants.KFactor);
winnerImage.Votes++;
bool?success = await repository.SaveChangesAsync();
if (success is null)
{
return(StatusCode(StatusCodes.Status500InternalServerError));
}
else
{
return(Ok());
}
}
public void ComputeExpectation_ratingsGiven_ShouldReturnExpectation()
{
// Arrange
decimal ratingA = 123.4M;
decimal ratingB = 865.23M;
decimal expectation = (decimal)(1 / (1 + Math.Pow(10, (double)((ratingB - ratingA) / 400))));
EloRatingCalculator ratingCalculator = new EloRatingCalculator();
// Act
decimal computedExpectation = ratingCalculator.ComputeExpectation(ratingA, ratingB);
// Assert
Assert.Equal(expectation, computedExpectation);
}