/**
* Given a team ('A'/'B'), determines new team rating.
*
* @param string $team
* @return float
*/
protected function getNewTeamRating($team)
{
$inputRatingFunction = 'getTeam' . $team . 'Rating';
if ($this->matchResult->getHigherTeam() == MatchResult::TEAMS_EQUAL) {
// team's ranking points equal before game
if ($this->matchResult->getResult() == MatchResult::DRAW) {
// no change
return $this->ratingsInput->{$inputRatingFunction}();
}
if ($this->matchResult->getResult() == $team) {
// this team wins and gets points increase
return $this->ratingsInput->{$inputRatingFunction}() + $this->exchange->getExchangeAmount();
}
// team lost
return $this->ratingsInput->{$inputRatingFunction}() - $this->exchange->getExchangeAmount();
}
if ($this->matchResult->getHigherTeam() == $team) {
// team in question is higher ranked before game
if ($this->matchResult->getResult() == $team) {
// team won
return $this->ratingsInput->{$inputRatingFunction}() + $this->exchange->getExchangeAmount();
}
// team lost or drew, as they're higher ranked they lose points
return $this->ratingsInput->{$inputRatingFunction}() - $this->exchange->getExchangeAmount();
}
// if we get here we're dealing with lower-ranked team before game
if ($this->matchResult->getResult() == $team || $this->matchResult->getResult() == MatchResult::DRAW) {
// lower ranked team gains points from win or draw
return $this->ratingsInput->{$inputRatingFunction}() + $this->exchange->getExchangeAmount();
}
// lower ranked team lost
return $this->ratingsInput->{$inputRatingFunction}() - $this->exchange->getExchangeAmount();
}
/**
* Calculates rating points exchange between teams and returns it.
*
* @return float the points exchange
* @throws InvalidMatchResultException if cannot determine match result
*/
public function calculate()
{
$base = $this->ratingsGap / Calculate::MAX_RATINGS_GAP;
if ($this->matchResult->isUnderdogWin() || $this->matchResult->equalsWin()) {
$this->exchangeAmount = 1 + $base;
$this->applyWeightings();
return $this->exchangeAmount;
}
if ($this->matchResult->isHigherTeamWin()) {
$this->exchangeAmount = 1 - $base;
$this->applyWeightings();
return $this->exchangeAmount;
}
if ($this->matchResult->getResult() == MatchResult::DRAW) {
$this->exchangeAmount = $base;
$this->applyWeightings();
return $this->exchangeAmount;
}
throw new InvalidMatchResultException('Cannot calculate exchange: Invalid MatchResult Type');
}
