/**
* Returns the previous round in the game.
* If this is a repeated step, then this is the previous repetition of this step
* (unless this is the first repetition).
* Otherwise, it is the last repetition of the previous step.
*
* @throws DoesNotExistException if there is no previous step
* @return Round the previous round
*/
public function previousRound()
{
if ($this->repetition == 0) {
return new Round($this->step->previousStep(), $this->step->repeat);
} else {
if ($this->step->isRepeated()) {
return new Round($this->step, $this->repetition - 1);
} else {
throw new Exception('internal error: this is not a repeated step, so the only legal value for repetition is 0 ' . "(current value is {$this->repetition})");
}
}
}
