Implemented Sonneborn-Berger

src/Tiebreaks.php

@@ -188,4 +188,22 @@ abstract class Tiebreaks extends Tournament
         }
         return $tiebreak;
     }
+
+
+    /**
+     * @param Player $player
+     * @return float|int|null
+     */
+    protected function calculateSonneborn(Player $player)
+    {
+        $tiebreak = 0;
+        foreach ($player->getPairings() as $key => $pairing) {
+            if (array_search($pairing->getResult(), Constants::Won) !== false) {
+                $tiebreak += $pairing->getOpponent()->getPoints();
+            } elseif (array_search($pairing->getResult(), Constants::draw) !== false) {
+                $tiebreak += $pairing->getOpponent()->getPoints() / 2;
+            }
+        }
+        return $tiebreak;
+    }
 }

src/Tournament.php

@@ -308,6 +308,9 @@ class Tournament extends Tiebreaks
             case Tiebreak::BuchholzMed:
                 return $this->calculateBuchholz($player, 1, 1);
                 break;
+            case Tiebreak::Sonneborn:
+                return $this->calculateSonneborn($player);
+                break;
             default:
                 return null;
         }