Bowling

src/BowlingGame.php

@@ -0,0 +1,88 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App;
+
+use Assert\Assert;
+use Tightenco\Collect\Support\Collection;
+
+final class BowlingGame
+{
+    private const MAX_PINS_PER_FRAME = 10;
+    private const NUMBER_OF_FRAMES = 10;
+
+    private Collection $rolls;
+
+    public function __construct()
+    {
+        $this->rolls = new Collection();
+    }
+
+    public function roll(int $pins): void
+    {
+        Assert::that($pins)
+            ->greaterOrEqualThan(0,
+                'You cannot knock down a negative number of pins. Knocked down %d.')
+            ->lessOrEqualThan(self::MAX_PINS_PER_FRAME,
+                'You can only knock down a maximum of 10 pins in a roll. Knocked down 12.');
+
+        $this->rolls->push($pins);
+    }
+
+    public function getScore(): int
+    {
+        $score = 0;
+        $roll = 0;
+
+        foreach (range(1, self::NUMBER_OF_FRAMES) as $frame) {
+            if ($this->isStrike($roll)) {
+                $score += $this->rolls[$roll];
+                $score += $this->bonusForStrike($roll);
+
+                $roll += 1;
+                continue;
+            }
+
+            if ($this->isSpare($roll)) {
+                $score += $this->defaultFrameScore($roll);
+                $score += $this->bonusForSpare($roll);
+
+                $roll += 2;
+                continue;
+            }
+
+            $score += $this->defaultFrameScore($roll);
+
+            $roll += 2;
+        }
+
+        return $score;
+    }
+
+    private function bonusForSpare(int $roll): int
+    {
+        return $this->rolls->get($roll + 2);
+    }
+
+    private function bonusForStrike(int $roll): int
+    {
+        return $this->rolls[$roll + 1] + $this->rolls[$roll + 2];
+    }
+
+    private function defaultFrameScore(int $roll): int
+    {
+        return $this->rolls[$roll] + $this->rolls[$roll + 1];
+    }
+
+    private function isSpare(int $roll): bool
+    {
+        return $this->defaultFrameScore($roll)
+            == self::MAX_PINS_PER_FRAME;
+    }
+
+    private function isStrike(int $roll): bool
+    {
+        return $this->rolls[$roll] == self::MAX_PINS_PER_FRAME;
+    }
+}