Improve metric threshold

app/Models/Metric.php

@@ -12,10 +12,12 @@
 namespace CachetHQ\Cachet\Models;
 
 use AltThree\Validator\ValidatingTrait;
+use AltThree\Validator\ValidationException;
 use CachetHQ\Cachet\Models\Traits\SortableTrait;
 use CachetHQ\Cachet\Presenters\MetricPresenter;
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Model;
+use Illuminate\Support\MessageBag;
 use McCool\LaravelAutoPresenter\HasPresenter;
 
 class Metric extends Model implements HasPresenter
@@ -57,6 +59,13 @@ class Metric extends Model implements HasPresenter
      */
     const VISIBLE_HIDDEN = 2;
 
+    /**
+     * Array of acceptable threshold minutes.
+     *
+     * @var int[]
+     */
+    const ACCEPTABLE_THRESHOLDS = [1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60];
+
     /**
      * The model's attributes.
      *
@@ -200,6 +209,26 @@ class Metric extends Model implements HasPresenter
         return $this->display_chart;
     }
 
+    /**
+     * Validate the model before save.
+     *
+     * @throws \AltThree\Validator\ValidationException
+     *
+     * @return void
+     */
+    public function validate()
+    {
+        $messages = [];
+
+        if (60 % $this->threshold === 0) {
+            $messages[] = 'Threshold must be divisible by 60.';
+        }
+
+        if ($messages) {
+            throw new ValidationException(new MessageBag($messages));
+        }
+    }
+
     /**
      * Get the presenter class.
      *