Tests for pro rata refunds

app/Services/Subscription/SubscriptionService.php

@@ -299,6 +299,24 @@ class SubscriptionService
 
     }
 
+    /**
+     * Calculates the pro rata refund between two dates
+     * using a daily calculation.
+     * 
+     * @param float $amount 
+     * @param Carbon $from_date 
+     * @param Carbon $to_date 
+     * @param int $frequency The billing interval
+     * @return float 
+     */
+    private function proRataRefund(float $amount, Carbon $from_date, Carbon $to_date, int $frequency) :float
+    {
+        $days = $from_date->diffInDays($to_date);
+        $days_in_frequency = $this->getDaysInFrequencySpecific($frequency);
+
+        return round( ($days/$days_in_frequency) * $amount);
+    }
+
     /**
      * Returns refundable set of line items
      * transformed for direct injection into
@@ -934,6 +952,41 @@ class SubscriptionService
 
     }
 
+    private function getDaysInFrequencySpecific($frequency)
+    {
+
+        switch ($frequency) {
+            case RecurringInvoice::FREQUENCY_DAILY:
+                return 1;
+            case RecurringInvoice::FREQUENCY_WEEKLY:
+                return 7;
+            case RecurringInvoice::FREQUENCY_TWO_WEEKS:
+                return 14;
+            case RecurringInvoice::FREQUENCY_FOUR_WEEKS:
+                return now()->diffInDays(now()->addWeeks(4));
+            case RecurringInvoice::FREQUENCY_MONTHLY:
+                return now()->diffInDays(now()->addMonthNoOverflow());
+            case RecurringInvoice::FREQUENCY_TWO_MONTHS:
+                return now()->diffInDays(now()->addMonthNoOverflow(2));
+            case RecurringInvoice::FREQUENCY_THREE_MONTHS:
+                return now()->diffInDays(now()->addMonthNoOverflow(3));
+            case RecurringInvoice::FREQUENCY_FOUR_MONTHS:
+                return now()->diffInDays(now()->addMonthNoOverflow(4));
+            case RecurringInvoice::FREQUENCY_SIX_MONTHS:
+                return now()->diffInDays(now()->addMonthNoOverflow(6));
+            case RecurringInvoice::FREQUENCY_ANNUALLY:
+                return now()->diffInDays(now()->addYear());
+            case RecurringInvoice::FREQUENCY_TWO_YEARS:
+                return now()->diffInDays(now()->addYears(2));
+            case RecurringInvoice::FREQUENCY_THREE_YEARS:
+                return now()->diffInDays(now()->addYears(3));
+            default:
+                return 0;
+        }
+
+    }
+
+
 
     /**
     * 'email' => $this->email ?? $this->contact->email,

tests/Unit/RefundUnitTest.php

@@ -0,0 +1,95 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/invoiceninja source repository
+ *
+ * @copyright Copyright (c) 2021. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://opensource.org/licenses/AAL
+ */
+namespace Tests\Unit;
+
+use App\Models\RecurringInvoice;
+use App\Utils\Ninja;
+use Illuminate\Support\Carbon;
+use Tests\TestCase;
+
+/**
+ * @test
+ */
+class RefundUnitTest extends TestCase
+{
+
+    public function setUp() :void
+    {
+        parent::setUp();
+    }
+
+    public function testProRataRefundMonthly()
+    {
+        $refund = $this->proRataRefund(10, Carbon::parse('2021-01-01'), Carbon::parse('2021-01-31'), RecurringInvoice::FREQUENCY_MONTHLY);
+
+        $this->assertEquals(9.68, $refund);
+
+        $this->assertEquals(30, Carbon::parse('2021-01-01')->diffInDays(Carbon::parse('2021-01-31')));
+
+    }
+
+    public function testProRataRefundYearly()
+    {
+
+        $refund = $this->proRataRefund(10, Carbon::parse('2021-01-01'), Carbon::parse('2021-01-31'), RecurringInvoice::FREQUENCY_ANNUALLY);
+
+        $this->assertEquals(0.82, $refund);
+    }
+
+    public function testDiffInDays()
+    {
+
+        $this->assertEquals(30, Carbon::parse('2021-01-01')->diffInDays(Carbon::parse('2021-01-31')));
+
+    }
+
+    private function proRataRefund(float $amount, Carbon $from_date, Carbon $to_date, int $frequency) :float
+    {
+        $days = $from_date->diffInDays($to_date);
+        $days_in_frequency = $this->getDaysInFrequencySpecific($frequency);
+
+        return round( (($days/$days_in_frequency) * $amount),2);
+    }
+
+    private function getDaysInFrequencySpecific($frequency)
+    {
+
+        switch ($frequency) {
+            case RecurringInvoice::FREQUENCY_DAILY:
+                return 1;
+            case RecurringInvoice::FREQUENCY_WEEKLY:
+                return 7;
+            case RecurringInvoice::FREQUENCY_TWO_WEEKS:
+                return 14;
+            case RecurringInvoice::FREQUENCY_FOUR_WEEKS:
+                return now()->diffInDays(now()->addWeeks(4));
+            case RecurringInvoice::FREQUENCY_MONTHLY:
+                return now()->diffInDays(now()->addMonthNoOverflow());
+            case RecurringInvoice::FREQUENCY_TWO_MONTHS:
+                return now()->diffInDays(now()->addMonthNoOverflow(2));
+            case RecurringInvoice::FREQUENCY_THREE_MONTHS:
+                return now()->diffInDays(now()->addMonthNoOverflow(3));
+            case RecurringInvoice::FREQUENCY_FOUR_MONTHS:
+                return now()->diffInDays(now()->addMonthNoOverflow(4));
+            case RecurringInvoice::FREQUENCY_SIX_MONTHS:
+                return now()->diffInDays(now()->addMonthNoOverflow(6));
+            case RecurringInvoice::FREQUENCY_ANNUALLY:
+                return now()->diffInDays(now()->addYear());
+            case RecurringInvoice::FREQUENCY_TWO_YEARS:
+                return now()->diffInDays(now()->addYears(2));
+            case RecurringInvoice::FREQUENCY_THREE_YEARS:
+                return now()->diffInDays(now()->addYears(3));
+            default:
+                return 0;
+        }
+    }
+
+}