project grouped invoice calculator (#892)

src/Invoice/Calculator/AbstractSumInvoiceCalculator.php

@@ -0,0 +1,46 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Invoice\Calculator;
+
+use App\Entity\Timesheet;
+use App\Invoice\CalculatorInterface;
+
+/**
+ * A calculator that sums up the timesheet records by activity.
+ */
+abstract class AbstractSumInvoiceCalculator extends AbstractMergedCalculator implements CalculatorInterface
+{
+    abstract protected function calculateSumIdentifier(Timesheet $timesheet): string;
+
+    /**
+     * @return Timesheet[]
+     */
+    public function getEntries()
+    {
+        $entries = $this->model->getEntries();
+        if (empty($entries)) {
+            return [];
+        }
+
+        /** @var Timesheet[] $timesheets */
+        $timesheets = [];
+
+        foreach ($entries as $entry) {
+            $id = $this->calculateSumIdentifier($entry);
+            if (!isset($timesheets[$id])) {
+                $timesheets[$id] = new Timesheet();
+            }
+            $timesheet = $timesheets[$id];
+            $this->mergeTimesheets($timesheet, $entry);
+        }
+
+        return array_values($timesheets);
+    }
+}