added rounding rules and hourly rates factor #112 (#128)

* added unit tests and documentation #112
* fixed DashboardController
* added CONTRIBUTION guidelines
* fixed license year

src/Timesheet/Calculator/RateCalculator.php

@@ -0,0 +1,86 @@
+<?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\Timesheet\Calculator;
+
+use App\Entity\Timesheet;
+use App\Entity\UserPreference;
+use App\Timesheet\CalculatorInterface;
+
+/**
+ * Implementation to calculate the rate for a timesheet record.
+ */
+class RateCalculator implements CalculatorInterface
+{
+    /**
+     * @var array
+     */
+    protected $rates;
+
+    /**
+     * RateCalculator constructor.
+     * @param array $rates
+     */
+    public function __construct(array $rates)
+    {
+        $this->rates = $rates;
+    }
+
+    /**
+     * @param Timesheet $record
+     */
+    public function calculate(Timesheet $record)
+    {
+        if ($record->getEnd() === null) {
+            return;
+        }
+
+        $rate = $this->calculateRate($record);
+        $factor = $this->getRateFactor($record);
+
+        $record->setRate($rate * $factor);
+    }
+
+    /**
+     * @param Timesheet $record
+     * @return float
+     */
+    protected function getRateFactor(Timesheet $record)
+    {
+        $factor = 0;
+        foreach ($this->rates as $rateFactor) {
+            $weekday = $record->getEnd()->format('l');
+            $days = array_map('strtolower', $rateFactor['days']);
+            if (in_array(strtolower($weekday), $days)) {
+                if ($rateFactor['factor'] <= 0) {
+                    throw new \InvalidArgumentException(
+                        'A rate factor smaller or equals 0 is not allowed, given: ' . $rateFactor['factor']
+                    );
+                }
+                $factor += $rateFactor['factor'];
+            }
+        }
+
+        if ($factor <= 0) {
+            $factor = 1;
+        }
+
+        return $factor;
+    }
+
+    /**
+     * @param Timesheet $record
+     * @return float
+     */
+    protected function calculateRate(Timesheet $record)
+    {
+        $hourlyRate = (float) $record->getUser()->getPreferenceValue(UserPreference::HOURLY_RATE, 0);
+        return (float) $hourlyRate * ($record->getDuration() / 3600);
+    }
+}