Add DateTimeComparator class

README.md

@@ -91,3 +91,31 @@ Helps you equals on objects on a similar way as [java](http://stackoverflow.com/
 #### equals
 
 Method that you must implements to check if the object taking as parameter is equals or not.
+
+### DateTimeComparator class
+
+#### ::greatest
+
+Compare two \DateTimeInterface and return the greatest
+_If one of given \DateTimeInterface parameters is null, return is the other one \DateTimeInterface_
+_If both \DateTimeInterface parameters are null, return is null_
+
+```php
+DateTimeComparator::greatest($dateTime1, $dateTime2) : ?\DateTimeInterface
+```
+
+* `$dateTime1` The first \DateTimeInterface or null
+* `$dateTime2` The second \DateTimeInterface or null
+
+#### ::lowest
+
+Compare two \DateTimeInterface and return the lowest
+_If one of given \DateTimeInterface parameters is null, return is the other one \DateTimeInterface_
+_If both \DateTimeInterface parameters are null, return is null_
+
+```php
+DateTimeComparator::lowest($dateTime1, $dateTime2) : ?\DateTimeInterface
+```
+
+* `$dateTime1` The first \DateTimeInterface or null
+* `$dateTime2` The second \DateTimeInterface or null

spec/Nekland/Tools/DateTimeComparatorSpec.php

@@ -0,0 +1,60 @@
+<?php
+
+namespace spec\Nekland\Tools;
+
+use PhpSpec\ObjectBehavior;
+use Prophecy\Argument;
+
+class DateTimeComparatorSpec extends ObjectBehavior
+{
+    function it_is_initializable()
+    {
+        $this->shouldHaveType('Nekland\Tools\DateTimeComparator');
+    }
+
+    function it_should_return_greatest_date_time()
+    {
+        $dateTimeImmutable1 = new \DateTimeImmutable('+2 days');
+        $dateTimeImmutable2 = new \DateTimeImmutable();
+
+        $dateTime1 = new \DateTime('+2 days');
+        $dateTime2 = new \DateTime();
+
+        // DateTimeImmutable tests
+        $this::greatest($dateTimeImmutable1, $dateTimeImmutable2)->shouldReturn($dateTimeImmutable1);
+        $this::greatest($dateTimeImmutable2, $dateTimeImmutable1)->shouldReturn($dateTimeImmutable1);
+        $this::greatest($dateTimeImmutable1, null)->shouldReturn($dateTimeImmutable1);
+        $this::greatest(null, $dateTimeImmutable1)->shouldReturn($dateTimeImmutable1);
+
+        // DateTime tests
+        $this::greatest($dateTime1, $dateTime2)->shouldReturn($dateTime1);
+        $this::greatest($dateTime2, $dateTime1)->shouldReturn($dateTime1);
+        $this::greatest($dateTime1, null)->shouldReturn($dateTime1);
+        $this::greatest(null, $dateTime1)->shouldReturn($dateTime1);
+
+        $this::greatest(null, null)->shouldReturn(null);
+    }
+
+    function it_should_return_lowest_date_time()
+    {
+        $dateTimeImmutable1 = new \DateTimeImmutable();
+        $dateTimeImmutable2 = new \DateTimeImmutable('+2 days');
+
+        $dateTime1 = new \DateTime();
+        $dateTime2 = new \DateTime('+2 days');
+
+        // DateTimeImmutable tests
+        $this::lowest($dateTimeImmutable1, $dateTimeImmutable2)->shouldReturn($dateTimeImmutable1);
+        $this::lowest($dateTimeImmutable2, $dateTimeImmutable1)->shouldReturn($dateTimeImmutable1);
+        $this::lowest($dateTimeImmutable1, null)->shouldReturn($dateTimeImmutable1);
+        $this::lowest(null, $dateTimeImmutable1)->shouldReturn($dateTimeImmutable1);
+
+        // DateTime tests
+        $this::lowest($dateTime1, $dateTime2)->shouldReturn($dateTime1);
+        $this::lowest($dateTime2, $dateTime1)->shouldReturn($dateTime1);
+        $this::lowest($dateTime1, null)->shouldReturn($dateTime1);
+        $this::lowest(null, $dateTime1)->shouldReturn($dateTime1);
+
+        $this::lowest(null, null)->shouldReturn(null);
+    }
+}

src/DateTimeComparator.php

@@ -0,0 +1,61 @@
+<?php
+
+namespace Nekland\Tools;
+
+class DateTimeComparator
+{
+    /**
+     * Get the greatest DateTime between the twice given as parameter
+     * If one DateTime is null, return the other
+     * If the twice DateTime are null, return null
+     */
+    public static function greatest(\DateTimeInterface $dateTime1 = null, \DateTimeInterface $dateTime2 = null)
+    {
+        // - If one DateTime is null, return the other date
+        // - If the twice DateTime are null, return null
+        if (\is_null($dateTime1) || \is_null($dateTime2)) {
+            return self::getNonNullableDateTime($dateTime1, $dateTime2);
+        }
+
+        return $dateTime1 > $dateTime2 ? $dateTime1 : $dateTime2;
+    }
+
+    /**
+     * Get the lowest DateTime between the twice given as parameter
+     * If one DateTime is null, return the other
+     * If the twice DateTime are null, return null
+     */
+    public static function lowest(\DateTimeInterface $dateTime1 = null, \DateTimeInterface $dateTime2 = null)
+    {
+        // - If one DateTime is null, return the other date
+        // - If the twice DateTime are null, return null
+        if (\is_null($dateTime1) || \is_null($dateTime2)) {
+            return self::getNonNullableDateTime($dateTime1, $dateTime2);
+        }
+
+        return $dateTime1 < $dateTime2 ? $dateTime1 : $dateTime2;
+    }
+
+    /**
+     * Check which DateTime parameter is null
+     * Use this method when you know that at least one or more DateTime is/are null
+     * - Only one DateTime is null: return the other one which is the greatest/lowest DateTime by default
+     * - The twice DateTime are null: return null since no DateTime could be returned
+     */
+    private static function getNonNullableDateTime(\DateTimeInterface $dateTime1 = null, \DateTimeInterface $dateTime2 = null)
+    {
+        if (\is_null($dateTime1) && \is_null($dateTime2)) {
+            return null;
+        }
+
+        // If date1 is null, the only result can be date2
+        if (\is_null($dateTime1)) {
+            return $dateTime2;
+        }
+
+        // If date2 is null, the only result can be date1
+        if (\is_null($dateTime2)) {
+            return $dateTime1;
+        }
+    }
+}