From 7712dc925b1e9bc6615b9c47434245aad2e77931 Mon Sep 17 00:00:00 2001
From: Alexander Wanyoike <wanyoike.alexander@gmail.com>
Date: Wed, 14 Apr 2021 14:12:49 +0100
Subject: [PATCH 1/2] Implement filtration and first

---
 src/SegmentSet.php            | 13 +++++++++++++
 tests/unit/SegmentSetTest.php | 25 +++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/src/SegmentSet.php b/src/SegmentSet.php
index f313d71..5a31f27 100644
--- a/src/SegmentSet.php
+++ b/src/SegmentSet.php
@@ -85,6 +85,19 @@ public function getIterator()
         }
     }
 
+    public function filter(callable $predicate): SegmentSet
+    {
+        return self::of(array_filter($this->segments, $predicate));
+    }
+
+    public function first(): ?Segment
+    {
+        if ($this->size() === 0) {
+            return null;
+        }
+        return reset($this->segments);
+    }
+
     public function toJson(?string $action): array
     {
         $itemData = [];
diff --git a/tests/unit/SegmentSetTest.php b/tests/unit/SegmentSetTest.php
index 73aa63f..314cd1e 100644
--- a/tests/unit/SegmentSetTest.php
+++ b/tests/unit/SegmentSetTest.php
@@ -3,6 +3,7 @@
 namespace SnowIO\DataLakeDataModel\Test;
 
 use PHPUnit\Framework\TestCase;
+use SnowIO\DataLakeDataModel\Segment;
 use SnowIO\DataLakeDataModel\SegmentSet;
 use SnowIO\DataLakeDataModel\Test\ACME\DataLake\Segments\Price;
 use SnowIO\DataLakeDataModel\Test\ACME\DataLake\Segments\Stock;
@@ -68,4 +69,28 @@ public function testEquals()
         self::assertFalse($otherSegments->equals($segments));
     }
 
+    public function testFiltration()
+    {
+        $segments = SegmentSet::of([
+            Price::fromJson(SegmentTest::getPriceJson()),
+            Stock::fromJson(SegmentTest::getStockJson())
+        ]);
+
+        $filteredSegments = $segments->filter(function (Segment $segment) {
+           return $segment->getSegmentId()  === Price::NAME;
+        });
+
+        self::assertEquals(1, $filteredSegments->size());
+    }
+
+    public function testFirst()
+    {
+        $segments = SegmentSet::of([
+            $price = Price::fromJson(SegmentTest::getPriceJson()),
+            Stock::fromJson(SegmentTest::getStockJson())
+        ]);
+
+        $actual = $segments->first();
+        self::assertTrue($actual->equals($price));
+    }
 }
\ No newline at end of file

From ca00fcb68533765c92b91df8e975e13a4caf5a2c Mon Sep 17 00:00:00 2001
From: Alexander Wanyoike <wanyoike.alexander@gmail.com>
Date: Thu, 15 Apr 2021 13:13:18 +0100
Subject: [PATCH 2/2] Return null for empty segment sets

---
 tests/unit/SegmentSetTest.php | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tests/unit/SegmentSetTest.php b/tests/unit/SegmentSetTest.php
index 314cd1e..cad4fba 100644
--- a/tests/unit/SegmentSetTest.php
+++ b/tests/unit/SegmentSetTest.php
@@ -93,4 +93,12 @@ public function testFirst()
         $actual = $segments->first();
         self::assertTrue($actual->equals($price));
     }
+
+    public function testFirstWithEmptySegmentSet()
+    {
+        $segments = SegmentSet::of([]);
+
+        $actual = $segments->first();
+        self::assertNull($actual);
+    }
 }
\ No newline at end of file