add projection

composer.json

@@ -3,7 +3,7 @@
     "type": "library",
     "description": "",
     "require": {
-        "php": ">= 7.2",
+        "php": ">= 7.1",
         "ramsey/uuid": "^3.8"
     },
     "require-dev": {

spec/AlbertDonCelis/DDD/Infrastructure/ProjectorSpec.php

@@ -0,0 +1,66 @@
+<?php
+
+namespace spec\AlbertDonCelis\DDD\Infrastructure;
+
+use AlbertDonCelis\DDD\Domain\EventInterface;
+use AlbertDonCelis\DDD\Infrastructure\Projection\ProjectionInterface;
+use AlbertDonCelis\DDD\Infrastructure\Projector;
+use Faker\Factory;
+use PhpSpec\ObjectBehavior;
+use PHPUnit\Framework\Assert;
+use Prophecy\Argument;
+
+/**
+ * Class ProjectorSpec
+ * @package spec\AlbertDonCelis\DDD\Infrastructure
+ *
+ * @mixin Projector
+ */
+class ProjectorSpec extends ObjectBehavior
+{
+    function it_is_initializable()
+    {
+        $this->shouldHaveType(Projector::class);
+    }
+
+    /**
+     * @param ProjectionInterface $projection
+     */
+    public function it_should_register_projection(ProjectionInterface $projection)
+    {
+        $projections = [];
+        $randomCount = rand(1, 10);
+
+        for ($count = 0; $randomCount > $count ; $count++) {
+
+            $listenTo = Factory::create()->userName();
+            $projection->listenToEventNameOf()->shouldBeCalledTimes($randomCount)->willReturn($listenTo);
+            $projections[$listenTo][] = $projection;
+            $this->register($projection)->shouldReturn($this);
+        }
+
+        $registerProjections = $this->registeredProjections();
+        $registerProjections->shouldReturn($projections);
+
+    }
+
+    public function it_should_subscribe(EventInterface $event, ProjectionInterface $projection) {
+
+        $projections = [];
+        $randomCount = rand(1, 10);
+        $listenToEvents = [];
+
+        for ($count = 0; $randomCount > $count ; $count++) {
+            $listenTo = Factory::create()->userName();
+            array_push($listenToEvents, $listenTo);
+            $projection->listenToEventNameOf()->shouldBeCalledTimes($randomCount)->willReturn($listenTo);
+            $projections[$listenTo][] = $projection;
+            $this->register($projection);
+        }
+        $event->eventName()->shouldBeCalledTimes(1)->willReturn($listenToEvents[$randomCount - 1]);
+        $projection->project($event)->shouldBeCalledTimes(1);
+        $this->subscribeTo($event);
+    }
+
+
+}

src/AlbertDonCelis/DDD/Infrastructure/Projection/ProjectionInterface.php

@@ -0,0 +1,19 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: albert
+ * Date: 2019-04-11
+ * Time: 08:04
+ */
+
+namespace AlbertDonCelis\DDD\Infrastructure\Projection;
+
+use AlbertDonCelis\DDD\Domain\EventInterface;
+
+interface ProjectionInterface
+{
+
+    public function listenToEventNameOf(): string;
+
+    public function project(EventInterface $event): void;
+}

src/AlbertDonCelis/DDD/Infrastructure/Projector.php

@@ -0,0 +1,41 @@
+<?php
+
+namespace AlbertDonCelis\DDD\Infrastructure;
+
+use AlbertDonCelis\DDD\Domain\EventInterface;
+use AlbertDonCelis\DDD\Infrastructure\Projection\ProjectionInterface;
+
+class Projector
+{
+    private $projections = [];
+
+    public function register(ProjectionInterface $projection): self
+    {
+        $this->projections[$projection->listenToEventNameOf()][] = $projection;
+
+        return $this;
+    }
+
+    public function registeredProjections(): array
+    {
+        return $this->projections;
+    }
+
+    private function hasSubscriber(string $listenToEventNameOf): bool
+    {
+        return array_key_exists($listenToEventNameOf, $this->projections);
+    }
+
+    public function subscribeTo(EventInterface $event)
+    {
+        $eventListenTo = $event->eventName();
+
+        if ($this->hasSubscriber($eventListenTo)) {
+
+            /** @var ProjectionInterface $projection */
+            foreach ($this->projections[$eventListenTo] as $projection) {
+                $projection->project($event);
+            }
+        }
+    }
+}