From d55650c02c544287b843d76ea13f166fd4e813a3 Mon Sep 17 00:00:00 2001
From: twent <twentprod@gmail.com>
Date: Tue, 7 Mar 2023 16:49:45 +0300
Subject: [PATCH] =?UTF-8?q?=E2=9C=85=20Add=20Proxy=20pattern?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 README.md                                     |  1 +
 src/Patterns/Structural/Proxy/BankAccount.php | 11 ++++++++++
 .../Structural/Proxy/BankAccountProxy.php     | 20 +++++++++++++++++
 .../Structural/Proxy/HeavyBankAccount.php     | 21 ++++++++++++++++++
 tests/Feature/Structural/ProxyTest.php        | 22 +++++++++++++++++++
 5 files changed, 75 insertions(+)
 create mode 100644 src/Patterns/Structural/Proxy/BankAccount.php
 create mode 100644 src/Patterns/Structural/Proxy/BankAccountProxy.php
 create mode 100644 src/Patterns/Structural/Proxy/HeavyBankAccount.php
 create mode 100644 tests/Feature/Structural/ProxyTest.php

diff --git a/README.md b/README.md
index 9fe367d..f46bf44 100644
--- a/README.md
+++ b/README.md
@@ -34,3 +34,4 @@ How to dev:
    8. Facade
    9. Fluent Interface
    10. Flyweight
+   11. Proxy
diff --git a/src/Patterns/Structural/Proxy/BankAccount.php b/src/Patterns/Structural/Proxy/BankAccount.php
new file mode 100644
index 0000000..4d0cabd
--- /dev/null
+++ b/src/Patterns/Structural/Proxy/BankAccount.php
@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Twent\DesignPatterns\Structural\Proxy;
+
+interface BankAccount
+{
+    public function deposit(int $amount);
+    public function getBalance(): int;
+}
diff --git a/src/Patterns/Structural/Proxy/BankAccountProxy.php b/src/Patterns/Structural/Proxy/BankAccountProxy.php
new file mode 100644
index 0000000..17ad6ff
--- /dev/null
+++ b/src/Patterns/Structural/Proxy/BankAccountProxy.php
@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Twent\DesignPatterns\Structural\Proxy;
+
+final class BankAccountProxy extends HeavyBankAccount implements BankAccount
+{
+    private ?int $balance = null;
+
+    public function getBalance(): int
+    {
+        if (! $this->balance) {
+            // Call heavy operations
+            $this->balance = parent::getBalance();
+        }
+
+        return $this->balance;
+    }
+}
diff --git a/src/Patterns/Structural/Proxy/HeavyBankAccount.php b/src/Patterns/Structural/Proxy/HeavyBankAccount.php
new file mode 100644
index 0000000..8d4aa3c
--- /dev/null
+++ b/src/Patterns/Structural/Proxy/HeavyBankAccount.php
@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Twent\DesignPatterns\Structural\Proxy;
+
+class HeavyBankAccount implements BankAccount
+{
+    private array $transactions = [];
+
+    public function deposit(int $amount)
+    {
+        $this->transactions[] = $amount;
+    }
+
+    public function getBalance(): int
+    {
+        // Здесь ресурсоёмкие расчёты, "дорогое" взаимодействие с БД и т.д.
+        return array_sum($this->transactions);
+    }
+}
diff --git a/tests/Feature/Structural/ProxyTest.php b/tests/Feature/Structural/ProxyTest.php
new file mode 100644
index 0000000..9a6a15b
--- /dev/null
+++ b/tests/Feature/Structural/ProxyTest.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Structural;
+
+use Tests\TestCase;
+use Twent\DesignPatterns\Structural\Proxy\BankAccountProxy;
+
+final class ProxyTest extends TestCase
+{
+    public function testProxyPatternWorksFine(): void
+    {
+        $bankAccount = new BankAccountProxy();
+        $bankAccount->deposit(3000);
+        $this->assertSame(3000, $bankAccount->getBalance());
+
+        $bankAccount->deposit(5000);
+        // Heavy operations isn't running again
+        $this->assertSame(3000, $bankAccount->getBalance());
+    }
+}