From 0f026de5da5ff550a81cb48fb04f00b44aa16f60 Mon Sep 17 00:00:00 2001
From: Mal <=>
Date: Tue, 18 Aug 2020 11:46:03 +0200
Subject: [PATCH] Database transactions implemented

---
 .../controller/FingerprintPostController.php  | 13 +++++++--
 data/classes/core/DatabaseInterface.php       | 20 +++++++++++++
 data/classes/core/MySqlDatabase.php           | 28 +++++++++++++++++--
 3 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/data/classes/controller/FingerprintPostController.php b/data/classes/controller/FingerprintPostController.php
index 77dbc00..076927e 100644
--- a/data/classes/controller/FingerprintPostController.php
+++ b/data/classes/controller/FingerprintPostController.php
@@ -21,26 +21,35 @@ final class FingerprintPostController extends AbstractController
     {
         parent::handle();
 
+        $db = new MySqlDatabase();
         $json = json_decode($this->requestBody);
-        $fingerprint = new Fingerprint();
+        $fingerprint = new Fingerprint(null, $db);
 
         try {
             $fingerprint->setFingerprint($json->fingerprint);
             $fingerprint->setUserId($json->userId);
+
+            if (!$db->hasTransaction()) {
+                $db->startTransaction();
+            }
+
             $fingerprint->Save();
 
             $qrCode = new QrCode($fingerprint->getFingerprintId(), $fingerprint->getFingerprint());
             $qrCode->generate();
             $qrCode->save();
 
+            $db->commit();
+
             $this->response->setParameter('fingerprintId', $fingerprint->getFingerprintId());
         } catch (QrCodeException $e) {
-            $fingerprint->Delete();
+            $db->rollback();
 
             $this->response->setParameter('success', false);
             $this->response->setStatus(ServerStatus::INTERNAL_ERROR);
             $this->response->setMessage('An error occured during qr code creation!');
         } catch (Throwable $e) {
+            $db->rollback();
             $this->catchDatabaseException($e->getMessage(), $json);
         }
     }
diff --git a/data/classes/core/DatabaseInterface.php b/data/classes/core/DatabaseInterface.php
index 795ab51..68b6d7c 100644
--- a/data/classes/core/DatabaseInterface.php
+++ b/data/classes/core/DatabaseInterface.php
@@ -53,6 +53,26 @@ interface DatabaseInterface
      */
     public function Count(string $table, array $conditions = []): int;
 
+    /*
+     * Returns if there's an open transaction.
+     */
+    public function hasTransaction(): bool;
+
+    /*
+     * Starts a transaction that can later be committed or rolled back.
+     */
+    public function startTransaction(): void;
+
+    /*
+     * Quits a current transaction without saving.
+     */
+    public function rollback(): void;
+
+    /*
+     * Saves and exits a current transaction.
+     */
+    public function commit(): void;
+
     /**
      * Returns the primary key from the last inserted row.
      */
diff --git a/data/classes/core/MySqlDatabase.php b/data/classes/core/MySqlDatabase.php
index 5fe4533..b72e19b 100644
--- a/data/classes/core/MySqlDatabase.php
+++ b/data/classes/core/MySqlDatabase.php
@@ -2,14 +2,15 @@
 
 declare(strict_types=1);
 
-class MySqlDatabase implements DatabaseInterface
+final class MySqlDatabase implements DatabaseInterface
 {
 	private const CHARS_ALLOWED_IN_TABLE_NAMES = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890_-';
 
 	private ?PDO $connection;
 	private ?PDOStatement $cursor;
+    private bool $isTransactionOpen = false;
 
-	public function __construct(
+    public function __construct(
 		string $hostname = Setting::MYSQL_HOST,
 		string $user = Setting::MYSQL_USER,
 		string $password = Setting::MYSQL_PASSWORD,
@@ -236,6 +237,29 @@ class MySqlDatabase implements DatabaseInterface
         return (int)$result[0]['count(*)'];
     }
 
+    public function hasTransaction(): bool
+    {
+        return $this->isTransactionOpen;
+    }
+
+    public function startTransaction(): void
+    {
+        $this->connection->beginTransaction();
+        $this->isTransactionOpen = true;
+    }
+
+    public function rollback(): void
+    {
+        $this->connection->rollBack();
+        $this->isTransactionOpen = false;
+    }
+
+    public function commit(): void
+    {
+        $this->connection->commit();
+        $this->isTransactionOpen = false;
+    }
+
     /**
      * {@inheritDoc}
      */