Create cookie-based login and authentication system

lib/Session.php

@@ -0,0 +1,82 @@
+<?
+use Ramsey\Uuid\Uuid;
+use Safe\DateTime;
+
+/**
+ * @property User $User
+ * @property PollItem $PollItem
+ * @property string $Url
+ */
+class Session extends PropertiesBase{
+	public $UserId;
+	protected $_User = null;
+	public $Created;
+	public $SessionId;
+	public $_Url;
+
+
+	// *******
+	// GETTERS
+	// *******
+
+	protected function GetUrl(): string{
+		if($this->_Url === null){
+			$this->_Url = '/sessions/' . $this->SessionId;
+		}
+
+		return $this->_Url;
+	}
+
+
+	// *******
+	// METHODS
+	// *******
+
+	public function Create(?string $email = null): void{
+		$this->User = User::GetIfRegistered($email);
+		$this->UserId = $this->User->UserId;
+
+		$existingSessions = Db::Query('SELECT SessionId, Created from Sessions where UserId = ?', [$this->UserId]);
+
+		if(sizeof($existingSessions) > 0){
+			$this->SessionId = $existingSessions[0]->SessionId;
+			$this->Created = $existingSessions[0]->Created;
+		}
+		else{
+			$uuid = Uuid::uuid4();
+			$this->SessionId = $uuid->toString();
+			$this->Created = new DateTime();
+			Db::Query('INSERT into Sessions (UserId, SessionId, Created) values (?, ?, ?)', [$this->UserId, $this->SessionId, $this->Created]);
+		}
+	}
+
+	public static function GetLoggedInUser(): ?User{
+		$sessionId = HttpInput::Str(COOKIE, 'sessionid');
+
+		if($sessionId !== null){
+			$result = Db::Query('select u.* from Users u inner join Sessions s using (UserId) where s.SessionId = ?', [$sessionId], 'User');
+
+			if(sizeof($result) > 0){
+				// Refresh the login cookie for another 2 weeks
+				setcookie('sessionid', $sessionId, time() + 60 * 60 * 24 * 14 * 1, '/', SITE_DOMAIN, true, false); // Expires in two weeks
+				return $result[0];
+			}
+		}
+
+		return null;
+	}
+
+	public static function Get(?string $sessionId): Session{
+		if($sessionId === null){
+			throw new Exceptions\InvalidSessionException();
+		}
+
+		$result = Db::Query('SELECT * from Sessions where SessionId = ?', [$sessionId], 'Session');
+
+		if(sizeof($result) == 0){
+			throw new Exceptions\InvalidSessionException();
+		}
+
+		return $result[0];
+	}
+}