Untitled

<?php

	include('connect_db.php');

	$nameErr = $passwordErr = "";
	$name = $password = "";

	function input_check($data) {
		$data = trim($data);
		$data = stripslashes($data);
		$data = htmlspecialchars($data);
		return $data;
	};

	if($_SERVER["REQUEST_METHOD"] == "POST") {
		if (empty($_POST['user'])) {
			$nameErr = "<span style=\"color:red;\">Wrong username</span>";
		} else {
			$name = input_check($_POST['user']);
		}
		if (empty($_POST['password'])) {
			$passwordErr = "<span style=\"color:red;\">Wrong password</span>";
		} else {
			$password = input_check($_POST['password']);
		};


		$userExists = " SELECT COUNT(id) as is_exists FROM users WHERE username='".$_POST['user']."' AND password='".$_POST['password']."' ";
		$usernameFetch = mysqli_fetch_assoc($con->query($userExists));
		$addUser = "INSERT INTO users (username, password) VALUES ('$name', '$password')";


		if($nameErr == "" && $passwordErr == "") {
			if($usernameFetch['is_exists']) {
				header("Location:welcome.php");
			} else {
				//$con->query($addUser);
				echo "<p style=\"color:red;\">Wrong user or password</p>";
			}
		};
	};

?>


<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
	<h3>Log in</h3>
	<form action="<?php echo htmlspecialchars($_SERVER['PHP_SELF']);?>" method="POST">
		user: <input type="text" name="user" value="<?php echo $name; ?>">
		<?php echo $nameErr; ?>
		<br/>

		password: <input type="text" name="password" value="<?php echo $password; ?>">
		<?php echo $passwordErr; ?>
		<br/>

		<input type="submit" value="submit">
	</form>
</body>
</html>