public function getUserByEmailAndPassword($e_mail, $password) {

        $stmt = $this->conn->prepare("SELECT email, password, salt, name, surname, address FROM tbl_login WHERE email = ?");

        $stmt->bind_param("s", $e_mail);

        if ($stmt->execute()) {

            $stmt->store_result();
            $stmt->bind_result($email, $password, $salt, $name, $surname, $address);

            $user = array();

            while($stmt->fetch()) {
                $tmp = array();
                $tmp["name"] = $name;
                $tmp["surname"] = $surname;
                $tmp["address"] = $address;
                $tmp["email"] = $email;
                $tmp["salt"] = $salt;
                $tmp["password"] = $password;

                array_push($user, $tmp);
            }

            $stmt->close();

            return $user;

            // verifying user password
            $salt = $user['salt'];
            $encrypted_password = $user['password'];
            $hash = $this->checkhashSSHA($salt, $password);
            // check for password equality
            if ($encrypted_password == $hash) {
                // user authentication details are correct
                return $user;
            }
        } else {
            return NULL;
        }
    }

$response = array("error" => FALSE);

if (isset($_POST['email']) && isset($_POST['password'])) {

    // receiving the post params
    $email = $_POST['email'];
    $password = $_POST['password'];

    // get the user by email and password
    $user = $db->getUserByEmailAndPassword($email, $password);

    if ($user != false) {
        // user is found
        $response["error"] = FALSE;
        $response["user"]["name"] = $user["name"];
        $response["user"]["surname"] = $user["surname"];
        $response["user"]["address"] = $user["address"];
        $response["user"]["email"] = $user["email"];
        echo json_encode($response);
    } else {
        // user is not found with the credentials
        $response["error"] = TRUE;
        $response["error_msg"] = "Login credentials are wrong. Please try again!";
        $response["user"]["name"] = $user["name"];
        $response["user"]["surname"] = $user["surname"];
        $response["user"]["address"] = $user["address"];
        $response["user"]["email"] = $user["email"];
        echo json_encode($response);
    }
} else {
    // required post params is missing
    $response["error"] = TRUE;
    $response["error_msg"] = "Required parameters email or password is missing!";
    echo json_encode($response);