//avoid Undefined variable
$errors = [];

if (Input::exists('post'))
{
    $validate = new Validate;

    $validation = $validate->check($_POST, array(
        'username' => array(
            'required' => true
        ),

        'password' => array(
            'required' => true
        )
    ));


    if ($validation->passed())
    {

        $data = $this->_model->get_member_hash(Input::get('username'));

        if (Password::password_verify(Input::get('password'), $data[0]->admin_password))
        {
            echo 'correct data';
        }
        else
        {
            echo 'incorrect data';
        }
    }
    else
    {
        $errors = $validation->errors();
    }

public function get_member_hash($username)
    {
        return $this->_db->read('SELECT * FROM ' . DATABASE_PREFIX . 'admins WHERE admin_email=:email OR admin_username=:username', array(
            ':email'    => $username,
            ':username' => $username,
        ));
    }