def download_file(url, dest=None, chunk_size=1024, replace="ask",
                  label="Downloading {dest_basename} ({size:.2f}MB)",
                  expected_extension=None):
    """Download a file from a given URL and display progress.

    :param dest: If the destination exists and is a directory, the filename
        will be guessed from the Content-Disposition header. If the destination
        is an existing file, the user will either be prompted to overwrite, or
        the file will be replaced (depending on the value of **replace**). If
        the destination does not exist, it will be used as the filename.
    :param int chunk_size: bytes read in at a time.
    :param replace: If `False`, an existing destination file will not be
        overwritten.
    :param label: a string which is formatted and displayed as the progress bar
        label. Variables provided include *dest_basename*, *dest*, and *size*.
    :param expected_extension: if set, the filename will be sanitized to ensure
        it has the given extension. The extension should not start with a dot
        (`.`).
    """
    dest = Path(dest or url.split("/")[-1])
    response = get(url, stream=True)
    if (dest.exists()
            and dest.is_dir()
            and "Content-Disposition" in response.headers):
        content_disposition = rfc6266.parse_requests_response(response)
        if expected_extension is not None:
            filename = content_disposition.filename_sanitized(
                expected_extension)
        filename = secure_filename(filename)
        dest = dest / filename
    if dest.exists() and not dest.is_dir():
        if (replace is False
                or replace == "ask"
                and not click.confirm("Replace {}?".format(dest))):
            return str(dest)
    size = int(response.headers.get("content-length", 0))
    label = label.format(dest=dest, dest_basename=dest.name,
                         size=size/1024.0/1024)
    with click.open_file(str(dest), "wb") as f:
        content_iter = response.iter_content(chunk_size=chunk_size)
        with click.progressbar(content_iter, length=size/1024,
                               label=label) as bar:
            for chunk in bar:
                if chunk:
                    f.write(chunk)
                    f.flush()
    return str(dest)
def parsed_error_msg(self):
        """
        Parse the error messages we receive from SoftwareSecure

        Error messages are written in the form:

            `[{"photoIdReasons": ["Not provided"]}]`

        Returns:
            str[]: List of error messages.
        """
        parsed_errors = []
        error_map = {
            'EdX name not provided': 'name_mismatch',
            'Name mismatch': 'name_mismatch',
            'Photo/ID Photo mismatch': 'photos_mismatched',
            'ID name not provided': 'id_image_missing_name',
            'Invalid Id': 'id_invalid',
            'No text': 'id_invalid',
            'Not provided': 'id_image_missing',
            'Photo hidden/No photo': 'id_image_not_clear',
            'Text not clear': 'id_image_not_clear',
            'Face out of view': 'user_image_not_clear',
            'Image not clear': 'user_image_not_clear',
            'Photo not provided': 'user_image_missing',
        }

        try:
            messages = set()
            message_groups = json.loads(self.error_msg)

            for message_group in message_groups:
                messages = messages.union(set(*six.itervalues(message_group)))

            for message in messages:
                parsed_error = error_map.get(message)

                if parsed_error:
                    parsed_errors.append(parsed_error)
                else:
                    log.debug(u'Ignoring photo verification error message: %s', message)
        except Exception:   # pylint: disable=broad-except
            log.exception(u'Failed to parse error message for SoftwareSecurePhotoVerification %d', self.pk)

        return parsed_errors