"""Helper functions."""
from garcon_contrib.dynamo_feed_status import garcon_feed_status


def handle_download_error(status, err):
    """Handle download error.

    Returns `{'stop': True}` if file is not available,
    reraises an exception otherwise.

    Args:
        status (int): Error status.
        err (Exception): Error.
    Returns:
        dict: stop response

    """
    if status == 404:
        return {'stop': True}
    else:
        raise err


def handle_s3_download_error(err):
    """Handle S3 download error.

    Returns `{'stop': True}` if file is not available,
    reraises an exception otherwise.

    Args:
         err (S3ResponseError): Error.
    Returns:
        dict: stop response

    """
    return handle_download_error(err.status, err)


def handle_http_download_error(err):
    """Handle S3 download error.

    Returns `{'stop': True}` if file is not available,
    reraises an exception otherwise.

    Args:
         err (HTTPError): Error.
    Returns:
        dict: stop response

    """
    return handle_download_error(err.response.status_code, err)


def get_completed_tasks(feed_name, datestamp):
    """Return a list of completed tasks for execution lookup params.

    This does not have different behavior if the task does not exist in
    DynamoDB. Consider a non existing task execution as simply not having any
    completed tasks instead of an exception.

    Args:
        feed_name (str): Feed name of workflow execution for status updates.
        datestamp (str): Workflow generated date.

    Returns:
        list: List of task names, empty list if no tasks are completed.

    """
    status_item = garcon_feed_status._get_item(feed_name, datestamp)
    if not status_item:
        return []

    # this is called with _status at the end because the
    # garcon_feed_status.set_status function appends it automatically.
    tasks = status_item.get('completed_tasks_status', '').split(',')
    return tasks if any(tasks) else []


def is_completed_task(feed_name, datestamp, task_name):
    """Check DynamoDB for task completion status.

    Args:
        feed_name (str): Feed name of workflow execution for status updates.
        datestamp (str): Workflow generated date.
        task_name (str): Name of task.

    Returns:
        bool: True if task_name is found in marker attribute of DynamoDB item.

    """
    return task_name in get_completed_tasks(feed_name, datestamp)


def mark_completed_task(feed_name, datestamp, task_name):
    """Update DynamoDB item with task completion status note.

    Args:
        feed_name (str): Feed name of workflow execution for status updates.
        datestamp (str): Workflow generated date.
        task_name (str): Name of task.

    """
    completed_tasks = get_completed_tasks(feed_name, datestamp)
    if task_name not in completed_tasks:
        completed_tasks.append(task_name)
        garcon_feed_status.set_status(
            feed_name, datestamp, 'completed_tasks',
            ','.join(completed_tasks))