"""
Task status management functions via DynamoDB.

Similar to feed_status.py but used to check individual task statuses to see if
they can be safely skipped. This uses the same DynamoDB items created by the
feed_status functions, but uses a different attribute.

There are no pre-set constants of task statuses, and these functions are not
considered a replacement for feed_status functions.
"""

from garcon.contrib.dynamo_feed_status import \
    feed_status_ingestion as feed_status


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

    # this is called with _status at the end because the 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)
        feed_status.set_status(
            feed_name, datestamp, 'completed_tasks',
            ','.join(completed_tasks))