"""Logic Tier for Categories."""

from podcast.models import category as category_model


def get_categories():
    """Get all categories for podcasts.

    Returns:
        response.Response: containing a list of dicts with categories.
    """
    flat_categories = category_model.get_categories()['items']
    top_level = [category for category in flat_categories if category['parent_id'] is None]
    for tl in top_level:
        tl['children'] = []

    for category in flat_categories:
        if category['parent_id'] is None:
            continue

        for tl in top_level:
            if tl['id'] == category['parent_id']:
                tl['children'].append(category)

    return {'items': top_level}