"""Contains utility functions dealing with assets."""


def select_primary_assets(assets):
    """Choose asset for each extension available.

    Args:
        assets (list): Assets per sound recording

    Returns:
        dict: selected assets per extension
    """
    asset_map = {}

    # filter out assets not easily retrievable for delivery
    assets = [
        x for x in assets
        if x['source'] == 'ows-assets-db'
    ]

    # select first occurance of each extension, lowest tuid first
    for asset in sorted(assets, key=lambda x: min([t['tuid'] for t in x['tracks']])):  # noqa:E501
        extension = str.lower(asset['extension'])
        if extension not in asset_map:
            asset_map[extension] = {
                'uuid': asset['asset_id'],
                'filename': asset['filename'],
                'extension': extension
            }

    # list of assets, no duplicates
    return [v for _, v in sorted(asset_map.items())]