import pandas as pd


def reorder_artists(df: pd.DataFrame, popularity: int) -> pd.DataFrame:
    """
    Returns dataframe sorted by different rules
    Args:
        df: input dataframe to sort
        popularity: artist popularity values used in business rule

    Returns:
        Dataframe

    """
    # calculate lower limit
    intercept = 0.78
    slope = -5.75
    lower_limit = max(
        round((intercept * popularity) + slope), 0
    )  # in case of no popularity set limit to zero

    # pick artists that exceed lower limit but take only 10
    popular_artists = df[df["POPULARITY"] > lower_limit].index.values.tolist()[0:10]
    # print(popular_artists)
    # print(lower_limit)
    # generate new order if lower limit list was created with meaningful values
    if len(popular_artists) > 0 and lower_limit >= 0:
        all_artists = df.index.values.tolist()
        all_artists = [x for x in all_artists if x not in popular_artists]
        df = df.loc[popular_artists + all_artists][0:25]
        return df
    else:
        df = df[0:25]
        return df