from typing import Optional, Sequence
from simfile.types import Chart, Charts, Simfile

# When you have multiple parameters of the same type (str in this case),
# it's good practice to use a * pseudo-argument to require them to be named
def find_chart(
    charts: Sequence[Chart], *, stepstype: str, difficulty: str
) -> Optional[Chart]:
    for chart in charts:
        if chart.stepstype == stepstype and chart.difficulty == difficulty:
            return chart


def remove_other_charts(
    sf: Simfile, *, stepstype="dance-single", difficulty="Challenge"
):
    the_chart = find_chart(sf.charts, stepstype=stepstype, difficulty=difficulty)
    if the_chart:
        # Replace the simfile's charts with a list of one
        sf.charts = [the_chart]  # type: ignore
    else:
        # You could alternatively raise an exception, pick a different chart,
        # set sf.charts to an empty list, etc.
        print(f"No {stepstype} {difficulty} chart found for {repr(sf)}")