"""Print a quick summary of a CSV file."""
import csv
import sys


def summarize(rows):
    """Return (row count, column names) for a list of dict rows."""
    if not rows:
        return 0, []
    return len(rows), list(rows[0])


def main():
    with open(sys.argv[1], newline="", encoding="utf-8") as f:
        rows = list(csv.DictReader(f))
    count, columns = summarize(rows)
    print(f"{count} rows, {len(columns)} columns")
    for column in columns:
        print(" -", column)


if __name__ == "__main__":
    main()