import csv
from pathlib import Path


def filesize_csv(input_dir: Path, output_dir: Path) -> None:
    output_file = output_dir / "files.csv"
    with output_file.open("w") as fw:
        writer = csv.writer(fw)
        writer.writerow(["date", "filename", "mtime", "filesize"])

        for j in input_dir.glob("*.json"):
            p_date = j.stem
            p_fname = j.name
            stat = j.stat()
            p_mtime = stat.st_mtime
            p_size = stat.st_size
            writer.writerow([p_date, p_fname, p_mtime, p_size])


def ensure_dirs(input_dir: Path, output_dir: Path):
    if not input_dir.is_dir():
        raise ValueError
    output_dir.mkdir(exist_ok=True, parents=True)


def main(input: str, output: str) -> None:
    input_dir = Path(input)
    output_dir = Path(output)
    ensure_dirs(input_dir, output_dir)
    filesize_csv(input_dir, output_dir)


if __name__ == "__main__":
    import sys

    if not len(sys.argv) == 3:
        print("Please provide exactly one input directory and one output directory.")
        sys.exit(1)
    inp = sys.argv[1]
    out = sys.argv[2]
    main(inp, out)