import argparse as ap
from skvideo.io import FFmpegReader, FFmpegWriter
from pathlib import Path
import tqdm
from warnings import warn

DEFAULT_FPS = 25

parser = ap.ArgumentParser(description="add rate information")
parser.add_argument("inputfiles", nargs="+",
    help="the files to convert")
parser.add_argument("-r", "--rate", type=int, default=DEFAULT_FPS,
    help="the output frame rate")
parser.add_argument("-d", "--destination", default=None,
    help="the output directory")

class SkipConversionWarning(UserWarning):
    pass

def convert(inputfile, rate=None, destination=None):
    if rate is None:
        rate = DEFAULT_FPS
    if destination is None:
        destination = Path()
    inputfile = Path(inputfile)
    if inputfile.suffix != '.avi':
        warn(f"does not seem like a video file: {inputfile.name}", SkipConversionWarning, stacklevel=2)
        return
    outputfile = destination / inputfile.name
    if outputfile.exists():
        warn(f"already converted: {outputfile.name}", SkipConversionWarning, stacklevel=2)
        return
    with FFmpegReader(str(inputfile)) as src:
        with FFmpegWriter(str(outputfile), outputdict={"-framerate": str(rate), "-c:v": "libx264"}) as dst:
            for frame in tqdm.tqdm(src.nextFrame(), desc=outputfile.name, unit="frame"):
                dst.writeFrame(frame)

def main(inputfiles=[], rate=None, destination=None):
    for inputfile in inputfiles:
        convert(inputfile, rate=rate, destination=destination)

if __name__ == "__main__":
    kwargs = vars(parser.parse_args())
    main(**kwargs)