# Python 3.9

import sys

def restore_bili_video(video_path):
    print("Restoring... "+video_path)
    ext=video_path[video_path.rfind("."):]
    fin=open(video_path,"rb")
    if fin.read(1)!=b"\xff":
        print("This file is not encrypted by bilibili.")
        fin.close()
        return
    fout=open(video_path[:-len(ext)]+"_restore"+ext,"wb")
    is_video_file=False
    while True:
        b=fin.read(4096 if is_video_file else 1)
        if b==b"":
            break
        if not is_video_file and b == b"\xff":
            continue
        is_video_file=True
        fout.write(b)
    fin.close()
    fout.close()

if len(sys.argv) < 2:
    print("Usage: "+sys.argv[0]+" <video1> [video2] ...")
else:
    for i in range(1,len(sys.argv)):
        restore_bili_video(sys.argv[i])