slug generator (from uuid)

slug.py

from base64 import urlsafe_b64decode, urlsafe_b64encode
from uuid import UUID, uuid4
from binascii import Error as BinasciiError

def slug():
    uuid_ = uuid4()
    return uuid2slug(uuid_)

# https://stackoverflow.com/a/53543324/1522342
def uuid2slug(uuid_):
    if isinstance(uuid_, str):
        try:
            uuid_ = UUID(uuid_)
        except ValueError:
            return None
    return urlsafe_b64encode(uuid_.bytes).decode('utf8').rstrip('=\n')

# https://stackoverflow.com/a/53543324/1522342
def slug2uuid(slug):
    if len(slug) != 22:
        return None

    b64 = f'{slug}=='
    try:                                                                                                                                                                                                                                     
        bytes = urlsafe_b64decode(b64)                                                                                                                                                                                                       
    except BinasciiError:                                                                                                                                                                                                                    
        return None                                                                                                                                                                                                                          
    if len(bytes) != 16:                                                                                                                                                                                                                     
        return None                                                                                                                                                                                                                          
    return UUID(bytes=bytes)                                                                                                                                                                                                                 
                                                                                                                                                                                                                                             
if __name__ == '__main__':                                                                                                                                                                                                                   
    import sys                                                                                                                                                                                                                               
    result = None                                                                                                                                                                                                                            
                                                                                                                                                                                                                                             
    if len(sys.argv) < 2:                                                                                                                                                                                                                    
        result = slug()                                                                                                                                                                                                                      
    else:                                                                                                                                                                                                                                    
        candidate = sys.argv[1]                                                                                                                                                                                                              
                                                                                                                                                                                                                                             
    if not result:
        result = slug2uuid(candidate)
    
    if not result:
        result = uuid2slug(candidate)
    
    if not result:
        sys.exit(1)

    print(str(result))