def copy_over_if_duplicate(settings,submission_id,output_folder):
    """Check if there is already a copy of the submission downloaded in the download path.
   If there is, copy the existing version to the suppplied output location then return True
   If no copy can be found, return False"""
    assert_is_string(submission_id)
    # Generate expected filename pattern
    expected_submission_filename = "*"+submission_id+".*"
    # Generate search pattern
    glob_string = os.path.join(settings.output_folder, "*", expected_submission_filename)
    # Use glob to check for existing files matching the expected pattern
    glob_matches = glob.glob(glob_string)
    # Check if any matches, if no matches then return False
    if len(glob_matches) == 0:
        return False
    else:
        # If there is an existing version:
        for glob_match in glob_matches:
            # If there is an existing version in the output path, nothing needs to be copied
            if output_folder in glob_match:
                return False
            else:
                # Copy over submission file and metadata JSON
                logging.info("Trying to copy from previous download: "+glob_match)
                # Check output folders exist
                # Build expected paths
                match_dir, match_filename = os.path.split(glob_match)
                expected_json_input_filename = submission_id+".json"
                expected_json_input_folder = os.path.join(match_dir, "json")
                expected_json_input_location = os.path.join(expected_json_input_folder, expected_json_input_filename)
                json_output_folder = os.path.join(output_folder, "json")
                json_output_filename = submission_id+".json"
                json_output_path = os.path.join(json_output_folder, json_output_filename)
                submission_output_path = os.path.join(output_folder,match_filename)
                # Redownload if a file is missing
                if not os.path.exists(glob_match):
                    logging.debug("Submission file to copy is missing.")
                    return False
                if not os.path.exists(expected_json_input_location):
                    logging.debug("JSON file to copy is missing.")
                    return False
                # Ensure output path exists
                if not os.path.exists(json_output_folder):
                    os.makedirs(json_output_folder)
                if not os.path.exists(output_folder):
                    os.makedirs(output_folder)
                logging.info("Copying files for submission: "+submission_id+" from "+match_dir+" to "+output_folder)
                # Copy over files
                try:
                    # Copy submission file
                    shutil.copy2(glob_match, submission_output_path)
                    # Copy JSON
                    shutil.copy2(expected_json_input_location, json_output_path)
                    return True
                except IOError, err:
                    logging.error("Error copying files!")
                    logging.exception(err)
                    return False
 
 
def download_submission(settings,search_tag,submission_id):
    """Download a submission from Derpibooru"""
    assert_is_string(search_tag)
    assert_is_string(submission_id)
    setup_browser()
    #logging.debug("Downloading submission:"+submission_id)
    # Build JSON paths
    json_output_filename = submission_id+".json"
    json_output_path = os.path.join(settings.output_folder,search_tag,"json",json_output_filename)
    # Check if download can be skipped
    # Check if JSON exists
    if os.path.exists(json_output_path):
        logging.debug("JSON for this submission already exists, skipping.")
        return
    # Check for dupliactes in download folder
    output_folder = os.path.join(settings.output_folder,search_tag)
    if copy_over_if_duplicate(settings, submission_id, output_folder):
        return
    # Build JSON URL
    json_url = "https://derpibooru.org/"+submission_id+".json?key="+settings.api_key
    # Load JSON URL
    json_page = get(json_url)
    if not json_page:
        return
    # Convert JSON to dict
    json_dict = decode_json(json_page)
    # Check if submission is deleted
    if check_if_deleted_submission(json_dict):
        logging.debug(json_page)
        return
    # Extract needed info from JSON
    image_url = json_dict["image"]
    image_filename = json_dict["file_name"]
    image_file_ext = json_dict["original_format"]
    # Build image output filenames
    if settings.output_long_filenames:
        image_output_filename = settings.filename_prefix+image_filename+"."+image_file_ext
    else:
        image_output_filename = settings.filename_prefix+submission_id+"."+image_file_ext
    image_output_path = os.path.join(output_folder,image_output_filename)
    # Load image data
    authenticated_image_url = image_url+"?key="+settings.api_key
    logging.debug("Loading submission image: "+authenticated_image_url)
    image_data = get(authenticated_image_url)
    if not image_data:
        return
    # Image should always be bigger than this, if it isn't we got a bad file
    if len(image_data) < 100:
        logging.error("Image data was too small! "+str(image_data))
        return
    # Save image
    save_file(image_output_path, image_data, True)
    # Save JSON
    save_file(json_output_path, json_page, True)
    logging.debug("Download successful")