PFERD

Programm zum Flotten, Einfachen Runterladen von Dateien

Installation

Ensure that you have at least Python 3.8 installed.

To install PFERD or update your installation to the latest version, run this wherever you want to install/have installed PFERD:

$ pip install git+https://github.com/Garmelon/PFERD@rewrite

The use of venv is recommended.

Example setup

In this example, python3 refers to at least Python 3.8.

If you just want to get started and crawl your entire ILIAS Desktop instead of a given set of courses, please replace example_config.py with example_config_personal_desktop.py in all of the instructions below (curl call and python3 run command).

A full example setup and initial use could look like:

$ mkdir Vorlesungen
$ cd Vorlesungen
$ python3 -m venv .
$ . bin/activate
$ pip install git+https://github.com/Garmelon/PFERD@rewrite
$ curl -O https://raw.githubusercontent.com/Garmelon/PFERD/rewrite/example_config.py
$ python3 example_config.py
$ deactivate

Subsequent runs of the program might look like:

$ cd Vorlesungen
$ . bin/activate
$ python3 example_config.py
$ deactivate

Usage

A PFERD config is a normal python file that starts multiple synchronizers which do all the heavy lifting. While you can create and wire them up manually, you are encouraged to use the helper methods provided in PFERD.Pferd.

The synchronizers take some input arguments specific to their service and a transformer. The transformer receives the computed path of an element in ILIAS and can return either an output path (so you can rename files or move them around as you wish) or None if you do not want to save the given file.

Additionally the ILIAS synchronizer allows you to define a crawl filter. This filter also receives the computed path as the input, but is only called or directoties. If you return True, the directory will be crawled and searched. If you return False the directory will be ignored and nothing in it will be passed to the transformer.

In order to help you with writing your own transformers and filters, PFERD ships with a few powerful building blocks:

Method	Description
glob	Returns a transform that returns None if the glob does not match and the unmodified path otherwise.
predicate	Returns a transform that returns None if the predicate does not match the path and the unmodified path otherwise.
move_dir(source, target)	Returns a transform that moves all files from the source to the target dir.
move(source, target)	Returns a transform that moves the source file to target.
rename(old, new)	Renames a single file.
re_move(regex, sub)	Moves all files matching the given regular expression. The different captured groups are available under their index and can be used together with normal python format methods: re_move(r"Blatt (\d+)\.pdf", "Blätter/Blatt_{1:0>2}.pdf"),.
re_rename(old, new)	Same as re_move but operates on the path names instead of the full path.

And PFERD also offers a few combinator functions:

• keep
keep just returns the input path unchanged. It can be very useful as the last argument in an attempt call, to leave everything not matching a rule unchanged.
• optionally(transformer)
  Wraps a given transformer and returns its result if it is not None. Otherwise returns the input path unchanged.
• do(transformers)
do accepts a series of transformers and applies them in the given order to the result of the previous one. If any transformer returns None, do short-circuits and also returns None. This can be used to perform multiple renames in a row:

  do(
      # Move them
      move_dir("Vorlesungsmaterial/Vorlesungsvideos/", "Vorlesung/Videos/"),
      # Fix extensions (if they have any)
      optionally(re_rename("(.*).m4v.mp4", "{1}.mp4")),
      # Remove the 'dbs' prefix (if they have any)
      optionally(re_rename("(?i)dbs-(.+)", "{1}")),
  ),
  

• attempt(transformers)
attempt applies the passed transformers in the given order until it finds one that does not return None. If it does not find any, it returns None. This can be used to give a list of possible transformations and it will automatically pick the first one that fits:

  attempt(
      # Move all videos. If a video is passed in, this `re_move` will succeed
      # and attempt short-circuits with the result.
      re_move(r"Vorlesungsmaterial/.*/(.+?)\.mp4", "Vorlesung/Videos/{1}.mp4"),
      # Move the whole folder to a nicer name - now without any mp4!
      move_dir("Vorlesungsmaterial/", "Vorlesung/"),
      # If we got another file, keep it.
      keep,
  )
  

All of these combinators are used in the provided example config, if you want to see some more true-to-live usages.

A short, but commented example

def filter_course(path: PurePath) -> bool:
    # Note that glob returns a Transformer
    #  - a function from PurePath -> Optional[PurePath]
    # So we need to apply the result of 'glob' to our input path.
    # We need to crawl the 'Tutorien' folder as it contains the one we want.
    if glob("Tutorien/")(path):
        return True
    # If we found 'Tutorium 10', keep it!
    if glob("Tutorien/Tutorium 10")(path):
        return True
    # Discard all other folders inside 'Tutorien'
    if glob("Tutorien/*")(path):
        return False

    # All other dirs (including subdirs of 'Tutorium 10') should be searched :)
    return True

enable_logging() # needed once before calling a Pferd method
# Create a Pferd instance rooted in the same directory as the script file
# This is not a test run, so files will be downloaded (default, can be omitted)
pferd = Pferd(Path(__file__).parent, test_run=False)

# Use the ilias_kit helper to synchronize an ILIAS course
pferd.ilias_kit(
    # The folder all of the course's content should be placed in
    Path("My cool course"),
    # The course ID (found in the URL when on the course page in ILIAS)
    "course id",
    # A path to a cookie jar. If you synchronize multiple ILIAS courses, setting this
    # to a common value requires you to only login once.
    cookies=Path("ilias_cookies.txt"),
    # A transform to apply to all found paths
    transform=transform_course,
    # A crawl filter limits what paths the cralwer searches
    dir_filter=filter_course,
)