Recurring ICal events for Python
================================

.. image:: https://github.com/niccokunzmann/python-recurring-ical-events/actions/workflows/tests.yml/badge.svg
   :target: https://github.com/niccokunzmann/python-recurring-ical-events/actions/workflows/tests.yml
   :alt: GitHub CI build and test status

.. image:: https://badge.fury.io/py/recurring-ical-events.svg
   :target: https://pypi.python.org/pypi/recurring-ical-events
   :alt: Python Package Version on Pypi

.. image:: https://img.shields.io/pypi/dm/recurring-ical-events.svg
   :target: https://pypi.org/project/recurring-ical-events/#files
   :alt: Downloads from Pypi

.. image:: https://img.shields.io/opencollective/all/open-web-calendar?label=support%20on%20open%20collective
   :target: https://opencollective.com/open-web-calendar/
   :alt: Support on Open Collective


ICal has some complexity to it:
Events, TODOs and Journal entries can be repeated, removed from the feed and edited later on.
This tool takes care of these circumstances.

Let's put our expertise together and build a tool that can solve this!

* day light saving time (DONE)
* recurring events (DONE)
* recurring events with edits (DONE)
* recurring events where events are omitted (DONE)
* recurring events events where the edit took place later (DONE)
* normal events (DONE)
* recurrence of dates but not hours, minutes, and smaller (DONE)
* endless recurrence (DONE)
* ending recurrence (DONE)
* events with start date and no end date (DONE)
* events with start as date and start as datetime (DONE)
* `RRULE <https://www.kanzaki.com/docs/ical/rrule.html>`_ (DONE)
* `RDATE <https://www.kanzaki.com/docs/ical/rdate.html>`_ (DONE)
* `DURATION <https://www.kanzaki.com/docs/ical/duration.html>`_ (DONE)
* `EXDATE <https://www.kanzaki.com/docs/ical/exdate.html>`_ (DONE)
* `X-WR-TIMEZONE` compatibilty (DONE)

Not included:

* EXRULE (deprecated), see `8.3.2.  Properties Registry
  <https://tools.ietf.org/html/rfc5545#section-8.3.2>`_

Installation
------------

.. code:: shell

    pip install recurring-ical-events

Example
-------

.. code-block:: python

    import icalendar
    import recurring_ical_events
    import urllib.request

    start_date = (2019, 3, 5)
    end_date =   (2019, 4, 1)
    url = "http://tinyurl.com/y24m3r8f"

    ical_string = urllib.request.urlopen(url).read()
    calendar = icalendar.Calendar.from_ical(ical_string)
    events = recurring_ical_events.of(calendar).between(start_date, end_date)
    for event in events:
        start = event["DTSTART"].dt
        duration = event["DTEND"].dt - event["DTSTART"].dt
        print("start {} duration {}".format(start, duration))

Output:

.. code-block:: text

    start 2019-03-18 04:00:00+01:00 duration 1:00:00
    start 2019-03-20 04:00:00+01:00 duration 1:00:00
    start 2019-03-19 04:00:00+01:00 duration 1:00:00
    start 2019-03-07 02:00:00+01:00 duration 1:00:00
    start 2019-03-08 01:00:00+01:00 duration 2:00:00
    start 2019-03-09 03:00:00+01:00 duration 0:30:00
    start 2019-03-10 duration 1 day, 0:00:00


Usage
-----

The `icalendar <https://pypi.org/project/icalendar/>`_ module is responsible for parsing and converting calendars.
The `recurring_ical_events <https://pypi.org/project/recurring-ical-events/>`_ module uses such a calendar and creates all repetitions of its events within a time span.

To import this module, write 

.. code:: Python

    import recurring_ical_events

There are several methods you can use to unfold repeating events, such as ``at(a_time)`` and ``between(a_start, an_end)``.

``at(a_date)``
**************

You can get all events which take place at ``a_date``.
A date can be a year, e.g. ``2023``, a month of a year e.g. January in 2023 ``(2023, 1)``, a day of a certain month e.g. ``(2023, 1, 1)``, an hour e.g. ``(2023, 1, 1, 0)``, a minute e.g. ``(2023, 1, 1, 0, 0)``, or second as well as a `datetime.date <https://docs.python.org/3/library/datetime.html#datetime.date>`_ object and `datetime.datetime <https://docs.python.org/3/library/datetime.html#datetime.datetime>`_.

The start and end are inclusive. As an example: if an event is longer than one day it is still included if it takes place at ``a_date``.

.. code:: Python

    a_date =  2023   # a year
    a_date = (2023,) # a year
    a_date = (2023, 1) # January in 2023
    a_date = (2023, 1, 1) # the 1st of January in 2023
    a_date = "20230101"   # the 1st of January in 2023
    a_date = (2023, 1, 1, 0) # the first hour of the year 2023
    a_date = (2023, 1, 1, 0, 0) # the first minute in 2023
    a_date = datetime.date(2023) # the first day in 2023
    a_date = datetime.date(2023, 1, 1) # the first day in 2023
    a_date = datetime.datetime.now() # this exact second
    
    events = recurring_ical_events.of(an_icalendar_object).at(a_date)

The resulting ``events`` are a list of icalendar events, see below.

``between(start, end)``
***********************

``between(start, end)`` returns all events happening between a start and an end time. Both arguments can be `datetime.datetime`_, `datetime.date`_, tuples of numbers passed as arguments to `datetime.datetime`_ or strings in the form of
``%Y%m%d`` (``yyyymmdd``) and ``%Y%m%dT%H%M%SZ`` (``yyyymmddThhmmssZ``).
For examples, see ``at(a_date)`` above.

.. code:: Python

    events = recurring_ical_events.of(an_icalendar_object).between(start, end)

The resulting ``events`` are in a list, see below.

``events`` as list
******************

The result of both ``between(start, end)`` and ``at(a_date)`` is a list of `icalendar`_ events.
By default, all attributes of the event with repetitions are copied, like UID and SUMMARY.
However, these attributes may differ from the source event:

* **DTSTART** which is the start of the event instance. (always present)
* **DTEND** which is the end of the event instance. (always present)
* **RDATE**, **EXDATE**, **RRULE** are the rules to create event repetitions.
  They are **not** included in repeated events, see `Issue 23 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/23>`_.
  To change this, use ``of(calendar, keep_recurrence_attributes=True)``.

Different Components, not just Events
*************************************

By default the ``recurring_ical_events`` only selects events as the name already implies.
However, there are different components available in a calendar.
You can select which components you like to have returned by passing ``components`` to the ``of`` function:

.. code:: Python

    of(a_calendar, components=["VEVENT"])

Here is a template code for choosing the supported types of components:

.. code:: Python

   events = recurring_ical_events.of(calendar).between(...)
   journals = recurring_ical_events.of(calendar, components=["VJOURNAL"]).between(...)
   todos = recurring_ical_events.of(calendar, components=["VTODO"]).between(...)
   all = recurring_ical_events.of(calendar, components=["VTODO", "VEVENT", "VJOURNAL"]).between(...)

If a type of component is not listed here, it can be added.
Please create an issue for this in the source code repository.

Speed
*****

If you use ``between()`` or ``at()``
several times, it is faster to re-use the object coming from ``of()``.

.. code:: Python

    rcalendar = recurring_ical_events.of(an_icalendar_object)
    events_of_day_1 = rcalendar.at(day_1)
    events_of_day_2 = rcalendar.at(day_2)
    events_of_day_3 = rcalendar.at(day_3)
    # ...

Version Fixing
**************

If you use this library in your code, you may want to make sure that
updates can be received but they do not break your code.
The version numbers are handeled this way: ``a.b.c`` example: ``0.1.12``

- ``c`` is changed for each minor bug fix.
- ``b`` is changed whenever new features are added.
- ``a`` is changed when the interface or major assumptions change that may break your code.

So, I recommend to version-fix this library to stay with the same ``a``
while ``b`` and ``c`` can change.

Support
-------

.. image:: https://img.shields.io/opencollective/all/open-web-calendar?label=support%20on%20open%20collective
   :target: https://opencollective.com/open-web-calendar/
   :alt: Support on Open Collective

This library is part of the
`Open Web Calendar Collective <https://opencollective.com/open-web-calendar/>`_.
We accept donations to sustain our work, once or regular.
Open Collective makes it easy for you to give and
for us to receive.
Consider donating money to open-source as everyone benefits.

Development
-----------

1. Optional: Install virtualenv and Python3 and create a virtual environment.

   .. code-block:: shell

       virtualenv -p python3 ENV
       source ENV/bin/activate

2. Install the packages.

   .. code-block:: shell

       pip install -r requirements.txt -r test-requirements.txt

3. Run the tests

   .. code-block:: shell

       pytest

New Releases
------------

To release new versions,

1. edit the Changelog Section
2. edit setup.py, the ``__version__`` variable
3. create a commit and push it
4. Wait for `GitHub Actions <https://github.com/niccokunzmann/python-recurring-ical-events/actions>`_ to finish the build.
5. run

   .. code-block:: shell

       python3 setup.py tag_and_deploy

6. notify the issues about their release

Testing
*******

This project's development is driven by tests.
Tests assure a consistent interface and less knowledge lost over time.
If you like to change the code, tests help that nothing breaks in the future.
They are required in that sense.
Example code and ics files can be transferred into tests and speed up fixing bugs.

You can view the tests in the `test folder
<https://github.com/niccokunzmann/python-recurring-ical-events/tree/master/test>`_.
If you have a calendar ICS file for which this library does not
generate the desired output, you can add it to the ``test/calendars``
folder and write tests for what you expect.
If you like, `open an issue <https://github.com/niccokunzmann/python-recurring-ical-events/issues>`_ first, e.g. to discuss the changes and
how to go about it.

Changelog
---------

- v2.0.1

  - Fixed crasher with duplicate RRULE. See `Pull Request 104 <https://github.com/niccokunzmann/python-recurring-ical-events/pull/104>`_

- v2.0.0b

  - Only return ``VEVENT`` by default. Add ``of(... ,components=...)`` parameter to select which kinds of components should be returned. See `Issue 101 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/101>`_.
  - Remove ``beta`` indicator. This library works okay: Feature requests come in, not so much bug reports.

- v1.1.0b

  - Add repeated TODOs and Journals. See `Pull Request 100 <https://github.com/niccokunzmann/python-recurring-ical-events/pull/100>`_ and `Issue 97 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/97>`_.

- v1.0.3b

  - Remove syntax anomalies in README.
  - Switch to GitHub actions because GitLab decided to remove support.

- v1.0.2b

  - Add support for ``X-WR-TIMEZONE`` calendars which contain events without an explicit time zone, see `Issue 86 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/86>`_.
  
- v1.0.1b

  - Add support for ``zoneinfo.ZoneInfo`` time zones, see `Issue 57 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/57>`_.
  - Migrate from Travis CI to Gitlab CI.
  - Add code coverage on Gitlab.

- v1.0.0b

  - Remove Python 2 support, see `Issue 64 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/64>`_.
  - Remove support for Python 3.5 and 3.6.
  - Note: These deprecated Python versions may still work. We just do not claim they do.
  - ``X-WR-TIMEZONE`` support, see `Issue 71 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/71>`_.

- v0.2.4b

  - Events with a duration of 0 seconds are correctly returned.
  - ``between()`` and ``at()`` take the same kind of arguments. These arguments are documented.

- v0.2.3b

  - ``between()`` and ``at()`` allow arguments with time zones now when calendar events do not have time zones, reported in `Issue 61 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/61>`_ and `Issue 52 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/52>`_.

- v0.2.2b

  - Check that ``at()`` does not return an event starting at the next day, see `Issue 44 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/44>`_.

- v0.2.1b

  - Check that recurring events are removed if they are modified to leave the requested time span, see `Issue 62 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/62>`_.

- v0.2.0b

  - Add ability to keep the recurrence attributes (RRULE, RDATE, EXDATE) on the event copies instead of stripping them. See `Pull Request 54 <https://github.com/niccokunzmann/python-recurring-ical-events/pull/54>`_.

- v0.1.21b

  - Fix issue with repetitions over DST boundary. See `Issue 48 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/48>`_.

- v0.1.20b

  - Fix handling of modified recurrences with lower sequence number than their base event `Pull Request 45 <https://github.com/niccokunzmann/python-recurring-ical-events/pull/45>`_

- v0.1.19b

  - Benchmark using `@mrx23dot <https://github.com/mrx23dot>`_'s script and speed up recurrence calculation by factor 4, see `Issue 42 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/42>`_.

- v0.1.18b

  - Handle `Issue 28 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/28>`__ so that EXDATEs match as expected.
  - Handle `Issue 27 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/27>`_ so that parsing some rrule UNTIL values does not crash.

- v0.1.17b

  - Handle `Issue 28 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/28>`__ where passed arguments lead to errors where it is expected to work.

- v0.1.16b

  - Events with an empty RRULE are handled like events without an RRULE.
  - Remove fixed dependency versions, see `Issue 14 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/14>`_

- v0.1.15b

  - Repeated events also include subcomponents. `Issue 6 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/6>`_

- v0.1.14b

  - Fix compatibility `issue 20 <https://github.com/niccokunzmann/python-recurring-ical-events/issues/20>`_: EXDATEs of different time zones are now supported.

- v0.1.13b

  - Remove attributes RDATE, EXDATE, RRULE from repeated events `Issue 23`_
  - Use vDDDTypes instead of explicit date/datetime type `Pull Request 19 <https://github.com/niccokunzmann/python-recurring-ical-events/pull/19>`_
  - Start Changelog

Libraries Used
--------------

- `python-dateutil <https://pypi.org/project/python-dateutil/>`_ - to compute the recurrences of events using ``rrule``
- `icalendar`_ - the library used to parse ICS files
- `pytz <https://pypi.org/project/pytz/>`_ - for timezones
- `x-wr-timezone <https://github.com/niccokunzmann/x-wr-timezone>`_ for handling the non-standard ``X-WR-TIMEZONE`` property.

Related Projects
----------------

- `icalevents <https://github.com/irgangla/icalevents>`_ - another library for roughly the same use-case
- `Open Web Calendar <https://github.com/niccokunzmann/open-web-calendar>`_ - a web calendar to embed into websites which uses this library
- `icspy <https://icspy.readthedocs.io/>`_ - to create your own calendar events

Media
-----

Nicco Kunzmann talked about this library at the
FOSSASIA 2022 Summit:

.. image:: https://niccokunzmann.github.io/ical-talk-fossasia-2022/youtube.png
   :target: https://youtu.be/8l3opDdg92I?t=10369
   :alt: Talk about this library at the FOSSASIA 2022 Summit

Research
--------

- `RFC 5545 <https://tools.ietf.org/html/rfc5545>`_
- `RFC 7986 <https://tools.ietf.org/html/rfc7986>`_ -- an update to RFC 5545. It does not change any properties useful for scheduling events.
- `Stackoverflow question this is created for <https://stackoverflow.com/questions/30913824/ical-library-to-iterate-recurring-events-with-specific-instances>`_
- `<https://github.com/oberron/annum>`_

  - `<https://stackoverflow.com/questions/28829261/python-ical-get-events-for-a-day-including-recurring-ones#28829401>`_

- `<https://stackoverflow.com/questions/20268204/ical-get-date-from-recurring-event-by-rrule-and-dtstart>`_
- `<https://github.com/collective/icalendar/issues/162>`_
- `<https://stackoverflow.com/questions/46471852/ical-parsing-reoccuring-events-in-python>`_
- RDATE `<https://stackoverflow.com/a/46709850/1320237>`_

  - `<https://tools.ietf.org/html/rfc5545#section-3.8.5.2>`_
