ical-gen.py

#!/usr/bin/env -S uv --quiet run --no-project --script --
# https://peps.python.org/pep-0723/
# https://github.com/astral-sh/uv
# /// script
# # Docopt issues SyntaxWarning in Python 3.12
# requires-python = ">=3.11,<3.12"
# dependencies = [
#   "docopt >=0.6.2",
#   "icalendar >=4.0.1",
#   "python-dateutil >=2.7.2",
# ]
# ///

"""
Usage:
    {prog} START_DT_WITH_TIMEZONE END_DT_WITH_TIMEZONE [--summary=TEXT] [--description=TEXT]
        [--attachment=PATH]... [--url=URL] [--output=PATH]
    {prog} --help
    {prog} --version

Options:
    -s, --summary=TEXT      Summary
                            [default: Event]
    -d, --description=TEXT  Description
    -u, --url=URL           URL
    -a, --attachment=PATH   Path to a file to attach to the calendar event.
    -o, --output=PATH       Path to the file to be written.
                            [default: ./event.ics]
"""


import sys, os, datetime, json, mimetypes, urllib.request, base64
import icalendar
import docopt
import dateutil.parser


# TODO Use https://openflights.org/data.html to give options of entering airport code instead of timezone. Also see if it has route info and if it is possible to generate the entire calendar event by just providing flight code and departure date.


__prog__ = "ical-gen.py"
__product__ = f"The {json.dumps(__prog__)} Script"
__version__ = "0.0.0"


def main(*, args):
	params = docopt.docopt(
		doc=__doc__.format(
			prog=__prog__,
		),
		argv=args,
		help=True,
		version=__version__,
		options_first=False,
	)
	assert params.pop("--help") == False
	assert params.pop("--version") == False
	dtstart = parse_dt(params.pop("START_DT_WITH_TIMEZONE"))
	dtend = parse_dt(params.pop("END_DT_WITH_TIMEZONE"))
	summary = params.pop("--summary") or "Event"
	description = params.pop("--description") or f"Generated By: {__product__}"
	url = params.pop("--url")
	attachments = params.pop("--attachment")
	output_path = params.pop("--output")
	assert not params, params

	print("Summary:     {}"      .format(summary))
	print("Start:       {:%c %z}".format(dtstart))
	print("End:         {:%c %z}".format(dtend))
	print("Duration:    {}"      .format(dtend - dtstart))
	print("Description: {}"      .format(description))
	print(file=sys.stderr)

	event = icalendar.Event()
	event.add("SUMMARY", icalendar.vText(summary))
	event.add("DESCRIPTION", icalendar.vText(description))
	event.add("DTSTART", icalendar.vDatetime(dtstart))
	event.add("DTEND", icalendar.vDatetime(dtend))
	if url is not None:
		event.add("URL", icalendar.vUri(url))
	for path in attachments:
		add_attachment_to_calendar_event(event, path)
	calendar = icalendar.Calendar()
	#TODO:vruyr:bugs Verify with the standard.
	calendar.add("PRODID", f"-//{__product__}//vruyr.com//EN")
	calendar.add("VERSION", "2.0")
	calendar.add_component(event)

	with open(output_path, "wb") as fo:
		fo.write(calendar.to_ical())


def add_attachment_to_calendar_event(event, path):
	mtype, dummy_encoding = mimetypes.MimeTypes().guess_type(urllib.request.pathname2url(path))
	assert mtype is not None
	with open(path, "rb") as fo:
		filebytes = fo.read()
	#TODO:vruyr:bugs The vBinary() seems to do a roundtrip encoding to and from unicode which
	#                might corrupt the data.
	#                See https://github.com/collective/icalendar/issues/205
	b = icalendar.prop.vInline(base64.b64encode(filebytes).decode("ascii"))
	b.params["VALUE"] = "BINARY"
	b.params["ENCODING"] = "BASE64"
	b.params["FMTTYPE"] = mtype
	#TODO:vruyr:bugs What is the standard way to set the filename?
	b.params["X-APPLE-FILENAME"] = os.path.basename(path)
	event.add("ATTACH", b, encode=False)


def parse_dt(dt_s):
	dt = dateutil.parser.parse(dt_s)
	dt = dt.replace(tzinfo=datetime.timezone(dt.tzinfo.utcoffset(dt)))
	return dt


if __name__ == "__main__":
	sys.exit(main(args=sys.argv[1:]))