import caldav
import vobject
from datetime import datetime, date, time
import yaml

server_url = "https://***REMOVED***
cal_user = "tobias"
cal_url = "https://***REMOVED***
cal_category = "Veranstaltung"
result_file = "../content/pages/termine.md"
now = datetime.now().astimezone()

cal_properties = [ # taken from ical specification
  # descriptive  
  "attach", "categories", "class", "comment", "description", "geo", "location", "percent-complete", "priority", "resources", "status", "summary",
  # date and time
  "completed", "dtend", "due", "dtstart", "duration", "freebusy", "transp", 
  # timezone components
  "tzid", "tzname", "tzoffsetfrom", "tzoffsetto", "tzurl",
  # relationship
  "attendee", "contact", "organizer", "recurrence-id", "related-to", "url", "uid",
  # recurrence
  "exdate", "exrule", "rdate", "rrule",
  # alarm
#  "action", "repeat", "trigger",
  # change management
  "created", "dtstamp", "last-modified", "sequence"
]
cal_prop_datetimes = ["dtend", "due", "dtstart", "duration", "dtstamp", "last-modified"]


"""Converts a datetime.datetime or datetime.date object into an aware datetime object."""
def fixDatetime(d, t=None, tz=None):
  if not tz:
    tz = now.tzinfo
  
  # datetime object is made aware if necessary
  if type(d) == datetime:
    if d.tzinfo:
      return d
    else: 
      return datetime(d.date(), d.time(), tz)
  
  # raise error if d is neither datetime nor date
  elif type(d) != date:
    raise TypeError("parameter must be a datetime.date or datetime.datetime object")

  # d is a date object
  if not t:
    t = time(23, 59, 59, tzinfo=tz)    # if no time parameter was passed, use 23:59:59 
  if not t.tzinfo:
    t.replace(tzinfo=tz)
  return datetime.combine(d, t)


# get password
with open(".caldav_pass", "r") as f:
  cal_pass = f.read().strip()

# create vobject calendar
vcal = vobject.newFromBehavior("vcalendar")

# establish connection to caldav server 
with caldav.DAVClient(url=server_url, username=cal_user, password=cal_pass) as dav_client:
  # establish connection to calendar
  dav_cal = dav_client.calendar(url=cal_url)

  # put all events from caldav calendar into vobject calendar
  for e in dav_cal.events():
    for ev in e.instance.contents["vevent"]:
      vcal.add(ev)
  
# we only want events belonging to a specific category 
events = [e for e in vcal.getChildren() if "categories" in e.contents.keys() and cal_category in map(lambda x: x.value[0], e.contents["categories"])]

# convert events into a structure suitable for Pelican 
e_tmp = []
for e in events:
  d = {}
  for k, v in e.contents.items():
    # only keep specific calendar properties
    if not k in cal_properties:
      continue

    # v is usually a list with a single item 
    if len(v) == 1:
      d[k] = v[0].value
    # but sometimes there's more than one item (this only ever happens when k is "categories")
    # and in this case, each list item's value is itself a one item list (which is stupid but that's how vobject handles categories)
    else:
      d[k] = [v[i].value[0] for i in range(len(v))]
  e_tmp.append(d)
events = e_tmp

# fix dates and datetimes
for e in events:
  for k in e.keys():
    if k in cal_prop_datetimes:
      e[k] = fixDatetime(e[k])

# keep only future events  
events = [e for e in events if e["dtstart"] >= now]

# sort by start date
events.sort(key=lambda e: e["dtstart"])

# write data as YAML
with open(result_file, 'w') as f:
  f.write("---\n")
  yaml.dump({"termine": events}, f)
  f.write("---\n")
  f.write("written at " + datetime.today().isoformat(" "))