#!/usr/bin/python3

import sys
import os.path
from icalendar import Calendar
import recurring_ical_events
from bs4 import BeautifulSoup
import warnings
from dateutil.parser import parse
import datetime
import csv

warnings.filterwarnings("ignore", category=UserWarning, module='bs4') # We don't want warnings about URL's. We just what the URL printed, if there.

if len(sys.argv) <= 1:
    print("Please call this script with an ics-file as parameter.\n")
    print("Even better, call it with start and end dates:\n")
    print(sys.argv[0] + " myexport.ics 20210101 20210201")
    print(sys.argv[0] + " myexport.ics 2021-01-01T00:00:00 2021-01-31T23:59:59\n")
    print("NOTE: If you need data in another timezone than the system is set to, override like this before running the script:")
    print("export TZ=\"Europe/Copenhagen\"\n")
    exit(1)

filename = sys.argv[1]
# TODO: use regex to get file extension (chars after last period), in case it's not exactly 3 chars.
file_extension = str(sys.argv[1])[-3:]
headers = ('Summary', 'UID', 'Description', 'Location', 'Start Time', 'End Time', 'URL')

class CalendarEvent:
    summary = ''
    uid = ''
    description = ''
    location = ''
    start = ''
    end = ''
    url = ''

    def __init__(self, name):
        self.name = name

events = []

def removehtml(html):
    # Almost word for word copy from here: https://stackoverflow.com/questions/328356/extracting-text-from-html-file-using-python

    soup = BeautifulSoup(html, features="html.parser")
    # kill all script and style elements
    for script in soup(["script", "style"]):
        script.extract() # remove it

    text = soup.get_text() # Get plain text

    # break into lines and remove leading and trailing space on each
    lines = (line.strip() for line in text.splitlines())
    # break multi-headlines into a line each
    chunks = (phrase.strip() for line in lines for phrase in line.split("  "))
    # drop blank lines
    text = '\n'.join(chunk for chunk in chunks if chunk)

    return text

def open_cal():
    if os.path.isfile(filename):
        if file_extension == 'ics':
            print("Extracting events from file:", filename)
            f = open(sys.argv[1], 'rb')
            gcal = Calendar.from_ical(f.read())
            revents = recurring_ical_events.of(gcal).between(istart,istop)

#           for component in gcal.walk():
            for component in revents:
                event = CalendarEvent("event")
                v=(dir(component).count('get')) # Only proces data if object is a valid event
                if (v != 0):
                     if component.get('TRANSP') == 'TRANSPARENT': 
                         continue #skip all day events and the like
                     if component.get('SUMMARY') is None or component.get('SUMMARY') == "":
                         continue #skip blank items
                     event.summary = component.get('SUMMARY')
                     event.uid = component.get('UID')
                     if component.get('DESCRIPTION') is None or component.get('DESCRIPTION') == "":
                         continue #skip blank items
                     event.description = component.get('DESCRIPTION')
                     event.location = component.get('LOCATION')
                     if hasattr(component.get('dtstart'), 'dt'):
                         event.start = component.get('dtstart').dt
                     if hasattr(component.get('dtend'), 'dt'):
                         event.end = component.get('dtend').dt

                     if type(now) != type(event.start): # If we get a datetime.date object, convert to datetime.datetime
                         event.start=datetime.datetime.combine(event.start, datetime.time.min)
                     if type(now) != type(event.end): # If we get a datetime.date object, convert to datetime.datetime
                         event.end=datetime.datetime.combine(event.end, datetime.time.max)
                     event.start = event.start.astimezone()
                     event.end = event.end.astimezone()
                     event.url = component.get('URL')
                     events.append(event)
            f.close()
        else:
            print("You entered ", filename, ". ")
            print(file_extension.upper(), " is not a valid file format. Looking for an ICS file.")
            exit(0)
    else:
        print("I can't find the file ", filename, ".")
        print("Please enter an ics file located in the same folder as this script.")
        exit(0)


def csv_write(icsfile):
    csvfile = icsfile[:-3] + "csv"
    spent=0
    evcount=0
    evskip=0
    try:
        with open(csvfile, 'w') as myfile:
            wr = csv.writer(myfile, quoting=csv.QUOTE_ALL)
            wr.writerow(headers)
            for event in sortedevents:
                values = (event.summary.encode('utf-8').decode(), 
                          event.uid, 
                          removehtml(event.description.encode('utf-8').decode()), 
                          event.location.encode('utf-8').decode() if event.location is not None else "", 
                          event.start, 
                          event.end, 
                          event.url)
                wr.writerow(values)
                evcount+=1
            print("Wrote " + str(evcount) + " events to ", csvfile)
    except IOError:
        print("Could not open file! Please close Excel!")
        exit(0)

now=datetime.datetime.now()
istart=datetime.datetime.fromtimestamp(0) # Start of UNIX epoch (1970-01-01T00:00:00)
istop=now+datetime.timedelta(seconds=157680000) # Stop 5 years in the future, if no enddate is given, to make sure reucurring events don't go on forever ...

if len(sys.argv) > 3:
   if sys.argv[2] != '':
      istart=parse(sys.argv[2])
   if sys.argv[3] != '':
      istop=parse(sys.argv[3])

open_cal() # Open ics file and do initial parsing of events
sortedevents=sorted(events, key=lambda obj: obj.start) # Make sure events are in chronological order
csv_write(filename)