import sys
import os.path
from icalendar import Calendar
import csv

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:
    """Calendar event class"""
    summary = ''
    uid = ''
    description = ''
    location = ''
    start = ''
    end = ''
    url = ''

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

events = []


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

            for component in gcal.walk():
                event = CalendarEvent("event")
                if component.get('SUMMARY') == None: continue #skip blank items
                event.summary = component.get('SUMMARY')
                event.uid = component.get('UID')
                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


                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"
    try:
        with open(csvfile, 'w') as myfile:
            wr = csv.writer(myfile, quoting=csv.QUOTE_ALL)
            wr.writerow(headers)
            for event in events:
                values = (event.summary, event.uid, event.description, event.location, event.start, event.end, event.url)
                wr.writerow(values)
            print("Wrote to ", csvfile, "\n")
    except IOError:
        print("Could not open file! Please close Excel!")
        exit(0)


def debug_event(class_name):
    print("Contents of ", class_name.name, ":")
    print(class_name.summary)
    print(class_name.uid)
    print(class_name.description)
    print(class_name.location)
    print(class_name.start)
    print(class_name.end)
    print(class_name.url, "\n")

open_cal()
csv_write(filename)
#debug_event(event)