#!/usr/bin/python3

import sys
import os
from icalendar import Calendar, Event
from textwrap import fill, indent

FIELDS = ('summary','location','organiser',
          'flags','uid','rrule')
COLSEP = ': '

COLUMNS = int(os.getenv('COLUMNS', 80))-10
WIDTH = max(len(i) for i in FIELDS)
INDENT = WIDTH + len(COLSEP)

def dtstrs(event):
    start, end = event.get('dtstart').dt, event.get('dtend')
    if not end:
        duration = event.get('duration').dt
        end = start + duration
    else:
        end = end.dt

    def strftime(dt, strf):
        return dt.astimezone().strftime(strf)

    ret = []

    try:
        if start.tzinfo == end.tzinfo:
            ret.append(strftime(start, '%F %R'))

        else:
            ret.append(strftime(start, '%F %R %Z'))

        if start.date() == end.date():
            ret.append(strftime(end, '%T %Z'))

        else:
            ret.append(strftime(end, '%F %R %Z'))

        return ret

    except AttributeError:
        return map(lambda d: d.strftime('%F'), (start, end))

def parse_ics_file(fp):
    cal = Calendar.from_ical(fp.read())

    for event in cal.walk():
        if event.name != "VEVENT": continue
        print('{} → {}'.format(*dtstrs(event)))
        flags = []
        for k in ('status', 'class', 'transp', 'priority'):
            t = event.get(k)
            if t: flags.append((k, t))
        event['flags'] = ' '.join('{}:{}'.format(*f) for f in flags)
        for label in FIELDS:
            if label in event:
                text = fill(str(event[label]), width=COLUMNS-INDENT,
                            initial_indent='', subsequent_indent=' '*INDENT)
                print(f'{label.capitalize():>{WIDTH}s}{COLSEP}{text}')

        if 'description' in event:
            output = ['']
            lines = event['description'].split('\n')
            for line in lines:
                output.append(fill(line, width=COLUMNS, initial_indent=' ',
                                   subsequent_indent=' '))
            print('\n'.join(output))

if __name__ == '__main__':

    if len(sys.argv) > 1 and sys.argv[1] != '-':
        for f in sys.argv[1:]:
            with open(f) as fp:
                parse_ics_file(fp)
    else:
        parse_ics_file(sys.stdin)