#!/usr/bin/python3
import pickle

import os
import os.path
import sys

import re
import math

import sched
import datetime
import time
from dateutil.parser import parse

import http.client as httplib

from googleapiclient.discovery import build
from google_auth_oauthlib.flow import InstalledAppFlow
from google.auth.transport.requests import Request

from courses import Courses
from config import USERCALENDARID, TIMEZONE, SCHEDULER_DELAY

courses = Courses()


def authenticate():
    print('Authenticating')
    # If modifying these scopes, delete the file token.pickle.
    scopes = ['https://www.googleapis.com/auth/calendar.readonly']
    creds = None
    # The file token.pickle stores the user's access and refresh tokens, and is
    # created automatically when the authorization flow completes for the first
    # time.
    if os.path.exists('token.pickle'):
        with open('token.pickle', 'rb') as token:
            creds = pickle.load(token)

    # If there are no (valid) credentials available, let the user log in.
    if not creds or not creds.valid:
        if creds and creds.expired and creds.refresh_token:
            print('Refreshing credentials')
            creds.refresh(Request())
        else:
            print('Need to allow access')
            flow = InstalledAppFlow.from_client_secrets_file('credentials.json', scopes)
            creds = flow.run_local_server(port=0)
        # Save the credentials for the next run
        with open('token.pickle', 'wb') as token:
            pickle.dump(creds, token)

    service = build('calendar', 'v3', credentials=creds)
    return service


def join(*args):
    return ' '.join(str(e) for e in args if e)


def truncate(string, length):
    ldots = ' ...'
    if len(string) < length:
        return string
    return string[:length - len(ldots)] + ldots


def summary(text):
    return truncate(re.sub(r'X[0-9A-Za-z]+', '', text).strip(), 50)


def gray(text):
    return '%{F#999999}' + text + '%{F-}'


def formatdd(begin, end):
    minutes = math.ceil((end - begin).seconds / 60)

    if minutes == 1:
        return '1 minute'

    if minutes < 60:
        return f'{minutes} min'

    hours = math.floor(minutes / 60)
    rest_minutes = minutes % 60

    if hours > 5 or rest_minutes == 0:
        return f'{hours} hours'

    return '{}:{:02d} h'.format(hours, rest_minutes)


def location(text):
    if not text:
        return ''
    match = re.search(r'\((.*)\)', text)

    if not match:
        return ''

    return f'{gray("in")} {match.group(1)}'


def text(events, now):
    current = next((e for e in events if e['start'] < now < e['end']), None)

    if not current:
        nxt = next((e for e in events if now <= e['start']), None)
        if nxt:
            return join(
                summary(nxt['summary']),
                gray('in'),
                formatdd(now, nxt['start']),
                location(nxt['location'])
            )
        return ''

    nxt = next((e for e in events if e['start'] >= current['end']), None)
    if not nxt:
        return join(gray('Ends in'), formatdd(now, current['end']) + '!')

    if current['end'] == nxt['start']:
        return join(
            gray('Ends in'),
            formatdd(now, current['end']) + gray('.'),
            gray('Afterwards'),
            summary(nxt['summary']),
            location(nxt['location'])
        )

    return join(
        gray('Ends in'),
        formatdd(now, current['end']) + gray('.'),
        gray('Afterwards'),
        summary(nxt['summary']),
        location(nxt['location']),
        gray('after a break of'),
        formatdd(current['end'], nxt['start'])
    )


def activate_course(event):
    course = next(
        (course for course in courses
         if course.info['title'].lower() in event['summary'].lower()),
        None
    )

    if not course:
        return

    courses.current = course


def main():
    scheduler = sched.scheduler(time.time, time.sleep)

    print('Initializing')

    service = authenticate()

    print('Authenticated')
    # Call the Calendar API
    now = datetime.datetime.now(tz=TIMEZONE)

    morning = now.replace(hour=6, minute=0, microsecond=0)
    evening = now.replace(hour=23, minute=59, microsecond=0)

    print('Searching for events')

    def get_events(calendar):
        events_result = service.events().list(
            calendarId=calendar,
            timeMin=morning.isoformat(),
            timeMax=evening.isoformat(),
            singleEvents=True,
            orderBy='startTime'
        ).execute()
        events = events_result.get('items', [])
        return [
            {
                'summary': event['summary'],
                'location': event.get('location', None),
                'start': parse(event['start']['dateTime']),
                'end': parse(event['end']['dateTime'])
            }
            for event in events
            if 'dateTime' in event['start']
        ]

    events = get_events(USERCALENDARID)
    # events = get_events('primary') + get_events('school-calendar@import.calendar.google.com')
    print('Done')

    def print_message():
        now = datetime.datetime.now(tz=TIMEZONE)
        print(text(events, now))
        if now < evening:
            scheduler.enter(SCHEDULER_DELAY, 1, print_message)

    for event in events:
        # absolute entry, priority 1
        scheduler.enterabs(event['start'].timestamp(), 1, activate_course, argument=(event,))

    # Immediate, priority 1
    scheduler.enter(0, 1, print_message)
    scheduler.run()


def wait_for_internet_connection(url, timeout=1):
    while True:
        conn = httplib.HTTPConnection(url, timeout=5)
        try:
            conn.request("HEAD", "/")
            conn.close()
            return True
        except:
            conn.close()


if __name__ == '__main__':
    os.chdir(sys.path[0])
    print('Waiting for connection')
    wait_for_internet_connection('www.google.com')
    main()