lumbung-calendar-prototype/event_feed.py

#!/bin/python3

#lumbung.space calendar feed generator
#© 2021 roel roscam abbing gplv3 etc

from ics import Calendar  
import requests
import jinja2
import os
import shutil
from slugify import slugify
from natural import date
from event_feed_config import calendar_url, output_dir
from urllib.parse import urlparse
import arrow
import re

cal = Calendar(requests.get(calendar_url).text)

env = jinja2.Environment(
    loader=jinja2.FileSystemLoader(os.path.curdir) 
    )

if not os.path.exists(output_dir):
    os.mkdir(output_dir)

template = env.get_template('event_template.md')

existing_posts = os.listdir(output_dir)

def findURLs(string):
    """
    return all URLs in a given string
    """
    regex = r"(?i)\b((?:https?://|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}/)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()\[\]{};:'\".,<>?«»“”‘’]))"
    url = re.findall(regex,string)      
    return [x[0] for x in url]     

def find_imageURLS(string):
    """
    return all image URLS in a given string
    """
    regex = r"(?:http\:|https\:)?\/\/.*?\.(?:png|jpg|jpeg|gif|svg)" 

    img_urls = re.findall(regex, string, flags=re.IGNORECASE)
    return img_urls 

def create_metadata(event):
    """
    construct a formatted dict of event metadata for use as frontmatter for HUGO post
    """

    if event.location:
        location_urls = findURLs(event.location)

        if location_urls:
            location_url = location_urls[0]
            event.location = '[{}]({})'.format(urlparse(location_url).netloc, location_url)


    event_metadata = {
    'name':event.name,
    'created':event.created.format(),
    'description': event.description,
    'localized_begin': '           '.join(localize_time(event.begin)), #non-breaking space characters to defeat markdown
    'begin': event.begin.format(),
    'end': event.end.format(),
    'duration': date.compress(event.duration),
    'location': event.location,
    'uid': event.uid,
    'images' : find_imageURLS(event.description) # currently not used in template
    }

    return event_metadata

def localize_time(date):
    """
    Turn a given date into various timezones
    Takes arrow objects
    """

    # 3 PM Kassel, Germany, 4 PM Ramallah/Jerusalem, Palestina (QoF),
    # 8 AM Bogota, Colombia (MaMa), 8 PM Jakarta, Indonesia (Gudskul),
    # 1 PM (+1day) Wellington, New Zealand (Fafswag), 9 AM Havana, Cuba (Instar).
    

    tzs = [
          ('Kassel','Europe/Berlin'),
          ('Bamako', 'Europe/London'),
          ('Palestine','Asia/Jerusalem'),
          ('Bogota','America/Bogota'),
          ('Jakarta','Asia/Jakarta'),
          ('Makassar','Asia/Makassar'),
          ('Wellington', 'Pacific/Auckland')
          ]

    localized_begins =[]
    for location, tz in tzs:
        localized_begins.append( #javascript formatting because of string creation from hell
            '__{}__ {}'.format(
                str(location),
                str(date.to(tz).format("YYYY-MM-DD __HH:mm__"))
                )
            )
    return localized_begins

def create_event_post(post_dir, event):
    """
    Create HUGO post based on calendar event metadata
    Searches for image URLS in description and downloads them
    Function is also called when post is in need of updating
    In that case it will also delete images no longer in metadata
    TODO: split this up into more functions for legibility
    """
    
    if not os.path.exists(post_dir):
        os.mkdir(post_dir)

    event_metadata = create_metadata(event)

    #list already existing images
    #so we can later delete them if we dont find them in the event metadata anymore 
    existing_images = os.listdir(post_dir)
    try:
        existing_images.remove('index.md')
        existing_images.remove('.timestamp')
    except:
        pass

    for img in event_metadata['images']:

        #parse img url to safe local image name
        img_name = os.path.basename(img)
        fn, ext = os.path.splitext(img_name)
        img_name =  slugify(fn) + '.' + ext
        
        local_image = os.path.join(post_dir, img_name)
        
        if not os.path.exists(local_image):
            #download preview image
            response = requests.get(img, stream=True)
            with open(local_image, 'wb') as img_file:
                shutil.copyfileobj(response.raw, img_file)
                print('Downloaded image for event "{}"'.format(event.name))
            # TODO fix bug here
            event_metadata['description'] = event_metadata['description'].replace(img, '![]({})'.format(img_name))
        if img_name in existing_images:
            existing_images.remove(img_name)

    for left_over_image in existing_images:
        #remove images we found, but which are no longer in remote event
        os.remove(os.path.join(post_dir,left_over_image))
        print('deleted image', left_over_image)

    with open(os.path.join(post_dir,'index.md'),'w') as f:
        post = template.render(event = event_metadata)
        f.write(post)
        print('created post for', event.name, '({})'.format(event.uid))

    with open(os.path.join(post_dir,'.timestamp'),'w') as f:
        f.write(event_metadata['created'])


def update_event_post(post_dir, event):
    """
    Update a post based on the VCARD event 'created' field which changes when updated
    """ 
    if os.path.exists(post_dir):
        old_timestamp = open(os.path.join(post_dir,'.timestamp')).read()
        if event.created > arrow.get(old_timestamp):
            print('Updating', event.name, '({})'.format(event.uid))
            create_event_post(post_dir, event)
        else:
            print('Event current: ', event.name, '({})'.format(event.uid))

for event in list(cal.events):

    post_dir = os.path.join(output_dir, event.uid)

    if event.uid not in existing_posts: 
        #if there is an event we dont already have, make it
        create_event_post(post_dir, event)

    elif event.uid in existing_posts: 
        #if we already have it, update
        update_event_post(post_dir, event)
        existing_posts.remove(event.uid) # create list of posts which have not been returned by the calendar
        

for post in existing_posts: 
    #remove events not returned by the calendar (deletion) 
    print('deleted', post) 
    shutil.rmtree(os.path.join(output_dir,post))