#!/usr/bin/python3
# coding: utf-8


from abc import ABC, abstractmethod
from urllib.parse import urlparse
import urllib.request
import os
from selenium import webdriver
from selenium.webdriver.chrome.service import Service
from selenium.webdriver.chrome.options import Options
import icalendar
from datetime import datetime, date




class Downloader(ABC):

    def __init__(self):
        pass

    @abstractmethod
    def download(self, url):
        pass

class SimpleDownloader(Downloader):

    def __init__(self):
        super().__init__()


    def download(self, url):
        print("Downloading {}".format(url))

        try:
            resource = urllib.request.urlopen(url)
            data = resource.read().decode(resource.headers.get_content_charset())
            return data
        except:
            return None



class ChromiumHeadlessDownloader(Downloader):

    def __init__(self):
        super().__init__()
        options = Options()
        options.add_argument("--headless=new")
        service = Service("/usr/bin/chromedriver")
        self.driver = webdriver.Chrome(service=service, options=options)


    def download(self, url):
        print("Download {}".format(url))

        self.driver.get(url)
        return driver.page_source


class Extractor(ABC):

    def __init__(self):
        self.header = {}
        self.events = []

    @abstractmethod
    def extract(self, content, url, url_human = None):
        pass

    def set_header(self, url):
        self.header["url"] = url
        self.header["date"] = datetime.now()

    def clear_events(self):
        self.events = []

    def add_event(self, title, category, start_day, location, description, tags, url=None, url_human=None, start_time=None, end_day=None, end_time=None, last_modified=None, published=False):
        if title is None:
            print("ERROR: cannot import an event without name")
            return
        if start_day is None:
            print("ERROR: cannot import an event without start day")
            return

        event = {
            "title": title,
            "category": category,
            "start_day": start_day,
            "location": location,
            "descritpion": description,
            "tags": tags,
            "published": published
        }
        if url is not None:
            event["url"] = url
        if url_human is not None:
            event["url_human"] = url_human
        if start_time is not None:
            event["start_time"] = start_time
        if end_day is not None:
            event["end_day"] = end_day
        if end_time is not None:
            event["end_time"] = end_time

        if last_modified is not None:
            event["last_modified"] = last_modified

        self.events.append(event)

    def default_value_if_exists(self, default_values, key):
        return default_values[key] if default_values is not None and key in default_values else None

    def get_structure(self):
        return { "header": self.header, "events": self.events}

class ICALExtractor(Extractor):

    def __init__(self):
        super().__init__()

    def get_item_from_vevent(self, event, name, raw = False):
        try:
            r = event.decoded(name)
            if raw:
                return r
            else:
                return r.decode()
        except:
            return None

    def get_dt_item_from_vevent(self, event, name):
        item = self.get_item_from_vevent(event, name, raw = True)

        day = None
        time = None

        if item is not None:
            if isinstance(item, datetime):
                day = item.date()
                time = item.time()
            elif isinstance(item, date):
                day = item
                time = None

        return day, time


    def extract(self, content, url, url_human = None, default_values = None, published = False):
        print("Extracting ical events from {}".format(url))
        self.set_header(url)
        self.clear_events()
        
        calendar = icalendar.Calendar.from_ical(content)

        for event in calendar.walk('VEVENT'):
            title = self.get_item_from_vevent(event, "SUMMARY")
            category = self.default_value_if_exists(default_values, "category")

            start_day, start_time = self.get_dt_item_from_vevent(event, "DTSTART")

            end_day, end_time = self.get_dt_item_from_vevent(event, "DTEND")

            location = self.get_item_from_vevent(event, "LOCATION")
            if location is None:
                location = Zself.default_value_if_exists(default_values, "location")

            description = self.get_item_from_vevent(event, "DESCRIPTION")

            last_modified = self.get_item_from_vevent(event, "LAST_MODIFIED")

            uuid = self.get_item_from_vevent(event, "UID")

            if uuid is not None:
                event_url = url + "#" + uuid

            tags = self.default_value_if_exists(default_values, "tags")

            last_modified = self.get_item_from_vevent(event, "LAST-MODIFIED", raw = True)

            rrule = self.get_item_from_vevent(event, "RRULE", raw = True)
            if rrule is not None:
                print("Recurrent event not yet supported", rrule)

            self.add_event(title, category, start_day, location, description, tags, url=event_url, url_human=url_human, start_time=start_time, end_day=end_day, end_time=end_time, last_modified=last_modified, published=published)

        return self.get_structure()



class URL2Events:

    def __init__(self, downloader, extractor):

        self.downloader = downloader
        self.extractor = extractor

    def process(self, url, url_human = None, cache = None, default_values = None):

        if cache and os.path.exists(cache):
            print("Loading cache ({})".format(cache))
            with open(cache) as f:
                content = "\n".join(f.readlines())
        else:
            content = self.downloader.download(url)

            if cache:
                print("Saving cache ({})".format(cache))
                dir = os.path.dirname(cache)
                if dir != "" and not os.path.exists(dir):
                    os.makedirs(dir)
                with open(cache, "w") as text_file:
                    text_file.write(content)

        return self.extractor.extract(content, url, url_human, default_values)


if __name__ == "__main__":

    u2e = URL2Events(SimpleDownloader(), ICALExtractor())
    url = "https://calendar.google.com/calendar/ical/programmation.lesaugustes%40gmail.com/public/basic.ics"
    url_human = "https://www.cafelesaugustes.fr/la-programmation/"

    events = u2e.process(url, url_human, cache = "cache-augustes.ical", default_values = {"category": "Autre", "location": "Café lecture les Augustes"}, published = True)

    #print(events)