import datetime
import json
import uuid
from collections import defaultdict
from io import BytesIO
from typing import Iterable, Mapping

from flask import Flask, request, render_template, send_file
from icalendar import Calendar, Event, Alarm

app = Flask(__name__)

# Source JSON created from http://vvc.gov.lv/export/sites/default/files/paplasinatais_saraksts.pdf


def generate_ical_for_mapping(cal: Mapping[datetime.date, Iterable[str]]) -> BytesIO:
    ical = Calendar()
    ical['VERSION'] = "2.0"
    ical['PRODID'] = "NameDays"
    for date, names in sorted(cal.items(), key=lambda x: x[0]):
        ev = Event()
        ev.add("SUMMARY", ", ".join(sorted(names)))
        ev.add("DTSTART", date)
        ev.add("DTEND", date + datetime.timedelta(days=1))
        ev.add("DTSTAMP", datetime.datetime(2000, 1, 1))
        ev.add("RRULE", {"FREQ": "YEARLY"})
        ev.add("CATEGORY", "Anniversary")
        ev.add("UID", uuid.uuid4())
        alert = Alarm()
        alert.add("action", "DISPLAY")
        alert.add("TRIGGER", datetime.timedelta(hours=9))
        alert.add("DESCRIPTION", "Default description")
        ev.add_component(alert)
        ical.add_component(ev)
    return BytesIO(ical.to_ical(True))


@app.route('/', methods=["POST", "GET"])
def calendar():
    with open("vardadienas.json") as f:
        vdienas = json.load(f)
    names_dict = {
        f"{int(month):02}_{int(day):02}_{name}": name
        for month, month_data in vdienas.items()
        for day, day_data in month_data.items()
        for names in day_data.values()
        for name in names
    }
    if request.method == "POST":
        cal = defaultdict(list)
        for selected_name in request.form.getlist("words"):
            if selected_name in names_dict:
                month, day, name = selected_name.split("_")
                date = datetime.date(2000, int(month), int(day))
                cal[date].append(name)
        if cal:
            name = f"{uuid.uuid4().hex}.ics"
            f = generate_ical_for_mapping(cal)
            return send_file(f, mimetype="text/calendar", as_attachment=True, download_name=name)
    words = ((k,v) for k,v in sorted(names_dict.items(), key=lambda x: x[1]))
    return render_template("namedays.html", words=words)


if __name__ == "__main__":
    app.run("0.0.0.0", 5000, True, False)