#!/usr/bin/env python3

from sys import argv
from urllib.parse import urljoin
from xml.etree.ElementTree import Element, SubElement, indent, tostring

from helpers import guess_language, read_concerts, tmplocale


LOCALIZED_TEXT = {
    'en': {
        'title': 'Bellefeuille Quartet',
        'indexpath': 'en/',
        'description': 'News from the Bellefeuille quartet',
    },
    'fr': {
        'title': 'Quatuor Bellefeuille',
        'indexpath': '/',
        'description': 'Des nouvelles du quatuor Bellefeuille',
    },
}

LOCALIZED_FORMATS = {
    'en': {
        'title': lambda c: f'{c.time.strftime("%B %-d %Y")} in {c.place}',
    },
    'fr': {
        'title': lambda c: f'{c.time.strftime("%-d %B %Y")} à {c.place}',
    },
}


def text_element(tag, text, /, **kwargs):
    elt = Element(tag, **kwargs)
    elt.text = text
    return elt


def generate_concert(concert, concerts_url, lang):
    formatters = LOCALIZED_FORMATS[lang]

    item = Element('item')

    with tmplocale(lang):
        title = formatters['title'](concert)
    item.append(text_element('title', title))

    anchor = f'concert-{concert.time.strftime("%F")}'
    item.append(text_element('link', f'{concerts_url}#{anchor}'))

    return item


def generate_concerts(concerts_src, concerts_url, lang):

    for c in read_concerts(concerts_src):
        yield generate_concert(c, concerts_url, lang)


def main(concerts_src, feed_dst, domain):
    lang = guess_language(concerts_src)
    text = LOCALIZED_TEXT[lang]

    url = f'https://{domain}'
    index_url = urljoin(url, text['indexpath'])
    concerts_url = urljoin(index_url, 'concerts.html')

    rss = Element('rss', version='2.0')

    channel = SubElement(rss, 'channel')

    channel.extend((
        text_element('title', text['title']),
        text_element('link', index_url),
        text_element('description', text['description']),
    ))

    image = SubElement(channel, 'image')
    image.extend((
        text_element('url', urljoin(url, 'images/logo.svg')),
        text_element('link', concerts_url),
    ))

    channel.append(text_element('language', lang))

    items = generate_concerts(concerts_src, concerts_url, lang)
    channel.extend(tuple(items))

    indent(rss)

    with open(feed_dst, 'wb') as feed:
        feed.write(tostring(rss, encoding='utf-8', xml_declaration=True))


if __name__ == '__main__':
    main(argv[1], argv[2], argv[3])