from os import path, listdir
from datetime import date
from configparser import ConfigParser

from flask import (
    Flask,
    redirect,
    render_template,
    request,
    url_for,
    g,
    Response
)


# ---------- APP CONFIG ------------------------------------------------------


app = Flask(__name__)


# ---------- LOCALES FUNCTIONS -----------------------------------------------


def load_all_locales():
    translations = {}
    locales_dir = "locales"

    locales_code_default = ('en', 'ru', 'es')
    locales_code_extra = []
    locales_code = ()

    for filename in listdir(locales_dir):
        if filename.endswith(".ini"):
            cp = ConfigParser()
            lang = path.splitext(filename)[0]
            with open(path.join(locales_dir, filename), encoding="utf-8") as f:
                cp.read_file(f)

            if lang not in locales_code_default:
                locales_code_extra.append(lang)

            translations[lang] = {
                section: dict(cp[section]) for section in cp.sections()
            }

    locales_code = locales_code_default + tuple(sorted(locales_code_extra))
    locales_name = {l: translations[l]['title']['language'] for l in locales_code}

    return translations, locales_name, locales_code


translations, locales_name, locales_code = load_all_locales()


# ---------- HELPER FUNCTIONS ------------------------------------------------


def get_best_lang():
    return request.accept_languages.best_match(locales_code) or "en"


def render_localized_template(lang, template_name):
    if lang not in locales_code:
        return redirect(url_for("index", lang=get_best_lang()))

    return render_template(
        template_name,
        year=date.today().year,
    )


@app.before_request
def before_request():
    if args := request.view_args:
        g.locale = args.get('lang', 'en')
        g.translations = translations.get(g.locale, get_best_lang())
        g.locales_name = locales_name


@app.context_processor
def inject_translations():
    def translate(text, **kwargs):
        section, key = text.split(":", 1)

        template = g.translations \
            .get(section, {}) \
            .get(key, f"${section}: {key}$")

        try:
            return template.format(**kwargs)
        except:
            return template

    return {'_': translate}


# ---------- MAIN PAGES ------------------------------------------------------


@app.route("/")
def home():
    return redirect(url_for("index", lang=get_best_lang()))


@app.route("/<lang>")
def index(lang):
    return render_localized_template(lang, "index.html")


@app.route("/<lang>/download")
def download(lang):
    return render_localized_template(lang, "download.html")


# ---------- ROBOTS.TXT + SITEMAP.XML ----------------------------------------


@app.route("/robots.txt")
def robots_txt():
    base_url = request.url_root.rstrip("/")
    content = [
        "User-agent: *",
        "Disallow:",
        f"Sitemap: {base_url}/sitemap.xml",
    ]
    return Response("\n".join(content), mimetype="text/plain")


@app.route("/sitemap.xml")
def sitemap_xml():
    base_url = request.url_root.rstrip("/")
    today = date.today().isoformat()

    urls = []
    for lang in locales_code:
        urls.append(f"{base_url}/{lang}")
        urls.append(f"{base_url}/{lang}/download")

    xml_lines = [
        '<?xml version="1.0" encoding="UTF-8"?>',
        '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">',
    ]
    for loc in urls:
        xml_lines.extend(
            [
                "  <url>",
                f"    <loc>{loc}</loc>",
                f"    <lastmod>{today}</lastmod>",
                "    <changefreq>monthly</changefreq>",
                "    <priority>0.8</priority>",
                "  </url>",
            ]
        )
    xml_lines.append("</urlset>")

    return Response("\n".join(xml_lines), mimetype="application/xml")


# ---------- APP ENTRY -------------------------------------------------------


if __name__ == "__main__":
    app.run(host="0.0.0.0", debug=True)