#!/usr/bin/env python3

from datetime import datetime
from typing import List

def _format_date(dt):
    """convert a datetime into an RFC 822 formatted date
    Input date must be in GMT.
    Stolen from PyRSS2Gen.
    """
    # Looks like:
    #   Sat, 07 Sep 2002 00:00:01 GMT
    # Can't use strftime because that's locale dependent
    #
    # Isn't there a standard way to do this for Python?  The
    # rfc822 and email.Utils modules assume a timestamp.  The
    # following is based on the rfc822 module.
    return "%s, %02d %s %04d %02d:%02d:%02d GMT" % (
            ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"][dt.weekday()],
            dt.day,
            ["Jan", "Feb", "Mar", "Apr", "May", "Jun",
             "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"][dt.month-1],
            dt.year, dt.hour, dt.minute, dt.second)

class RSSItem:
    title: str
    url: str
    content: str
    date: str
    enclosures: List[str]
    guid: str


class RSSFeed:
    title: str
    url: str
    description: str
    content: List[RSSItem]


def buildRSS(feed_data: RSSFeed):
    """
        feed_data = {
            title, url, description,
            content = [{
                title, url, content, date, [enclosures], guid
            }]
        }
    """

    feed = f"""<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0" xmlns:media="http://search.yahoo.com/mrss/">
  <channel>
    <title>{feed_data['title']}</title>
    <link>{feed_data['url']}</link>
    <description>{feed_data['description']}</description>
    <lastBuildDate>{_format_date(datetime.now())}</lastBuildDate>"""

    for item in feed_data["content"]:
        feed += "    <item>"
        feed += f"      <title><![CDATA[{item.get('title', 'N/A')}]]></title>"
        feed += f"      <link>{item.get('url', 'N/A')}</link>"
        feed += f"      <description><![CDATA[{item.get('content', 'N/A')}]]></description>"
        if "date" in item:
            if type(item["date"]) is str:
                feed += f"      <pubDate>{item['date']}</pubDate>"
            else:
                feed += f"      <pubDate>{_format_date(item['date'])}</pubDate>"
        for enclosure in item.get("enclosures", []):
            feed += f"      <media:content url=\"{enclosure}\" />"
        if "guid" in item:
            feed += f"      <guid>{item['guid']}</guid>"
        feed += "    </item>"

    feed += "  </channel>"
    feed += "</rss>"
    return feed