#!/usr/bin/env python3

from dataclasses import dataclass
from datetime import datetime


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.
    weekdays = [
        "Mon",
        "Tue",
        "Wed",
        "Thu",
        "Fri",
        "Sat",
        "Sun",
    ]
    months = [
        "Jan",
        "Feb",
        "Mar",
        "Apr",
        "May",
        "Jun",
        "Jul",
        "Aug",
        "Sep",
        "Oct",
        "Nov",
        "Dec",
    ]
    return "%s, %02d %s %04d %02d:%02d:%02d GMT" % (
        weekdays[dt.weekday()],
        dt.day,
        months[dt.month - 1],
        dt.year,
        dt.hour,
        dt.minute,
        dt.second,
    )


@dataclass
class RSSItem:
    title: str
    url: str
    content: str
    date: str
    enclosures: list[str]
    guid: str


@dataclass
class RSSFeed:
    title: str
    url: str
    description: str
    content: list[RSSItem]


def escape(str):
    str = str.replace("&", "&")
    return str


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>{escape(feed_data.description)}</description>
    <lastBuildDate>{_format_date(datetime.now())}</lastBuildDate>"""

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

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