#!/usr/bin/env python3

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.
    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)

def buildRSS(title, url, description, content):
    """
    Feed basic info: title, url, descriptions
    Content: List[Dict{title, url, content, date, enclosures, guid}]
    """

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

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

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