get.py

from retry import retry
import requests, requests.exceptions

class StatusCodeError(Exception):
    def __init__(self, code, url):
        self.code = code
        self.url = url
    def __str__(self):
        return 'request for {} returned status code {}'.format(self.url, self.code)

@retry((requests.exceptions.ConnectionError, StatusCodeError, ValueError), tries=6, wait=300)
def get(uri, json=False):
    r = requests.get(uri)
    if r.status_code != 200:
        raise StatusCodeError(r.status_code, uri)
    if json:
        return r.json()
    return r

retry.py

# so damn useful it deserved its own file

import time

def retry(Exceptions, tries=10, wait=1):
    if type(Exceptions) == Exception:
        Exceptions = (Exceptions,)
    def retryer(f):
        def deco(*args, **kwargs):
            for i in range(tries - 1):
                try:
                    return f(*args, **kwargs)
                except Exceptions:
                    time.sleep(wait)
            return f(*args, **kwargs)
        return deco
    return retryer

run.py

#!/usr/bin/env python3

import sys
from urllib.parse import quote_plus
from xml.dom.minidom import parseString as parseXML
import datetime
from get import get

lament = lambda *args, **kwargs: print(*args, file=sys.stderr, **kwargs)

parseDate = lambda s: datetime.datetime.strptime(s+'+0000', '%Y-%m-%dT%H:%M:%SZ%z')
formatDate = lambda dt: dt.strftime('%FT%TZ')

# we only need a handful of mime types so we may as well inline them
mimes = {
    'png': 'image/png',
    'jpg': 'image/jpeg',
    'gif': 'image/gif',
    'swf': 'application/x-shockwave-flash',
}

class Untitled:
    template = """
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<feed xmlns="http://www.w3.org/2005/Atom">
</feed>
""".strip()

    def __init__(self, urls, max_entries=512):
        self.urls = urls
        self.max_entries = max_entries
        self.title = 'Danbooru - Personalized Feed'
        self.items = []

    def parse(self, q):
        url = self.urls['atom'] + quote_plus(q)
        xml = get(url).text
        dom = parseXML(xml)

        entries = dom.getElementsByTagName('entry')
        for entry in entries:
            getText = lambda tn: entry.getElementsByTagName(tn)[0].firstChild.nodeValue

            item = {
                'title': getText('title'),
                'id': getText('id').split('/')[-1],
                'updated': getText('updated'),
                'summary': getText('summary'),
                'img': entry.getElementsByTagName('img')[0].getAttribute('src'),
                'query': q,
            }
            item['updated_unix'] = parseDate(item['updated']).timestamp()

            self.items.append(item)

    def generate(self):
        self.items = sorted(self.items, key=lambda d: d['updated_unix'], reverse=True)
        self.items = self.items[:self.max_entries]

        now = formatDate(datetime.datetime.utcnow())

        dom = parseXML(self.template)
        feed = dom.firstChild

        def newText(entity_name, text):
            e = dom.createElement(entity_name)
            e.appendChild(dom.createTextNode(text))
            return e

        def newLink(**kwargs):
            link = dom.createElement('link')
            for k, v in kwargs.items():
                link.setAttribute(k, v)
            return link

        feed.appendChild(newText('title', self.title))
        feed.appendChild(newLink(href=self.urls['feed'], rel='self'))
        feed.appendChild(newText('id', self.urls['feed']))
        feed.appendChild(newText('updated', now))

        for item in self.items:
            ext = item['img'].split('.')[-1]
            mime = mimes[ext]
            alt = self.urls['post'] + item['id']
            query_quote = quote_plus(item['query'])

            entry = dom.createElement('entry')
            entry.appendChild(newText('title', item['title']))
            entry.appendChild(newLink(href=alt, rel="alternate"))
            entry.appendChild(newText('id', alt))
            entry.appendChild(newText('published', item['updated']))
            entry.appendChild(newText('updated', item['updated']))
            entry.appendChild(newLink(rel="enclosure", type=mime, href=item['img']))
            entry.appendChild(newText('summary', item['summary']))

            author = dom.createElement('author')
            author.appendChild(newText('name', item['query']))
            author.appendChild(newText('uri', self.urls['query'] + query_quote))

            entry.appendChild(author)

            feed.appendChild(entry)

        return dom.toxml()

urls = {
    'atom': 'https://danbooru.donmai.us/posts.atom?limit=48&tags=',
    'post': 'https://danbooru.donmai.us/posts/',
    'img': 'https://danbooru.donmai.us/ssd/data/preview/',
    'query': 'https://danbooru.donmai.us/posts?tags=',
}

if __name__ == '__main__':
    urls['feed'] = sys.argv[1]

    untitled = Untitled(urls)

    queries = sys.stdin.read()

    for q in queries.splitlines():
        lament(q)
        untitled.parse(q)

    print(untitled.generate())