Display recently played tracks on All Classical.

nowplaying.py

import sys
import urllib
import re
import argparse
from datetime import datetime, timedelta
from bs4 import BeautifulSoup

parser = argparse.ArgumentParser(description="Display recently played tracks on All Classical.")
parser.add_argument("-p", "--performer", action="store_true", 
                    help="Include performer information in output")
parser.add_argument("indexes", default="0", nargs='?', metavar="M[{..|-}N]", 
                    help="(optional) Indexes of tracks to display. Either a single number or a range, indicated by a number followed by either '..' or '-' and another number. The most recent track is 0; a range whose start is higher than its end is not supported.")
# Switch to use cached file rather than getting data from the net.
# Due to its _optional_ capture of a filename, this must be the last flag in
# the command line.
parser.add_argument("--use-cached", nargs='?', dest="cache", 
                    const="sample/allclassicalplaylist.txt", 
                    help=argparse.SUPPRESS)

arguments = parser.parse_args()

start = end = None
try:
    start = int(arguments.indexes)
# Not an integer? Could be a sequence specifier "n..x" or "n-x"
except ValueError:
    match = re.match(r"(\d+)([.]{2}|-)(\d+)", arguments.indexes)
    if match:
        start = int(match.group(1))
        end = int(match.group(3)) + 1

# Can't figure it out? Use defaults.
start = start or 0
end = end or start + 1

if arguments.cache:
    with open(arguments.cache, 'r') as f:
        playlist = f.read()
else:
    playlist = urllib.urlopen("http://www.allclassical.org/assets/playlist/playlistFormat.php").read()
playsoup = BeautifulSoup(playlist)

# Some programs don't have track listings. Check age of last entry; if it's
# too old, warn that the info might not be accurate.
if not arguments.cache:
    last_date = datetime.strptime(playsoup.find("span", "pl_time").string,
                                  "%I:%M %p")
    now = datetime.now()
    last_date = datetime.combine(now, last_date.time())
    if now - last_date > timedelta(minutes=30):
        print "The last time associated with a track in the playlist is more than 30 minutes ago. This might not actually be the most recently played piece.\n"
get_span_list = (lambda tag_name: 
                   [tag.string for tag in playsoup.find_all("span", 
                                                   "pl_"+tag_name)[start:end]])

# Slicing already handles out-of-bounds indexes, so no need to adjust them
titles = get_span_list("title")
composers = get_span_list("composer")
performers = (get_span_list("ensemble") if arguments.performer else 
                ["" for i in range(start, end)])
perf_by = ", performed by " if arguments.performer else ""

# Composer's name is last name first unless Anonymous
composers = [' '.join(reversed(composer.split(', '))) for composer 
                     in composers if not composer.startswith("Anonymous")]

for title, composer, performer in zip(titles, composers, performers):
    print u'"{0}" by {1}{2}{3}'.format(title, composer, perf_by, performer)