#!/usr/bin/python

import re, urllib, urllib2, argparse, os

parser = argparse.ArgumentParser(description='Downloads all full-size images in an arbitrary 4chan thread.')

parser.add_argument('urllist', metavar='url', type=str, nargs=1,
                   help='the URL of the thread')
parser.add_argument('-n', '--newdir', dest='newdir', action='store_true',
                   help='create a new directory for this thread in the current directory')
                   
args = parser.parse_args()
options = vars(args)

regex = 'href="(\/\/images\.4chan\.org\/b\/src\/[0-9]+\.[a-z]+)"'
url = options['urllist'][0]

try:
	page = urllib2.urlopen(url).read()
except ValueError:
	print "That does not look like a valid URL."
	exit(1)
except urllib2.HTTPError:
	print "The given URL returns a HTTP 404 status code - the thread may have died."
	exit(1)

if options['newdir'] == True:
	thread_id = url.split('/')[-1]
	target_dir = "%s/" % thread_id

	if not os.path.exists(thread_id):
		os.makedirs(thread_id)
else:
	target_dir = ""

search = re.compile(regex)
matches = search.finditer(page)

urls = []

for match in matches:
	if match.group(1) not in urls:
		urls.append(match.group(1))

current = 1
total = len(urls)

print "Parsed thread. Total images: %d" % total

for downloadurl in urls:
	downloadurl = "http:%s" % downloadurl
	filename = downloadurl.split('/')[-1]
	path = target_dir + filename
	urllib.urlretrieve(downloadurl, path)
	print "Downloaded %s (%d/%d)." % (filename, current, total)
	current += 1