#!/int/python1.5
#
# notify.py -- notify about web page changes
#
# Keith Waclena <k-waclena@uchicago.edu>
#

__author__     = "Keith Waclena, k-waclena@uchicago.edu"
__version__    = "0.2"
__patchlevel__ = "0"
__production__ = 0

CHUNKSIZE = 16 * 1024

import sys, shelve, urllib, md5
from urlparse import urlparse, urlunparse
from string import join
import main

class summary:
    def __init__(self, digest, size):
	self.digest, self.size = digest, size

def summarize(fp):
    """Return an MD5 message digest (checksum) of all the data on open file fp.
    """
    m = md5.new()
    size = 0
    while 1:
	chunk = fp.read(CHUNKSIZE)
	if not chunk: break
	m.update(chunk)
	size = size + len(chunk)
    return summary(m.digest(), size)

def normalize(url):
    """Normalize url by stripping any query and fragment parts; also,
    if original url was of the form `www.foo.com', convert this to
    `http://www.foo.com'.
    """
    (scheme, netloc, path, _, _, frag) = urlparse(url, "http")
    if not netloc and path:
	return urlunparse((scheme, path, "", "", "", ""))
    else:
	return urlunparse((scheme, netloc, path, "", "", ""))

class Main(main.main):
    Usage = "-[vqadscu] database [url ...]"

    try:
	options = [main.opt("v", doc = "set VERBOSITY level to 1"),
		   main.opt("q", doc = "quiet mode; no output, only exit status"),
		   main.opt("a", doc = "add urls to database, don't check"),
		   main.opt("d", doc = "delete urls from database, don't check"),
		   main.opt("s", doc = "show urls in database"),
		   main.opt("c", doc = "list urls that have changed"),
		   main.opt("u", doc = "autoupdate of checksums of urls that have"
			    " changed"),]
    except main.opt, o:
	main.dryrot("%s: %s" % (o, o.error))

    def main(self):
	((self.verbose.verbosity, self.quiet, adding, deleting, showing,
	  self.changed, self.updating),
	 self.args) = main.opts(self.options).getopt("v", "q", "a",
						     "d","s", "c", "u")
	self.db = None
	if self.args:
	    self.database = self.args[0]
	    self.db = shelve.open(self.database)
	    self.args = self.args[1:]
	try:
	    if adding:
		self.add()
	    elif deleting:
		self.delete()
	    elif showing:
		self.show()
	    else:
		# checking...
		if self.args:
		    # check all urls in database
		    allswell = self.check(self.args)
		else:
		    # check named urls only
		    allswell = self.check(self.db.keys())
		if allswell or self.changed:
		    sys.exit(0)
		else:
		    sys.exit(1)
	finally:
	    if self.db: self.db.close()

    def check(self, urls):
	"""Check all URLs in urls (a sequence of strings).
	"""
	from operator import __and__
	results = []
	for url in urls:
	    url = normalize(url)
	    self.verbose.partial(1, "%s, " % url)
	    try:
		fp = urllib.urlopen(url)
	    except IOError, (_, msg):
		self.verbose.finish(1, "%s" % msg)
		continue
	    else:
		self.verbose.finish(1, "done")
	    try:
		previous = self.db[url].digest
	    except KeyError:
		self.warning("%s not in database" % url)
		continue
	    s = summarize(fp)
	    if s.digest == previous:
		results.append(1)
		if self.quiet:
		    pass
		elif self.changed:
		    pass
		else:
		    print "same\t%s" % url
	    else:
		results.append(0)
		if self.quiet:
		    pass
		elif self.changed:
		    print url
		else:
		    print "DIFFER\t%s" % url
		if self.updating:
		    self.verbose(1, "updating %s" % url)
		    self.db[url] = s
	return reduce(__and__, results, 1)

    def add(self):
	"""Add urls in self.args to database.
	"""
	for url in self.args:
	    url = normalize(url)
	    self.verbose.partial(1, "adding %s, " % url)
	    try:
		fp = urllib.urlopen(url)
	    except IOError, (_, msg):
		self.verbose.finish(1, "%s" % msg)
		continue
	    else:
		self.verbose.finish(1, "done")
	    self.db[url] = summarize(fp)

    def delete(self):
	"""Delete urls in self.args from database.
	"""
	for url in self.args:
	    url = normalize(url)
	    try:
		del self.db[url]
		self.verbose(1, "deleted %s" % url)
	    except KeyError:
		self.warning("%s not in database" % url)

    def show(self):
	"""Show all urls in database in a parsable form on stdout.
	"""
	def md5repr(digest):
	    return join(map(lambda c: "%x" % ord(c), digest), "")
	for key in self.db.keys():
	    s = self.db[key]
	    print "%s\t%s\t%s" % (md5repr(s.digest), s.size, key)

Main(production = __production__)()

# Local Variables:
# py-indent-offset: 4
# fill-column: 76
# End: