#!/usr/bin/python
#
import optparse
import apt
import sys
import re
import os


class PkgEntry(object):
	def __init__(self, package=None, version=None, filename=None, sourcepkg=None, ucsversion=None):
		self.package = package
		self.version = version
		self.filename = filename
		self.sourcepkg = sourcepkg
		self.ucsversion = ucsversion

	def _get_value(self, line):
		return line.split(': ', 1)[1]

	def scan(self, entry, ucsversion):
		if ucsversion:
			self.ucsversion = ucsversion
		for line in entry.splitlines():
			if line.startswith('Package: '):
				self.package = self._get_value(line)
			elif line.startswith('Version: '):
				self.version = self._get_value(line)
			elif line.startswith('Filename: '):
				self.filename = self._get_value(line)
			elif line.startswith('Source: '):
				self.sourcepkg = self._get_value(line)

	def is_ok(self):
		return bool(self.package) and bool(self.version)


def load_packages_file(filename, target_dict, ucsversion):
	if not os.path.exists(filename):
		print 'E: %r does not exist' % (filename,)
		return

	# load file
	content = open(filename, 'r').read()
	for entry in content.split('\n\n'):
		# scan each entry
		item = PkgEntry()
		item.scan(entry, ucsversion)
		if item.is_ok():
			if item.package in target_dict:
				if apt.VersionCompare(target_dict[item.package].version, item.version) < 0:
					target_dict[item.package] = item
			else:
				target_dict[item.package] = item


def load_version(version):
	major, minor, patchlevel = [int(x) for x in version.replace('-', '.').split('.', 2)]

	target = {}
	for i_minor in xrange(0, minor+1):
		for i_patchlevel in xrange(0, 99):
			fn = '/var/univention/buildsystem2/apt/ucs_%d.%d-0' % (major, i_minor)
			if not i_patchlevel == 0:
				fn = '/var/univention/buildsystem2/apt/ucs_%d.%d-0-ucs%d.%d-%d' % (major, i_minor, major, i_minor, i_patchlevel)
			if not os.path.isdir(fn):
				break

			print 'Loading', fn
			for arch in ('all', 'i386', 'amd64'):
				load_packages_file(os.path.join(fn, arch, 'Packages'), target, os.path.basename(fn))

			fn = '/var/univention/buildsystem2/apt/ucs_%d.%d-0-errata%d.%d-%d' % (major, i_minor, major, i_minor, i_patchlevel)
			if os.path.isdir(fn):
				print 'Loading', fn
				for arch in ('all', 'i386', 'amd64'):
					load_packages_file(os.path.join(fn, arch, 'Packages'), target, os.path.basename(fn))
	return target


def compare(old, new):
	errors = 0
	pkglist = sorted(new.keys())
	srcpkglist = set()
	for pkg in pkglist:
		if pkg in old:
			if apt.VersionCompare(old[pkg].version, new[pkg].version) > 0:
				if errors == 0:
					print
					print '--------------------------------------------------------------------------------------'
					print '  The following packages use a smaller package version within the newer UCS release:'
					print '--------------------------------------------------------------------------------------'
					print
				print 'PKG: %s' % (pkg,)
				print '   %s: %s' % (old[pkg].ucsversion, old[pkg].version)
				print '   %s: %s' % (new[pkg].ucsversion, new[pkg].version)
				srcpkg = new[pkg].sourcepkg
				if not srcpkg:
					srcpkg = pkg
				srcpkglist.add(srcpkg)
				print '   Src pkg: %s' % (srcpkg,)
				print
				errors += 1

	print
	print 'Affected source packages:'
	for pkg in sorted(list(srcpkglist)):
		print '  %s' % (pkg,)
	print

	print 'Number of affected binary packages: %d' % (errors,)
	print 'Number of affected source packages: %d' % (len(srcpkglist),)
	return 1 if errors else 0


def main():
	usage = '''%progname <old ucs version> <new ucs version>

Loads all Packages files up to last major version for both given versions
and compares the available package versions.'''
	parser = optparse.OptionParser(usage=usage)
	(options, args) = parser.parse_args()

	if len(args) != 2:
		parser.print_usage()
		sys.exit(1)

	print 'Comparing UCS versions %s and %s:\n' % (args[0], args[1])

	old = load_version(args[0])
	new = load_version(args[1])

	sys.exit(compare(old, new))

if __name__ == '__main__':
	main()