#!/usr/bin/env python
# Copyright 2011 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2

import optparse
import os
import types

os.environ["PORTDIR_OVERLAY"] = ""

import portage

def process_deps(deps, use=None):
	if not use:
		use = []
	result = []
	for index, x in enumerate(deps):
		if type(x) == types.ListType:
			continue
		elif x == "||":  # Any-of.
			result.extend(process_deps(deps[index + 1], use))
		elif x[-1] == "?":  # Use-conditional.
			result.extend(process_deps(deps[index + 1], use + [x[:-1]]))
		elif x[0] == "!":  # Blocker.
			result.append((portage.dep_getkey(x), True, use))
		else:
			result.append((portage.dep_getkey(x), False, use))
	return result

if __name__ == "__main__":
	parser = optparse.OptionParser()
	parser.add_option("-i", "--input", dest="input_filename", default="package.keywords", help="Input filename for generated package.keywords file [default=%default]")
	parser.add_option("-o", "--output", dest="output_filename", default="package.rdeps", help="Output filename for generated package.rdeps file [default=%default]")
	parser.add_option("-v", "--verbose", dest="verbose", action="store_true", default=False)

	(options, args) = parser.parse_args()
	if not options.input_filename:
		parser.error("--input option is required")
	if not options.output_filename:
		parser.error("--output option is required")
	if args:
		parser.error("unrecognized command-line args")

	reverse_deps = {}
	for pkg in portage.portdb.cp_all():
		deps = []
		for match in portage.portdb.match(pkg):
			deps.extend(process_deps(portage.dep.paren_reduce(portage.portdb.aux_get(match, ['DEPEND', 'RDEPEND', 'PDEPEND'])[0])))
		for cp, blocker, use in deps:
			if blocker:
				continue
			if cp not in reverse_deps:
				reverse_deps[cp] = {}
			if pkg not in reverse_deps[cp]:
				reverse_deps[cp][pkg] = []
			if use not in reverse_deps[cp][pkg]:
				reverse_deps[cp][pkg].append(use)

	with open(options.input_filename, "r") as input_file:
		with open(options.output_filename, "w") as output_file:
			for line in input_file:
				if line == "\n" or line.startswith("#"):
					continue

				if not line.endswith("\n"):
					line += "\n"
				cpv = line[1:-1]
				pn = portage.versions.pkgsplit(cpv)[0]
				if pn in reverse_deps:
					output_file.write("# Reverse dependencies for %s\n" % pn)
					for cp, use_combinations in reverse_deps[pn].items():
						if use_combinations != [[]]:
							output_file.write("# One of the following USE flag combinations is required:\n")
							for use_combination in use_combinations:
								output_file.write("#\t%s\n" % ",".join(use_combination))
						output_file.write("%s\n" % cp)
				elif options.verbose:
					print 'No reverse dependencies for %s' % pn