#!/usr/bin/python3

# depgraph
# Copyright (C) 2008 Stefano Zacchiroli <zack@debian.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

"""Graph the dependencies of all packages contained in a given Packages
file.

Only consider Depends fields. Versioned dependencies are considered as they
were not versioned. The graph is returned in output as a (non normalized)
graphviz graph suitable to be processed by dot (for an unstable/main Packages
file, generating the final graph will take a while ...)."""

import sys
from debian import deb822

__fresh_id = 0

def main():
    if len(sys.argv) != 2:
        print("Usage: depgraph PACKAGES_FILE")
        sys.exit(2)

    def get_id():
        global __fresh_id
        __fresh_id += 1
        return ("NODE_%d" % __fresh_id)

    def emit_arc(node1, node2):
        print('  "%s" -> "%s" ;' % (node1, node2))
    def emit_node(node, dsc):
        print('  "%s" [label="%s"] ;' % (node, dsc))

    print("digraph depgraph {")
    for pkg in deb822.Packages.iter_paragraphs(open(sys.argv[1])):
        name = pkg['package']
        rels = pkg.relations
        for deps in rels['depends']:
            if len(deps) == 1:
                emit_arc(name, deps[0]['name'])
            else:   # output an OR node
                or_node = get_id()
                emit_arc(name, or_node)
                emit_node(or_node, 'OR')
                for dep in deps:
                    emit_arc(or_node, dep['name'].lower())
                    # even though it is forbidden by policy, there are some
                    # dependencies with upper case letter in the archive,
                    # apparently apt-get turn them to lowercase ...
    print("}")

if __name__ == '__main__':
    main()