#!/usr/local/bin/python

import topdl
import StringIO

def topology_to_route_file(top, filename=None, file=None):
    # Outfile will point to the output target, either a file or a string buffer
    outf = None
    closeit = True
    if all([filename, file]): return False
    elif file: 
	closeit = False
	outf = file
    elif filename: outf = open(filename, 'w')
    else: outf = StringIO.StringIO()

    for e in top.elements:
	if not isinstance(e, topdl.Computer): continue
	myips = set()
	mylinks = { }
	for inf in e.interface:
	    ip = inf.get_attribute('ip4_address')
	    if ip: myips.add(ip)
	    for sub in inf.subs:
		for oinf in sub.interfaces:
		    dip = oinf.get_attribute('ip4_address')
		    if dip is not None and dip not in myips:
			if ip not in mylinks: mylinks[ip] = []
			mylinks[ip].append(dip)
	print >>outf, '%s: %s' % (e.name, ','.join(myips))
	for ip, links in mylinks.items():
	    print >>outf, '%s: %s' % (ip, ','.join(links))
    outf.flush()
    # If this routine built a string, return it
    if isinstance(outf, StringIO.StringIO): rv = outf.getvalue()
    else: rv = True
    if closeit: outf.close()
    return rv