#!/usr/bin/python

import getopt, sys, pprint

shortopts = 'h:l:r:s'

locals = []
remotes = []
hosts = []
destination = None
shebang = False

optlist, arglist = getopt.gnu_getopt(sys.argv[1:], shortopts)

#   Only allow one destination!
if len(arglist) == 1:
    destination = dict(zip( ('host', 'port'), arglist[0].rsplit(':', 1) ))
else:
    raise ValueError, "Provide a single destination host"

#   Get the ports and intermediate hosts
for opt, val in optlist:
    if opt == '-l':
        port = dict(zip( ('local', 'mid', 'remote'), val.split(':', 2) ))
        locals.append(port)
    elif opt == '-r':
        port = dict(zip( ('remote', 'mid', 'local'), val.split(':', 2) ))
        remotes.append(port)
    elif opt == '-h':
        hosts.append(dict(zip( ('host', 'port'), val.rsplit(':', 1) )))
    elif opt == '-s':
        shebang = True

if shebang:
    print '#!/bin/bash -i'
#   If there are no intermediate hosts, do it the simple way!
if len(hosts) == 0:
    forwards = []

    for f in locals:
        forwards.append('-L%s:localhost:%s' % (f['local'], f['remote']))
    for f in remotes:
        forwards.append('-R%s:localhost:%s' % (f['remote'], f['local']))
        
    if destination.has_key('port'):
        print 'ssh', ' '.join(forwards), '-p', destination['port'], destination['host']
    else:
        print 'ssh', ' '.join(forwards), destination['host']

# Here comes the complex way!!!
else:
    first = ' '.join(['-L%s:localhost:%s' % (f['local'], f['mid']) for f in locals] \
            +['-R%s:localhost:%s' % (f['mid'], f['local']) for f in remotes])
    last = ' '.join(['-L%s:localhost:%s' % (f['mid'], f['remote']) for f in locals] \
            +['-R%s:localhost:%s' % (f['remote'], f['mid']) for f in remotes])
    mid = ' '.join(['-L%s:localhost:%s' % (f['mid'], f['mid']) for f in locals] \
            +['-R%s:localhost:%s' % (f['mid'], f['mid']) for f in remotes])

    def mkcmd(i, hostlist):
        slashes = '\\' * i
        if len(hostlist) == 0:
            if destination.has_key('port'):
                return '-p ' + destination['port'] + ' ' + destination['host']
            else:
                return destination['host']
        else:
            host = hostlist[0]
            port = '';
            if host.has_key('port'): port = '-p ' + host['port'] + ' '
            return '%s%s -t %s"ssh %s %s%s"' % (port, host['host'], slashes, [last,mid][len(hostlist) > 1], \
                    mkcmd(i+1, hostlist[1:]), slashes)

    print 'ssh', first, mkcmd(0, hosts)