#!/usr/bin/python

import sys, os, re

def stripmod(ppkg):
	if ppkg[0] == '|': 
		return ppkg[1:]
	else:
		return ppkg


def getdeps(pkg):
	p = os.popen("apt-cache show " + pkg)
	reply = p.read()
	p.close()

	m = re.search("\nDepends: ([^\n]+)\n", reply)
	if not m:
		return []

	deplist = []

	depstr = m.groups(1)[0] + ","
	deps = re.finditer(" *([^,]+),", depstr)
	if not deps: raise "!match groups"
	
	for dep in [m.group(1) for m in deps]:
		alt = dep.find('|') != -1
		pkgs = re.finditer(" *([^|]+)", dep)
		if not pkgs: raise "!match pkgs"
		
		for pkg in [m.groups(1)[0] for m in pkgs]:
			name_m = re.search(" *([^( ]+) *(\\(.+\\))?", pkg)			
			if not name_m: raise "!match name"
			name = name_m.groups(1)[0]
			
			if alt: name = '|' + name
			deplist.append(name)

	return deplist


def deptree(ppkg, pool = {}, depth = 0):
	pkg = stripmod(ppkg)
		
	pool[pkg] = True

	seen = []
	unseen = []
	for dep in getdeps(pkg):
		if pool.has_key(dep):
			seen.append(dep)
		else:
			unseen.append(dep)
	
	seen_list = ' '.join(seen)
	if seen_list: seen_list = "(seen: %s)" % seen_list

	print ''.join(['.' for i in xrange(depth)]) + ppkg, seen_list
	
	for dep in unseen:
		deptree(dep, pool, depth + 1)


if __name__ == "__main__":
	if len(sys.argv) < 2:
		print "syntax: %s pkgname" % sys.argv[0]
		sys.exit()
	
	deptree(sys.argv[1])