#!/usr/bin/python
#    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 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program; if not, write to the Free Software
#    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
import difflib
import os
import sys
import tarfile
import time

def taropen(fn, pos=None):
    r = tarfile.open(fn, "r:*")
    if pos is not None:
        r.seek(pos)
    return r

def do_diff(ai, bi, a, b, fa, fb):
    # XXX handle type changes e.g., dir<->link<->file
    # XXX handle mode changes e.g., 0644 -> 0755
    a = (a and a.readlines() or [])
    b = (b and b.readlines() or [])
    d = list(difflib.unified_diff(a, b, fa, fb,
            time.ctime(ai.mtime), time.ctime(bi.mtime)))
    if not d: return
    print "diff -u %s %s" % (fa, fb)
    sys.stdout.writelines(d)

def rlc(fn, n):
    return "/".join(fn.split("/")[n:])

def tardiff(a, b, xa=0, xb=0):
    if isinstance(xa, basestring): xa = int(xa)
    if isinstance(xb, basestring): xb = int(xb)

    ta = taropen(a)
    tb = taropen(b)

    na = dict((rlc(i.name, xa), i) for i in ta)
    nb = dict((rlc(i.name, xb), i) for i in tb)
    
    all = set(na) | set(nb)

    for fn in sorted(all):
        if fn in na and fn in nb:
            do_diff(
                    na[fn], nb[fn],
                    ta.extractfile(na[fn]),
                    tb.extractfile(nb[fn]),
                    os.path.join(os.path.basename(a), na[fn].name),
                    os.path.join(os.path.basename(b), nb[fn].name))
        elif fn in ta: print "Only in %s: %s" % (a, fn)
        else: print "Only in %s: %s" % (b, fn)

if __name__ == '__main__':
    tardiff(*sys.argv[1:])