#!/usr/bin/env python3

# Usage:
# _from=krebs state_dir=. python sed-plugin.py 'dick butt'
# _from=krebs state_dir=. python sed-plugin.py 's/t/l/g'
## dick bull
import shelve
from os import environ
from os.path import join
from sys import argv
d = shelve.open(join(environ['state_dir'],'sed-plugin.shelve'),writeback=True)
usr = environ['_from']
import re

def is_regex(line):
    myre = re.compile(r'^s/((?:\\/|[^/])+)/((?:\\/|[^/])*)/([ig]*)$')
    return myre.match(line)

line = argv[1]
m = is_regex(line)

if m:
    f,t,flagstr = m.groups()
    fn = f.replace('\/','/')
    tn = t.replace('\/','/')
    flags =  0
    count = 1
    if flagstr:
        if 'i' in flagstr:
            flags = re.IGNORECASE
        if 'g' in flagstr:
            count = 0
    else:
        flagstr = ''
    last = d.get(usr,None)
    if last:
        from subprocess import Popen,PIPE
        import shutil
        from os.path import realpath
        # sed only needs stdin/stdout, we protect state_dir with this
        # input to read/write arbitrary files:
        #   s/.\/\/; w /tmp/i       (props to waldi)
        # conclusion: sed is untrusted and we handle it like this
        p = Popen(['proot',
            # '-v','1',
            '-w','/', # cwd is root
            '-b','/nix/store', # mount important folders
            '-b','/usr',
            '-b','/bin',
            '-r','/var/empty', # chroot to /var/empty
            realpath(shutil.which('sed')),
            's/{}/{}/{}'.format(f,t,flagstr)],stdin=PIPE,stdout=PIPE )
        so,se = p.communicate(bytes("{}\n".format(last),"UTF-8"))
        if p.returncode:
            print("something went wrong when trying to process your regex: {}".format(se.decode()))
        ret = so.decode()
        print("\x1b[1m{}\x1b[0m meinte: {}".format(usr,ret.strip()))
        if ret:
            d[usr] = ret

    else:
        print("no last message")
else:
    d[usr] = line

d.close()