from INN import *
from email.header import decode_header
import sys
import string
import random
import os

def intern(headerName):
    return sys.intern(headerName)

Newsgroups  = intern("Newsgroups")
Path        = intern("Path")
References  = intern("References")
Subject     = intern("Subject")
UserAgent   = intern("User-Agent")
__BODY__    = intern("__BODY__")
__LINES__   = intern("__LINES__")

saved_art_path = "/usr/local/news/spool/pythai"

def log(s):
    syslog("notice", s)

def tostr(mv):
    return mv.tobytes().decode("utf-8")

class InndFilter:
    def __init__(self):
        syslog("notice", "Filter starting")
        if not os.path.isdir(saved_art_path):
            os.mkdir(saved_art_path)

    def copy_spam(self, art):
        name = ''.join(random.choice(string.ascii_letters + string.digits) for i in range(0, 64))
        path = os.path.join(saved_art_path, name)
        f = open(os.path.join(saved_art_path, path + ".tmp"), "wb")
        for key in art:
            if key != __BODY__ and key != __LINES__ and art[key] != None:
                f.write(key.encode("utf-8"))
                f.write(b": ")
                f.write(art[key].tobytes())
                f.write(b"\n")
        f.write(b"\n")
        f.write(art[__BODY__].tobytes())
        f.close()
        os.rename(path + ".tmp", path + ".to-rewrite")

    def filter_art(self, art):
        log("Article arrived")

        if art[References] != None:
            log("Whitelisting, because has references")
            return None

        if "google-groups.googlegroups.com" not in tostr(art[Path]):
            log("Whitelisting, because google groups not in Path")
            log("Path is: %s" % tostr(art[Path]))
            return None

        if tostr(art[UserAgent]) != "G2/1.0":
            log("Whitelisting, because User-Agent is not G2/1.0")
            return None

        if art[Subject] == None:
            log("Whitelisting, because Subject is empty")
            return None

#        if "pl.soc.polityka" not in tostr(art[Newsgroups]):
#            log("Whitelisting, because checked group is not in Newsgroups")
#            return None

        try:
            subjlist = decode_header(tostr(art[Subject]))

            if len(subjlist) == 0:
                log("List of tokens in subject is zero")
                return None

            if subjlist[0][1] == None:
                log("First subject token has no encoding")
                return None

            if subjlist[0][1].lower() != "utf-8":
                log("First subject token is not in UTF-8")
                return None

            subj = subjlist[0][0].decode("utf-8")
        except Exception as e:
            log("Exception when decoding Subject: %s" % e)
            return None

        for ch in subj:
            if ord(ch) >= 0x0e00 and ord(ch) <= 0x0eff:
                log("Article classified as spam")
                self.copy_spam(art)
                return "Spam not welcome"

        log("Article classified as ham")
        return None

spamfilter = InndFilter()
try:
    set_filter_hook(spamfilter)
    syslog('n', "spamfilter successfully hooked into INN")
except Exception as errmsg:
    syslog('e', "Cannot obtain INN hook for spamfilter: %s" % errmsg[0])