#!/usr/bin/python
#
# Copyright 2002 Specialized Systems Consultants
#
# You are licensed to use this software under the provisions
# of the Gnu General Public License, version 2 or later.
#
# Suggestions and patches to: Dan Wilder <dan@ssc.com>
#
# Tue Oct 29 09:24:35 PST 2002 dhw

"""
dup.py -- Filter a piece of email, inserting an

X-Duplicate: yes

header if we've seen this thing before.

Usage: dup.py dbfilename <inputmail >outputmail
"""

import fcntl
import shelve
import md5
from sys import stdin, argv, exit

if len(argv) < 2:
    print("""
Usage: dup.py dbfilename <inputmail >outputmail
""")
    exit(1)

# Get db file name and related lock file name,
# /some/place/a/dbfile
# /some/place/a/.dbfile.lock

dupdb = argv[1]

parts = dupdb.split("/")

duplock = parts[:-1]
duplock.append("." + parts[-1:][0] + ".lock")
duplock = "/".join(duplock)

# Grab the email message
# Break up the mail into head and body.
# Omit X-Duplicate header, if found.
# Thanks, we'll add our own if we want one.

head = []
body = []

for line in stdin.readlines():
    if body:
        body.append(line)
        continue
    if line == "\n":
        body.append(line)
        continue
    if line.find("X-Duplicate: yes") == 0:
        continue
    head.append(line)

# calculate body md5sum

sum = md5.new("".join(body)).hexdigest()

# Open a shelve under lock.
# If it doesn't exist create it.

lockfd = open(duplock, "w")
fcntl.lockf(lockfd, fcntl.LOCK_EX)

try:
    dupfd = shelve.open(dupdb, "w")
except:
    dupfd = shelve.open(dupdb, "c")

# If we've seen this sum before we'll add the header,
# if not, write this sum to the shelve file.

if dupfd.has_key(sum):
    duphdr = "X-Duplicate: yes\n"
else:
    duphdr = None
    dupfd[sum] = 1

dupfd.close()

fcntl.lockf(lockfd, fcntl.LOCK_UN)
lockfd.close()

for line in head:
    print line,

if duphdr:
    print duphdr,

for line in body:
    print line,

exit(0)