#!/usr/bin/python

'''
## Description

A script to get mail from info@example.com and re-write  the 'From"' Header
as "From: John Doe via info at example.com <noreply@example.com>'"

## Installation Instuctions

* Place the script under */usr/local/sbin/rewrite_from.py*.
* Edit */etc/aliases*:
```
info: "|/usr/local/sbin/rewrite_from.py"
```
* Run the `newaliases` command.
'''

import sys
import email
import smtplib
import re

DEBUG = 1
MAIL_SERVER = 'localhost'
TO = ["ceo@example.com", "ceoexternalmail@gmail.com"]

def main():
    '''
    Main Function
    '''

    raw_msg = ''

    for line in sys.stdin:
        raw_msg = raw_msg + line

    msg = email.message_from_string(raw_msg)
    reply_to_re = re.search(
        r'([a-zA-Z0-9_.+-]+@[a-zA-Z0-9-.]+\.[a-zA-Z0-9-.]+)',
        msg['From'])

    if reply_to_re:
        reply_to = reply_to_re.group(1)

    from_re = re.search(
        r'^ *(.+) +<?([a-zA-Z0-9_.+-]+@[a-zA-Z0-9-.]+\.[a-zA-Z0-9-.]+)>?',
        msg['From'])

    if from_re:
        from_h = from_re.group(1)

    if msg['Reply-To']:
        msg['Reply-To'] = reply_to
        msg.replace_header('Reply-To', reply_to)
    else:
        msg.add_header('Reply-To', reply_to)

    msg.replace_header('From', from_h + ' via info at example.com <noreply@example.com>')

    send_mail = smtplib.SMTP('localhost')
    send_mail.sendmail(msg['From'], TO, msg.as_string())
    send_mail.quit()

    if DEBUG:
        filename = "/tmp/msg.out"
        out = open(filename, 'w')
        out.write(msg.as_string())

if __name__ == "__main__":
    main()