#!/usr/bin/env python
import email, sys, time, random, mimetypes, os, types
"""
Strip MIME attachments from an email when they are larger than MSG_MAX_SIZE,
   store them in MSG_DIR, and replace the MIME part with a link to MSG_URL,
   which should be a URL that exposes MSG_DIR.

Example procmail recipe:

MSG_MAX_SIZE=102400
MSG_URL=http://www.yourdomain.tld/mime/
MSG_DIR=/var/www/www.youdomain.tld/mime/.
:0 fw
* > $MSG_MAX_SIZE
| $HOME/bin/mime_strip_to_dir.py

"""

def env_config(key, value):
    if os.environ.has_key(key):
        if type(value) == types.FloatType:
            return float( os.environ.get(key) )
        if type(value) == types.IntType:
            return int( os.environ.get(key) )
        return os.environ.get(key)
    return value

MSG_MAX_SIZE = env_config("MSG_MAX_SIZE", 512 * 1024)
MSG_URL      = env_config("MSG_URL", "http://example.com/private/")
MSG_DIR      = env_config("MSG_DIR", "/var/www/example.com/web/private/.")

email_file = sys.stdin
if len( sys.argv ) > 1:
    email_file = open( sys.argv[1] )

def strip_to_dir(part, path):
    if part.get_content_maintype() == 'multipart':
        return
    filename = part.get_filename()
    if not filename:
        ext = mimetypes.guess_extension(part.get_content_type())
        if not ext:
            ext = ".bin"
        filename = time.strftime("%Y%m%d-%H%M%S") + str(random.random()) + ext
    #filename = email_filename + '_' + msg['From']
    fp = open( os.path.join( path , filename ), 'wb' )
    fp.write(part.get_payload(decode=True))
    fp.close()
    os.chmod( os.path.join( path , filename ) , 0644)
    url = MSG_URL
    try:
        part.replace_header('Content-Disposition', '')
        part.replace_header('Content-Type', 'text/plain')
        part.replace_header('Content-Transfer-Encoding', '7bit')
    except KeyError: pass
    part.set_payload("   Attachment saved to %(url)s%(filename)s " % locals())
    return part

def ignore_email(msg):
    print msg.as_string()
    sys.exit(0)

msg = email.message_from_file( email_file )

if len( msg.as_string() ) < MSG_MAX_SIZE:
    ignore_email(msg)
if not msg.is_multipart():
    ignore_email(msg)

parts = []
for part in msg.walk():
    if len( part.as_string() ) > MSG_MAX_SIZE:
        part = strip_to_dir(part, MSG_DIR )
    if part:
        parts.append(part)
msg.set_payload(parts)
print msg.as_string()