#!/usr/bin/python

import os, argparse, hashlib, email, email.header, email.utils, glob

parser = argparse.ArgumentParser(description='Parses emails into an SQLite database and an attachment folder.')

parser.add_argument('-p', dest='pattern', action='store', default='*',
                   help='glob pattern (including path) that has to be matched for a file to be parsed')

parser.add_argument('-I', '--ignore-invalid', dest='ignore_invalid', action='store_true',
                   help='process invalid e-mail files anyway, for example when missing message-id headers')

args = parser.parse_args()
options = vars(args)

def getheader(header_text, default="ascii"):
	headers = email.header.decode_header(header_text)
	try:
		header_sections = [unicode(text, charset or default) for text, charset in headers]
	except UnicodeDecodeError:
		header_sections = [unicode(text, 'windows-1252') for text, charset in headers]
	except LookupError:
		return u""
	
	return u"".join(header_sections)
	
def find_submessages(message):
	if message.is_multipart():
		return [find_submessages(part) for part in message.get_payload()]
	else:
		return message

def flatten(x):
	# http://kogs-www.informatik.uni-hamburg.de/~meine/python_tricks
	result = []
	for el in x:
		if hasattr(el, "__iter__") and not isinstance(el, basestring):
			result.extend(flatten(el))
		else:
			result.append(el)
	return result

def get_charset(part):
	charset = None
	
	if part.get_content_charset():
		charset = part.get_content_charset()
	elif part.get_charset():
		charset = part.get_charset()
	
	if charset is None or charset == "default" or charset.startswith("us-ascii"):
		return "ascii"
	else:
		return charset

# Select all files matching the given pattern
file_list = glob.glob(options['pattern'])

finished = 0

for email_file in file_list:
	# To save time when updating a database, let's first check whether the filename is already present in the database as a hash.
	# There is no need to check for the format here, since if the filename is not a valid hash, it simply won't match anything.
	
	message = email.message_from_file(open(email_file, 'r'))

	if message['message-id'] is None:
		if options['ignore_invalid'] == True:
			message_id = message['date']
			print "WARNING: %s does not contain a valid message-id header. Falling back to date." % email_file
		else:
			print "%s is not a valid e-mail file." % email_file
			finished += 1
			continue
	else:
		message_id = message['message-id']
	
	if 'subject' not in message or message['subject'] is None:
		subject = ""
	else:
		subject = message['subject']
	
	sha1_hash = hashlib.sha1("%s/%s/%s/%s" % (message['from'], message['to'], message_id, subject)).hexdigest()
	
	new_path = "%s/%s.eml" % (os.path.dirname(email_file), sha1_hash)
	
	os.rename(email_file, new_path)
	print "%s -> %s" % (email_file, new_path)
		
	finished += 1
	
print "Renamed %d files." % finished