#!/usr/bin/python

import os, argparse, hashlib, email, email.header, email.utils, glob, sqlite3, time

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('-d', dest='database', action='store', default='emails.db',
                   help='path of the database that should be used to store the emails (will be created if it does not exist yet)')
                   
parser.add_argument('-a', dest='attachment_dir', action='store', default='attachments',
                   help='path where attachments should be stored (will be created if it does not exist yet)')
                   
parser.add_argument('-f', '--forced', dest='forced', action='store_true',
                   help='force insertion into database, even if entries already exist')

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

def getheader(header_text, default="ascii"):
	headers = email.header.decode_header(header_text)
	header_sections = [unicode(text, charset or default) for text, charset in headers]
	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):
	if part.get_content_charset():
		return part.get_content_charset()
	elif part.get_charset():
		return part.get_charset()
	else:
		return "ascii"

# Connect to database
database = sqlite3.connect(options['database'])
cursor = database.cursor()

try:
	# Create attachment directory first
	os.makedirs(options['attachment_dir'])
except OSError:
	pass

try:
	# Try to create emails table
	cursor.execute("CREATE TABLE emails (`message_id`, `from`, `to`, `subject`, `date`, `body`, `html`, `hash`)")
except sqlite3.OperationalError:
	pass
	
try:
	# Try to create attachments table
	cursor.execute("CREATE TABLE attachments (`message_hash`, `filename`, `type`, `hash`, `size`)")
except sqlite3.OperationalError:
	pass

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

for email_file in file_list:
	message = email.message_from_file(open(email_file))
	
	if message['message-id'] is None:
		print "%s is not a valid e-mail file." % email_file
	else:
		if 'subject' not in message or message['subject'] is None:
			subject = ""
		else:
			subject = message['subject']
		
		textbody = ""
		htmlbody = ""
		attachment_list = []
		
		sha1_hash = hashlib.sha1("%s/%s/%s/%s" % (message['from'], message['to'], message['message-id'], subject)).hexdigest()
		
		message_parts = [find_submessages(message)]
		message_parts = flatten(message_parts)
		
		for part in message_parts:
			if part.get_filename() is None:
				# Part of the message
				if part.get_content_type() == "text/plain":
					if textbody == "":
						textbody = part.get_payload(decode=True).decode(get_charset(part))
				elif part.get_content_type() == "text/html" or part.get_content_type == "text/xhtml+xml" or part.get_content_type == "application/xhtml+xml":
					if htmlbody == "":
						htmlbody = part.get_payload(decode=True).decode(get_charset(part))
				else:
					# Technically this is supposed to be part of the message body, but we have no idea what format it is in...
					print "WARNING: Unknown message format encountered in %s, message may be incomplete." % sha1_hash
			else:
				# Attachment
				attachment_data = part.get_payload(decode=True)
				attachment_sha1 = hashlib.sha1(attachment_data).hexdigest()
				attachment_filename = part.get_filename()
				attachment_type = part.get_content_type()
				attachment_extension = os.path.splitext(attachment_filename)[1][1:]
				attachment_size = len(attachment_data)
				attachment_destination = "%s/%s.%s" % (options['attachment_dir'], attachment_sha1, attachment_extension)
				attachment_list.append((attachment_filename, attachment_type, attachment_sha1, attachment_size))
				
				attachment_file = open(attachment_destination, "w")
				attachment_file.write(attachment_data)
				attachment_file.close()
		
		try:
			timestamp = int(time.mktime(email.utils.parsedate(message['date'])))
		except TypeError:
			timestamp = 0
			print "WARNING: Failed to determine unix timestamp for %s." % sha1_hash
		
		cursor.execute("SELECT * FROM emails WHERE `Hash` = ?", (sha1_hash,))
		if len(cursor.fetchall()) == 0 or options['forced'] == True:
			new_row = (getheader(message['message-id']), getheader(message['from']), getheader(message['to']), getheader(subject), timestamp, textbody, htmlbody, sha1_hash)
			cursor.execute("INSERT INTO emails VALUES (?, ?, ?, ?, ?, ?, ?, ?)", new_row)
			print "Successfully parsed and inserted e-mail with SHA1 hash %s." % sha1_hash
		else:
			print "Skipping %s, already exists in the database." % sha1_hash
		
		if len(attachment_list) > 0:
			inserted = 0
			
			for attachment in attachment_list:
				cursor.execute("SELECT * FROM attachments WHERE `Hash` = ?", (attachment[2],))
				if len(cursor.fetchall()) == 0 or options['forced'] == True:
					new_row = (sha1_hash, attachment[0], attachment[1], attachment[2], attachment[3])
					cursor.execute("INSERT INTO attachments VALUES (?, ?, ?, ?, ?)", new_row)
					inserted += 1
				else:
					print "Skipping attachment %s, already exists in the database." % attachment[2]
			
			if inserted > 0:
				print "Successfully inserted %d attachment(s) for %s." % (inserted, sha1_hash)

database.commit()
print "Changes successfully committed to database."