"""Recognizes simple heuristically delimited bounces."""

import re

from email.iterators import body_line_iterator
from email.quoprimime import unquote
from enum import Enum
from flufl.bounce.interfaces import IBounceDetector, NoTemporaryFailures
from public import public
from zope.interface import implementer


class ParseState(Enum):
    start = 0
    tag_seen = 1


def _unquote_match(match):
    return unquote(match.group(0))


def _quopri_decode(address):
    # Some addresses come back with quopri encoded spaces.  This will decode
    # them and strip the spaces.  We can't use the undocumebted
    # email.quoprimime.header_decode() because that also turns underscores
    # into spaces, which is not good for us.  Instead we'll use the
    # undocumented email.quoprimime.unquote().
    #
    # For compatibility with Python 3, the API requires byte addresses.
    unquoted = re.sub('=[a-fA-F0-9]{2}', _unquote_match, address)
    try:
        return unquoted.encode('us-ascii').strip()
    except UnicodeEncodeError:
        return b''


def _c(pattern):
    return re.compile(pattern, re.IGNORECASE)


# Pattern to match any valid email address and not much more.
VALID = _c(rb'^[\x21-\x3d\x3f\x41-\x7e]+@[a-z0-9._]+$')


# This is a list of tuples of the form
#
#     (start cre, end cre, address cre)
#
# where 'cre' means compiled regular expression, start is the line just before
# the bouncing address block, end is the line just after the bouncing address
# block, and address cre is the regexp that will recognize the addresses.  It
# must have a group called 'addr' which will contain exactly and only the
# address that bounced.
PATTERNS = [
    # sdm.de
    (_c(r'here is your list of failed recipients'),
     _c(r'here is your returned mail'),
     _c(r'<(?P<addr>[^>]*)>')),
    # sz-sb.de, corridor.com, nfg.nl
    (_c(r'the following addresses had'),
     _c(r'transcript of session follows'),
     _c(r'^ *(\(expanded from: )?<?(?P<addr>[^\s@]+@[^\s@>]+?)>?\)?\s*$')),
    # robanal.demon.co.uk
    (_c(r'this message was created automatically by mail delivery software'),
     _c(r'original message follows'),
     _c(r'rcpt to:\s*<(?P<addr>[^>]*)>')),
    # s1.com (InterScan E-Mail VirusWall NT ???)
    (_c(r'message from interscan e-mail viruswall nt'),
     _c(r'end of message'),
     _c(r'rcpt to:\s*<(?P<addr>[^>]*)>')),
    # Smail
    (_c(r'failed addresses follow:'),
     _c(r'message text follows:'),
     _c(r'\s*(?P<addr>\S+@\S+)')),
    # newmail.ru
    (_c(r'This is the machine generated message from mail service.'),
     _c(r'--- Below the next line is a copy of the message.'),
     _c(r'<(?P<addr>[^>]*)>')),
    # turbosport.com runs something called `MDaemon 3.5.2' ???
    (_c(r'The following addresses did NOT receive a copy of your message:'),
     _c(r'--- Session Transcript ---'),
     _c(r'[>]\s*(?P<addr>.*)$')),
    # usa.net
    (_c(r'Intended recipient:\s*(?P<addr>.*)$'),
     _c(r'--------RETURNED MAIL FOLLOWS--------'),
     _c(r'Intended recipient:\s*(?P<addr>.*)$')),
    # hotpop.com
    (_c(r'Undeliverable Address:\s*(?P<addr>.*)$'),
     _c(r'Original message attached'),
     _c(r'Undeliverable Address:\s*(?P<addr>.*)$')),
    # Another demon.co.uk format
    (_c(r'This message was created automatically by mail delivery'),
     _c(r'^---- START OF RETURNED MESSAGE ----'),
     _c(r"addressed to '(?P<addr>[^']*)'")),
    # Prodigy.net full mailbox
    (_c("User's mailbox is full:"),
     _c(r'Unable to deliver mail.'),
     _c(r"User's mailbox is full:\s*<(?P<addr>[^>]*)>")),
    # Microsoft SMTPSVC
    (_c(r'The email below could not be delivered to the following user:'),
     _c(r'Old message:'),
     _c(r'<(?P<addr>[^>]*)>')),
    # Yahoo on behalf of other domains like sbcglobal.net
    (_c(r'Unable to deliver message to the following address\(es\)\.'),
     _c(r'--- Original message follows\.'),
     _c(r'<(?P<addr>[^>]*)>:')),
    # googlemail.com
    (_c(r'Delivery to the following recipient failed'),
     _c(r'----- Original message -----'),
     _c(r'^\s*(?P<addr>[^\s@]+@[^\s@]+)\s*$')),
    # kundenserver.de
    (_c(r'A message that you sent could not be delivered'),
     _c(r'^---'),
     _c(r'<(?P<addr>[^>]*)>')),
    # another kundenserver.de
    (_c(r'A message that you sent could not be delivered'),
     _c(r'^---'),
     _c(r'^(?P<addr>[^\s@]+@[^\s@:]+):')),
    # thehartford.com / songbird
    (_c(r'Del(i|e)very to the following recipients (failed|was aborted)'),
     # this one may or may not have the original message, but there's nothing
     # unique to stop on, so stop on the first line of at least 3 characters
     # that doesn't start with 'D' (to not stop immediately) and has no '@'.
     # Also note that simple_30.txt contains an apparent misspelling in the
     # MTA's DSN section.
     _c(r'^[^D][^@]{2,}$'),
     _c(r'^[\s*]*(?P<addr>[^\s@]+@[^\s@]+)\s*$')),
    # and another thehartfod.com/hartfordlife.com
    (_c(r'^Your message\s*$'),
     _c(r'^because:'),
     _c(r'^\s*(?P<addr>[^\s@]+@[^\s@]+)\s*$')),
    # kviv.be (InterScan NT)
    (_c(r'^Unable to deliver message to'),
     _c(r'\*+\s+End of message\s+\*+'),
     _c(r'<(?P<addr>[^>]*)>')),
    # earthlink.net supported domains
    (_c(r'^Sorry, unable to deliver your message to'),
     _c(r'^A copy of the original message'),
     _c(r'\s*(?P<addr>[^\s@]+@[^\s@]+)\s+')),
    # ademe.fr
    (_c(r'^A message could not be delivered to:'),
     _c(r'^Subject:'),
     _c(r'^\s*(?P<addr>[^\s@]+@[^\s@]+)\s*$')),
    # andrew.ac.jp
    (_c(r'^Invalid final delivery userid:'),
     _c(r'^Original message follows.'),
     _c(r'\s*(?P<addr>[^\s@]+@[^\s@]+)\s*$')),
    # E500_SMTP_Mail_Service@lerctr.org
    (_c(r'------ Failed Recipients ------'),
     _c(r'-------- Returned Mail --------'),
     _c(r'<(?P<addr>[^>]*)>')),
    # cynergycom.net
    (_c(r'A message that you sent could not be delivered'),
     _c(r'^---'),
     _c(r'(?P<addr>[^\s@]+@[^\s@)]+)')),
    # LSMTP for Windows
    (_c(r'^--> Error description:\s*$'),
     _c(r'^Error-End:'),
     _c(r'^Error-for:\s+(?P<addr>[^\s@]+@[^\s@]+)')),
    # Qmail with a tri-language intro beginning in spanish
    (_c(r'Your message could not be delivered'),
     _c(r'^-'),
     _c(r'<(?P<addr>[^>]*)>:')),
    # socgen.com
    (_c(r'Your message could not be delivered to'),
     _c(r'^\s*$'),
     _c(r'(?P<addr>[^\s@]+@[^\s@]+)')),
    # dadoservice.it
    (_c(r'Your message has encountered delivery problems'),
     _c(r'Your message reads'),
     _c(r'addressed to\s*(?P<addr>[^\s@]+@[^\s@)]+)')),
    # gomaps.com
    (_c(r'Did not reach the following recipient'),
     _c(r'^\s*$'),
     _c(r'\s(?P<addr>[^\s@]+@[^\s@]+)')),
    # EYOU MTA SYSTEM
    (_c(r'This is the deliver program at'),
     _c(r'^-'),
     _c(r'^(?P<addr>[^\s@]+@[^\s@<>]+)')),
    # A non-standard qmail at ieo.it
    (_c(r'this is the email server at'),
     _c(r'^-'),
     _c(r'\s(?P<addr>[^\s@]+@[^\s@]+)[\s,]')),
    # pla.net.py (MDaemon.PRO ?)
    (_c(r'- no such user here'),
     _c(r'There is no user'),
     _c(r'^(?P<addr>[^\s@]+@[^\s@]+)\s')),
    # mxlogic.net
    (_c(r'The following address failed:'),
     _c(r'Included is a copy of the message header'),
     _c(r'<(?P<addr>[^>]+)>')),
    # fastdnsservers.com
    (_c(r'The following recipient\(s\) could not be reached'),
     _c(r'\s*Error Type'),
     _c(r'^(?P<addr>[^\s@]+@[^\s@<>]+)')),
    # xxx.com (simple_36.txt)
    (_c(r'Could not deliver message to the following recipient'),
     _c(r'\s*-- The header'),
     _c(r'Failed Recipient: (?P<addr>[^\s@]+@[^\s@<>]+)')),
    # mta1.service.uci.edu
    (_c(r'Message not delivered to the following addresses'),
     _c(r'Error detail'),
     _c(r'\s*(?P<addr>[^\s@]+@[^\s@)]+)')),
    # Dovecot LDA Over quota MDN (bogus - should be DSN).
    (_c(r'^Your message'),
     _c(r'^Reporting'),
     _c(r'Your message to <?(?P<addr>[^\s<@]+@[^\s@>]+)>? was automatically'
        ' rejected')),
    # mail.ru
    (_c(r'A message that you sent was rejected'),
     _c(r'This is a copy of your message'),
     _c(r'\s(?P<addr>[^\s@]+@[^\s@]+)')),
    # MailEnable
    (_c(r'Message could not be delivered to some recipients.'),
     _c(r'Message headers follow'),
     _c(r'Recipient: \[SMTP:(?P<addr>[^\s@]+@[^\s@]+)\]')),
    # Next one goes here...
    ]


@public
@implementer(IBounceDetector)
class SimpleMatch:
    """Recognizes simple heuristically delimited bounces."""

    PATTERNS = PATTERNS

    def process(self, msg):
        """See `IBounceDetector`."""
        addresses = set()
        new_addresses = set()
        # MAS: This is a mess. The outer loop used to be over the message
        # so we only looped through the message once.  Looping through the
        # message for each set of patterns is obviously way more work, but
        # if we don't do it, problems arise because scre from the wrong
        # pattern set matches first and then acre doesn't match.  The
        # alternative is to split things into separate modules, but then
        # we process the message multiple times anyway.
        for scre, ecre, acre in self.PATTERNS:
            state = ParseState.start
            for line in body_line_iterator(msg):
                if state is ParseState.start:
                    if scre.search(line):
                        state = ParseState.tag_seen
                if state is ParseState.tag_seen:
                    mo = acre.search(line)
                    if mo:
                        address = mo.group('addr')
                        if address:
                            addresses.add(_quopri_decode(address))
                    elif ecre.search(line):
                        break
            if len(addresses) > 0:
                break
        for address in addresses:
            if VALID.match(address):
                new_addresses.add(address)
        return NoTemporaryFailures, new_addresses
