#!/usr/bin/env python

# -*- coding: utf-8 -*-
# regression_mime_struct
# Copyright (C) 2014 LEAP
# Copyright (c) Twisted Matrix Laboratories.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
"""
Simple Regression Tests for checking MIME struct handling using IMAP4 client.

Iterates trough all mails under a given folder and tries to APPEND them to
the server being tested. After FETCHING the pushed message, it compares
the received version with the one that was saved, and exits with an error
code if they do not match.
"""
import os
import StringIO
import sys

from email.parser import Parser

from twisted.internet import protocol
from twisted.internet import ssl
from twisted.internet import defer
from twisted.internet import stdio
from twisted.mail import imap4
from twisted.protocols import basic
from twisted.python import log


REGRESSIONS_FOLDER = os.environ.get(
    "REGRESSIONS_FOLDER", "regressions_test")
print "[+] Using regressions folder:", REGRESSIONS_FOLDER

parser = Parser()


def get_msg_parts(raw):
    """
    Return a representation of the parts of a message suitable for
    comparison.

    :param raw: string for the message
    :type raw: str
    """
    m = parser.parsestr(raw)
    return [dict(part.items())
            if part.is_multipart()
            else part.get_payload()
            for part in m.walk()]


def compare_msg_parts(a, b):
    """
    Compare two sequences of parts of messages.

    :param a: part sequence for message a
    :param b: part sequence for message b

    :return: True if both message sequences are equivalent.
    :rtype: bool
    """
    # XXX This could be smarter and show the differences in the
    # different parts when/where they differ.
    #import pprint; pprint.pprint(a[0])
    #import pprint; pprint.pprint(b[0])

    def lowerkey(d):
        return dict((k.lower(), v.replace('\r', ''))
                    for k, v in d.iteritems())

    def eq(x, y):
        # For dicts, we compare a variation with their keys
        # in lowercase, and \r removed from their values
        if all(map(lambda i: isinstance(i, dict), (x, y))):
            x, y = map(lowerkey, (x, y))
        return x == y

    compare_vector = map(lambda tup: eq(tup[0], tup[1]), zip(a, b))
    all_match = all(compare_vector)

    if not all_match:
        print "PARTS MISMATCH!"
        print "vector: ", compare_vector
        index = compare_vector.index(False)
        from pprint import pprint
        print "Expected:"
        pprint(a[index])
        print ("***")
        print "Found:"
        pprint(b[index])
        print

    return all_match


def get_fd(string):
    """
    Return a file descriptor with the passed string
    as content.
    """
    fd = StringIO.StringIO()
    fd.write(string)
    fd.seek(0)
    return fd


class TrivialPrompter(basic.LineReceiver):
    promptDeferred = None

    def prompt(self, msg):
        assert self.promptDeferred is None
        self.display(msg)
        self.promptDeferred = defer.Deferred()
        return self.promptDeferred

    def display(self, msg):
        self.transport.write(msg)

    def lineReceived(self, line):
        if self.promptDeferred is None:
            return
        d, self.promptDeferred = self.promptDeferred, None
        d.callback(line)


class SimpleIMAP4Client(imap4.IMAP4Client):
    """
    A client with callbacks for greeting messages from an IMAP server.
    """
    greetDeferred = None

    def serverGreeting(self, caps):
        self.serverCapabilities = caps
        if self.greetDeferred is not None:
            d, self.greetDeferred = self.greetDeferred, None
            d.callback(self)


class SimpleIMAP4ClientFactory(protocol.ClientFactory):
    usedUp = False
    protocol = SimpleIMAP4Client

    def __init__(self, username, onConn):
        self.ctx = ssl.ClientContextFactory()

        self.username = username
        self.onConn = onConn

    def buildProtocol(self, addr):
        """
        Initiate the protocol instance. Since we are building a simple IMAP
        client, we don't bother checking what capabilities the server has. We
        just add all the authenticators twisted.mail has.  Note: Gmail no
        longer uses any of the methods below, it's been using XOAUTH since
        2010.
        """
        assert not self.usedUp
        self.usedUp = True

        p = self.protocol(self.ctx)
        p.factory = self
        p.greetDeferred = self.onConn

        p.registerAuthenticator(imap4.PLAINAuthenticator(self.username))
        p.registerAuthenticator(imap4.LOGINAuthenticator(self.username))
        p.registerAuthenticator(
            imap4.CramMD5ClientAuthenticator(self.username))

        return p

    def clientConnectionFailed(self, connector, reason):
        d, self.onConn = self.onConn, None
        d.errback(reason)


def cbServerGreeting(proto, username, password):
    """
    Initial callback - invoked after the server sends us its greet message.
    """
    # Hook up stdio
    tp = TrivialPrompter()
    stdio.StandardIO(tp)

    # And make it easily accessible
    proto.prompt = tp.prompt
    proto.display = tp.display

    # Try to authenticate securely
    return proto.authenticate(
        password).addCallback(
        cbAuthentication,
        proto).addErrback(
        ebAuthentication, proto, username, password
    )


def ebConnection(reason):
    """
    Fallback error-handler. If anything goes wrong, log it and quit.
    """
    log.startLogging(sys.stdout)
    log.err(reason)
    return reason


def cbAuthentication(result, proto):
    """
    Callback after authentication has succeeded.

    Lists a bunch of mailboxes.
    """
    return proto.select(
        REGRESSIONS_FOLDER
    ).addCallback(
        cbSelectMbox, proto
    ).addErrback(
        ebSelectMbox, proto, REGRESSIONS_FOLDER)


def ebAuthentication(failure, proto, username, password):
    """
    Errback invoked when authentication fails.

    If it failed because no SASL mechanisms match, offer the user the choice
    of logging in insecurely.

    If you are trying to connect to your Gmail account, you will be here!
    """
    failure.trap(imap4.NoSupportedAuthentication)
    return InsecureLogin(proto, username, password)


def InsecureLogin(proto, username, password):
    """
    Raise insecure-login error.
    """
    return proto.login(
        username, password
    ).addCallback(
        cbAuthentication, proto)


def cbSelectMbox(result, proto):
    """
    Callback invoked when select command finishes successfully.

    If any message is in the test folder, it will flag them as deleted and
    expunge.
    If no messages found, it will start with the APPEND tests.
    """
    print "SELECT: %s EXISTS " % result.get("EXISTS", "??")

    if result["EXISTS"] != 0:
        # Flag as deleted, expunge, and do an examine again.
        print "There is mail here, will delete..."
        return cbDeleteAndExpungeTestFolder(proto)

    else:
        return cbAppendNextMessage(proto)


def ebSelectMbox(failure, proto, folder):
    """
    Errback invoked when the examine command fails.

    Creates the folder.
    """
    log.err(failure)
    log.msg("Folder %r does not exist. Creating..." % (folder,))
    return proto.create(folder).addCallback(cbAuthentication, proto)


def ebExpunge(failure):
    log.err(failure)


def cbDeleteAndExpungeTestFolder(proto):
    """
    Callback invoked fom cbExamineMbox when the number of messages in the
    mailbox is not zero. It flags all messages as deleted and expunge the
    mailbox.
    """
    return proto.setFlags(
        "1:*", ("\\Deleted",)
    ).addCallback(
        lambda r: proto.expunge()
    ).addCallback(
        cbExpunge, proto
    ).addErrback(
        ebExpunge)


def cbExpunge(result, proto):
    return proto.select(
        REGRESSIONS_FOLDER
    ).addCallback(
        cbSelectMbox, proto
    ).addErrback(ebSettingDeleted, proto)


def ebSettingDeleted(failure, proto):
    """
    Report errors during deletion of messages in the mailbox.
    """
    print failure.getTraceback()


def cbAppendNextMessage(proto):
    """
    Appends the next message in the global queue to the test folder.
    """
    # 1. Get the next test message from global tuple.
    try:
        next_sample = SAMPLES.pop()
    except IndexError:
        # we're done!
        return proto.logout()

    print "\nAPPEND %s" % (next_sample,)
    raw = open(next_sample).read()
    msg = get_fd(raw)
    return proto.append(
        REGRESSIONS_FOLDER, msg
    ).addCallback(
        lambda r: proto.select(REGRESSIONS_FOLDER)
    ).addCallback(
        cbAppend, proto, raw
    ).addErrback(
        ebAppend, proto, raw)


def cbAppend(result, proto, orig_msg):
    """
    Fetches the message right after an append.
    """
    # XXX keep account of highest UID
    uid = "1:*"

    return proto.fetchSpecific(
        '%s' % uid,
        headerType='',
        headerArgs=['BODY.PEEK[]'],
    ).addCallback(
        cbCompareMessage, proto, orig_msg
    ).addErrback(ebAppend, proto, orig_msg)


def ebAppend(failure, proto, raw):
    """
    Errorback for the append operation
    """
    print "ERROR WHILE APPENDING!"
    print failure.getTraceback()


def cbPickMessage(result, proto):
    """
    Pick a message.
    """
    return proto.fetchSpecific(
        '%s' % result,
        headerType='',
        headerArgs=['BODY.PEEK[]'],
        ).addCallback(cbCompareMessage, proto)


def cbCompareMessage(result, proto, raw):
    """
    Display message and compare it with the original one.
    """
    parts_orig = get_msg_parts(raw)

    if result:
        keys = result.keys()
        keys.sort()
    else:
        print "[-] GOT NO RESULT"
        return proto.logout()

    latest = max(keys)

    fetched_msg = result[latest][0][2]
    parts_fetched = get_msg_parts(fetched_msg)

    equal = compare_msg_parts(
        parts_orig,
        parts_fetched)

    if equal:
        print "[+] MESSAGES MATCH"
        return cbAppendNextMessage(proto)
    else:
        print "[-] ERROR: MESSAGES DO NOT MATCH !!!"
        print "    ABORTING COMPARISON..."
        # FIXME logout and print the subject ...
        return proto.logout()


def cbClose(result):
    """
    Close the connection when we finish everything.
    """
    from twisted.internet import reactor
    reactor.stop()


def main():
    import glob
    import sys

    if len(sys.argv) != 4:
        print "Usage: regressions <user> <pass> <samples-folder>"
        sys.exit()

    hostname = "localhost"
    port = "1984"
    username = sys.argv[1]
    password = sys.argv[2]

    samplesdir = sys.argv[3]

    if not os.path.isdir(samplesdir):
        print ("Could not find samples folder! "
               "Make sure of copying mail_breaker contents there.")
        sys.exit()

    samples = glob.glob(samplesdir + '/*')

    global SAMPLES
    SAMPLES = []
    SAMPLES += samples

    onConn = defer.Deferred(
    ).addCallback(
        cbServerGreeting, username, password
    ).addErrback(
        ebConnection
    ).addBoth(cbClose)

    factory = SimpleIMAP4ClientFactory(username, onConn)

    from twisted.internet import reactor
    reactor.connectTCP(hostname, int(port), factory)
    reactor.run()


if __name__ == '__main__':
    main()