#!/usr/bin/env python3
#
# Extract git patchset from notmuch emails
#
# Copyright (C) 2017 Aurelien Aptel <aurelien.aptel@gmail.com>
#
# 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 <https://www.gnu.org/licenses/>.

import mailbox
import sys
import tempfile
import subprocess
import re
import getopt

def get_body(message):
    body = None
    if message.is_multipart():
        for part in message.walk():
            if part.is_multipart():
                for subpart in part.walk():
                    if subpart.get_content_type() == 'text/plain':
                        body = subpart.get_payload(decode=True)
            elif part.get_content_type() == 'text/plain':
                body = part.get_payload(decode=True)
    elif message.get_content_type() == 'text/plain':
        body = message.get_payload(decode=True)

    if isinstance(body, bytes):
        body = body.decode('utf-8')
    return body


def is_git_patch(msg):
    # we want to skip cover letters, hence why we look for @@
    body = get_body(msg)
    match = re.search(r'''\n@@ [0-9 +,-]+ @@''', body)
    # return ("git-send-email" in msg['x-mailer'] and match)
    return match

def has_reroll_count(msg, v):
    subject_prefix = get_subject_prefix(msg['subject'])
    if subject_prefix is not None:
        return "v"+str(v) in subject_prefix \
            or (v == 1 and not any(entry[0] == 'v' for entry in subject_prefix))

def get_subject_prefix(s):
    match = re.search(r'''\[(.*PATCH.*)\]''', s)
    if match:
        return match.group(1).split()

# if Subject: contains [PATCH nn/mm] then any text before that should
# be stripped, as it should not form part of the commit message.  (The
# debbugs system prepends 'Bug#nnnnnn: ')
def munge_subject(msg):
    match = re.search(r'''\[(.*PATCH.*)\].*$''', msg['subject'])
    if match:
        del msg['subject']
        msg['subject'] = match.group(0)

def main():
    try:
        opts, query = getopt.getopt(sys.argv[1:], "v:", ["reroll-count="])
    except getopt.GetoptError as err:
        sys.stderr.write(str(err)+"\n")
        sys.exit(2)
    reroll_count = 1
    for o, a in opts:
        if o in ("-v", "--reroll-count"):
            reroll_count = int(a)
    with tempfile.NamedTemporaryFile() as in_mb_file:
        out = subprocess.check_output(['notmuch', 'show', '--format=mbox']+query)
        in_mb_file.write(out)
        in_mb_file.flush()

        in_mb = mailbox.mbox(in_mb_file.name)
        with tempfile.NamedTemporaryFile() as out_mb_file:
            out_mb = mailbox.mbox(out_mb_file.name)
            for m in in_mb:
                if is_git_patch(m) and has_reroll_count(m, reroll_count):
                    sys.stderr.write(m['subject']+"\n")
                    munge_subject(m)
                    out_mb.add(m)
            out_mb.flush()
            print(open(out_mb_file.name).read())

if __name__ == '__main__':
    main()