#!/usr/bin/python3
#
# git-changelog - Output a rpm changelog
#
# Copyright (C) 2009  Red Hat, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# Author: David Cantrell <dcantrell@redhat.com>
# Author: Brian C. Lane <bcl@redhat.com>

import os
import re
import subprocess
import sys
import textwrap
from argparse import ArgumentParser



class ChangeLog:
    def __init__(self, tag):
        self.tag = tag
        self.ignore = None

    def _getCommitDetail(self, commit, field, long=False):
        proc = subprocess.Popen(['git', 'log', '-1',
                                 "--pretty=format:%s" % field, commit],
                                stdout=subprocess.PIPE,
                                stderr=subprocess.PIPE).communicate()

        ret = proc[0].decode("utf8").strip("\n").split('\n')

        if long:
            return ret

        if len(ret) == 1 and ret[0].find('@') != -1:
            ret = ret[0].split('@')[0]
        elif len(ret) == 1:
            ret = ret[0]
        else:
            ret = filter(lambda x: x != '', ret)

        return ret

    def getBugs(self, msg):
        """Get the Resolves/Related bugs from the commit.
        Bug in first line is considered Resolves
        """
        bugs = []
        if not msg:
            return []

        # summary line format is ^.*#([0-9]+).*
        # Make sure the bz# isn't likely to be a github issue
        for line in msg:
            m = re.match(r"^(Resolves|Related|Conflicts):\ +(rhbz#|RHEL-)(\d+)", line)
            if m and m.group(1) and m.group(2) and m.group(3):
                bugs.append((m.group(1), m.group(2), m.group(3)))
            else:
                # Assume summary line references are still rhbz# only
                m = re.match(r"^.*#(\d+).*", line)
                if m and m.group(1) and int(m.group(1)) > 100000:
                    bugs.append(("Resolves", "rhbz#", m.group(1)))

        return bugs

    def getLog(self):
        rev_range = "%s.." % (self.tag)
        proc = subprocess.Popen(['git', 'log', '--pretty=oneline', rev_range],
                                stdout=subprocess.PIPE,
                                stderr=subprocess.PIPE).communicate()
        lines = filter(lambda x: x.find('l10n: ') != 41 and \
                                 x.find('Merge commit') != 41 and \
                                 x.find('Merge branch') != 41,
                       proc[0].decode("utf8").strip('\n').split('\n'))

        if self.ignore and self.ignore != '':
            for commit in self.ignore.split(','):
                lines = filter(lambda x: not x.startswith(commit), lines)

        log = []
        for line in lines:
            fields = line.split(' ')
            commit = fields[0]

            summary = self._getCommitDetail(commit, "%s")
            long = self._getCommitDetail(commit, "%b", True)
            author = self._getCommitDetail(commit, "%aE")

            msg = ["%s (%s)" % (summary.strip(), author)]
            for r, kind, bz in self.getBugs(long):
                msg.append("%s: %s%s" % (r, kind, bz))
            log.append(msg)

        return log

    def formatLog(self):
        s = ""
        for msg in self.getLog():
            sublines = textwrap.wrap(msg[0], 120)

            s = s + "- %s\n" % sublines[0]
            for line in sublines[1:] + msg[1:]:
                s = s + "  %s\n" % line

        return s

def main():
    parser = ArgumentParser(description="Generate changelog entries from git commits")
    parser.add_argument("-t", "--tag", dest="tag",
                      help="Last tag, changelog is commits after this tag")
    args = parser.parse_args()

    cl = ChangeLog(args.tag)
    print(cl.formatLog())

if __name__ == "__main__":
    main()