#!/usr/bin/python
# -*- coding: utf-8 -*-

# Authors:
#   Thomas Woerner <twoerner@redhat.com>
#
# Copyright (C) 2020 Red Hat
# see file 'COPYING' for use and warranty information
#
# 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/>.

import sys
import argparse
import subprocess


usage = "Usage: changelog [options] [<new version>]"
parser = argparse.ArgumentParser(usage=usage)
parser.add_argument("--tag", dest="tag",
                    help="git tag")
options, args = parser.parse_known_args()

if len(args) == 1:
    new_version = args[0]
elif len(args) != 0:
    parser.error("new version is not set")
else:
    new_version = None

if options.tag is None:
    tag = subprocess.check_output(
        "git describe --tags $(git rev-list --tags --max-count=1)",
        shell=True)
    options.tag = tag.decode("utf-8").strip()

version = options.tag[1:]

command = ["git", "log", "%s.." % options.tag]
process = subprocess.run(command,
                         stdout=subprocess.PIPE,
                         stderr=subprocess.PIPE)

if process.returncode != 0:
    print("git log failed: %s" % process.stderr.decode("utf8").split("\n")[0])
    sys.exit(1)

if new_version is not None:
    s = "ansible-freeipa-%s" % new_version
    print(s)
    print("=" * len(s))
    print()

commits = {}
prs = {}
authors = {}

lines = process.stdout.decode("utf-8").split("\n")

class Ref:
    def __init__(self, commit):
        self.commit = commit


def store(commits, prs, authors, commit, author, merge, msg):
    if commit is not None:
        if msg[0].startswith("Merge pull request #"):
            pr = int(msg[0].split()[3][1:])
            if len(msg) > 1:
                prs[pr] = msg[1].strip()
            else:
                prs[pr] = Ref(merge)
        else:
            commits[commit] = msg[0].strip()
            authors.setdefault(author, []).append(commit)


def get_commit(commits, commit):
    _commits = [value for key, value in commits.items()
                if key.startswith(commit)]
    if len(_commits) == 1:
        return _commits[0]
    return commit


commit = None
author = None
merge = None
msg = None
for line in lines:
    line = line.rstrip()
    if line.startswith("commit "):
        store(commits, prs, authors, commit, author, merge, msg)
        author = None
        msg = []
        commit = line[7:]
    elif line.startswith("    "):
        msg.append(line[4:])
    else:
        try:
            key, value = line.split(":", 1)
            if key == "Author":
                author = value.split("<")[0].strip()
            elif key == "Merge":
                merge = value.split()[1].strip()
            # Ignore Date, ..
        except ValueError:
            pass

# Add final commit
if commit:
    store(commits, prs, authors, commit, author, merge, msg)

s = "Changes since %s" % version
print("%s" % s)
print("-" * len(s))
print()

prs_sorted = sorted(prs.keys(), reverse=True)
for pr in prs_sorted:
    if isinstance(prs[pr], Ref):
        msg = get_commit(commits, prs[pr].commit)
    else:
        msg = prs[pr]
    print("  - %s (#%d)" % (msg, pr))
print()

s = "Detailed changelog since %s by author" % version
print("%s" % s)
print("-" * len(s))
print("  %d authors, %d commits" % (len(authors), len(commits)))
print()

authors_sorted = sorted(authors.keys())
for author in authors_sorted:
    print("%s (%d)\n" % (author, len(authors[author])))
    for commit in authors[author]:
        print("  - %s" % commits[commit])
    print()