#!/usr/bin/python3
# -*- coding: utf-8 -*-

# Copyright (C) 2018 SUSE LLC
#
# 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 2
# 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, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
# USA.

# This script is used by the commit hook to detect if there are changes in the
# sorted section. Developers may commit to kernel-source without having changed
# the sorted section and used the git-sort tools, therefore without having the
# pygit2 module available. Therefore, this script should avoid a dependency on
# pygit2 since it's not present on a default python install and we don't want to
# force developers to install pygit2 just to commit unrelated changes to
# kernel-source.

import argparse
import contextlib
import errno
import sys

import exc
from patch import Patch


start_text = "sorted patches"
end_text = "end of sorted patches"


def split(series):
    before = []
    inside = []
    after = []

    whitespace = []
    comments = []

    current = before
    for line in series:
        l = line.strip()

        if l == "":
            if comments:
                current.extend(comments)
                comments = []
            whitespace.append(line)
            continue
        elif l.startswith("#"):
            if whitespace:
                current.extend(whitespace)
                whitespace = []
            comments.append(line)

            if current == before and l.lower() == "# %s" % (start_text,):
                current = inside
            elif current == inside and l.lower() == "# %s" % (end_text,):
                current = after
        else:
            if comments:
                current.extend(comments)
                comments = []
            if whitespace:
                current.extend(whitespace)
                whitespace = []
            current.append(line)
    if comments:
        current.extend(comments)
        comments = []
    if whitespace:
        current.extend(whitespace)
        whitespace = []

    if current is before:
        raise exc.KSNotFound("Sorted subseries not found.")

    current.extend(comments)
    current.extend(whitespace)

    return (before, inside, after,)


def filter_patches(line):
    line = line.strip()

    if line == "" or line.startswith(("#", "-", "+",)):
        return False
    else:
        return True


def firstword(value):
    return value.split(None, 1)[0]


filter_series = lambda lines : [firstword(line) for line in lines
                                if filter_patches(line)]


@contextlib.contextmanager
def find_commit(commit, series, mode="rb"):
    """
    commit: unabbreviated git commit id
    series: list of lines from series.conf
    mode: mode to open the patch files in, should be "rb" or "r+b"

    Caller must chdir to where the entries in series can be found.

    Returns patch.Patch instances
    """
    for name in filter_series(series):
        patch = Patch(open(name, mode=mode))
        found = False
        if commit in [firstword(value)
                      for value in patch.get("Git-commit")
                      if value]:
            found = True
            yield name, patch
        patch.writeback()
        if found:
            return
    raise exc.KSNotFound()


if __name__ == "__main__":
    parser = argparse.ArgumentParser(
        description="Extract the sorted patches section of a series.conf file.")
    parser.add_argument("-n", "--name-only", action="store_true",
                        help="Print only patch names.")
    parser.add_argument("series", nargs="?", metavar="series.conf",
                        help="series.conf file. Default: read input from stdin.")
    args = parser.parse_args()

    if args.series is not None:
        f = open(args.series)
    else:
        f = sys.stdin
    lines = f.readlines()

    try:
        before, inside, after = split(lines)
    except exc.KSNotFound:
        pass
    else:
        if args.name_only:
            inside = filter_series(inside)
            inside = [line + "\n" for line in inside]

        try:
            sys.stdout.writelines(inside)
            # Avoid an unsightly error that may occur when not all output is
            # read:
            # Exception ignored in: <_io.TextIOWrapper name='<stdout>' mode='w' encoding='UTF-8'>
            # BrokenPipeError: [Errno 32] Broken pipe
            sys.stdout.flush()
        except BrokenPipeError:
            sys.stderr.close()
            sys.exit()