#!/bin/sh

# Convert git log output to ChangeLog format for GNU Emacs.

# Copyright (C) 2014-2015 Free Software Foundation, Inc.

# 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/>.

# Written by Paul Eggert

LC_ALL=C
export LC_ALL

gen_origin=${1?}

# If this is not a Git repository, just generate an empty ChangeLog.
test -d ${srcprefix}.git || {
  # Remove any old ChangeLog, in case it is a vc-dwim symlink.
  rm -f "${distprefix}ChangeLog" || exit
  >"${distprefix}ChangeLog"
  exit
}

# Use Gnulib's packaged ChangeLog generator.
${srcprefix}build-aux/gitlog-to-changelog --ignore-matching='^; ' \
  "$gen_origin.." >"${distprefix}ChangeLog.tmp" || exit

if test -s "${distprefix}ChangeLog.tmp"; then

  # Find the years covered by the generated ChangeLog, so that
  # a proper copyright notice can be output.
  years=`
    sed -n 's/^\([0-9][0-9]*\).*/\1/p' "${distprefix}ChangeLog.tmp" |
    sort -nu
  `
  start_year=
  end_year=
  for year in $years; do
    : ${start_year:=$year}
    end_year=$year
  done

  if test "$start_year" = "$end_year"; then
    year_range=$start_year
  else
    year_range=$start_year-$end_year
  fi

  # Append a proper copyright notice.
  sed "1d
       s/\\(Copyright[ (C)]*\\)[0-9]*-[0-9]*/\\1$year_range/
       s/^# //
       /http:/q
  " <Makefile.in >>"${distprefix}ChangeLog.tmp" || exit
fi

# Install the generated ChangeLog.
mv -f "${distprefix}ChangeLog.tmp" "${distprefix}ChangeLog"