#!/bin/sh
# $UFP$

# Copyright © 2019-2021 Trond Endrestøl <trond.endrestol@ximalas.info>

# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.

# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.

#set -x
#set -eu -o pipefail
set -u -o pipefail

## Kids, remember the simplicity of running Subversion through GNU Parallel.
#parallel svn update --accept=theirs-full --non-interactive ::: /usr/ports /usr/src
## Now, compare that to what follows.

# Determine which git executable to run.
GIT_CANDIDATES="/usr/local/bin/git /usr/bin/git /usr/bin/gitlite"
readonly GIT_CANDIDATES

for cand in ${GIT_CANDIDATES}; do
  if [ -x ${cand} ]; then
    GIT=${cand}
    break
  fi
done

if [ -z "${GIT}" ]; then
  echo "${0}: neither of ${GIT_CANDIDATES} are useable" >/dev/stderr
  exit 69
fi

readonly GIT

ncpu=`sysctl -n hw.ncpu`
readonly ncpu

# Usage: update_git_wc <directory> <freebsd-branch> <local-branch>
#
#  E.g.: update_git_wc /usr/src   main      main+local
#        update_git_wc /usr/src   stable/13 stable/13+local
#        update_git_wc /usr/ports main      main+local
#
update_git_wc () {
  if [ ${#} -ne 3 ]; then
    echo "Usage: ${0} <directory> <freebsd-branch> <local-branch>" >/dev/stderr
    return 69
  fi

  date || return

  echo "Updating Git WC in ${1} ..." || return

  local BASENAME=`basename ${1}`
  local FSTYPE=`df -T ${1} | tail -1 | awk '{print $2;exit}'`
  local FSDEV=`df ${1} | tail -1 | awk '{print $1;exit}'`
  local TIMESTAMP=`date +%Y%m%d-%H%M%S`

  if [ "${FSTYPE}" = zfs ]; then
    zfs snapshot -r ${FSDEV}/.git@${TIMESTAMP} || return
  fi

  ${GIT} -C ${1} diff ${2}..${3} > /var/backups/git-diff-${BASENAME}-${TIMESTAMP}.diff || return

  ${GIT} -C ${1} stash                                || return
  ${GIT} -C ${1} checkout ${2}                        || return
  ${GIT} -C ${1} pull -j ${ncpu} --no-edit --no-ff -p || {
    ${GIT} -C ${1} prune -v                             || return
    ${GIT} -C ${1} remote prune freebsd                 || return
    ${GIT} -C ${1} gc --auto                            || return
    ${GIT} -C ${1} pull -j ${ncpu} --no-edit --no-ff -p || return
    }
  ${GIT} -C ${1} rebase ${2} ${3} || return
  [ -n "`${GIT} -C ${1} stash list`" ] && { ${GIT} -C ${1} stash pop || return; } || true

  echo || return
}

update_git_wc /usr/src   main main+local || exit
#update_git_wc /usr/ports main main+local || exit

#update_git_wc /usr/zstd-3.src   main main+local || exit
#update_git_wc /usr/zstd-3.ports main main+local || exit
#update_git_wc /usr/zstd-3.src   main main+local || exit
#update_git_wc /usr/zstd-9.ports main main+local || exit
#update_git_wc /usr/zstd-9.src   main main+local || exit
#update_git_wc /usr/zstd-9.ports main main+local || exit
#update_git_wc /usr/zstd-12.src   main main+local || exit
#update_git_wc /usr/zstd-12.ports main main+local || exit
#update_git_wc /usr/zstd-19.src   main main+local || exit
#update_git_wc /usr/zstd-19.ports main main+local || exit

date

# EOF