#!/bin/sh
#
# mfh - Merge from head to a given branch
#
# Usage: mfh [<branch>] <revnumber> [<revnumber>]
#   <branch> is optional and defaults to latest branch
#   If supplying multiple revnumbers, put them in chronological order
#     (111111 111112 111113)
#
# Copyright 2013 Baptiste Daroussin
# All rights reserved.
#
# 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.
#
# MAINTAINER=	portmgr@FreeBSD.org

set -eu

LF=$(printf '\nX')
LF=${LF%X}
IFS="${LF}"

err() {
	echo "$@" >&2
	exit 1
}

clean() {
	rm -rf "${dir}"
	exit 1
}

ask() {
	question=${1}

	answer=x
	while [ "${answer}" != "y" -a "${answer}" != "n" ] ; do
		printf "%s [y/n] " "${question}"
		read -r answer
	done

	[ "${answer}" = "y" ] && return 0
	return 1
}

: "${svnserver:="svn+ssh://repo.FreeBSD.org"}"

if [ -n "$(command -v svn 2>/dev/null)" ]; then
	svn=svn
elif [ -n "$(command -v svnlite 2>/dev/null)" ]; then
	svn=svnlite
else
	err "Neither svn(1) nor svnlite(1) found. Please install devel/subversion."
fi

latest_branch=$("${svn}" ls ${svnserver}/ports/branches/|sed -ne '/^2.*Q./s|/$||p'|tail -1)

[ $# -lt 1 ] && err "$(basename "$0") requires at least 1 arguments: [<branch>] <revnumber> [<revnumber>...]"
branch=$1

# I sure hope by 2030 we'll be doing something else. Yes, famous last words.
if expr "${branch}" : '20[12][0-9]Q[1-4]' > /dev/null; then
	shift
	if [ "${latest_branch}" != "${branch}" ]; then
		ask "/!\\ The latest branch is ${latest_branch}, do you really want to commit to ${branch}?" || exit 1
	fi
else
	branch=${latest_branch}
fi

for rev in "$@"
do
  rev=${rev##r} # remove a leading "r"
  case ${rev} in
    ''|*[!-0-9]*) err "revision \"${rev}\" should be a number" ;;
  esac
done


trap "rc=\$? ; rm -rf \"\${dir}\" ; exit \$rc" EXIT
dir=$(mktemp -d /tmp/merge.XXXXXX)
cd "${dir}"
"${svn}" co --depth=empty ${svnserver}/ports/branches/"${branch}"
filelist=""

printf "MFH:" > commit.txt
for rev in "$@"
do
  rev=${rev##r}
  printf " r%s" "${rev}" >> commit.txt
done
echo >> commit.txt
for rev in "$@"
do
  rev=${rev##r}
  for f in $("${svn}" diff --summarize -c "r${rev}" "${svnserver}/ports/head"); do
	  case ${f} in
	  */*) ;;
	  *)continue;;
	  esac
	  f=${f#*/ports/head/}
	  f=${f%/*}
	  filelist="${filelist}${LF}${f}"
  done
  "${svn}" log "-r${rev##-}" ${svnserver}/ports/head | sed '1,2d;$d;/^MFH:/d' \
      | sed '$d' >> commit.txt
done
filelist=$(printf '%s\n' "${filelist}" | sort -u)
"${svn}" up --parents $(printf '%s\n' $filelist \
    | sed "s}^}${branch}/}")
"${svn}" up --quiet "${branch}"
for rev in "$@"
do
  rev=${rev##r}
  "${svn}" merge -c "r${rev}" ^/head/ "${branch}"
done
"${svn}" up --quiet "${branch}"
"${svn}" status "${branch}"
"${svn}" diff "${branch}"
echo "All the merge work was done in ${dir}/${branch}."
ask "Do you want to commit? (no = start a shell)" || (
    echo "Dropping you to a shell so you can investigate. Exit the shell to resume this script."
    cd "${branch}"
    pwd
    su -m $(id -un) || :
    ask "Do you want to commit now? (no = clean up and abort)" || clean
)
echo >> commit.txt
echo "Approved by:	" >> commit.txt
${EDITOR:-vi} commit.txt
while ! "${svn}" ci -F commit.txt "${branch}"; do
	if ! ask "Commit failed. Re-edit message and try again?"; then
		save_log="$(mktemp -t mfh)"
		cp -f commit.txt "${save_log}"
		echo "Saving commit log to ${save_log}"
		break
	fi
	${EDITOR:-vi} commit.txt
done
rm -rf "${dir}"
trap - 0