#!/bin/sh
#
# mfh - Merge from head to a given branch
# 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
		read -p "${question} [y/n] " answer
	done

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

[ $# -ne 2 ] && err "$(basename $0) requires 2 arguments: <branch> <revnumber>"
branch=$1
rev=${2##r} # remove a leading "r"
case ${rev} in
''|*[!0-9]*) err "revision should be a number" ;;
esac

: ${svnserver:="svn.FreeBSD.org"}

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

trap "rc=\$? ; rm -rf \"\${dir}\" ; exit \$rc" EXIT
dir=$(mktemp -d /tmp/merge.XXXXXX)
cd "${dir}"
"${svn}" co --depth=empty svn+ssh://${svnserver}/ports/branches/"${branch}"
filelist=""
# svn:// is faster than svn+ssh://. Use it wherever it's possible.
for f in $("${svn}" diff --summarize -c ${rev} svn://${svnserver}/ports/head); do
	case ${f} in
	*/*) ;;
	*)continue;;
	esac
	f=${f#*/ports/head/}
	f=${f%/*}
	filelist="${filelist}${LF}${f}"
done
filelist=$(printf '%s\n' "${filelist}" | sort -u)
echo "MFH: r${rev}" > commit.txt
"${svn}" log -r${rev} svn://${svnserver}/ports/head | sed '1,2d;$d;/^MFH:/d' >> commit.txt
"${svn}" up --parents $(printf '%s\n' $filelist \
    | sed "s}^}${branch}/}")
"${svn}" up --quiet "${branch}"
"${svn}" merge -c r${rev} ^/head/ "${branch}"
"${svn}" up --quiet "${branch}"
"${svn}" status "${branch}"
"${svn}" diff "${branch}"
ask "Do you want to commit? (no = start a shell)" || (
    echo "Dropping you to a shell so you can investigate. Exit the shell to resume this script."
    cd "${branch}"
    pwd
    su -m $(id -un) || :
    ask "Do you want to commit now? (no = clean up and abort)" || clean
)
${EDITOR:-vi} commit.txt
"${svn}" ci -F commit.txt "${branch}"
rm -rf "${dir}"
trap - 0