#!/bin/sh
#
# Copyright (c) 2015 Ryan Stone. 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.
#

# This script is used to submit a series of git commits to Differential.  Each
# commit is submitted as a separate review.  For each review, this script will
# create a branch called review_DXXXX (e.g. review_D2185 for Differential
# revision D2185).  When you need to make a change to a review, checkout the
# review_D2185 branch, commit your change with "git commit --fixup HEAD".  To\
# upload the change to Differential, use the command:
#   $ arc diff --update D2185 review_D2185_base
#
# When your reviews are complete, merge all of the review_DXXXX branches
# together, and then do a git rebase -ik to meld the code review fixes into the
# commit that they fixed.  Now you have a clean series of patches to push to
# git.

usage()
{
	echo "Usage: arcgit <-c commit | -r commit1~..commit2> [-R reviewer] " >&2
	echo "       [-C subscriber] [-T testplan] [-n]" >&2
}

error()
{
	echo "$@" >&2
	usage
	rm -f $phab_before $phab_after $arc_msg
	exit 1
}

create_review()
{
	local commit phab_id arc_dir
	unset phab_before phab_after arc_msg
	commit=$1

	phab_before=`mktemp -t arcoutput`
	phab_after=`mktemp -t arcoutput`
	echo "Create review for '`git show $commit -s --oneline`'"

	if [ -n "$dry_run" ]
	then
		return
	fi

	git checkout $commit > /dev/null || error "Could not checkout $commit"

	arc_dir="$(git rev-parse --git-dir)/arc"
	arc_msg="$arc_dir/create-message"
	mkdir -p $arc_dir
	git show -s --format='%B' HEAD > $arc_msg
	echo >> $arc_msg
	echo "Test Plan:" >> $arc_msg
	cat $test_plan >> $arc_msg
	echo >> $arc_msg
	echo "Reviewers:" >> $arc_msg
	echo "$reviewers" >> $arc_msg
	echo >> $arc_msg
	echo "Subscribers:" >> $arc_msg
	echo "$cc_list" >> $arc_msg
	echo >> $arc_msg

	arc list > $phab_before
	yes | env EDITOR=true arc diff --create --allow-untracked HEAD~
	arc list > $phab_after

	headline="$(git show $commit -s --format=%s)"
	phab_id=`comm -13 "$phab_before" "$phab_after" | fgrep "$headline" \
	    | egrep -o 'D[0-9]+:' | tr -d ':'`

	if [ -z "$phab_id" ]
	then
		error "Could not get review ID"
	fi

	git branch review_${phab_id}_base HEAD~

	git checkout -b review_$phab_id
	cat - <<EOF | git commit --allow-empty -F -
squash! $headline

Differential Revision:	https://reviews.freebsd.org/$phab_id
Reviewed by:
EOF
}

unset range test_plan reviewers cc_list dry_run

while getopts ":c:C:nr:R:T:" o
do
	case "$o" in
	c)
		range="${OPTARG}~..${OPTARG}"
		;;
	C)
		if [ -z "$cc_list" ]
		then
			cc_list="$OPTARG"
		else
			cc_list="$cc_list, $OPTARG"
		fi
		;;
	n)
		dry_run=1
		;;
	r)
		range=$OPTARG
		;;
	R)
		if [ -z "$reviewers" ]
		then
			reviewers="$OPTARG"
		else
			reviewers="$reviewers, $OPTARG"
		fi
		;;
	T)
		test_plan=$OPTARG
		;;
	*)
		error "Unrecognized argument '-$OPTARG'"
	esac
done

shift $((OPTIND - 1))
OPTIND=1

if [ -n "$1" ]
then
        error "Unrecognized argument $1"
fi

if [ -z "$range" ]
then
	error "-c or -r argument is mandatory"
fi

if [ -n "$test_plan" -a ! -r "$test_plan" ]
then
	error "$test_plan is not readable"
fi

if ! type git > /dev/null 2> /dev/null
then
	error "Install devel/git first"
fi

if ! type arc > /dev/null 2> /dev/null
then
	error "Install devel/arcanist first"
fi

git update-index -q --refresh
if ! git diff-index --quiet --cached HEAD
then
	error "index is unclean"
fi

if ! git diff-files --quiet
then
	error "Working directory is unclean"
fi

if git ls-files --other --error-unmatch . > /dev/null 2> /dev/null
then
	error "Working directory contains untracked files"
fi

# We have to do a git checkout in order to run arc, so save the original branch
# so that we can check it out again once we're done.
if ! orig_branch=$(git symbolic-ref --short -q HEAD)
then
	orig_branch=$(git show -s --pretty='%H' HEAD)
fi

git log --format=%H $range | tail -r | while read -r commit
do
	create_review $commit < /dev/null
done

# Note that due to the use of the pipeline above, the body of the while loop
# above runs in a subshell.  If it exits with an error, execution resumes
# here rather than exiting the script, so we have to cache the right exit code
# and return it when we're done cleaning up.
code=$?

git checkout $orig_branch

exit $code