#!/bin/sh
# SPDX-License-Identifier: GPL-2.0+
#
# git-request-pull wrapper with sanity checks
#

baserev=
headrev=

parse_options() {
	# The code below if borrowed from git-request-pull

	# Skip all options
	while [[ $# != 0 ]] ; do
		case "$1" in
		-p)
			;;
		--)
			shift
			break
			;;
		-*)
			return
			;;
		*)
			break
			;;
		esac
		shift
	done

	local base=$1
	local head=

	baserev=$(git rev-parse --verify --quiet "$base"^0)
	if [[ -z "$baserev" ]] ; then
		return
	fi

	local=${3%:*}
	local=${local:-HEAD}
	head=$(git symbolic-ref -q "$local")
	head=${head:-$(git show-ref --heads --tags "$local" | cut -d' ' -f2)}
	head=${head:-$(git rev-parse --quiet --verify "$local")}

	if [[ -z "$head" ]] ; then
		return
	fi

	headrev=$(git rev-parse --verify --quiet "$head"^0)
}

check_commits() {
	if [[ -z "$baserev" || -z "$headrev" ]] ; then
		# git request-pull will catch this issue
		return
	fi

	local author
	local commit
	local committer
	local errors=0
	local sob

	for commit in $(git rev-list ^$baserev $headrev) ; do
		local msg=$(git cat-file commit "$commit")
		local summary=$(git show --pretty='format:%h ("%s")' -s $commit)

		# 1. The commit message shall have Signed-off-by lines
		# corresponding the committer and the author.
		local committer=$(echo "$msg" | grep '^committer ' | head -1 | \
				cut -d ' ' -f 2- | rev | cut -d ' ' -f 3- | rev)
		if ! echo -E "$msg" | grep -Fqx "Signed-off-by: ${committer}"
		then
			echo "Commit $summary is not signed off by committer"
			errors=$((errors+1))
		fi

		local author=$(echo "$msg" | grep '^author ' | head -1 | \
				cut -d ' ' -f 2- | rev | cut -d ' ' -f 3- | rev)
		if ! echo -E "$msg" | grep -Fqx "Signed-off-by: ${author}"
		then
			echo "Commit $summary is not signed off by author"
			errors=$((errors+1))
		fi

		# 2. Fixes: tags shall reference an ancestor commit.
		local fixes=$(echo "$msg" | grep '^Fixes: ')
		if [ -n "$fixes" ] ; then
			fixes=$(echo "$fixes" | sed 's/^Fixes: \([0-9a-f]\+\) (.*)$/\1/')
			git merge-base --is-ancestor $fixes $baserev >/dev/null 2>&1 || {
				echo "Commit $summary contains a Fixes: tag referencing $fixes not present in history"
				errors=$((errors+1))
			}
		fi
	done

	if [[ $errors != 0 ]] ; then
		echo "$errors errors found, please fix"
		exit 1
	fi
}

parse_options $*
check_commits

git request-pull $*