Git pre-push hook that prints correct github PR creation url

pre-push

#!/bin/sh

remote="$1"
url="$2"

z40=0000000000000000000000000000000000000000
if [[ ! "$url" =~ github ]]; then
	echo "doesn't match github"
	exit 0
fi

upstream=$(git rev-parse --abbrev-ref --symbolic-full-name @{u} || true)
if [[ -z "$upstream" ]]; then
	echo "no upstream set, skipping"
	exit 0
fi
remote=$(echo $upstream | sed 's@/.*@@')
remote=$(git remote get-url $remote)

if [[ "$remote" =~ @ ]]; then
	# Convert from ssh to https
	core=$(echo $remote | sed 's/^.*:\(.*\).git$/\1/')
	remote="https://github.com/$core"
fi
upstream_branch=$(echo $upstream | sed 's@^[^/]*/@@')

read local_ref local_sha remote_ref remote_sha
if [[ -z "$remote_sha" || "$remote_sha" != "$z40" ]]; then
	echo "not new branch, skipping"
	exit 0
fi

tgt_owner=$(echo "$url" | sed 's@.*:\(.*\)/.*@\1@')
tgt_branch=$(echo "$remote_ref" | sed 's@refs/heads/@@')

echo "${remote}/compare/${upstream_branch}...${tgt_owner}:${tgt_branch}?expand=1"

exit 0