git-checkout-url

#! /usr/bin/env bash

# Author: Thomas DEBESSE <dev@illwieckz.net>
# License: ISC

set -u -e
shopt -s extglob

_error () { echo "ERROR: ${1}" >&2; false; }

url="${1:-}"

[ -n "${url}" ] || _error 'missing url'

case "${url}" in
	*/-/merge_requests/+([0-9]))
		remote="${url/\/-\/merge_requests\/*/}.git"
		ref="merge-requests/${url/*\//}/head"
		;;
	*/merge_requests/+([0-9]))
		remote="${url/\/merge_requests\/*/}.git"
		ref="merge-requests/${url/*\//}/head"
		;;
	*/pull/+([0-9]))
		remote="${url/\/pull\/*/}.git"
		ref="pull/${url/*\//}/head"
		;;
	*/-/tree/*)
		remote="${url/\/-\/tree\/*/}.git"
		ref="${url/*\/-\/tree\//}"
		;;
	*/tree/*)
		remote="${url/\/tree\/*/}.git"
		ref="${url/*\/tree\//}"
		;;
	*)
		_error "unknown url format"
esac

git fetch "${remote}" "${ref}"
git checkout FETCH_HEAD