#!/bin/sh

function usage {
	echo "Usage:"
	echo
	echo "	$0 search_pattern [-- <pathspec> ]"
	echo "	$0 search_pattern replacement [-- <pathspec> ]"
	echo
	echo "Pattern should be a basic regexp as accepted by grep and sed."
	echo "For information on pathspec syntax, see git documentation."
	echo
	exit 1
}


if [ "$1" == "--" ]; then
	usage
elif [ "$#" -eq 1 ]  || [ "$2" == "--" ]; then
	pattern="$1"
	shift
	git grep -I -n "$pattern" "$@"
elif [ "$#" -eq 2 ] || [ "$3" == "--" ]; then

	if ( git status --porcelain | grep '^.[^ ]' ); then
		echo "You have unstaged changes in your tree."
		echo "Either stage them with 'git add', commit them,"
		echo "or discard them with 'git checkout -- .'"
		exit 1
	fi

	pattern="$1"
	replacement="$2"
	shift
	shift
	git grep -I -l "$pattern" "$@" | xargs sed -i "s/$pattern/$replacement/g"
else
	usage
fi