#!/bin/sh

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
}

check_unstaged()
{
	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
}

_slashify()
{
	# Some shells have shoddy handling of backslashes in echo.
	printf '%s\n' "$1" | sed 's/\([^\\]\)\//\1\\\//g'
}

if [ "$1" = "--" ]; then
	usage
elif [ "$1" = "-d" ]; then
	check_unstaged

	pattern=`_slashify "$2"`
	shift
	shift
	git grep -I -l "$pattern" "$@" | xargs sed -i "/$pattern/d"

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

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