#!/bin/sh

#
# Copyright (c) 2019 Jiří Zárevúcky
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

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