#!/bin/bash

usage() {
	echo 'usage:'
	echo "  `basename $0` [options] [path...] pattern"
	echo "  `basename $0` [options] -f FILE [path...]"
	echo
	echo 'options:'
	echo '  -user uname  - File is owned by user uname.'
	echo '  -group gname - File belongs to group gname.'
	echo '  -maxdepth n  - Descend at most n levels of directories'
	echo '  -f FILE      - Obtain patterns from FILE, one per line'
	echo '  -i           - Ignore case distinctions'
	echo '  -v           - Invert the sense of matching.'
}

# Pokud se jedna o posledni parametr a grep
# nema parametr -f nastavi PATTERN, jinak prida
# parametr do seznamu cest
read_path() {
	if [ $2 -eq 1 -a $PATFILE -eq 0 ] ; then
		PATTERN="$1"
	else
		if [ -d "$1" ] ; then			
			PATHS[$DIR_NUM]="$1"
			DIR_NUM=$((DIR_NUM+1))
		else
			echo "$1: no such directory"
			exit 1
		fi 
	fi	
}

# Grep a "inverzni" grep s pozadovanymy parametry
# nad danym souborem
grep_file() {
	if [ $INVERT -eq 1 ] ; then
		if ! grep $GREPOPT "$PATTERN" "$1" ; then
			echo "`pwd`/$1"
		fi 
	else
		if grep $GREPOPT "$PATTERN" "$1" ; then
			echo "`pwd`/$1"
		fi
	fi
}

# Vlastni vyhledavaci funkce. Rekurzivne
# prochazi aktualni adresar
search() {
	for i in * ; do
		if [ -d "$i" -a -x "$i" ] && ! [ -L "$i" ] ; then
			if [ $1 -lt $MAXDEPTH ] ; then
				cd "$i"
				DEPTH=$(($1+1))
        		search $DEPTH
        		DEPTH=$(($1-1))
				cd ..
			fi
        else
			if [ -f "$i" ] ; then
				GREP=1
				if [ $USR ] ; then
					FO=`ls -l "$i" | awk '{print $3}'`
					if [ "$USR" != "$FO" ] ; then
						GREP=0
					fi
				fi
				if [ $GRP ] ; then	
					FG=`ls -l "$i" | awk '{print $4}'`				
					if [ "$GRP" != "$FG" ] ; then
						GREP=0
					fi
				fi
				
				if [ $GREP -eq 1 ] ; then
					grep_file "$i"
				fi
			fi
		fi
	done
}


# Rozparsovani vstupu

if [ $# -lt 1 ] ; then
	usage
	exit 1
fi

PARA=1; DIR_NUM=0; INVERT=0; PATFILE=0

while [ $# -ne 0 ] ; do
	case "$1" in
		-user)
			if [ $PARA -eq 0 -o $# -lt 2 ] ; then
				read_path "$1" $#
				shift
			else
				USR="$2"
				shift 2
			fi
			;;
		-group)
			if [ $PARA -eq 0 -o $# -lt 2 ] ; then
				read_path $1 $#
				shift
			else
				GRP="$2"
				shift 2
			fi
			;;
		-maxdepth)
			if [ $PARA -eq 0 -o $# -lt 2 ] ; then
				read_path "$1" $#
				shift
			else
				if ! [ $2 -gt 0 -o $2 -le 0 ] 2>/dev/null ; then
					echo "invalid maxdepth value"
					exit 1
				fi			
				MAXDEPTH=$2
				shift 2
			fi
			;;
		-f)
			if [ $PARA -eq 0 -o $# -lt 2 ] ; then
				read_path "$1" $#
				shift
			else
				if [ ! -f "$2" ] ; then
					echo "$2: no such pattern file"
					exit 1
				fi
				PATTERN="`pwd`/$2"
				PATFILE=1
				shift 2
			fi
			;;
		-i)
			if [ $PARA -eq 0 ] ; then
				read_path "$1" $#
			else
				GREPOPT="$GREPOPT -i"
			fi
			shift
			;;
		-v)
			if [ $PARA -eq 0 ] ; then
				read_path "$1" $#
			else
				INVERT=1
			fi
			shift
			;;
		-h|-help)
			if [ $PARA -eq 0 ] ; then
				read_path "$1" $#
				shift
			else
				usage
				exit 1
			fi
			;;
		*)
			read_path "$1" $#
			PARA=0
			shift
			;;
	esac
done


# implicitni cesta je ./
if [ $DIR_NUM -eq 0 ] ; then
	PATHS[0]='./'
	DIR_NUM=1
fi

# implicitni hloubka prohledavani
# je nekonecno (skoro...)
if [ ! $MAXDEPTH ] ; then
	MAXDEPTH=1024
fi

# implicitni parametry grepu
if [ $PATFILE -eq 1 ] ; then
	GREPOPT="$GREPOPT -q -f"
else
	GREPOPT="$GREPOPT -q -e"
fi

# Vyhledavani v zadanych adresarich
PWD=`pwd`
DIR_NUM=$((DIR_NUM-1))
while [ $DIR_NUM -ge 0 ] ; do
	cd "${PATHS[$DIR_NUM]}"
	search 1
	DIR_NUM=$((DIR_NUM-1))
	cd "$PWD"
done