#!/bin/bash
# command options and arguments interpreter example
# simple version

# the name of the script without a path

name=`basename $0`

help()
{
	echo "-l <dir/file names...> -> lowerize file/folder name"
	echo "-u <dir/file names...> -> uppercase file/folder name"
	echo "-r [-l|u] -> lowerize or uppercase file/folder name recursively"
	echo "<sed pattern> <dir/file names...> -> call sed command operating on file/folder name"
	echo "-r <sed pattern> <dir/file names...> -> call sed command operating on file/folder recursively"
	echo "-h -> display this message"
}




uppercase()
{
	if test "$1" = $name
	then
		error_msg "you cannot modify name of this script!"
		exit 3
	fi


        if test -z "$1"
        then
                error_msg "missing filename for -u"
                exit 1
        fi
	if test -f "$1"
        then
                if test -d "$1"
                then
                        error_msg "$1 is neither a file nor folder"
                        exit 3
                fi
        fi

	mv "$1" $(echo "$1" | sed -r -e 's/.*/\U&/');

		

}

lowercase()
{
	if test "$1" = $name
        then
                error_msg "you cannot modify name of this script!"
                exit 3
        fi
	if test -z "$1"
	then
		error_msg "missing filename for -l"
		exit 1
	fi
	if test -f "$1"
	then
		if test -d "$1"
		then
			error_msg "$1 is neither a file nor the folder"
			exit 2
		fi
	fi
	mv "$1" $(echo "$1" | sed -r -e 's/.*/\L&/');
}

sneed()
{
	if test "$2" = $name
        then
                error_msg "you cannot modify name of this script!"
                exit 3
        fi
	if test -z "$1"
	then
		error_msg "missing sed pattern"
		exit 1
	fi
	if test -z "$2"
	then
		error_msg "missing sed filename"
		exit 2
	fi
    	if test -f "$2"
        then
                if test -d "$2"
                then
                        error_msg "$2 is neither a file nor folder"
                        exit 3
                fi
        fi

	mv "$2" $(echo "$2" | sed $1)
}

recursionSneed()
{
	if test -z "$1"
	then
		error_msg "missing sed pattern"
		exit 1
	fi

	if test -z "$2"
	then
		error_msg "missing sed filename"
		exit 2
	fi

	if test -f "$2"
	then
		if test -d "$2"
		then
			error_msg "$2 is neither a file or folder"
			exit 3
		fi
	fi
	filename="$2"
	sneed "$1" "$filename" 
	filename="$(echo "$filename" | sed $1)"
	echo $filename
        for item in "$filename"/*
        do
                if test -d "$item"
                then
                        recursionSneed "$1" "$item"
                fi
                if test -f "$item"
                then
                        sneed "$1" "$item" 
                fi
        done
}

recursionLowercase()
{
	lowercase "$1"
	set "$(echo "$1" | sed -r -e 's/.*/\L&/')"
	for item in "$1"/* 
	do
		if test -d "$item"
		then
			recursionLowercase "$item"
		fi
		if test -f "$item"
		then
			lowercase "$item"
		fi
	done
}

recursionUppercase()
{
	uppercase "$1"
        set "$(echo "$1" | sed -r -e 's/.*/\U&/')"
        for item in "$1"/*
        do
                if test -d "$item"
                then
                        recursionUppercase "$item"
                fi
                if test -f "$item"
                then
                        uppercase "$item"
                fi
        done

}

recursion()
{
	if test -z "$1"
	then
		error_msg "missing argument for -r"
		exit 1
	fi
	
       	case "$1" in
		-l|--lowercase) recursionLowercase "$2";;
       	        -u|--uppercase) recursionUppercase "$2";;
               	*) recursionSneed "$1" "$2";;
	esac
}



# function for printing error messages to diagnostic output
error_msg() 
{ 
        echo "$name: error: $1" 1>&2 
}



# if no arguments given
if test -z "$1"
then
	help
fi


# do with command line arguments
case "$1" in
	-h|--help) help;;
	-l|--lowercase) lowercase "$2";;
	-r|--recursion) recursion "$2" "$3" ;;
	-u|--upercase) uppercase "$2";;
	*) sneed "$1" "$2" ;;
esac