acme/bin/t2s

#!/usr/bin/env bash

n_spaces="$1"

if [ ! "$n_spaces" ]; then
	n_spaces=4
fi

if [ $n_spaces -lt 1 ]; then
	echo 'Sorry. Number of spaces should be a positive number'
	exit 1
fi

space=''
i=0
while [ true ]; do
	space="$space "
	i=$(( $i + 1 ))
	if [ $i -eq $n_spaces ]; then
		break
	fi
done

while IFS='' read -r line || [[ -n "$line" ]]; do
	if [[ ${line:0:1} != '	' ]]; then
		echo "$line"
		continue
	fi

	# Line length
	line_len=${#line}

	# Get leading tabs and their length
	tabs=$(echo "$line" | sed -n 's/^\(	*\)\(.*\)$/\1/p')
	tabs_len=${#tabs}

	line_without_tabs_len=$(( $line_len - $tabs_len ))
	line_without_tabs=${line:$tabs_len:$line_without_tabs_len}

	spaces=$(echo "$tabs" | sed "s/	/$space/g")
	echo "$spaces$line_without_tabs"
done