Rewrite t2s in Bash (although it is slow)

bin/t2s

@@ -1,17 +1,42 @@
-#!/usr/bin/env perl
+#!/usr/bin/env bash
 
-use strict;
+n_spaces="$1"
-use warnings;
 
-my $N_SPACES = $ARGV[0] || 4;
+if [ ! "$n_spaces" ]; then
+	n_spaces=4
+fi
 
-while (my $line = <STDIN>) {
+if [ $n_spaces -lt 1 ]; then
-	# Skip empty lines
+	echo 'Sorry. Number of spaces should be a positive number'
-	print "\n" and next if $line !~ m/\S/;
+	exit 1
+fi
 
-	$line =~ m/^(\t*)(.+)$/;
+space=''
-	my $n_tabs   = length($1);
+i=0
-	my $n_spaces = $n_tabs * $N_SPACES;
+while [ true ]; do
+	space="$space "
+	i=$(( $i + 1 ))
+	if [ $i -eq $n_spaces ]; then
+		break
+	fi
+done
 
-	print ' ' x $n_spaces . "$2\n";
+while IFS='' read -r line || [[ -n "$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