###############################################################################
## File decimater
#
# Decimates a file on line basis. Reads an input file and generates an 
# output file that is a stripped version of the input. The stripped file
# contains the following lines from the input file:
#   line 1
#   line 1 + lines_to_skip
#   line 1 + 2*lines_to_skip
#   ...
#
# Usage: dcmate <filename> <lines_to_skip>
#
# Author: L. Hollevoet 
###############################################################################

#!/usr/bin/perl -w

use strict;
use GetOpt::Std;

if (! $ARGV[0] =~ /\w+/ || ! $ARGV[1] =~ /\d+/){
    print "\nUsage info: dcmate.pl <filename> <decimation rate>\n\n";
    exit(0);
}

my $file_in = $ARGV[0];
my $decimate_value = $ARGV[1];

my $file_out = $file_in;
$file_out =~ s/\.(\w+)$/_stripped\.$1/;

if (-e $file_in && -f $file_in){
    open(IN , "<$file_in") || die "Could not open input file $file_in: $!\n";
    open(OUT, ">$file_out") || die "Could not open output file $file_out: $!\n";
} else {
    die "Input file $file_in does not exist!\n";
}

my $counter=0;

while (<IN>){

    if ($counter == 0){
	print OUT;
    }

    if ($counter == $decimate_value){
	$counter = 0;
    } else {
	$counter++;
    }
}

close (IN);
close (OUT);