#!/usr/bin/env perl

use strict;
use warnings;

my $usage = "usage: $0 pairs.stats.sorted max_cov max_pct_stdev\n\n";

my $pair_stats_file = $ARGV[0] or die $usage;
my $max_cov = $ARGV[1] or die $usage;
my $max_pct_stdev = $ARGV[2] or die $usage;

main: {

    my $count_no_cov = 0;
    my $count_aberrant_and_discarded = 0;
    my $count_selected = 0;
    my $count_total = 0;

    open (my $fh, $pair_stats_file) or die $!;
    while (<$fh>) {

        $count_total++;

        chomp;
        my $line = $_;
        my ($med_cov, $avg_cov, $stdev, $pct_dev, $core_acc) = split(/\t/);
        
        $core_acc =~ s|/[12]$||;
        
        if ($med_cov < 1) { 
            
            $count_no_cov++;   ## this shouldn't happen in modern versions of this process. (bh 10-2013)
            next; 
        }
        
        if ($pct_dev > $max_pct_stdev) { 
            
            # print STDERR "// excluding $_ as aberrant\n";
            
            $count_aberrant_and_discarded++;
            next; 
        }
                                
        if (rand(1) <= $max_cov/$med_cov) {
            print "$core_acc\n";
            $count_selected++;
        }
    }
    close $fh;
    
    print STDERR "$count_selected / $count_total = " . sprintf("%.2f", $count_selected/$count_total*100) . "% reads selected during normalization.\n";
    print STDERR "$count_aberrant_and_discarded / $count_total = " . sprintf("%.2f", $count_aberrant_and_discarded/$count_total*100) . "% reads discarded as likely aberrant based on coverage profiles.\n";
    print STDERR "$count_no_cov / $count_total = " . sprintf("%.2f", $count_no_cov/$count_total*100) . "% reads missing kmer coverage (N chars included?).\n";
    

    exit(0);
}