#! /usr/bin/env perl
use strict;
use warnings;

use 5.010;

die "Usage: $0 report status\n" if 2 != @ARGV;

my $report_file = shift @ARGV;
my $status_file = shift @ARGV;

# hash for lookup of already seen datasets
my %seen;

# open report for reading
open my $rfh, '<', $report_file or die "open($report_file,<) failed: $!";
# open status for writing (appending), change to > for overwriting
open my $wfh, '>>', $status_file or die "open($status_file,>>) failed: $!";

LINE:
while ( my $line = <$rfh> ) {
    warn "(D) read: $line\n";

    # skip empty lines
    next LINE if $line =~ m/^\s*$/;

    chomp $line;
    # split into fields
    my ( $field1, $field2, $date1, $date2 ) = split m/\t/, $line;

    # no action if "date2" is not "-"; read next line
    next LINE if $date2 ne '-';

    # prepare a string to compare from first three fields
    my $to_save = join "\t", $field1, $field2, $date1;

    # check dataset (and register it). If not yet seen, write it to status file
    if ( ! $seen{ $to_save }++ ) {
        say $wfh $to_save;
    }

}

close $wfh or die "close($status_file) failed: $!;";
close $rfh;


__END__