#!/usr/bin/perl

use warnings 'all';
use strict;
use Getopt::Long;

my $match_emails;
my $match_names;
my $order_by = 'count';
Getopt::Long::Configure(qw(bundling));
GetOptions(
        'emails|e!' => \$match_emails,
        'names|n!'  => \$match_names,
        'count|c'   => sub { $order_by = 'count' },
        'time|t'    => sub { $order_by = 'stamp' },
) or exit 1;
$match_emails = 1 unless $match_names;

my $email = {};
my $name = {};

open(my $fh, '-|', "git log --format='%at <%aE> %aN'");
while(<$fh>) {
        my ($t, $e, $n) = /(\S+) <(\S+)> (.*)/;
        mark($email, $e, $n, $t);
        mark($name, $n, $e, $t);
}
close($fh);

if ($match_emails) {
        foreach my $e (dups($email)) {
                foreach my $n (vals($email->{$e})) {
                        show($n, $e, $email->{$e}->{$n});
                }
                print "\n";
        }
}
if ($match_names) {
        foreach my $n (dups($name)) {
                foreach my $e (vals($name->{$n})) {
                        show($n, $e, $name->{$n}->{$e});
                }
                print "\n";
        }
}
exit 0;

sub mark {
        my ($h, $k, $v, $t) = @_;
        my $e = $h->{$k}->{$v} ||= { count => 0, stamp => 0 };
        $e->{count}++;
        $e->{stamp} = $t unless $t < $e->{stamp};
}

sub dups {
        my $h = shift;
        return grep { keys($h->{$_}) > 1 } keys($h);
}

sub vals {
        my $h = shift;
        return sort {
                $h->{$b}->{$order_by} <=> $h->{$a}->{$order_by}
        } keys($h);
}

sub show {
        my ($n, $e, $h) = @_;
        print "$n <$e> ($h->{$order_by})\n";
}