Rename files according to the date

rename_files_to_date.pl

#!/usr/bin/perl -w
use strict;
use warnings;
use POSIX 'strftime';
use File::Basename;

sub trim { my $s = shift; $s =~ s/^\s+|\s+$//g; return $s };

sub get_files_from_directory {
    my $path = $_[0];
    opendir my $dir, $path or die "Cannot open directory: $!";
    my @files = readdir($dir);
    @files = grep(!/^\.$|^\.\.$/, @files);
    closedir $dir;
    return @files;
}

sub group_files_by_date {
    my ($dir, @files) = @_;
    my %groups = ();

    foreach my $file (@files) {
        my $timestamp = (stat "$dir/$file")[9];
        my $date = strftime("%Y%m%d", localtime($timestamp));

        if (not exists $groups{$date}) {
            @{$groups{$date}} = ();
        }
        push @{$groups{$date}}, "$dir/$file";
    }

    return %groups;
}

sub sort_files_in_groups {
    my (%groups) = @_;
    foreach my $key (sort keys %groups) {
        my $files = $groups{$key};
        @{$groups{$key}} = sort { (stat $a)[9] <=> (stat $b)[9] } @{$files};
    }
    return %groups;
}

sub build_new_name {
    my ($date, $num, $dir, $ext) = @_;
    my $zero_num = sprintf("%02d", $num);
    return "$dir${date} ${zero_num}${ext}";
}

sub name_pairs {
    my (%groups) = @_;
    my %pairs;
    foreach my $key (keys %groups) {
        my $files = $groups{$key};
        for (my $i = 0; $i < scalar @{$files}; $i++) {
            my $file = @{$files}[$i];
            my ($basename, $dir, $ext) = fileparse($file, qr/\.[^.]*/);
            my $new_name = &build_new_name($key, $i + 1, $dir, $ext);
            $pairs{$file} = $new_name;
        }
    }
    return %pairs;
}

sub print_pairs {
    my (%pairs) = @_;
    foreach my $key (keys %pairs) {
        print "$key\t->\t$pairs{$key}\n";
    }
}

sub rename_files {
    my (%pairs) = @_;
    foreach my $key (keys %pairs) {
        rename $key, $pairs{$key};
    }
}

sub save_log {
    my (%pairs) = @_;
    my $file = 'rename_files_to_date.log';
    open(my $fh, '>', $file);
    foreach my $key (keys %pairs) {
        print $fh "$key\t->\t$pairs{$key}\n";
    }
    close $fh;
}

sub main {
    my @argv = @_;
    my $dir = $argv[0];

    my @files = &get_files_from_directory($dir);

    my %groups = &group_files_by_date($dir, @files);
    %groups = &sort_files_in_groups(%groups);
    my %pairs = &name_pairs(%groups);
    &print_pairs(%pairs);

    print "\nWARNING: Rename is irreversible. Recommend to make a backup.\n",
        "Confirm rename files? (y/N) ";
    my $choice = <STDIN>;
    print $choice;
    exit 0 unless trim($choice) eq 'y';

    &rename_files(%pairs);
    &save_log(%pairs);
    print "Done. Log file also saved.\n";
}

&main(@ARGV);