#!/usr/bin/perl
# vi: set tabstop=4 shiftwidth=4 expandtab : #
# version: 2.20200726
use strict;
use warnings;

my @files = <*>;
my %new_files;

foreach my $file (@files) {
    if ($file =~ m#\.(jpe?g|png|gif)$#) {
        my ($file_mtime) = (stat($file))[9];
        
        my $new_file = "$file_mtime";
        my $suffix = 1;
        while (exists $new_files{$new_file}) {
            $new_file = "$file_mtime-$suffix";
            $suffix = $suffix + 1;
        }
        $new_files{$new_file} = $file;
    } 
}

my @sorted_keys = sort(keys(%new_files));
my $cc = 0;
foreach my $key (@sorted_keys) {
    my $file = $new_files{$key};
    $file =~ m#\.(.+)$#;
    my $ext = $1;
    my $new_file = "$key.$ext";

    if (not ($new_file eq $file)) {
        print "$file  ->  $new_file\n";
        rename($file, $new_file) || die "Can't rename file '$file'! Cause: $!";
        $cc = $cc + 1;
    }
}

print "-------------------\n";
print "rename $cc files\n";