#!/usr/bin/env perl
use warnings;
use strict;
use Time::Piece;
use File::Spec::Functions qw/ no_upwards catfile /;
use Getopt::Long qw/ HelpMessage :config posix_default gnu_compat
	bundling auto_help /;
use Data::Dumper;
$Data::Dumper::Quotekeys=0;
$Data::Dumper::Useqq=$Data::Dumper::Sortkeys=1;

=head1 SYNOPSIS

 myrename.pl [OPTIONS] PATH
 OPTIONS:
   -r | --run        - Actually perform actions
   -v | --verbose    - With --run, report actions
   -q | --quiet      - Suppress warning messages
   -d | --debug      - Enable debugging (overrides -v and -q)

=cut

GetOptions(
	'r|run'      => \( my $RUN     ),
	'v|verbose'  => \( my $VERBOSE ),
	'q|quiet'    => \( my $QUIET   ),
	'd|debug'    => \( my $DEBUG   ),
	version    => sub { print q$myrename.pl v0.01$,"\n"; exit },
	) or HelpMessage(-exitval=>255);
HelpMessage(-exitval=>255) unless @ARGV==1;
if ( $DEBUG ) { $VERBOSE=1; $QUIET=0; }
my $PATH = $ARGV[0];
print STDERR Data::Dumper->Dump([$PATH],['PATH']) if $DEBUG;

opendir my $dh, $PATH or die "$PATH: $!";
my @FILES = sort grep { -f catfile($PATH,$_) } no_upwards readdir $dh;
closedir $dh;
print STDERR Data::Dumper->Dump([\@FILES],['*FILES']) if $DEBUG;

my %files;
FILE: for my $origfile (@FILES) {
	my ($uid,$time,$file) = $origfile =~ /\A(\d+_)((?:\d+_){6})(.+)\z/
		or do { warn "No match, skipping $origfile\n"
			unless $QUIET; next FILE };
	print STDERR Data::Dumper->Dump([$uid,$time,$file],
		[qw/uid time file/]) if $DEBUG;
	$time = Time::Piece->strptime($time, '%Y_%m_%d_%H_%M_%S_')->epoch;
	push @{ $files{$file} }, { origfile => $origfile, time=>$time };
}
@$_ = sort { $b->{time} <=> $a->{time} } @$_ for values %files;
print STDERR Data::Dumper->Dump([\%files],['*files']) if $DEBUG;

for my $file (sort keys %files) {
	my $keep = shift @{ $files{$file} };
	my $srcfile = catfile($PATH,$keep->{origfile});
	my $dstfile = catfile($PATH,$file);
	print "Rename $srcfile to $dstfile\n" if !$RUN || $VERBOSE;
	die "Destination file exists: $dstfile\n" if -e $dstfile;
	# NOTE: There is a possible race condition between -e and rename
	if ($RUN) {
		rename($srcfile, $dstfile)
			or die "rename($srcfile, $dstfile): $!";
	}
	for my $drop ( @{ $files{$file} } ) {
		my $dropfile = catfile($PATH,$drop->{origfile});
		print "Drop $dropfile\n" if !$RUN || $VERBOSE;
		if ($RUN) {
			unlink($dropfile) or die "unlink($dropfile): $!";
		}
	}
}
warn "This was a dry-run, no actions performed\n" unless $RUN;

##</code><code>##

No match, skipping 2007_5_22_15_34_23_Table_-_2007522_XYZ_W3.pdf
Rename x/8_2007_5_22_22_34_12_Table_-_2007522_XYZ_W3.pdf to x/Table_-_2007522_XYZ_W3.pdf
Drop x/8_2007_5_22_15_34_23_Table_-_2007522_XYZ_W3.pdf
Rename x/8_2007_5_22_15_34_23_Table_-_2008522_XYZ_W3.pdf to x/Table_-_2008522_XYZ_W3.pdf