#!/usr/bin/env perl
#
# martin, 2020-07-22
#
# dv-rename renames .dv files using the 'Recorded date' tag
# returned by MediaInfo. Make sure the 'mediainfo' binary
# is in your path.
#
# Usage:
# ./dv-rename *.dv      # dry run
# ./dv-rename -f *.dv   # serious run

use strict;
use warnings;
use 5;

use File::Basename qw/basename dirname/;
use File::Copy qw/move/;
use File::Spec::Functions qw/catfile/;
use IPC::Open2 qw/open2/;

sub sanitize_recdate {
  my $date = shift;

  chomp $date;

  # Replace spaces with a dot
  $date =~ s/\s+/./g;

  # Replace double colons with dashes
  $date =~ s/:/-/g;

  # Remove '.000' if present
  $date =~ s/\.000\b//g;

  return $date;
}

sub rename_file {
  my $fn = shift;
  my $mode = shift;

  my $dry = 0;

  if (defined $mode and $mode eq 'dry-run') {
    $dry = 1;
  }

  my $fndir = dirname $fn;
  my $fnbase = basename $fn;

  my $pid = open2(my $child_out, my $child_in,
                  mediainfo => '--Output=General;%Recorded_Date%',
                  $fn);

  my $recdate = sanitize_recdate(readline $child_out);

  waitpid($pid, 0);

  my $rc = $? >> 8;
  if ($rc != 0) {
    die "Fatal: mediainfo exited with status $rc\n";
  }

  my $newbase = "$recdate.dv";
  my $newpath = catfile($fndir, $newbase);

  print "[Rename:] $fn => $newpath\n";

  if (-e $newpath) {
    die "Fatal: $newpath already exists!\n";
  }

  if (!$dry) {
    move($fn, $newpath);
  }
}

sub main {
  if ($ARGV[0] ne '-f') {
    # Dry run mode
    print "[Mode:] Using dry run mode to preview changes!\n";
    my @files = @ARGV;
    rename_file($_, 'dry-run') for @files;
    print "This has been a dry run, use -f to commit.\n";
  } else {
    # Serious mode
    shift @ARGV;
    my @files = @ARGV;
    rename_file($_) for @files;
  }
}

main;