time2filename.pl

#!/usr/bin/perl
#
# this programm uses Image::ExifTool by Phil Harvey
# download and install it: http://www.sno.phy.queensu.ca/~phil/exiftool/

use File::Copy;
use Image::ExifTool 'ImageInfo';
use File::Basename;
use File::stat;
use Time::localtime;
use Date::Parse;
use DateTime;

use constant FALSE => 0;
use constant TRUE  => 1;

# no arguments given? print help and exit
if ($#ARGV == -1) {
  print_help();
  exit(1);
}

# variables for storing command line arguments
my $dontcheckarguments = FALSE;
my $verbose = FALSE;
my $pretend = FALSE;
my $adjust = 0;

for my $fromfile (@ARGV) {

  # check for arguments
  if ($dontcheckarguments == FALSE) {
      if ($fromfile eq "-h") {
          print_help();
          next;
      } elsif ($fromfile eq "-v") {
          $verbose = TRUE;
          next;
      } elsif ($fromfile eq "-p") {
          $pretend = TRUE;
          $verbose = TRUE;
          next;
      } elsif ($fromfile =~ /^-a-?\d*/) {
          $adjust = substr($fromfile, 2);
          next;
      } elsif ($fromfile eq "--") {
          $dontcheckarguments = TRUE;
          next;
      }
  }

  # get exif creation timestamp of file
  my $info = ImageInfo($fromfile);
  my $estamp = $info->{"DateTimeOriginal"};
  my $esecs; # seconds since epoch

  # if no timestamp in file -> use other info
  if (length($estamp) != 19) {
    if ($fromfile =~ /^VID_\d{8}_\d{6}\..*$/) {
      # Android Video: timestamp is in filename 
      print "No EXIF Timestamp. Using date+time from filename: $fromfile\n";
      $timestring = $fromfile; 
      $timestring =~ s/VID_(\d{4})(\d{2})(\d{2})_(\d{2})(\d{2})(\d{2})\..*$/\1-\2-\3 \4:\5:\6/;
      $esecs = str2time($timestring);
    } else {
      # -> use mod-time of file
      print "No EXIF Timestamp. Using modification time: $fromfile\n";
      $esecs = stat($fromfile)->mtime;
    }
  } else {
      $esecs = str2time($estamp);
  }

  # eventually adjust time
  $esecs += $adjust;

  # prepare timestamp
  my $timestamp = sprintf "%4d-%02d-%02d %02d-%02d-%02d", 
          localtime($esecs)->year+1900, 
          localtime($esecs)->mon+1, 
          localtime($esecs)->mday, 
          localtime($esecs)->hour, 
          localtime($esecs)->min, 
          localtime($esecs)->sec;
  $timestamp =~ s/:/-/g;

  # cut fromfile in file's name and dir name
  $filename = basename($fromfile);
  $dirname  = dirname($fromfile);

  # strip existing timestamp from beginning of fromfile
  # (formats checked are: NNNN.NN.NN and NNNN.NN.NN.NN.NN.NN
  #  where N is a digit and . is no digit)
  $newname = $filename;
  $newname =~ s/^[0-9]{4}([^0-9][0-9]{2}){2}(([^0-9][0-9]{2}){3})?//;

  # strip delimiter characters (-_ ) from beginning of fromfile
  $newname =~ s/^(-|_| )*//;

  # check if the new name would be the same as the old name
  if ($filename eq "$timestamp $newname") {
      if ($verbose == TRUE) {
          print "name is OK, doing nothing: $fromfile\n";
      }
      next;
  }

  # rename the file

  # counter for adding a number, if the file name already exists
  $try = 0;
  while (1) {

      # build target fromfile
      if ($try == 0) {
          $filenumber = "";
      } else {
          $filenumber = "-" . $try;
      }
      $tofile = "$dirname/$timestamp$filenumber $newname";

      # test if file already exists
      if (-e "$tofile") { 
          # increase number and do the loop again
          $try = $try + 1;
          next;
      }

      # move file
      if ($verbose == TRUE) {
          if ($pretend == TRUE) {
              print "not ";
          }
          print "renaming '$fromfile' to '$tofile'\n";
      }
      if ($pretend == FALSE) {
          move($fromfile, $tofile);
      }
      last;
  }
}

sub print_help {
    print "time2filename.pl will add prepend a files name with a timestamp.\n";
    print "If present it will use the EXIF-Timestamp included in the file.\n";
    print "If not it will use the files modification time.\n";
    print "\n";
    print "command line arguments:\n";
    print "  -p      just pretend to rename files, do nothing (implies -v)\n";
    print "  -a<sec> adjust time by <sec> seconds. can be negative\n";
    print "  -v      be verbose\n";
    print "  --      stop arguments scanning (for files named -v or the like)\n";
    print "  -h      print this help\n";
    print "\n";
    print "hint: to recurse into subdirectories use\n";
    print "  find <pathname ...> -exec time2filename.pl -p {} \\;\n";
}