#!/usr/bin/env perl

=pod

=head1 NAME

digikam-extract - find files by tag in a DigiKam 4 database

=head1 SYNOPSIS

    # List photos tagged "mom-album-2020":
    digikam-extract --tag mom-album-2020

    # Copy tagged items to current dir, renamed by date:
    digikam-extract --tag mom-album-2020 --copy

    # Same, but falling back to file mtime for anything with a year of 1980:
    digikam-extract --tag mom-album-2020 --ctime-fallback 1980 --copy

=head1 DESCRIPTION

A silly hack for tagging photos in DigiKam and then copying the tagged stuff
into a separate directory and renaming the files according to their creation
date.  If I need this workflow again, I may generalize this, but it's probably
worth noting that the database schema is effectively an undocumented API and
could easily get yanked out from under this code at any time.

=head1 OPTIONS

=over 4

=item B<--tag> [tagname]

Specify a tag to search for.  Required.

=item B<--copy> [path]

Copy files to destination path.  Defaults to working directory.

=item B<--dest> [path]

Specify a destination path.

=item B<--ctime-fallback> [year]

Specify a year which probably means that the camera's date wasn't set, and fall
back to whatever DigiKam's db thinks the modification time is instead.

=item B<--dbfile> [path]

Specify location of DigiKam4 database file.

=item B<--date-format> "format"

Specify date format for target filenames.  See strftime(3) for date format.

Defaults to C<%Y-%m-%d-%H%M%S>.

=item B<--root> [path]

Specify a gallery path.  Must correspond to a root album folder defined in
Collections Settings in DigiKam.  No trailing slash.

=item B<--help>

Print help and exit.

=back

=head1 AUTHOR

Brennen Bearnes

=cut

use warnings;
use strict;

use Cwd;
use DBI;
use Data::Dumper;
use File::Basename;
use File::Spec;
use Getopt::Long;
use Pod::Usage;
use SQL::Abstract;
use Time::Piece;
use Time::Seconds;
use File::Copy;
use File::HomeDir;

my $HOME = File::HomeDir->my_home;

# Handle options, including help generated from the POD above.
# TODO: This should use digikam config to extract current path to db
#       and roots should be extracted from the database, most likely.
my $copy = 0;
my $tag;
my $dest = getcwd();
my $ctime_fallback;
my $date_format = '%Y-%m-%d-%H%M%S';
my $dbfile = $HOME . "/digikam-db/digikam4.db";
my $root = $HOME . '/workspace/photos';

GetOptions(
  'copy'             => \$copy,
  'dest=s'           => \$dest,
  'tag=s'            => \$tag,
  'root=s'           => \$root,
  'dbfile=s'         => \$dbfile,
  'ctime-fallback=s' => \$ctime_fallback,
  'date-format'      => \$date_format,
  'help'             => sub { pod2usage(-verbose => 2) },
) or pod2usage(-verbose => 1, );

# Handle a couple of likely failure modes:
unless (defined $tag) {
  print "Please specify a tag name with --tag\n";
  exit(2);
}

foreach my $path ($dest, $root) {
  die("$path is not a directory")
    unless -d $path;
}

my $query = q{
  SELECT i.id, ii.creationDate, i.modificationDate, ar.specificPath,
         a.relativePath, i.name AS image_name, t.name AS tag_name
    FROM Tags t JOIN ImageTags it ON it.tagid = t.id
         JOIN Images i ON it.imageid = i.id
         JOIN Albums a ON i.album = a.id
         JOIN AlbumRoots ar ON ar.id = a.albumRoot
         JOIN ImageInformation ii ON ii.imageid = i.id
    WHERE
      t.name = ? AND ar.specificPath = ?
    ;
};

my $dbh = DBI->connect("dbi:SQLite:dbname=$dbfile", "", "");
my @bind = ($tag, $root);

my $sth = $dbh->prepare($query);
$sth->execute(@bind);

unless ($copy) {
  print "Dry run.  Would copy:\n\n"
}

my %sources;
while (my $data = $sth->fetchrow_hashref()) {
  my $cdate = Time::Piece->strptime($data->{creationDate}, "%Y-%m-%dT%T");
  my $mdate = Time::Piece->strptime($data->{modificationDate}, "%Y-%m-%dT%T");

  my $date = $cdate->strftime($date_format);
  if (defined $ctime_fallback) {
    # If we got a year to fall back to the mtime for, then do that -
    # so like if a bunch of stuff has 1980 because the clock wasn't
    # set right on the camera...
    if ($ctime_fallback eq $cdate->strftime('%Y')) {
      $date = $mdate->strftime($date_format);
    }
  }

  # print "$date\t";
  my $source = $root . $data->{'relativePath'} . "/" . $data->{image_name};
  my $dest = "$dest/$date-$data->{image_name}";

  if (defined $sources{$dest}) {
    die("Collision: $source and $sources{$dest} would collide, making no copies");
  } else {
    $sources{$dest} = $source;
  }
}

foreach my $dest (keys %sources) {
  my $source = $sources{$dest};
  print "$source -> $dest\n";
  next unless $copy;

  if (-e $dest) {
    print "Destination already exists: $dest\n";
  } else {
    copy($source, $dest);
  }
}

unless ($copy) {
  print "\nAdd --copy to invocation to copy to $dest\n";
}