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use strict;
use warnings;
use POSIX qw(strftime);

# fix lib paths, some may be relative
BEGIN { # BEGIN RT CMD BOILERPLATE
    require File::Spec;
    require Cwd;
    my @libs = ("@RT_LIB_PATH@", "@LOCAL_LIB_PATH@");
    my $bin_path;

    for my $lib (@libs) {
        unless ( File::Spec->file_name_is_absolute($lib) ) {
            $bin_path ||= ( File::Spec->splitpath(Cwd::abs_path(__FILE__)) )[1];
            $lib = File::Spec->catfile( $bin_path, File::Spec->updir, $lib );
        }
        unshift @INC, $lib;
    }

}

# Read in the options
my %opts;
use Getopt::Long;
GetOptions( \%opts,
    "help|h",
    "verbose|v",
    "age=s",
    "batchsize=s",
    "dry-run",
);

if ($opts{'help'}) {
    require Pod::Usage;
    print Pod::Usage::pod2usage(-verbose => 2);
    exit;
}

if ($opts{'dry-run'}) {
    RT->Logger->info("(DRY-RUN, no changes made)");
    # dry-run implies verbose output
    $opts{verbose} = 1;
}

use RT -init;

# Ensure we only run one of these processes at once
use Fcntl ':flock';
exit unless flock main::DATA, LOCK_EX | LOCK_NB;

use Digest::SHA qw//;

my $ExternalStorage = RT->System->ExternalStorage;

die "\%ExternalStorage is not configured\n"
    unless $ExternalStorage;

if ($ExternalStorage->can('IsWriteable')) {
    my ($ok, $msg) = $ExternalStorage->IsWriteable;
    die $msg if !$ok;
}

# pull out the previous high-water mark for each object type
my $last = RT->System->FirstAttribute("ExternalStorage");
$last = $last ? $last->Content : {};

for my $class (qw/RT::Attachments RT::ObjectCustomFieldValues/) {
    my $column = $class eq 'RT::Attachments' ? "Content" : "LargeContent";
    my $id = $last->{$class} || 0;
    my $batchsize = $opts{'batchsize'} || 1;

    while (1) {
        my $attach = $class->new($RT::SystemUser);
        $attach->Limit(
            FIELD    => 'id',
            OPERATOR => '>',
            VALUE    => $id,
        );
        $attach->Limit(
            FIELD           => 'ContentEncoding',
            OPERATOR        => '!=',
            VALUE           => 'external',
            ENTRYAGGREGATOR => 'AND',
        );

        if ($opts{'age'}) {
            my $agelimit = strftime "%F", localtime(time()-$opts{'age'}*24*60*60);
            $attach->Limit(
                FIELD           => 'Created',
                OPERATOR        => '<',
                VALUE           => $agelimit,
                ENTRYAGGREGATOR => 'AND',
            );
        }

        if ($class eq "RT::ObjectCustomFieldValues") {
            $attach->{'find_disabled_rows'} = 1;
        }

        $attach->RowsPerPage(100);
        while ( my $a = $attach->Next and $batchsize > 0) {
            $id = $a->id;

            if ($opts{'batchsize'}) {
                $batchsize -= 1;
            }

            my ($ok, $why) = $a->ShouldStoreExternally;
            if (!$ok) {
                if ($opts{verbose}) {
                    RT->Logger->info("Skipping $class $id because: $why");
                }
                next;
            }

            # Explicitly get bytes (not characters, which ->$column would do)
            my $content = $a->_DecodeLOB(
                "application/octet-stream",
                $a->ContentEncoding,
                $a->_Value( $column, decode_utf8 => 0),
            );

            # Attempt to write that out
            if ($opts{verbose}) {
                RT->Logger->info("Storing $class $id");
            }

            my ($key, $msg) = ('DRY-RUN', '');
            if (!$opts{'dry-run'}) {
                ($key, $msg) = Store( $content, $a );
                unless ($key) {
                    RT->Logger->error("Failed to store $class $id: $msg");
                    exit 1;
                }

                $RT::Handle->dbh->begin_work;

                (my $status, $msg ) = $a->__Set(
                    Field => $column, Value => $key
                );
                unless ($status) {
                    RT->Logger->error("Failed to update $column of $class $id: $msg");
                    exit 2;
                }

                ( $status, $msg ) = $a->__Set(
                    Field => 'ContentEncoding', Value => 'external',
                );
                unless ($status) {
                    RT->Logger->error("Failed to update ContentEncoding of $class $id: $msg");
                    exit 2;
                }

                $RT::Handle->dbh->commit;
            }

            if ($opts{verbose}) {
                RT->Logger->info("Stored $class $id as $key");
            }
        }

        last unless $attach->Count and $batchsize > 0;
    }
    $last->{$class} = $id;
}

if (!$opts{'dry-run'}) {
    # update high-water mark for each object type
    RT->System->SetAttribute( Name => "ExternalStorage", Content => $last );
}

sub Store {
    my $content = shift;
    my $attachment = shift;

    my $sha = Digest::SHA::sha256_hex( $content );
    return $ExternalStorage->Store( $sha => $content, $attachment );
}

=head1 NAME

rt-externalize-attachments - Move attachments from database to external storage

=head1 SYNOPSIS

    rt-externalize-attachments [options]

=head1 DESCRIPTION

rt-externalize-attachments is used to move attachments out of the database to
some external storage.

=head1 OPTIONS

=over 8

=item --age=AGE

If age is given, then only attachments older than C<AGE> days will be moved.
By default everything is moved.

=item --batchsize=NUM

If batchsize is given, then only C<NUM> number of attachments will be moved.
By default everything is moved.

=item -h

=item --help

Display this documentation

=item -v

=item --verbose

Log a message (at level "info") for each attachment, both before its
upload begins and after it completes.

=item --dry-run

Make a trial run and do no changes (mostly the same output as a real run is
produced). C<dry-run> implies verbose output.

=back

=head1 SEE ALSO

L<RT_Config.html/External-storage>, L<RT::ExternalStorage>

=cut

# don't remove; for locking (see call to flock above)
__DATA__