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package Mac::Finder::DSStore;

=head1 NAME

Mac::Finder::DSStore - Read and write Macintosh Finder DS_Store files

=head1 DESCRIPTION

C<Mac::Finder::DSStore> provides a handful of functions for reading and
writing the desktop database files created by the Macintosh Finder.

=head1 FUNCTIONS

Many functions take a C<$store> argument which is the opened file as
an instance of L<Mac::Finder::DSStore::BuddyAllocator>, or a C<$block>
argument which is a specific block of the file as an instance of
L<Mac::Finder::DSStore::BuddyAllocator::Block>.

=cut

use strict;
use warnings;
use POSIX qw(ceil);
use Carp qw(croak);
use Fcntl;
require Exporter;

our($VERSION) = '1.00';
our(@ISA) = qw(Exporter);
our(@EXPORT_OK) = qw( getDSDBEntries putDSDBEntries writeDSDBEntries makeEntries );

our($testpoint);

=head2 @records = &Mac::Finder::DSStore::getDSDBEntries($store[, $callback])

Retrieves the "superblock" pointed to by the C<DSDB> entry in the store's table
of contents, and traverses the B-tree it points to, returning a list of
the records in the tree. Alternately, you can supply a callback which will
be invoked for each record, and C<getDSDBEntries> will return an empty list.

=cut

sub getBTreeRootblock {
    my($store) = @_;
    return $store->blockByNumber($store->{toc}->{DSDB})->read(20, 'N*');
}

sub getDSDBEntries {
    my($file, $callback) = @_;

    my(@retval);

    $callback = sub { push(@retval, $_[0]); } unless defined $callback;

    my($rootnode, $height, $nrec, $nnodes, $blksize) = &getBTreeRootblock($file);
    
    my($n) = &traverse_btree($file, $rootnode, $callback);

    warn "Header node count ($nrec) not equal to actual node count ($n)"
	if $n != $nrec;

    @retval;
}

=head2 &Mac::Finder::DSStore::putDSDBEntries($store, $arrayref)

C<$arrayref> must contain a correctly ordered list of
C<Mac::Finder::DSStore::Entry> objects. They will be evenly
organized into a B-tree structure and written to the C<$store>. If there is
an existing tree of records in the file already, it will be deallocated.