package MozRepl::RemoteObject::Methods;
use strict;
use Scalar::Util qw(blessed);

use vars qw[$VERSION];
$VERSION = '0.40';

=head1 NAME

MozRepl::RemoteObject::Methods - Perl methods for mozrepl objects

=head1 SYNOPSIS

  my @links = $obj->MozRepl::RemoteObject::Methods::xpath('//a');

This module holds the routines that previously lived
as injected object methods on I<all> Javascript objects.

=head1 METHODS

=head2 C<< $obj->MozRepl::RemoteObject::Methods::invoke(METHOD, ARGS) >>

The C<< invoke() >> object method is an alternate way to
invoke Javascript methods. It is normally equivalent to 
C<< $obj->$method(@ARGS) >>. This function must be used if the
METHOD name contains characters not valid in a Perl variable name 
(like foreign language characters).
To invoke a Javascript objects native C<< __invoke >> method (if such a
thing exists), please use:

    $object->MozRepl::RemoteObject::Methods::invoke('__invoke', @args);

This method can be used to call the Javascript functions with the
same name as other convenience methods implemented
in Perl:

    __attr
    __setAttr
    __xpath
    __click
    ...

=cut

sub invoke {
    my ($self,$fn,@args) = @_;
    my $id = $self->__id;
    die unless $self->__id;
    
    ($fn) = $self->MozRepl::RemoteObject::Methods::transform_arguments($fn);
    my $rn = bridge($self)->name;
    @args = $self->MozRepl::RemoteObject::Methods::transform_arguments(@args);
    local $" = ',';
    my $js = <<JS;
$rn.callMethod($id,$fn,[@args])
JS
    return bridge($self)->unjson($js);
}

=head2 C<< $obj->MozRepl::RemoteObject::Methods::transform_arguments(@args) >>

This method transforms the passed in arguments to their JSON string
representations.

Things that match C< /^(?:[1-9][0-9]*|0+)$/ > get passed through.
 
MozRepl::RemoteObject::Instance instances
are transformed into strings that resolve to their
Javascript global variables. Use the C<< ->expr >> method
to get an object representing these.
 
It's also impossible to pass a negative or fractional number
as a number through to Javascript, or to pass digits as a Javascript string.

=cut
 
sub transform_arguments {
    my $self = shift;
    my $json = bridge($self)->json;
    map {
        if (! defined) {
             'null'
        } elsif (/^(?:[1-9][0-9]*|0+)$/) {
            $_
        #} elsif (ref and blessed $_ and $_->isa(__PACKAGE__)) {
        } elsif (ref and blessed $_ and $_->isa('MozRepl::RemoteObject::Instance')) {
            sprintf "%s.getLink(%d)", bridge($_)->name, id($_)
        } elsif (ref and blessed $_ and $_->isa('MozRepl::RemoteObject')) {
            $_->name
        } elsif (ref and ref eq 'CODE') { # callback
            my $cb = $self->bridge->make_callback($_);
            sprintf "%s.getLink(%d)", bridge($self)->name,
                                      id($cb)
        } elsif (ref) {
            $json->encode($_);
        } else {
            $json->encode($_)
        }
    } @_
};

# Helper to centralize the reblessing
sub hash_get {
    my $class = ref $_[0];
    bless $_[0], "$class\::HashAccess";
    my $res = $_[0]->{ $_[1] };
    bless $_[0], $class;
    $res
};

sub hash_get_set {
    my $class = ref $_[0];
    bless $_[0], "$class\::HashAccess";
    my $k = $_[-1];
    my $res = $_[0]->{ $k };
    if (@_ == 3) {
        $_[0]->{$k} = $_[1];
    };
    bless $_[0], $class;
    $res
};

=head2 C<< $obj->MozRepl::RemoteObject::Methods::id >>

Readonly accessor for the internal object id
that connects the Javascript object to the
Perl object.

=cut

sub id { hash_get( $_[0], 'id' ) };

=head2 C<< $obj->MozRepl::RemoteObject::Methods::on_destroy >>

Accessor for the callback
that gets invoked from C<< DESTROY >>.

=cut

sub on_destroy { hash_get_set( @_, 'on_destroy' )};

=head2 C<< $obj->MozRepl::RemoteObject::Methods::bridge >>

Readonly accessor for the bridge
that connects the Javascript object to the
Perl object.

=cut

sub bridge { hash_get( $_[0], 'bridge' )};

=head2 C<< MozRepl::RemoteObject::Methods::as_hash($obj) >>

=head2 C<< MozRepl::RemoteObject::Methods::as_array($obj) >>

=head2 C<< MozRepl::RemoteObject::Methods::as_code($obj) >>

Returns a reference to a hash/array/coderef. This is used
by L<overload>. Don't use these directly.

=cut


sub as_hash {
    my $self = shift;
    tie my %h, 'MozRepl::RemoteObject::TiedHash', $self;
    \%h;
};

sub as_array {
    my $self = shift;
    tie my @a, 'MozRepl::RemoteObject::TiedArray', $self;
    \@a;
};

sub as_code {
    my $self = shift;
    my $class = ref $self;
    my $id = id($self);
    my $context = hash_get($self, 'return_context');
    return sub {
        my (@args) = @_;
        my $bridge = bridge($self);
        
        my $rn = $bridge->name;
        @args = transform_arguments($self,@args);
        local $" = ',';
        my $js = <<JS;
    $rn.callThis($id,[@args])
JS
        return $bridge->expr($js,$context);
    };
};

sub object_identity {
    my ($self,$other) = @_;
    return if (   ! $other 
               or ! ref $other
               or ! blessed $other
               or ! $other->isa('MozRepl::RemoteObject::Instance')
               or ! $self->isa('MozRepl::RemoteObject::Instance'));
    my $left = id($self)
        or die "Internal inconsistency - no id found for $self";
    my $right = id($other);
    my $bridge = bridge($self);
    my $rn = $bridge->name;
    my $data = $bridge->expr(<<JS);
$rn.getLink($left)===$rn.getLink($right)
JS
}

=head2 C<< $obj->MozRepl::RemoteObject::Methods::xpath( $query [, $ref, $cont ] ) >>

Executes an XPath query and returns the node
snapshot result as a list.

This is a convenience method that should only be called
on HTMLdocument nodes.

The optional C<$ref> parameter can be a DOM node relative to which a
relative XPath expression will be evaluated. It defaults to C<undef>.

The optional C<$cont> parameter can be a Javascript function that
will get applied to every result. This can be used to directly map
each DOM node in the XPath result to an attribute. For example
for efficiently fetching the text value of an XPath query resulting in
textnodes, the two snippets are equivalent, but the latter executes
less roundtrips between Perl and Javascript:

    my @text = map { $_->{nodeValue} }
        $obj->MozRepl::RemoteObject::Methods::xpath( '//p/text()' )


    my $fetch_nodeValue = $bridge->declare(<<JS);
        function (e){ return e.nodeValue }
    JS
    my @text = map { $_->{nodeValue} }
        $obj->MozRepl::RemoteObject::Methods::xpath( '//p/text()', undef, $fetch_nodeValue )

Note that the result type is fetched with C< XPathResult.ORDERED_NODE_SNAPSHOT_TYPE >.
There is no support for retrieving results as C< XPathResult.ANY_TYPE > yet.

=cut

sub xpath {
    my ($self,$query,$ref,$cont) = @_; # $self is a HTMLdocument
    $ref ||= $self;
    my $js = <<'JS';
    function(doc,q,ref,cont) {
        var xres = doc.evaluate(q,ref,null,XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null );
        var map;
        if( cont ) {
            map = cont;
        } else {
            // Default is identity
            map = function(e){ return e };
        };
        var res = [];
        for ( var i=0 ; i < xres.snapshotLength; i++ )
        {
            res.push( map(xres.snapshotItem(i)));
        };
        return res
    }
JS
    my $snap = $self->bridge->declare($js,'list');
    $snap->($self,$query,$ref,$cont);
}


=head2 C<< MozRepl::RemoteObject::Methods::dive($obj) >>

Convenience method to quickly dive down a property chain.

If any element on the path is missing, the method dies
with the error message which element was not found.

This method is faster than descending through the object
forest with Perl, but otherwise identical.

  my $obj = $tab->{linkedBrowser}
                ->{contentWindow}
                ->{document}
                ->{body}

  my $obj = $tab->MozRepl::RemoteObject::Methods::dive(
      qw(linkedBrowser contentWindow document body)
  );

=cut

sub dive {
    my ($self,@path) = @_;
    my $id = id($self);
    die unless $id;
    my $rn = bridge($self)->name;
    (my $path) = transform_arguments($self,\@path);
    
    my $data = bridge($self)->unjson(<<JS);
$rn.dive($id,$path)
JS
}

1;

__END__

=head1 SEE ALSO

L<MozRepl::RemoteObject> for the objects to use this with

=head1 REPOSITORY

The public repository of this module is 
L<http://github.com/Corion/mozrepl-remoteobject>.

=head1 AUTHOR

Max Maischein C<corion@cpan.org>

=head1 COPYRIGHT (c)

Copyright 2011-2012 by Max Maischein C<corion@cpan.org>.

=head1 LICENSE

This module is released under the same terms as Perl itself.

=cut