package SVG::Extension;
use strict;
use warnings;

our $VERSION = '2.84';

=head1 NAME

SVG::Extension - additional methods

=cut

# although DTD declarations are not elements, we use the same API so we can
# manipulate the internal DTD subset using the same methods available for
# elements. At this state, all extensions are the same object class, but
# may be subclassed in the future to e.g. SVG::Extension::ELEMENT. Use
# e.g. isElementDecl() to determine types; this API will be retained
# irrespective.

use parent qw/SVG::Element/;

# DTD declarations handled in this module
use constant ELEMENT  => 'ELEMENT';
use constant ATTLIST  => 'ATTLIST';
use constant NOTATION => 'NOTATION';
use constant ENTITY   => 'ENTITY';

our @TYPES = ( ELEMENT, ATTLIST, NOTATION, ENTITY );
our %TYPES = map { $_ => 1 } @TYPES;

#-----------------

sub new {
    return shift->SUPER::new(@_);
}

sub internal_subset {
    my $self = shift;

    my $document = $self->{-docref};
    unless ( exists $document->{-internal} ) {
        $document->{-internal} = new SVG::Extension('internal');
        $document->{-internal}{-docref} = $document;
    }

    return $document->{-internal};
}

=head2 extension

return the element object

=cut

sub extension {
    my $self = shift;
    my $class = ref($self) || $self;

    return bless $self->SUPER::element(@_), $class;
}

#-----------------

=head2 element_decl

generate an element declaration in the DTD

=cut

sub element_decl {
    my ( $self, %attrs ) = @_;
    my $subset = $self->internal_subset();

    return $subset->extension( 'ELEMENT', %attrs );
}

=head2 attribute_decl

return generate an attribute list for an element

=cut

sub attribute_decl {
    my ( $element_decl, %attrs ) = @_;

    unless ( $element_decl->getElementType eq 'ELEMENT' ) {
        $element_decl->error(
            $element_decl => 'is not an ELEMENT declaration' );
        return;
    }

    return $element_decl->extension( 'ATTLIST', %attrs );
}

=head2 attlist_decl

=cut

sub attlist_decl {
    my ( $self, %attrs ) = @_;
    my $subset = $self->internal_subset();

    my $element_decl = $subset->getElementDeclByName( $attrs{name} );
    unless ($element_decl) {
        $subset->error( "ATTLIST declaration '$attrs{attr}'" =>
                "ELEMENT declaration '$attrs{name}' does not exist" );
        return;
    }

    return $element_decl->attribute_decl(%attrs);
}

=head2 notation_decl(%attrs)

return an extension object of type NOTATION

=cut

sub notation_decl {
    my ( $self, %attrs ) = @_;
    my $subset = $self->internal_subset();

    return $subset->extension( 'NOTATION', %attrs );
}

=head2 entity_decl(%attrs)

return an extension object of type 'ENTITY'

=cut

sub entity_decl {
    my ( $self, %attrs ) = @_;
    my $subset = $self->internal_subset();

    return $subset->extension( 'ENTITY', %attrs );
}

#-----------------

# this interim version of xmlify handles the vanilla extension
# format of one parent 'internal' element containing a list of
# extension elements. A hierarchical model will follow in time
# with the same render API.

=head2 xmilfy

=cut

sub xmlify {
    my $self = shift;
    my $decl = q{};

    if ( $self->{-name} ne 'internal' ) {
        $decl = '<!';
    SWITCH: foreach ( $self->{-name} ) {
            /^ELEMENT$/ and do {
                $decl .= "ELEMENT $self->{name}";

                $decl .= q{ } . $self->{model} if exists $self->{model};

                last SWITCH;
            };
            /^ATTLIST$/ and do {
                $decl .= "ATTLIST $self->{name} $self->{attr}";

                $decl
                    .= " $self->{type} "
                    . ( $self->{fixed} ? '#FIXED ' : q{} )
                    . $self->{default};

                last SWITCH;
            };
            /^NOTATION$/ and do {
                $decl .= "NOTATION $self->{name}";

                $decl .= q{ } . $self->{base} if exists $self->{base};
                if ( exists $self->{pubid} ) {
                    $decl .= "PUBLIC $self->{pubid} ";
                    $decl .= q{ } . $self->{sysid} if exists $self->{sysid};
                }
                elsif ( exists $self->{sysid} ) {
                    $decl .= ' SYSTEM ' . $self->{sysid}
                        if exists $self->{sysid};
                }

                last SWITCH;
            };
            /^ENTITY$/ and do {
                $decl
                    .= 'ENTITY '
                    . ( $self->{isp} ? '% ' : q{} )
                    . $self->{name};

                if ( exists $self->{value} ) {
                    $decl .= ' "' . $self->{value} . '"';
                }
                elsif ( exists $self->{pubid} ) {
                    $decl .= "PUBLIC $self->{pubid} ";
                    $decl .= q{ } . $self->{sysid} if exists $self->{sysid};
                    $decl .= q{ } . $self->{ndata} if $self->{ndata};
                }
                else {
                    $decl .= ' SYSTEM ' . $self->{sysid}
                        if exists $self->{sysid};
                    $decl .= q{ } . $self->{ndata} if $self->{ndata};
                }

                last SWITCH;
            DEFAULT:

            # we don't know what this is, but the underlying parser allowed it
                $decl .= "$self->{-name} $self->{name}";
            };
        }
        $decl .= '>' . $self->{-docref}{-elsep};
    }

    my $result = q{};
    if ( $self->hasChildren ) {
        $self->{-docref}->{-level}++;
        foreach my $child ( $self->getChildren ) {
            $result
                .= ( $self->{-docref}{-indent} x $self->{-docref}->{-level} )
                . $child->render();
        }
        $self->{-docref}->{-level}--;
    }

    return $decl . $result;
}

#some aliases for xmilfy

=head2 render

alias for xmlify

=head2 to_xml

alias for xmlify

=head2 serialise

alias for xmlify

=head2 serialise

alias for xmlify

=cut

*render    = \&xmlify;
*to_xml    = \&xmlify;
*serialise = \&xmlify;
*serialize = \&xmlify;

#-----------------

=head2 getDeclName

Simply an alias for the general method for SVG::Extension objects

=head2 getExtensionName

alias to getDeclName

=cut

# simply an alias for the general method for SVG::Extension objects
sub getDeclName {
    return shift->SUPER::getElementName();
}
*getExtensionName = \&getDeclName;

=head2 getDeclNames

return list of existing decl types by extracting it from the overall list
of existing element types

sub getDeclNames {

=head2 getExtensionNames

alias to getDeclNames

=cut

# return list of existing decl types by extracting it from the overall list
# of existing element types
sub getDeclNames {
    my $self = shift;

    return grep { exists $TYPES{$_} } $self->SUPER::getElementNames();
}
*getExtensionNames = \&getDeclNames;

#-----------------

# we can have only one element decl of a given name...
sub getElementDeclByName {
    my ( $self, $name ) = @_;
    my $subset = $self->internal_subset();

    my @element_decls = $subset->getElementsByName('ELEMENT');
    foreach my $element_decl (@element_decls) {
        return $element_decl if $element_decl->{name} eq $name;
    }

    return;
}

# ...but we can have multiple attributes. Note that this searches the master list
# which is not what you are likely to want in most cases. See getAttributeDeclByName
# (no 's') below, to search for an attribute decl on a particular element decl.
# You can use the result of this method along with getParent to find the list of
# all element decls that define a given attribute.
sub getAttributeDeclsByName {
    my ( $self, $name ) = @_;
    my $subset = $self->internal_subset();

    my @element_decls = $subset->getElementsByName('ELEMENT');
    foreach my $element_decl (@element_decls) {
        return $element_decl if $element_decl->{name} eq $name;
    }

    return;
}

#-----------------

sub getElementDecls {
    return shift->SUPER::getElements('ELEMENT');
}

sub getNotations {
    return shift->SUPER::getElements('NOTATION');
}
*getNotationDecls = \&getNotations;

sub getEntities {
    return shift->SUPER::getElements('ENTITY');
}
*getEntityDecls = \&getEntities;

sub getAttributeDecls {
    return shift->SUPER::getElements('ATTLIST');
}

#-----------------
# until/unless we subclass these, use the name. After (if) we
# subclass, will use the object class.

sub isElementDecl {
    return ( shift->getElementName eq ELEMENT ) ? 1 : 0;
}

sub isNotation {
    return ( shift->getElementName eq NOTATION ) ? 1 : 0;
}

sub isEntity {
    return ( shift->getElementName eq ENTITY ) ? 1 : 0;
}

sub isAttributeDecl {
    return ( shift->getElementName eq ATTLIST ) ? 1 : 0;
}

#-----------------

# the Decl 'name' is an attribute, the name is e.g. 'ELEMENT'
# use getElementName if you want the actual decl type
sub getElementDeclName {
    my $self = shift;

    if ( exists $self->{name} ) {
        return $self->{name};
    }

    return;
}

# identical to the above; will be smarter as and when we subclass
# as above, the name is ATTLIST, the 'name' is a property of the decl
sub getAttributeDeclName {
    my $self = shift;

    if ( exists $self->{name} ) {
        return $self->{name};
    }

    return;
}

# unlike other 'By' methods, attribute searches work from their parent element
# del only. Multiple element decls with the same attribute name is more than
# likely, so searching the master ATTLIST is not very useful. If you really want
# to do that, use getAttributeDeclsByName (with an 's') above.
sub getAttributeDeclByName {
    my ( $self, $name ) = @_;

    my @attribute_decls = $self->getElementAttributeDecls();
    foreach my $attribute_decl (@attribute_decls) {
        return $attribute_decl if $attribute_decl->{name} eq $name;
    }

    return;
}

# as this is element specific, we allow a 'ElementAttribute' name too,
# for those that like consistency at the price of brevity. Not that
# the shorter name is all that brief to start with...
*getElementAttributeDeclByName = \&getAttributeDeclByName;

# ...and for those who live their brevity:
*getAttributeDecl = \&getAttributeDeclByName;

sub hasAttributeDecl {
    return ( shift->getElementDeclByName(shift) ) ? 1 : 0;
}

#-----------------
# directly map to Child/Siblings: we presume this is being called from an
# element decl. You can use 'getChildIndex', 'getChildAtIndex' etc. as well

sub getElementAttributeAtIndex {
    my ( $self, $index, @children ) = @_;

    return $self->SUPER::getChildAtIndex( $index, @children );
}

sub getElementAttributeIndex {
    return shift->SUPER::getChildIndex(@_);
}

sub getFirstAttributeDecl {
    return shift->SUPER::getFirstChild();
}

sub getNextAttributeDecl {
    return shift->SUPER::getNextSibling();
}

sub getLastAttributeDecl {
    return shift->SUPER::getLastChild();
}

sub getPreviousAttributeDecl {
    return shift->SUPER::getPreviousSibling();
}

sub getElementAttributeDecls {
    return shift->SUPER::getChildren();
}

#-------------------------------------------------------------------------------

# These methods are slated for inclusion in a future release of SVG.pm. They
# will allow programmatic advance determination of the validity of various DOM
# manipulations. If you are in a hurry for this feature, get in touch!
#
# example:
#    if ($svg_object->allowsElement("symbol")) { ... }
#
#package SVG::Element;
#
#sub allowedElements {}
#sub allowedAttributes {}
#
#sub allowsElement {}
#sub allowsAttribute {}
#

#-------------------------------------------------------------------------------

1;
