package Tree::Transform::XSLTish;
use strict;
use warnings;
use Sub::Exporter;
use Params::Validate ':all';
use Tree::Transform::XSLTish::Utils;
use Tree::Transform::XSLTish::Transformer;
use Carp::Clan qw(^Tree::Transform::XSLTish);

our $VERSION='0.1';

Sub::Exporter::setup_exporter({
    exports => [qw(tree_rule default_rules new_transformer)],
    groups => {
        default => [ 'tree_rule',
                     'default_rules',
                     'new_transformer' => {-as => 'new'} ],
    }
});

sub default_rules {
    my $store=Tree::Transform::XSLTish::Utils::_rules_store(scalar caller);

    push @{$store->{by_match}},
        {match=> '/',priority=>0,action=>sub { $_[0]->apply_rules } },
        {match=> '*',priority=>0,action=>sub { $_[0]->apply_rules } },
            ;
    return;
}

sub tree_rule {
    my (%args)=validate(@_, {
        match => { type => SCALAR, optional => 1 },
        action => { type => CODEREF },
        name => { type => SCALAR, optional => 1},
        priority => { type => SCALAR, default => 1 },
    });

    # TODO at least one of 'name' and 'match' must be specified
    # TODO default priority mased on match

    my $store=Tree::Transform::XSLTish::Utils::_rules_store(scalar caller);

    if ($args{match}) {
        push @{$store->{by_match}},\%args;
    }
    if ($args{name}) {
        if (exists $store->{by_name}{$args{name}}) {
            carp "Duplicate rule named $args{name}, ignoring";
            return;
        }
        $store->{by_name}{$args{name}}=\%args;
    }

    return;
}

sub _transformer_class { 'Tree::Transform::XSLTish::Transformer' };

sub new_transformer {
    my $rules_package=shift;

    return _transformer_class->new(rules_package=>$rules_package,@_);
}

1;
__END__

=head1 NAME

Tree::Transform::XSLTish - transform tree data, like XSLT but in Perl

=head1 SYNOPSIS

  package MyTransform;
  use Tree::Transform::XSLTish;

  default_rules;

  tree_rule match => 'node[@id=5]', action => sub {
    return $_[0]->it->data();
  };

  package main;
  use My::Tree;

  my $tree= My::Tree->new();
  # build something inside the tree

  my ($node5_data)=MyTransform->new->transform($tree);

=head1 DESCRIPTION

This module allows you to transform tree with Perl subroutines, just
like XSLT does for XML documents.

It tries to model as closely as reasonable the semantic of XSLT.

=head1 REQUIREMENTS

=head1 AUTHOR

Gianni Ceccarelli <dakkar@thenautilus.net>

=cut