package Jifty::Subs::Render;
use strict;
use warnings;

use base qw/Jifty::Object/;

=head1 NAME

Jifty::Subs::Render - Helper for subscriptions rendering

=head1 SYNOPSIS

  Jifty::Subs::Render->render($id, $callback);

=head1 DESCRIPTION



=head2 render($id, $callback)

Render all outstanding messages, and call C<$callback> with render
mode, region name, and content.

=cut

sub render {
    my ( $class, $id, $callback ) = @_;
    my $got;

    # # of fragments sent
    my $sent = 0;

    # Get the IPC::PubSub::Subscriber object and do one fetch of all new
    # events it subscribes to, and put those into $got.
    my $subs
        = Jifty->bus->modify( "$id-subscriber", sub { $got = $_ ? $_->get_all : {} } );

    return 0 unless %$got;

    # Now we the render options for those channels (calling ->modify instead
    # of ->fetch because we want to block if someone else is touching it;
    # it's equivalent to ->modify("$id-render", sub { $_ }).
    my $render = Jifty->bus->modify("$id-render");

    my %coalesce;
    while ( my ( $channel, $msgs ) = each(%$got) ) {
        # Channel name is always App::Event::Class-MD5QUERIES
        my $event_class = $channel;
        $event_class =~ s/-.*//;

        unless ( UNIVERSAL::can( $event_class => 'new' ) ) {
            $class->log->error("Receiving unknown event $event_class from the Bus");
            $event_class = Jifty->app_class("Event");
        }

        foreach my $rv (@$msgs) {

            # XXX - We don't yet use $timestamp here.
            my ( $timestamp, $msg ) = @$rv;

            for my $render_info (values %{$render->{$channel}}) {
                if ($render_info->{coalesce} and $render_info->{mode} eq "Replace") {
                    my $hash = Digest::MD5::md5_hex( YAML::Dump([$render_info->{region}, $render_info->{render_with}] ) );
                    $class->log->debug("Coalesced duplicate region @{[$render_info->{region}]} with @{[$render_info->{render_with}]} from $channel event $msg") if exists $coalesce{$hash};
                    $coalesce{$hash} = [ $timestamp, $event_class, $msg, $render_info ] unless $coalesce{$hash} and $coalesce{$hash}[0] > $timestamp;
                } else {
                    $class->log->debug("Rendering $channel event $msg in @{[$render_info->{region}]} with @{[$render_info->{render_with}]}");
                    render_single( $event_class, $msg, $render_info, $callback );
                    $sent++;
                }
            }
        }
    }

    for my $c (values %coalesce) {
        my (undef, $event_class, $msg, $render_info) = @{$c};
        $class->log->debug("Rendering @{[$render_info->{region}]} with @{[$render_info->{render_with}]} for $event_class");
        render_single( $event_class, $msg, $render_info, $callback );
        $sent++;
    }

    return ($sent);
}

=head2 render_single CLASS, MESSAGE, INFO, CALLBACK

Renders a single region, based on the region information in C<INFO>.

=cut

sub render_single {
    my ($class, $msg, $render_info, $callback) = @_;

    my $region = Jifty::Web::PageRegion->new(
        name => $render_info->{region},
        path => $render_info->{render_with},
    );
    # So we don't warn about "duplicate region"s
    delete Jifty->web->{'regions'}{ $region->qualified_name };

    my $event_object   = $class->new($msg);
    # Region's arguments come from explicit arguments only
    $region->arguments( $render_info->{arguments} );

    $region->enter;
    # Also provide an 'event' argument, and fill in the render
    # arguments.  These don't show up in the region's arguments if
    # inspected, but do show up in the request.
    Jifty->handler->buffer->push( private => 1 );
    $region->render_as_subrequest(
        { %{$region->arguments}, event => $event_object, $event_object->render_arguments },
    );
    $callback->(
        $render_info->{mode},       
        $region->qualified_name,
        Jifty->handler->buffer->pop,
        $render_info->{attrs},
    );
    $region->exit;
}

1;