#  You may distribute under the terms of either the GNU General Public License
#  or the Artistic License (the same terms as Perl itself)
#
#  (C) Paul Evans, 2011-2013 -- leonerd@leonerd.org.uk

package Tangence::Server;

use strict;
use warnings;

use base qw( Tangence::Stream );

our $VERSION = '0.16';

use Carp;

use Scalar::Util qw( weaken );

use Tangence::Constants;
use Tangence::Server::Context;

# We will accept any version back to 1
use constant VERSION_MINOR_MIN => 1;

BEGIN {
   if( eval { require Sub::Name } ) {
      Sub::Name->import(qw( subname ));
   }
   else {
      # Emulate it by just returning the CODEref and ignoring setting the name
      *subname = sub { $_[1] };
   }
}

=head1 NAME

C<Tangence::Server> - mixin class for building a C<Tangence> server

=head1 SYNOPSIS

This class is a mixin, it cannot be directly constructed

 package Example::Server;
 use base qw( Base::Server Tangence::Server );

 sub new
 {
    my $class = shift;
    my %args = @_;

    my $registry = delete $args{registry};

    my $self = $class->SUPER::new( %args );

    $self->registry( $registry );

    return $self;
 }

 sub tangence_write
 {
    my $self = shift;
    $self->write( $_[0] );
 }

 sub on_read
 {
    my $self = shift;
    $self->tangence_readfrom( $_[0] );
 }

=head1 DESCRIPTION

This module provides mixin to implement a C<Tangence> server connection. It
should be mixed in to an object used to represent a single connection from a
client. It provides a location for the objects in server to store information
about the client connection, and coordinates passing messages between the
client and the objects in the server.

This is a subclass of L<Tangence::Stream> which provides implementations of
the required C<handle_request_> methods. A class mixing in C<Tangence::Server>
must still provide the C<write> method required for sending data to the
client.

For an example of a class that uses this mixin, see
L<Net::Async::Tangence::ServerProtocol>.

=cut

=head1 PROVIDED METHODS

The following methods are provided by this mixin.

=cut

sub subscriptions { shift->{subscriptions} ||= [] }
sub watches       { shift->{watches} ||= [] }

=head2 $server->registry( $registry )

=head2 $registry = $server->registry

Accessor to set or obtain the L<Tangence::Registry> object for the server.

=cut

sub registry
{
   my $self = shift;
   $self->{registry} = shift if @_;
   return $self->{registry};
}

sub tangence_closed
{
   my $self = shift;
   $self->SUPER::tangence_closed;

   if( my $subscriptions = $self->subscriptions ) {
      foreach my $s ( @$subscriptions ) {
         my ( $object, $event, $id ) = @$s;
         $object->unsubscribe_event( $event, $id );
      }

      undef @$subscriptions;
   }

   if( my $watches = $self->watches ) {
      foreach my $w ( @$watches ) {
         my ( $object, $prop, $id ) = @$w;
         $object->unwatch_property( $prop, $id );
      }

      undef @$watches;
   }
}

sub get_by_id
{
   my $self = shift;
   my ( $id ) = @_;

   return $self->registry->get_by_id( $id );
}

sub handle_request_CALL
{
   my $self = shift;
   my ( $token, $message ) = @_;
   
   my $objid = $message->unpack_int();

   my $ctx = Tangence::Server::Context->new( $self, $token );

   my $object = $self->registry->get_by_id( $objid ) or
      return $ctx->responderr( "No such object with id $objid" );

   my $response = eval { $object->handle_request_CALL( $ctx, $message ) };
   $@ and return $ctx->responderr( $@ );

   $ctx->respond( $response );
}

sub handle_request_SUBSCRIBE
{
   my $self = shift;
   my ( $token, $message ) = @_;
   
   my $objid = $message->unpack_int();
   my $event = $message->unpack_str();

   my $ctx = Tangence::Server::Context->new( $self, $token );

   my $object = $self->registry->get_by_id( $objid ) or
      return $ctx->responderr( "No such object with id $objid" );

   weaken( my $weakself = $self );

   my $id = $object->subscribe_event( $event,
      subname "__SUBSCRIBE($event)__" => sub {
         $weakself or return;
         my $object = shift;

         my $message = $object->generate_message_EVENT( $weakself, $event, @_ );
         $weakself->request(
            request     => $message,
            on_response => sub { "IGNORE" },
         );
      }
   );

   push @{ $self->subscriptions }, [ $object, $event, $id ];

   $ctx->respond( Tangence::Message->new( $self, MSG_SUBSCRIBED ) );
}

sub handle_request_UNSUBSCRIBE
{
   my $self = shift;
   my ( $token, $message ) = @_;
   
   my $objid = $message->unpack_int();
   my $event = $message->unpack_str();

   my $ctx = Tangence::Server::Context->new( $self, $token );

   my $object = $self->registry->get_by_id( $objid ) or
      return $ctx->responderr( "No such object with id $objid" );

   my $edef = $object->can_event( $event ) or
      return $ctx->responderr( "Object cannot respond to event $event" );

   # Delete from subscriptions and obtain id
   my $id;
   @{ $self->subscriptions } = grep { $_->[0] == $object and $_->[1] eq $event and ( $id = $_->[2], 0 ) or 1 }
                                 @{ $self->subscriptions };
   defined $id or
      return $ctx->responderr( "Not subscribed to $event" );

   $object->unsubscribe_event( $event, $id );

   $ctx->respond( Tangence::Message->new( $self, MSG_OK ) );
}

sub handle_request_GETPROP
{
   my $self = shift;
   my ( $token, $message ) = @_;
   
   my $objid = $message->unpack_int();

   my $ctx = Tangence::Server::Context->new( $self, $token );

   my $object = $self->registry->get_by_id( $objid ) or
      return $ctx->responderr( "No such object with id $objid" );

   my $response = eval { $object->handle_request_GETPROP( $ctx, $message ) };
   $@ and return $ctx->responderr( $@ );

   $ctx->respond( $response );
}

sub handle_request_GETPROPELEM
{
   my $self = shift;
   my ( $token, $message ) = @_;

   my $objid = $message->unpack_int();

   my $ctx = Tangence::Server::Context->new( $self, $token );

   my $object = $self->registry->get_by_id( $objid ) or
      return $ctx->responderr( "No such object with id $objid" );

   my $response = eval { $object->handle_request_GETPROPELEM( $ctx, $message ) };
   $@ and return $ctx->responderr( $@ );

   $ctx->respond( $response );
}

sub handle_request_SETPROP
{
   my $self = shift;
   my ( $token, $message ) = @_;
   
   my $objid = $message->unpack_int();

   my $ctx = Tangence::Server::Context->new( $self, $token );

   my $object = $self->registry->get_by_id( $objid ) or
      return $ctx->responderr( "No such object with id $objid" );

   my $response = eval { $object->handle_request_SETPROP( $ctx, $message ) };
   $@ and return $ctx->responderr( $@ );

   $ctx->respond( $response );
}

*handle_request_WATCH      = \&_handle_request_WATCHany;
*handle_request_WATCH_ITER = \&_handle_request_WATCHany;
sub _handle_request_WATCHany
{
   my $self = shift;
   my ( $token, $message ) = @_;
   
   my $objid = $message->unpack_int();
   my $prop  = $message->unpack_str();
   my $want_initial;
   my $iter_from;
   if( $message->type == MSG_WATCH ) {
      $want_initial = $message->unpack_bool();
   }
   elsif( $message->type == MSG_WATCH_ITER ) {
      $iter_from = $message->unpack_int();
   }

   my $ctx = Tangence::Server::Context->new( $self, $token );

   my $object = $self->registry->get_by_id( $objid ) or
      return $ctx->responderr( "No such object with id $objid" );

   my $pdef = $object->can_property( $prop ) or
      return $ctx->responderr( "Object does not have property $prop" );

   $self->_install_watch( $object, $prop );

   if( $message->type == MSG_WATCH ) {
      $ctx->respond( Tangence::Message->new( $self, MSG_WATCHING ) );
      $self->_send_initial( $object, $prop ) if $want_initial;
   }
   elsif( $message->type == MSG_WATCH_ITER ) {
      my $m = "iter_prop_$prop";
      my $iter = $object->$m( $iter_from );
      my $id = $self->message_state->{next_iterid}++;
      $self->peer_hasiter->{$id} = $iter;
      $ctx->respond( Tangence::Message->new( $self, MSG_WATCHING_ITER )
         ->pack_int( $id )
         ->pack_int( 0 ) # first index
         ->pack_int( $#{ $object->${\"get_prop_$prop"} } ) # last index
      );
   }
}

sub _send_initial
{
   my $self = shift;
   my ( $object, $prop ) = @_;

   my $m = "get_prop_$prop";
   return unless( $object->can( $m ) );

   eval {
      my $value = $object->$m();
      my $message = $object->generate_message_UPDATE( $self, $prop, CHANGE_SET, $value );
      $self->request(
         request     => $message,
         on_response => sub { "IGNORE" },
      );
   };
   warn "$@ during initial property fetch" if $@;
}

sub handle_request_UNWATCH
{
   my $self = shift;
   my ( $token, $message ) = @_;
   
   my $objid = $message->unpack_int();
   my $prop  = $message->unpack_str();

   my $ctx = Tangence::Server::Context->new( $self, $token );

   my $object = $self->registry->get_by_id( $objid ) or
      return $ctx->responderr( "No such object with id $objid" );

   my $pdef = $object->can_property( $prop ) or
      return $ctx->responderr( "Object does not have property $prop" );

   # Delete from watches and obtain id
   my $id;
   @{ $self->watches } = grep { $_->[0] == $object and $_->[1] eq $prop and ( $id = $_->[2], 0 ) or 1 }
                         @{ $self->watches };
   defined $id or
      return $ctx->responderr( "Not watching $prop" );

   $object->unwatch_property( $prop, $id );

   $ctx->respond( Tangence::Message->new( $self, MSG_OK ) );
}

sub handle_request_ITER_NEXT
{
   my $self = shift;
   my ( $token, $message ) = @_;

   my $iterid = $message->unpack_int();

   my $ctx = Tangence::Server::Context->new( $self, $token );

   my $iter = $self->peer_hasiter->{$iterid} or
      return $ctx->responderr( "No such iterator with id $iterid" );

   $iter->handle_request_ITER_NEXT( $ctx, $message );
}

sub handle_request_ITER_DESTROY
{
   my $self = shift;
   my ( $token, $message ) = @_;

   my $iterid = $message->unpack_int();

   my $ctx = Tangence::Server::Context->new( $self, $token );

   delete $self->peer_hasiter->{$iterid};

   $ctx->respond( Tangence::Message->new( $self, MSG_OK ) );
}

sub handle_request_INIT
{
   my $self = shift;
   my ( $token, $message ) = @_;

   my $major = $message->unpack_int();
   my $minor_max = $message->unpack_int();
   my $minor_min = $message->unpack_int();

   my $ctx = Tangence::Server::Context->new( $self, $token );

   if( $major != VERSION_MAJOR ) {
      return $ctx->responderr( "Major version $major not available" );
   }

   # Don't accept higher than the minor version we recognise
   $minor_max = VERSION_MINOR if $minor_max > VERSION_MINOR;
   $minor_min = VERSION_MINOR_MIN if $minor_min < VERSION_MINOR_MIN;

   if( $minor_max < $minor_min ) {
      return $ctx->responderr( "No suitable minor version available" );
   }

   # For unit tests or other synchronous cases, we need to set the version
   # -before- we send the message. But we'd better construct the response
   # message before setting the version, in case it makes a difference.
   my $response = Tangence::Message->new( $self, MSG_INITED )
      ->pack_int( $major )
      ->pack_int( $minor_max );

   $self->minor_version( $minor_max );

   $ctx->respond( $response );
}

sub handle_request_GETROOT
{
   my $self = shift;
   my ( $token, $message ) = @_;
   
   my $identity = $message->unpack_any();

   my $ctx = Tangence::Server::Context->new( $self, $token );

   my $root = $self->registry->get_by_id( 1 );

   $self->identity( $identity );

   $ctx->respond( Tangence::Message->new( $self, MSG_RESULT )
      ->pack_obj( $root )
   );
}

sub handle_request_GETREGISTRY
{
   my $self = shift;
   my ( $token ) = @_;

   my $ctx = Tangence::Server::Context->new( $self, $token );

   $ctx->respond( Tangence::Message->new( $self, MSG_RESULT )
      ->pack_obj( $self->registry )
   );
}

my %change_values = (
   on_set    => CHANGE_SET,
   on_add    => CHANGE_ADD,
   on_del    => CHANGE_DEL,
   on_push   => CHANGE_PUSH,
   on_shift  => CHANGE_SHIFT,
   on_splice => CHANGE_SPLICE,
   on_move   => CHANGE_MOVE,
);

sub _install_watch
{
   my $self = shift;
   my ( $object, $prop ) = @_;

   my $pdef = $object->can_property( $prop );
   my $dim = $pdef->dimension;

   weaken( my $weakself = $self );

   my %callbacks;
   foreach my $name ( @{ CHANGETYPES->{$dim} } ) {
      my $how = $change_values{$name};
      $callbacks{$name} = subname "__WATCH($prop:$name)__" => sub {
         $weakself or return;
         my $object = shift;

         my $message = $object->generate_message_UPDATE( $weakself, $prop, $how, @_ );
         $weakself->request(
            request     => $message,
            on_response => sub { "IGNORE" },
         );
      };
   }

   my $id = $object->watch_property( $prop, %callbacks );

   push @{ $self->watches }, [ $object, $prop, $id ];
}

sub object_destroyed
{
   my $self = shift;
   my ( $obj ) = @_;

   if( my $subs = $self->subscriptions ) {
      my $i = 0;
      while( $i < @$subs ) {
         my $s = $subs->[$i];

         $i++, next unless $s->[0] == $obj;

         my ( undef, $event, $id ) = @$s;
         $obj->unsubscribe_event( $event, $id );

         splice @$subs, $i, 1;
         # No $i++
      }
   }

   if( my $watches = $self->watches ) {
      my $i = 0;
      while( $i < @$watches ) {
         my $w = $watches->[$i];

         $i++, next unless $w->[0] == $obj;

         my ( undef, $prop, $id ) = @$w;
         $obj->unwatch_property( $prop, $id );

         splice @$watches, $i, 1;
         # No $i++
      }
   }

   $self->SUPER::object_destroyed( @_ );
}

=head1 AUTHOR

Paul Evans <leonerd@leonerd.org.uk>

=cut

0x55AA;