#!/usr/bin/perl

package Widget;
use Coro::State;
use Moose;

has 'results' => (is => 'rw');
has 'parent_state' => (is => 'rw');
has 'params' => (is => 'rw');

has 'state' => (is => 'rw', default => sub {
  my $self = shift;
  new Coro::State sub {
    $self->main(@{$self->params})
  }
});

sub yield {
  my ($self, @results) = @_;
  $self->results( [@results] );
  print STDERR "About to transfer...\n";
  $self->state->transfer($self->parent_state);
  print STDERR "back from transfer.\n";
  return @{$self->params};
}

sub exec {
  my ($self, @params) = @_;
  $self->params( \@params );
  my $parent = new Coro::State;
  $self->parent_state($parent);
  print STDERR "Transferring to child.\n";
  $parent->transfer($self->{state});
  print STDERR "Back from child.\n";
  #$self->parent_state(undef); # Kill circular reference!
  return wantarray ? @{$self->results} : $self->results->[0];
}

sub main { die "You should have overriden this!\n" }

package CounterWidget;
use Moose;
extends 'Widget';

use Data::UUID;

has 'uuid' => (
    is      => 'ro', 
    isa     => 'Str', 
    default => sub { 
        my $d = Data::UUID->new;
        $d->to_string($d->create);
    }
);

has 'request' => (is => 'rw');
has 'output' => (is => 'rw');

# Ask a question and keep asking until they answer. General purpose prompt.
sub prompt {
  my ($self, $msg, @ops) = @_;
  my $id = $self->uuid;
  $self->request->print("$msg<br>");
  for(my $i = 0; $i < scalar @ops; $i++) {
    $self->request->print(qq{<a href="?$id-option=$i">$ops[$i]</a>&nbsp;});
  }
  # Subtle! Halt, wait for next request, and grab the 'option' param
  $self->yield;
  my $option = $self->request->param("$id-option");
  return $option || $self->prompt($msg, @ops);
}

# Main is invoked when we get a new session
sub main {
  my ($self) = @_;

  # This keeps track of the number we're currently on
  my $counter = 0;

  # After we're done with that we enter a loop. Forever.
  while(1) {
    print STDERR "Displaying current count and waiting for instructions.\n";
    my $action = $self->prompt("Count: $counter", "++", "--");
    print STDERR "Got '$action' back from the user.\n";
    if($action eq '--' && $counter == 0) {
      my $choice = $self->prompt("Do you really want to GO NEGATIVE?", "Yes", "No");
      $action = '' if $choice eq 'No';
    }
    $counter++ if $action eq '++';
    $counter-- if $action eq '--';
    if($counter == 42) {
      $self->request->print(q{
        <h1>The Answer to Life, The Universe, and Everything</h1>
      });
    }
  }
}

# sub main {
  # my ($self, $request) = @_;
  # my $counter = 0;

  # print "In 'a' ($p - $thing)\n";
  # ($p) = $self->yield(42);
  # print "... more in a ...\n";
  # $self->yield(7);
  # print "... last of a.\n";
  # $self->yield;
# }

package main;

use Continuity;
Continuity->new( port => 8080 )->loop;

sub main {
  my ($request) = @_;
  my $child = CounterWidget->new(request => $request);
  $child->exec;
  $request->next;
  $child->exec;
  $request->next;
  $child->exec;
}