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package DBICTest::Util::LeakTracer;

use warnings;
use strict;

use Carp;
use Scalar::Util qw(isweak weaken blessed reftype);
use DBIx::Class::_Util qw(refcount hrefaddr refdesc);
use DBIx::Class::Optional::Dependencies;
use Data::Dumper::Concise;
use DBICTest::Util qw( stacktrace visit_namespaces );
use constant {
  CV_TRACING => !DBICTest::RunMode->is_plain && DBIx::Class::Optional::Dependencies->req_ok_for ('test_leaks_heavy'),
  SKIP_SCALAR_REFS => ( "$]" < 5.008004 ),
};

use base 'Exporter';
our @EXPORT_OK = qw(populate_weakregistry assert_empty_weakregistry visit_refs);

my $refs_traced = 0;
my $leaks_found = 0;
my %reg_of_regs;

sub populate_weakregistry {
  my ($weak_registry, $target, $note) = @_;

  croak 'Expecting a registry hashref' unless ref $weak_registry eq 'HASH';
  croak 'Target is not a reference' unless length ref $target;

  my $refaddr = hrefaddr $target;

  # a registry could be fed to itself or another registry via recursive sweeps
  return $target if $reg_of_regs{$refaddr};

  return $target if SKIP_SCALAR_REFS and reftype($target) eq 'SCALAR';

  weaken( $reg_of_regs{ hrefaddr($weak_registry) } = $weak_registry )
    unless( $reg_of_regs{ hrefaddr($weak_registry) } );

  # an explicit "garbage collection" pass every time we store a ref
  # if we do not do this the registry will keep growing appearing
  # as if the traced program is continuously slowly leaking memory
  for my $reg (values %reg_of_regs) {
    (defined $reg->{$_}{weakref}) or delete $reg->{$_}
      for keys %$reg;
  }

  if (! defined $weak_registry->{$refaddr}{weakref}) {
    $weak_registry->{$refaddr} = {
      stacktrace => stacktrace(1),
      weakref => $target,
    };
    weaken( $weak_registry->{$refaddr}{weakref} );
    $refs_traced++;
  }

  my $desc = refdesc $target;
  $weak_registry->{$refaddr}{slot_names}{$desc} = 1;
  if ($note) {
    $note =~ s/\s*\Q$desc\E\s*//g;
    $weak_registry->{$refaddr}{slot_names}{$note} = 1;
  }

  $target;
}

# Regenerate the slots names on a thread spawn
sub CLONE {
  my @individual_regs = grep { scalar keys %{$_||{}} } values %reg_of_regs;
  %reg_of_regs = ();

  for my $reg (@individual_regs) {
    my @live_slots = grep { defined $_->{weakref} } values %$reg
      or next;

    $reg = {};  # get a fresh hashref in the new thread ctx
    weaken( $reg_of_regs{hrefaddr($reg)} = $reg );

    for my $slot_info (@live_slots) {
      my $new_addr = hrefaddr $slot_info->{weakref};

      # replace all slot names
      $slot_info->{slot_names} = { map {
        my $name = $_;
        $name =~ s/\(0x[0-9A-F]+\)/sprintf ('(%s)', $new_addr)/ieg;
        ($name => 1);
      } keys %{$slot_info->{slot_names}} };

      $reg->{$new_addr} = $slot_info;
    }
  }
}

sub visit_refs {
  my $args = { (ref $_[0]) ? %{$_[0]} : @_ };

  $args->{seen_refs} ||= {};

  my $visited_cnt = '0E0';
  for my $i (0 .. $#{$args->{refs}} ) {

    next unless length ref $args->{refs}[$i]; # not-a-ref

    my $addr = hrefaddr $args->{refs}[$i];

    # no diving into weakregistries
    next if $reg_of_regs{$addr};

    next if $args->{seen_refs}{$addr}++;
    $visited_cnt++;

    my $r = $args->{refs}[$i];

    $args->{action}->($r) or next;

    # This may end up being necessarry some day, but do not slow things
    # down for now
    #if ( defined( my $t = tied($r) ) ) {
    #  $visited_cnt += visit_refs({ %$args, refs => [ $t ] });
    #}

    my $type = reftype $r;

    local $@;
    eval {
      if ($type eq 'HASH') {
        $visited_cnt += visit_refs({ %$args, refs => [ map {
          ( !isweak($r->{$_}) ) ? $r->{$_} : ()
        } keys %$r ] });
      }
      elsif ($type eq 'ARRAY') {
        $visited_cnt += visit_refs({ %$args, refs => [ map {
          ( !isweak($r->[$_]) ) ? $r->[$_] : ()
        } 0..$#$r ] });
      }
      elsif ($type eq 'REF' and !isweak($$r)) {
        $visited_cnt += visit_refs({ %$args, refs => [ $$r ] });