use Time::Local;

sub badcheck {
  $fromname = '' unless defined $fromname;
  $toname   = '' unless defined $toname;
  $subject  = '' unless defined $subject;
  $date     = '' unless defined $date;
  $text     = '' unless defined $text;

  my $reason = '';

  # Check if From, To or Subject are empty or begin with whitespace
  $reason .= 'From ' if ($fromname eq '' || $fromname =~ /^\s/);
  $reason .= 'To '   if ($toname   eq '' || $toname   =~ /^\s/);
  $reason .= 'Subj ' if ($subject  eq '' || $subject  =~ /^\s/);

  # Check if date is missing, invalid or too far in past/future
  if ($date eq '') {
    $reason .= 'DateMissing ';
  } else {
    my %mon = (
      Jan => 0, Feb => 1, Mar => 2, Apr => 3,
      May => 4, Jun => 5, Jul => 6, Aug => 7,
      Sep => 8, Oct => 9, Nov => 10, Dec => 11,
    );

    if ($date !~ /^\s*(\d{1,2})\s+([A-Z][a-z]{2})\s+(\d{2})\s+(\d{2}):(\d{2}):(\d{2})\s*$/) {
      $reason .= "DateFormat[$date] ";
    } elsif (!exists $mon{$2}) {
      $reason .= "DateMonth[$date] ";
    } else {
      my $year = ($3 >= 70) ? (1900 + $3) : (2000 + $3);
      my $t;

      eval {
        $t = Time::Local::timelocal($6, $5, $4, $1, $mon{$2}, $year);
      };

      if ($@) {
        $reason .= "DateParse[$date] ";
      } else {
        my $now = time();
        my $days = 90;  # Allowed drift in days (past/future)
        my $win  = $days * 24 * 60 * 60;  # days × hours × minutes × seconds

        $reason .= "DatePast[$date] "   if $t < ($now - $win);
        $reason .= "DateFuture[$date] " if $t > ($now + $win);
      }
    }
  }

  # Check if message body is empty
  my $body = $text;

  # Normalize line endings
  $body =~ s/\r\n/\n/g;
  $body =~ s/\r/\n/g;

  # Remove NUL bytes
  $body =~ s/\x00//g;

  # Strip non-content lines
  $body =~ s/^[ \t]*\n//mg;              # blank / whitespace-only lines
  $body =~ s/^AREA:.*\n?//img;           # AREA line
  $body =~ s/^\x01.*\n?//mg;             # all ^A kludge lines
  $body =~ s/^---.*\n?//mg;              # tear line
  $body =~ s/^ \* Origin: .*\n?//mg;     # origin line
  $body =~ s/^SEEN-BY:.*\n?//img;        # seen-by line
  $body =~ s/^(?:\x01)?PATH:.*\n?//img;  # PATH or ^APATH line

  # If nothing meaningful remains, flag it
  $reason .= 'Body ' if $body !~ /\S/;

  return "Invalid fields: $reason" if $reason ne '';

  return;  # explicitly return undef if OK
}
1;