use 5;
package Pod::Simple::JustPod;
# ABSTRACT: Pod::Simple formatter that extracts POD from a file containing
#           other things as well
use strict;
use warnings;

use Pod::Simple::Methody ();
our @ISA = ('Pod::Simple::Methody');

sub new {
  my $self = shift;
  my $new  = $self->SUPER::new(@_);

  $new->accept_targets('*');
  $new->keep_encoding_directive(1);
  $new->preserve_whitespace(1);
  $new->complain_stderr(1);
  $new->_output_is_for_JustPod(1);

  return $new;
}

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

sub check_that_all_is_closed {

  # Actually checks that the things we depend on being balanced in fact are,
  # so that we can continue in spit of pod errors

  my $self = shift;
  while ($self->{inL}) {
    $self->end_L(@_);
  }
  while ($self->{fcode_end} && @{$self->{fcode_end}}) {
    $self->_end_fcode(@_);
  }
}

sub handle_text {

  # Add text to the output buffer.  This is skipped if within a L<>, as we use
  # the 'raw' attribute of that tag instead.

  $_[0]{buffer} .= $_[1] unless $_[0]{inL} ;
}

sub spacer {

  # Prints the white space following things like =head1.  This is normally a
  # blank, unless BlackBox has told us otherwise.

  my ($self, $arg) = @_;
  return unless $arg;

  my $spacer = ($arg->{'~orig_spacer'})
                ? $arg->{'~orig_spacer'}
                : " ";
  $self->handle_text($spacer);
}

sub _generic_start {

  # Called from tags like =head1, etc.

  my ($self, $text, $arg) = @_;
  $self->check_that_all_is_closed();
  $self->handle_text($text);
  $self->spacer($arg);
}

sub start_Document    { shift->_generic_start("=pod\n\n"); }
sub start_head1       { shift->_generic_start('=head1', @_); }
sub start_head2       { shift->_generic_start('=head2', @_); }
sub start_head3       { shift->_generic_start('=head3', @_); }
sub start_head4       { shift->_generic_start('=head4', @_); }
sub start_encoding    { shift->_generic_start('=encoding', @_); }
# sub start_Para
# sub start_Verbatim

sub start_item_bullet { # Handle =item *
  my ($self, $arg) = @_;
  $self->check_that_all_is_closed();
  $self->handle_text('=item');

  # It can be that they said simply '=item', and it is inferred that it is to
  # be a bullet.
  if (! $arg->{'~orig_content'}) {
    $self->handle_text("\n\n");
  }
  else {
    $self->spacer($arg);
    if ($arg->{'~_freaky_para_hack'}) {

        # See Message Id <87y3gtcwa2.fsf@hope.eyrie.org>
        my $item_text = $arg->{'~orig_content'};
        my $trailing = quotemeta $arg->{'~_freaky_para_hack'};
        $item_text =~ s/$trailing$//;
        $self->handle_text($item_text);
    }
    else {
        $self->handle_text("*\n\n");
    }
  }
}

sub start_item_number {     # Handle '=item 2'
  my ($self, $arg) = @_;
  $self->check_that_all_is_closed();
  $self->handle_text("=item");
  $self->spacer($arg);
  $self->handle_text("$arg->{'~orig_content'}\n\n");
}

sub start_item_text {   # Handle '=item foo bar baz'
  my ($self, $arg) = @_;
  $self->check_that_all_is_closed();
  $self->handle_text('=item');
  $self->spacer($arg);
}

sub _end_item {
  my $self = shift;
  $self->check_that_all_is_closed();
  $self->emit;
}

*end_item_bullet = *_end_item;
*end_item_number = *_end_item;
*end_item_text   = *_end_item;

sub _start_over  {  # Handle =over
  my ($self, $arg) = @_;
  $self->check_that_all_is_closed();
  $self->handle_text("=over");

  # The =over amount is optional
  if ($arg->{'~orig_content'}) {
    $self->spacer($arg);
    $self->handle_text("$arg->{'~orig_content'}");
  }
  $self->handle_text("\n\n");
}

*start_over_bullet = *_start_over;
*start_over_number = *_start_over;
*start_over_text   = *_start_over;
*start_over_block  = *_start_over;

sub _end_over  {
  my $self = shift;
  $self->check_that_all_is_closed();
  $self->handle_text('=back');
  $self->emit;
}

*end_over_bullet = *_end_over;
*end_over_number = *_end_over;
*end_over_text   = *_end_over;
*end_over_block  = *_end_over;

sub end_Document    {
  my $self = shift;
  $self->emit;        # Make sure buffer gets flushed
  print {$self->{'output_fh'} } "=cut\n"
}

sub _end_generic  {
  my $self = shift;
  $self->check_that_all_is_closed();
  $self->emit;
}

*end_head1    = *_end_generic;
*end_head2    = *_end_generic;
*end_head3    = *_end_generic;
*end_head4    = *_end_generic;
*end_encoding = *_end_generic;
*end_Para     = *_end_generic;
*end_Verbatim = *_end_generic;

sub _start_fcode {
  my ($type, $self, $flags) = @_;

  # How many brackets is set by BlackBox unless the count is 1
  my $bracket_count = (exists $flags->{'~bracket_count'})
                       ? $flags->{'~bracket_count'}
                       : 1;
  $self->handle_text($type . ( "<" x $bracket_count));

  my $rspacer = "";
  if ($bracket_count > 1) {
    my $lspacer = (exists $flags->{'~lspacer'})
                  ? $flags->{'~lspacer'}
                  : " ";
    $self->handle_text($lspacer);

    $rspacer = (exists $flags->{'~rspacer'})
                  ? $flags->{'~rspacer'}
                  : " ";
  }

  # BlackBox doesn't output things for for the ending code callbacks, so save
  # what we need.
  push @{$self->{'fcode_end'}}, [ $bracket_count, $rspacer ];
}

sub start_B { _start_fcode('B', @_); }
sub start_C { _start_fcode('C', @_); }
sub start_E { _start_fcode('E', @_); }
sub start_F { _start_fcode('F', @_); }
sub start_I { _start_fcode('I', @_); }
sub start_S { _start_fcode('S', @_); }
sub start_X { _start_fcode('X', @_); }
sub start_Z { _start_fcode('Z', @_); }

sub _end_fcode {
    my $self = shift;
    my $fcode_end = pop @{$self->{'fcode_end'}};
    my $bracket_count = 1;
    my $rspacer = "";

    if (! defined $fcode_end) { # If BlackBox is working, this shouldn't
                                # happen, but verify
      $self->whine($self->{line_count}, "Extra '>'");
    }
    else {
      $bracket_count = $fcode_end->[0];
      $rspacer = $fcode_end->[1];
    }

    $self->handle_text($rspacer) if $bracket_count > 1;
    $self->handle_text(">" x $bracket_count);
}

*end_B   = *_end_fcode;
*end_C   = *_end_fcode;
*end_E   = *_end_fcode;
*end_F   = *_end_fcode;
*end_I   = *_end_fcode;
*end_S   = *_end_fcode;
*end_X   = *_end_fcode;
*end_Z   = *_end_fcode;

sub start_L {
    _start_fcode('L', @_);
    $_[0]->handle_text($_[1]->{raw});
    $_[0]->{inL}++
}

sub end_L {
  my $self = shift;
  $self->{inL}--;
  if ($self->{inL} < 0) {   # If BlackBox is working, this shouldn't
                            # happen, but verify
    $self->whine($self->{line_count}, "Extra '>' ending L<>");
    $self->{inL} = 0;
  }

  $self->_end_fcode(@_);
}

sub emit {
  my $self = shift;

  if ($self->{buffer} ne "") {
    print { $self->{'output_fh'} } "",$self->{buffer} ,"\n\n";

    $self->{buffer} = "";
  }

  return;
}

1;

__END__

=head1 NAME

Pod::Simple::JustPod -- just the Pod, the whole Pod, and nothing but the Pod

=head1 SYNOPSIS

 my $infile  = "mixed_code_and_pod.pm";
 my $outfile = "just_the_pod.pod";
 open my $fh, ">$outfile" or die "Can't write to $outfile: $!";

 my $parser = Pod::Simple::JustPod->new();
 $parser->output_fh($fh);
 $parser->parse_file($infile);
 close $fh or die "Can't close $outfile: $!";

=head1 DESCRIPTION

This class returns a copy of its input, translated into Perl's internal
encoding (UTF-8), and with all the non-Pod lines removed.

This is a subclass of L<Pod::Simple::Methody> and inherits all its methods.
And since, that in turn is a subclass of L<Pod::Simple>, you can use any of
its methods.  This means you can output to a string instead of a file, or
you can parse from an array.

This class strives to return the Pod lines of the input completely unchanged,
except for any necessary translation into Perl's internal encoding, and it makes
no effort to return trailing spaces on lines; these likely will be stripped.
If the input pod is well-formed with no warnings nor errors generated, the
extracted pod should generate the same documentation when formatted by a Pod
formatter as the original file does.

By default, warnings are output to STDERR

=head1 SEE ALSO

L<Pod::Simple>, L<Pod::Simple::Methody>

=head1 SUPPORT

Questions or discussion about POD and Pod::Simple should be sent to the
L<mailto:pod-people@perl.org> mail list. Send an empty email to
L<mailto:pod-people-subscribe@perl.org> to subscribe.

This module is managed in an open GitHub repository,
L<https://github.com/theory/pod-simple/>. Feel free to fork and contribute, or
to clone L<git://github.com/theory/pod-simple.git> and send patches!

Patches against Pod::Simple are welcome. Please send bug reports to
L<mailto:<bug-pod-simple@rt.cpan.org>.

=head1 COPYRIGHT AND DISCLAIMERS

Copyright (c) 2002 Sean M. Burke.

This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.

This program is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of
merchantability or fitness for a particular purpose.

=head1 AUTHOR

Pod::Simple was created by Sean M. Burke <sburke@cpan.org>.
But don't bother him, he's retired.

Pod::Simple is maintained by:

=over

=item * Allison Randal C<allison@perl.org>

=item * Hans Dieter Pearcey C<hdp@cpan.org>

=item * David E. Wheeler C<dwheeler@cpan.org>

=back

Pod::Simple::JustPod was developed by John SJ Anderson
C<genehack@genehack.org>, with contributions from Karl Williamson
C<khw@cpan.org>.

=cut
