package Module::Build::Notes;

# A class for persistent hashes

use strict;
use warnings;
our $VERSION = '0.4234';
$VERSION = eval $VERSION;
use Data::Dumper;
use Module::Build::Dumper;

sub new {
  my ($class, %args) = @_;
  my $file = delete $args{file} or die "Missing required parameter 'file' to new()";
  my $self = bless {
		    disk => {},
		    new  => {},
		    file => $file,
		    %args,
		   }, $class;
}

sub restore {
  my $self = shift;

  open(my $fh, '<', $self->{file}) or die "Can't read $self->{file}: $!";
  $self->{disk} = eval do {local $/; <$fh>};
  die $@ if $@;
  close $fh;
  $self->{new} = {};
}

sub access {
  my $self = shift;
  return $self->read() unless @_;

  my $key = shift;
  return $self->read($key) unless @_;

  my $value = shift;
  $self->write({ $key => $value });
  return $self->read($key);
}

sub has_data {
  my $self = shift;
  return keys %{$self->read()} > 0;
}

sub exists {
  my ($self, $key) = @_;
  return exists($self->{new}{$key}) || exists($self->{disk}{$key});
}

sub read {
  my $self = shift;

  if (@_) {
    # Return 1 key as a scalar
    my $key = shift;
    return $self->{new}{$key} if exists $self->{new}{$key};
    return $self->{disk}{$key};
  }

  # Return all data
  my $out = (keys %{$self->{new}}
	     ? {%{$self->{disk}}, %{$self->{new}}}
	     : $self->{disk});
  return wantarray ? %$out : $out;
}

sub _same {
  my ($self, $x, $y) = @_;
  return 1 if !defined($x) and !defined($y);
  return 0 if !defined($x) or  !defined($y);
  return $x eq $y;
}

sub write {
  my ($self, $href) = @_;
  $href ||= {};

  @{$self->{new}}{ keys %$href } = values %$href;  # Merge

  # Do some optimization to avoid unnecessary writes
  foreach my $key (keys %{ $self->{new} }) {
    next if ref $self->{new}{$key};
    next if ref $self->{disk}{$key} or !exists $self->{disk}{$key};
    delete $self->{new}{$key} if $self->_same($self->{new}{$key}, $self->{disk}{$key});
  }

  if (my $file = $self->{file}) {
    my ($vol, $dir, $base) = File::Spec->splitpath($file);
    $dir = File::Spec->catpath($vol, $dir, '');
    return unless -e $dir && -d $dir;  # The user needs to arrange for this

    return if -e $file and !keys %{ $self->{new} };  # Nothing to do

    @{$self->{disk}}{ keys %{$self->{new}} } = values %{$self->{new}};  # Merge
    $self->_dump($file, $self->{disk});

    $self->{new} = {};
  }
  return $self->read;
}

sub _dump {
  my ($self, $file, $data) = @_;

  open(my $fh, '>', $file) or die "Can't create '$file': $!";
  print {$fh} Module::Build::Dumper->_data_dump($data);
  close $fh;
}

my $orig_template = do { local $/; <DATA> };
close DATA;

sub write_config_data {
  my ($self, %args) = @_;

  my $template = $orig_template;
  $template =~ s/NOTES_NAME/$args{config_module}/g;
  $template =~ s/MODULE_NAME/$args{module}/g;
  $template =~ s/=begin private\n//;
  $template =~ s/=end private/=cut/;

  # strip out private POD markers we use to keep pod from being
  # recognized for *this* source file
  $template =~ s{$_\n}{} for '=begin private', '=end private';

  open(my $fh, '>', $args{file}) or die "Can't create '$args{file}': $!";
  print {$fh} $template;
  print {$fh} "\n__DATA__\n";
  print {$fh} Module::Build::Dumper->_data_dump([$args{config_data}, $args{feature}, $args{auto_features}]);
  close $fh;
}

1;


=head1 NAME

Module::Build::Notes - Create persistent distribution configuration modules

=head1 DESCRIPTION

This module is used internally by Module::Build to create persistent
configuration files that can be installed with a distribution.  See
L<Module::Build::ConfigData> for an example.

=head1 AUTHOR

Ken Williams <kwilliams@cpan.org>

=head1 COPYRIGHT

Copyright (c) 2001-2006 Ken Williams.  All rights reserved.

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

=head1 SEE ALSO

perl(1), L<Module::Build>(3)

=cut

__DATA__
package NOTES_NAME;
use strict;
my $arrayref = eval do {local $/; <DATA>}
  or die "Couldn't load ConfigData data: $@";
close DATA;
my ($config, $features, $auto_features) = @$arrayref;

sub config { $config->{$_[1]} }

sub set_config { $config->{$_[1]} = $_[2] }
sub set_feature { $features->{$_[1]} = 0+!!$_[2] }  # Constrain to 1 or 0

sub auto_feature_names { sort grep !exists $features->{$_}, keys %$auto_features }

sub feature_names {
  my @features = (sort keys %$features, auto_feature_names());
  @features;
}

sub config_names  { sort keys %$config }

sub write {
  my $me = __FILE__;

  # Can't use Module::Build::Dumper here because M::B is only a
  # build-time prereq of this module
  require Data::Dumper;

  my $mode_orig = (stat $me)[2] & 07777;
  chmod($mode_orig | 0222, $me); # Make it writeable
  open(my $fh, '+<', $me) or die "Can't rewrite $me: $!";
  seek($fh, 0, 0);
  while (<$fh>) {
    last if /^__DATA__$/;
  }
  die "Couldn't find __DATA__ token in $me" if eof($fh);

  seek($fh, tell($fh), 0);
  my $data = [$config, $features, $auto_features];
  print($fh 'do{ my '
	      . Data::Dumper->new([$data],['x'])->Purity(1)->Dump()
	      . '$x; }' );
  truncate($fh, tell($fh));
  close $fh;

  chmod($mode_orig, $me)
    or warn "Couldn't restore permissions on $me: $!";
}

sub feature {
  my ($package, $key) = @_;
  return $features->{$key} if exists $features->{$key};

  my $info = $auto_features->{$key} or return 0;

  require Module::Build;  # XXX should get rid of this
  foreach my $type (sort keys %$info) {
    my $prereqs = $info->{$type};
    next if $type eq 'description' || $type eq 'recommends';

    foreach my $modname (sort keys %$prereqs) {
      my $status = Module::Build->check_installed_status($modname, $prereqs->{$modname});
      if ((!$status->{ok}) xor ($type =~ /conflicts$/)) { return 0; }
      if ( ! eval "require $modname; 1" ) { return 0; }
    }
  }
  return 1;
}

=begin private

=head1 NAME

NOTES_NAME - Configuration for MODULE_NAME

=head1 SYNOPSIS

  use NOTES_NAME;
  $value = NOTES_NAME->config('foo');
  $value = NOTES_NAME->feature('bar');

  @names = NOTES_NAME->config_names;
  @names = NOTES_NAME->feature_names;

  NOTES_NAME->set_config(foo => $new_value);
  NOTES_NAME->set_feature(bar => $new_value);
  NOTES_NAME->write;  # Save changes


=head1 DESCRIPTION

This module holds the configuration data for the C<MODULE_NAME>
module.  It also provides a programmatic interface for getting or
setting that configuration data.  Note that in order to actually make
changes, you'll have to have write access to the C<NOTES_NAME>
module, and you should attempt to understand the repercussions of your
actions.


=head1 METHODS

=over 4

=item config($name)

Given a string argument, returns the value of the configuration item
by that name, or C<undef> if no such item exists.

=item feature($name)

Given a string argument, returns the value of the feature by that
name, or C<undef> if no such feature exists.

=item set_config($name, $value)

Sets the configuration item with the given name to the given value.
The value may be any Perl scalar that will serialize correctly using
C<Data::Dumper>.  This includes references, objects (usually), and
complex data structures.  It probably does not include transient
things like filehandles or sockets.

=item set_feature($name, $value)

Sets the feature with the given name to the given boolean value.  The
value will be converted to 0 or 1 automatically.

=item config_names()

Returns a list of all the names of config items currently defined in
C<NOTES_NAME>, or in scalar context the number of items.

=item feature_names()

Returns a list of all the names of features currently defined in
C<NOTES_NAME>, or in scalar context the number of features.

=item auto_feature_names()

Returns a list of all the names of features whose availability is
dynamically determined, or in scalar context the number of such
features.  Does not include such features that have later been set to
a fixed value.

=item write()

Commits any changes from C<set_config()> and C<set_feature()> to disk.
Requires write access to the C<NOTES_NAME> module.

=back


=head1 AUTHOR

C<NOTES_NAME> was automatically created using C<Module::Build>.
C<Module::Build> was written by Ken Williams, but he holds no
authorship claim or copyright claim to the contents of C<NOTES_NAME>.

=end private

