# 
# This file is part of Config-Model
# 
# This software is Copyright (c) 2010 by Dominique Dumont, Krzysztof Tyszecki.
# 
# This is free software, licensed under:
# 
#   The GNU Lesser General Public License, Version 2.1, February 1999
# 

package Config::Model::Backend::Yaml ;
BEGIN {
  $Config::Model::Backend::Yaml::VERSION = '1.207';
}

use Carp;
use strict;
use warnings ;
use Config::Model::Exception ;
use UNIVERSAL ;
use File::Path;
use Log::Log4perl qw(get_logger :levels);

use base qw/Config::Model::Backend::Any/;
use YAML::Any 0.303 ;


my $logger = get_logger("Backend::Yaml") ;

sub suffix { return '.yml' ; }

sub read {
    my $self = shift ;
    my %args = @_ ;

    # args is:
    # object     => $obj,         # Config::Model::Node object 
    # root       => './my_test',  # fake root directory, userd for tests
    # config_dir => /etc/foo',    # absolute path 
    # file       => 'foo.conf',   # file name
    # file_path  => './my_test/etc/foo/foo.conf' 
    # io_handle  => $io           # IO::File object

    return 0 unless defined $args{io_handle} ; # no file to read

    # load yaml file
    my $yaml = join ('',$args{io_handle}->getlines) ;

    # convert to perl data
    my $perl_data = Load $yaml 
      || croak "No data found in YAML file $args{file_path}";

    # load perl data in tree
    $self->{node}->load_data($perl_data) ;
    return 1 ;
}

sub write {
    my $self = shift ;
    my %args = @_ ;

    # args is:
    # object     => $obj,         # Config::Model::Node object 
    # root       => './my_test',  # fake root directory, userd for tests
    # config_dir => /etc/foo',    # absolute path 
    # file       => 'foo.conf',   # file name
    # file_path  => './my_test/etc/foo/foo.conf' 
    # io_handle  => $io           # IO::File object

    croak "Undefined file handle to write"
      unless defined $args{io_handle} ;

    my $perl_data = $self->{node}->dump_as_data() ;
    my $yaml = Dump $perl_data ;

    $args{io_handle} -> print ($yaml) ;

    return 1;
}

1;

__END__

=head1 NAME

Config::Model::Backend::Yaml - Read and write config as a YAML data structure

=head1 VERSION

version 1.207

=head1 SYNOPSIS

  # model declaration
  name => 'FooConfig',

  read_config  => [
                    { backend => 'yaml' , 
                      config_dir => '/etc/foo',
                      file  => 'foo.conf',      # optional
                      auto_create => 1,         # optional
                    }
                  ],

   element => ...
  ) ;


=head1 DESCRIPTION

This module is used directly by L<Config::Model> to read or write the
content of a configuration tree written with YAML syntax in
C<Config::Model> configuration tree.

Note that undefined values are skipped for list element. I.e. if a
list element contains C<('a',undef,'b')>, the data structure will
contain C<'a','b'>.


=head1 CONSTRUCTOR

=head2 new ( node => $node_obj, name => 'yaml' ) ;

Inherited from L<Config::Model::Backend::Any>. The constructor will be
called by L<Config::Model::AutoRead>.

=head2 read ( io_handle => ... )

Of all parameters passed to this read call-back, only C<io_handle> is
used. This parameter must be L<IO::File> object already opened for
read. 

It can also be undef. In this case, C<read()> will return 0.

When a file is read,  C<read()> will return 1.

=head2 write ( io_handle => ... )

Of all parameters passed to this write call-back, only C<io_handle> is
used. This parameter must be L<IO::File> object alwritey opened for
write. 

C<write()> will return 1.

=head1 AUTHOR

Dominique Dumont, (ddumont at cpan dot org)

=head1 SEE ALSO

L<Config::Model>, 
L<Config::Model::AutoRead>, 
L<Config::Model::Backend::Any>, 

=cut