# $Id$
package Youri::Config;

=head1 NAME

Youri::Config - Youri configuration handler

=head1 SYNOPSIS

    use Youri::Config;

    my $config = Youri::Config->new(
        command_spec => [
            'help|h!',
        ],
        file_spec => [
            'foo=s',
        ],
        directories => [ '/etc/youri', "$ENV{HOME}/.youri" ],
        file_name   => 'app.conf',
        caller      => $0,
    );

    # get configuration directive
    my $foo = $config->get('foo');

    # get configuration section
    my %bar = $config->get_section('bar');

=head1 DESCRIPTION

This class handle configuration for all YOURI tools.

It uses distinct command line and config files specification, but merges the
two inputs transparently, command line directives overriding config file
directives with the same name.

Given directories are scanned for a file with given name, and only the first
one found is used. If B<--config> argument is given on command line, no
scanning occurs. If no readable file is found, an exception is thrown.

==head1 FORMAT

The file format used is the one from AppConfig, with the additional ability to
use YAML. Here is an exemple configuration file:

    [updates]
    class    = Youri::Check::Check::Updates
    grabbers = <<EOF
    --- #YAML:1.0
    debian:
        class: Youri::Check::Check::Updates::Debian
        aliases:
            fuse: ~
    cpan:
        class: Youri::Check::Check::Updates::CPAN
    fedora:
        class: Youri::Check::Check::Updates::Fedora
    gentoo:
        class: Youri::Check::Check::Updates::Gentoo
    freshmeat:
        class: Youri::Check::Check::Updates::Freshmeat
        aliases:
            fuse: fuse-emulator
    EOF

As a side-effect of using YAML, the use of character '~' anywhere is prohibited.
Use ${HOME} instead.

=head1 SEE ALSO

AppConfig, YAML

=cut

use strict;
use warnings;
use AppConfig qw/:argcount :expand/;
use File::Spec;
use Pod::Usage;
use Carp;
use YAML;

sub new {
    my ($class, %options) = @_;

    my ($command_config, $file_config);

    # process command line
    if ($options{command_spec}) {
        $command_config = AppConfig->new(
            {
                CREATE => 1,
                GLOBAL => {
                    DEFAULT  => '',
                    EXPAND   => EXPAND_VAR | EXPAND_ENV,
                    ARGCOUNT => ARGCOUNT_ONE,
               }
            },
            @{$options{command_spec}}
        );
        $command_config->args();

        pod2usage(
            -input   => $options{caller},
            -verbose => 0
        )  if $command_config->get('help');
    }

    # process config file
    $file_config = AppConfig->new(
        {
            CREATE => 1,
            GLOBAL => {
                DEFAULT  => '',
                EXPAND   => EXPAND_VAR | EXPAND_ENV,
                ARGCOUNT => ARGCOUNT_ONE,
           }
        },
        @{$options{file_spec}}
    );

    # find configuration file to use
    my $main_file;
    
    if ($command_config) {
        my $file = $command_config->get('config');
        if ($file) {
            if (! -f $file) {
                carp "Non-existing file $file, skipping";
            } elsif (! -r $file) {
                carp "Non-readable file $file, skipping";
            } else {
                $main_file = $file;
            }
        };
    }

    unless ($main_file) {
        foreach my $directory (@{$options{directories}}) {
            my $file = "$directory/$options{file_name}";
            next unless -f $file && -r $file;
            $main_file = $file;
            last;
        }
    }

    croak 'No config file found, aborting' unless $main_file;
    $file_config->file($main_file);

    # process inclusions
    my $need_rescan;
    foreach my $include_file (split(/\s+/, $file_config->get('includes'))) {
        # convert relative path to absolute ones
        $include_file = File::Spec->rel2abs(
            $include_file, (File::Spec->splitpath($main_file))[1]
        );

        if (! -f $include_file) {
            warn "Non-existing file $include_file, skipping";
        } elsif (! -r $include_file) {
            warn "Non-readable file $include_file, skipping";
        } else {
            $file_config->file($include_file);
            $need_rescan = 1;
        }
    }

    $file_config->file($main_file) if $need_rescan;

    # merge command line configuration
    if ($command_config) {
        my %command_vars = $command_config->varlist('.*');
        while (my ($key, $value) = each %command_vars) {
            $file_config->set($key, $value);
        }
    }

    my $self = bless {
        _appconfig => $file_config
    }, $class;

    return $self;
}

=head2 get_section($id)

Simple wrapper around $config->varlist(), throwing a warning if section I<$id> doesn't exists.

=cut

sub get_section {
    my ($self, $id) = @_;
    croak "Not a class method" unless ref $self;

    my %values = $self->{_appconfig}->varlist('^' . $id . '_', 1);

    carp "No such section $id" unless %values;

    foreach my $value (values %values) {
        $value = _yamlize($value);
    }

    return %values;
}

sub get {
    my ($self, $variable) = @_;
    croak "Not a class method" unless ref $self;

    return _yamlize($self->{_appconfig}->get($variable));
}

sub _yamlize {
    my ($value) = @_;

    if ($value =~ /^--- #YAML:1.0/) {
        eval {
            $value = Load($value . "\n");
        };
        $value = undef if $@;
    }

    return $value;
}

=head1 COPYRIGHT AND LICENSE

Copyright (C) 2002-2006, YOURI project

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

=cut

1;