Config::Auto - Magical config file parser

    use Config::Auto;

    ### Not very magical at all.
    $config = Config::Auto::parse("myprogram.conf", format => "colon");

    ### Considerably more magical.
    $config = Config::Auto::parse("myprogram.conf");

    ### Highly magical.
    $config = Config::Auto::parse();

    ### Using the OO interface
    $ca     = Config::Auto->new( source => $text );
    $ca     = Config::Auto->new( source => $fh );
    $ca     = Config::Auto->new( source => $filename );

    $href   = $ca->score;           # compute the score for various formats

    $config = $ca->parse;           # parse the config

    $format = $ca->format;          # detected (or provided) config format
    $str    = $ca->as_string;       # config file stringified
    $fh     = $ca->fh;              # config file handle
    $file   = $ca->file;            # config filename
    $aref   = $ca->data;            # data from your config, split by newlines

    snerkconfig
    ~/snerkconfig
    /etc/snerkconfig
    /usr/local/etc/snerkconfig

    snerk.config
    ~/snerk.config
    /etc/snerk.config
    /usr/local/etc/snerk.config

    snerkrc
    ~/snerkrc
    /etc/snerkrc
    /usr/local/etc/snerkrc

    .snerkrc
    ~/.snerkrc
    /etc/.snerkrc
    /usr/local/etc/.snerkrc

    $VAR1 = {
        'nameserver' => [ '163.1.2.1', '129.67.1.1', '129.67.1.180' ],
        'search' => [ 'oucs.ox.ac.uk', 'ox.ac.uk' ]
    };

    $VAR1 = {
        'root' => [ 'x', '0', '0', 'root', '/root', '/bin/bash' ],
        ...
    };

    $VAR1 = {
        'append' => '""',
        'responsiveness' => '',
        'device' => '/dev/psaux',
        'type' => 'ps2',
        'repeat_type' => 'ms3'
    };

    $VAR1 = {
        'netgroup' => 'nis',
        'passwd' => 'compat',
        'hosts' => [ 'files', 'dns' ],
        ...
    };

package Config::Auto;

use strict;
use warnings;

use Carp qw[croak];

use vars qw[$VERSION $DisablePerl $Untaint $Debug];

$VERSION        = '0.34';
$DisablePerl    = 0;
$Untaint        = 0;
$Debug          = 0;

my %Methods = (
    perl   => \&_eval_perl,
    colon  => \&_colon_sep,
    space  => \&_space_sep,
    equal  => \&_equal_sep,
    bind   => \&_bind_style,
    irssi  => \&_irssi_style,
    ini    => \&_parse_ini,
    list   => \&_return_list,
    yaml   => \&_yaml,
    xml    => \&_parse_xml,
);

sub formats { return keys %Methods }

### generate accessors
{   no strict 'refs';
    for my $meth ( qw[format path source _fh _data _file _score _tmp_fh] ) {
        *$meth = sub {
            my $self        = shift;
            $self->{$meth}  = shift if @_;
            return $self->{$meth};
        };
    }
}

sub new {
    my $class   = shift;
    my %hash    = @_;
    my $self    = bless {}, $class;

    if( my $format = $hash{'format'} ) {

        ### invalid format
        croak "No such format '$format'" unless $Methods{$format};

        $self->format( $format );
    }

    ### set the other values that could be passed
    for my $key ( qw[source path] ) {
        $self->$key( defined $hash{$key} ? $hash{$key} : '' );
    }

    return $self;
}

sub parse {
    my $self = shift;

    ### XXX todo: re-implement magic configuration file finding based on $0

    ### procedural invocation, fix to OO
    unless( UNIVERSAL::isa( $self, __PACKAGE__ ) ) {
        $self = __PACKAGE__->new( source => $self, @_ )
                    or croak( "Could not parse '$self' => @_" );
    }

    my $file = $self->file;
    croak "No config file found!"           unless defined $file;
    croak "Config file $file not readable!" unless -e $file;

    ### from Toru Marumoto: Config-Auto return undef if -B $file
    ### <21d48be50604271656n153e6db6m9b059f57548aaa32@mail.gmail.com>
    # If a config file "$file" contains multibyte charactors like japanese,
    # -B returns "true" in old version of perl such as 5.005_003. It seems
    # there is no problem in perl 5.6x or newer.
    ### so check -B and only return only if
    unless( $self->format ) {
        return if $self->file and -B $self->file and $] >= '5.006';

        my $score = $self->score;

        ### no perl?
        delete $score->{perl} if exists $score->{perl} and $DisablePerl;

        ### no formats found
        croak "Unparsable file format!" unless keys %$score;

        ### Clear winner?
        {   my @methods = sort { $score->{$b} <=> $score->{$a} } keys %$score;
            if (@methods > 1) {
                croak "File format unclear! " .
                    join ",", map { "$_ => $score->{$_}"} @methods
                        if $score->{ $methods[0] } == $score->{ $methods[1] };
            }
            $self->format( $methods[0] );

            $self->_debug( "Using the following format for parsing: " . $self->format );
        }
    }

    return $Methods{ $self->format }->($self);
}

sub score {
    my $self = shift;

    return $self->_score if $self->_score;

    my $data = $self->data;

    return { xml  => 100 }  if $data->[0] =~ /^\s*<\?xml/;
    return { perl => 100 }  if $data->[0] =~ /^#!.*perl/;
    my %score;

    for (@$data) {
        ### it's almost definately YAML if the first line matches this
        $score{yaml} += 20              if /(?:\#|%)    # a #YAML or %YAML
                                                                                        YAML
                                                                                        (?::|\s)    # a YAML: or YAML[space]
                                                                                /x and $data->[0] eq $_;
        $score{yaml} += 20              if /^---/ and $data->[0] eq $_;
        $score{yaml} += 10              if /^\s+-\s\w+:\s\w+/;

        # Easy to comment out foo=bar syntax
        $score{equal}++                 if /^\s*#\s*\w+\s*=/;
        next if /^\s*#/;

        $score{xml}++                   for /(<\w+.*?>)/g;
        $score{xml}+= 2                 for m|(</\w+.*?>)|g;
        $score{xml}+= 5                 for m|(/>)|g;
        next unless /\S/;

        $score{equal}++, $score{ini}++  if m|^.*=.*$|;
        $score{equal}++, $score{ini}++  if m|^\S+\s+=\s+|;
        $score{colon}++                 if /^[^:]+:[^:=]+/;
        $score{colon}+=2                if /^\s*\w+\s*:[^:]+$/;
        $score{colonequal}+= 3          if /^\s*\w+\s*:=[^:]+$/; # Debian foo.
        $score{perl}+= 10               if /^\s*\$\w+(\{.*?\})*\s*=.*/;
        $score{space}++                 if m|^[^\s:]+\s+\S+$|;

        # mtab, fstab, etc.
        $score{space}++                 if m|^(\S+)\s+(\S+\s*)+|;
        $score{bind}+= 5                if /\s*\S+\s*{$/;
        $score{list}++                  if /^[\w\/\-\+]+$/;
        $score{bind}+= 5                if /^\s*}\s*$/  and exists $score{bind};
        $score{irssi}+= 5               if /^\s*};\s*$/ and exists $score{irssi};
        $score{irssi}+= 10              if /(\s*|^)\w+\s*=\s*{/;
        $score{perl}++                  if /\b([@%\$]\w+)/g;
        $score{perl}+= 2                if /;\s*$/;
        $score{perl}+=10                if /(if|for|while|until|unless)\s*\(/;
        $score{perl}++                  for /([\{\}])/g;
        $score{equal}++, $score{ini}++  if m|^\s*\w+\s*=.*$|;
        $score{ini} += 10               if /^\s*\[[\s\w]+\]\s*$/;
    }

    # Choose between Win INI format and foo = bar
    if (exists $score{ini}) {
        no warnings 'uninitialized';
        $score{ini} > $score{equal}
            ? delete $score{equal}
            : delete $score{ini};
    }

    # Some general sanity checks
    if (exists $score{perl}) {
        $score{perl} /= 2   unless ("@$data" =~ /;/) > 3 or $#$data < 3;
        delete $score{perl} unless ("@$data" =~ /;/);
        delete $score{perl} unless ("@$data" =~ /([\$\@\%]\w+)/);
    }

    $self->_score( \%score );

    return \%score;
}

sub data {
    my $self = shift;
    return $self->_data if $self->_data;

    my $src = $self->source;

    ### filehandle
    if( ref $src ) {
        my @data = <$src>;
        $self->_data( \@data );

        seek $src, 0, 0; # reset position!

    ### data
    } elsif ( $src =~ /\n/ ) {
        $self->_data( [ split $/, $src, -1 ] );

    ### filename
    } else {
        my $fh = $self->fh;
        my @data = <$fh>;
        $self->_data( \@data );

        seek $fh, 0, 0; # reset position!
    }

    return $self->_data;
}

sub fh {
    my $self = shift;
    return $self->_fh if $self->_fh;

    my $src = $self->source;

    ### filehandle
    if( ref $src ) {
        $self->_fh( $src );

    ### data
    } elsif ( $src =~ /\n/ ) {
        require IO::String;

        my $fh = IO::String->new;
        print $fh $src;
        $fh->setpos(0);

        $self->_fh( $fh );

    } else {
        my $fh;
        my $file = $self->file;

        if( open $fh, $file ) {
            $self->_fh( $fh );
        } else {
            $self->_debug( "Could not open '$file': $!" );
            return;
        }
    }

    return $self->_fh;
}

sub file {
    my $self = shift;
    return $self->_file if $self->_file;

    my $src = $self->source;

    ### filehandle or datastream, no file attached =/
    ### so write a temp file
    if( ref $src or $src =~ /\n/ ) {

        ### require only when needed
        require File::Temp;

        my $tmp = File::Temp->new;
        $tmp->print( ref $src ? <$src> : $src );
        $tmp->close;                    # write to disk

        $self->_tmp_fh( $tmp );         # so it won't get destroyed
        $self->_file( $tmp->filename );

        seek $src, 0, 0 if ref $src;    # reset position!

    } else {
        my $file = $self->_find_file( $src, $self->path ) or return;

        $self->_file( $file );
    }

    return $self->_file;
}

sub as_string {
    my $self = shift;
    my $data = $self->data;

    return join $/, @$data;
}

sub _find_file {
    my ($self, $file, $path) = @_;


    ### moved here so they are only loaded when looking for a file
    ### all to keep memory usage down.
    {   require File::Spec::Functions;
        File::Spec::Functions->import('catfile');

        require File::Basename;
        File::Basename->import(qw[dirname basename]);
    }

    my $bindir = dirname($0);
    my $whoami = basename($0);

    $whoami =~ s/\.(pl|t)$//;

    my @filenames = $file ||
                     ("${whoami}config", "${whoami}.config",
                      "${whoami}rc",    ".${whoami}rc");

    my $try;
    for my $name (@filenames) {

        return $name        if -e $name;
        return $try         if ( $try = $self->_chkpaths($path, $name) ) and -e $try;
        return $try         if -e ( $try = catfile($bindir,     $name) );
        return $try         if $ENV{HOME} && -e ( $try = catfile($ENV{HOME},  $name) );
        return "/etc/$name" if -e "/etc/$name";
        return "/usr/local/etc/$name"
                            if -e "/usr/local/etc/$name";
    }

    $self->_debug( "Could not find file for '". $self->source ."'" );

    return;
}

sub _chkpaths {
    my ($self, $paths, $filename) = @_;

    ### no paths? no point in checking
    return unless defined $paths;

    my $file;
    for my $path ( ref($paths) eq 'ARRAY' ? @$paths : $paths ) {
        return $file if -e ($file = catfile($path, $filename));
    }

    return;
}

sub _eval_perl   {

    my $self = shift;
    my $str  = $self->as_string;

    ($str) = $str =~ m/^(.*)$/s if $Untaint;

    my $cfg = eval "$str";
    croak __PACKAGE__ . " couldn't parse perl data: $@" if $@;
    return $cfg;
}

sub _parse_xml   {
    my $self = shift;

    ### Check if XML::Simple is already loaded
    unless ( exists $INC{'XML/Simple.pm'} ) {
        ### make sure we give good diagnostics when XML::Simple is not
        ### available, but required to parse a config
        eval { require XML::Simple; XML::Simple->import; 1 };
        croak "XML::Simple not available. Can not parse " .
              $self->as_string . "\nError: $@\n" if $@;
    }

    return XML::Simple::XMLin( $self->as_string );
}

sub _parse_ini   {
    my $self = shift;

    ### Check if Config::IniFiles is already loaded
    unless ( exists $INC{'Config/IniFiles.pm'} ) {
        ### make sure we give good diagnostics when XML::Simple is not
        ### available, but required to parse a config
        eval { require Config::IniFiles; Config::IniFiles->import; 1 };
        croak "Config::IniFiles not available. Can not parse " .
              $self->as_string . "\nError: $@\n" if $@;
    }

    tie my %ini, 'Config::IniFiles', ( -file => $self->file );
    return \%ini;
}

sub _return_list {
    my $self = shift;

    ### there shouldn't be any trailing newlines or empty entries here
    return [ grep { length } map { chomp; $_ } @{ $self->data } ];
}

### Changed to YAML::Any which selects the fastest YAML parser available
### (req YAML 0.67)
sub _yaml {
    my $self = shift;
    require YAML::Any;

    return YAML::Any::Load( $self->as_string );
}

sub _bind_style  { croak "BIND8-style config not supported in this release" }
sub _irssi_style { croak "irssi-style config not supported in this release" }

# BUG: These functions are too similar. How can they be unified?

sub _colon_sep {
    my $self = shift;
    my $fh   = $self->fh;

    my %config;
    while (<$fh>) {
        next if /^\s*#/;
        /^\s*(.*?)\s*:\s*(.*)/ or next;
        my ($k, $v) = ($1, $2);
        my @v;
        if ($v =~ /:/) {
            @v =  split /:/, $v;
        } elsif ($v =~ /, /) {
            @v = split /\s*,\s*/, $v;
        } elsif ($v =~ / /) {
            @v = split /\s+/, $v;
        } elsif ($v =~ /,/) { # Order is important
            @v = split /\s*,\s*/, $v;
        } else {
            @v = $v;
        }
        $self->_check_hash_and_assign(\%config, $k, @v);
    }
    return \%config;
}

sub _check_hash_and_assign {
    my $self = shift;

    my ($c, $k, @v) = @_;
    if (exists $c->{$k} and !ref $c->{$k}) {
        $c->{$k} = [$c->{$k}];
    }

    if (grep /=/, @v) { # Bugger, it's really a hash
        for (@v) {
            my ($subkey, $subvalue);

            ### If the array element has an equal sign in it...
            if (/(.*)=(.*)/) {
                ($subkey, $subvalue) = ($1,$2);

            ###...otherwise, if the array element does not contain an equals sign:
            } else {
                $subkey     = $_;
                $subvalue   = 1;
            }

            if (exists $c->{$k} and ref $c->{$k} ne "HASH") {
                # Can we find a hash in here?
                my $h=undef;
                for (@{$c->{$k}}) {
                    last if ref ($h = $_) eq "hash";
                }
                if ($h) { $h->{$subkey} = $subvalue; }
                else { push @{$c->{$k}}, { $subkey => $subvalue } }
            } else {
                $c->{$k}{$subkey} = $subvalue;
            }
        }
    } elsif (@v == 1) {
        if (exists $c->{$k}) {
            if (ref $c->{$k} eq "HASH") { $c->{$k}{$v[0]} = 1; }
            else {push @{$c->{$k}}, @v}
        } else { $c->{$k} = $v[0]; }
    } else {
        if (exists $c->{$k}) {
            if (ref $c->{$k} eq "HASH") { $c->{$k}{$_} = 1 for @v }
            else {push @{$c->{$k}}, @v }
        }
        else { $c->{$k} = [@v]; }
    }
}

{   ### only load Text::ParseWords once;
    my $loaded_tp;

    sub _equal_sep {
        my $self = shift;
        my $fh   = $self->fh;

        my %config;
        while (<$fh>) {
            next if     /^\s*#/;
            next unless /^\s*(.*?)\s*=\s*(.*)\s*$/;

            my ($k, $v) = ($1, $2);
            my @v;

            ### multiple enries, but no shell tokens?
            if ($v=~ /,/ and $v !~ /(["']).*?,.*?\1/) {
                $config{$k} = [ split /\s*,\s*/, $v ];
            } elsif ($v =~ /\s/) { # XXX: Foo = "Bar baz"

                ### only load once
                require Text::ParseWords unless $loaded_tp++;

                @v = Text::ParseWords::shellwords($v);

            } else {
                $config{$k} = $v;
            }
        }

        return \%config;
    }

    sub _space_sep {
        my $self = shift;
        my $fh   = $self->fh;

        my %config;
        while (<$fh>) {
            next if     /^\s*#/;
            next unless /\s*(\S+)\s+(.*)/;
            my ($k, $v) = ($1, $2);
            my @v;

            ### multiple enries, but no shell tokens?
            if ($v=~ /,/ and $v !~ /(["']).*?,.*?\1/) {
                @v = split /\s*,\s*/, $v;
            } elsif ($v =~ /\s/) { # XXX: Foo = "Bar baz"

                ### only load once
                require Text::ParseWords unless $loaded_tp++;

                @v = Text::ParseWords::shellwords($v);

            } else {
                @v = $v;
            }
            $self->_check_hash_and_assign(\%config, $k, @v);
        }
        return \%config;

    }
}
sub _debug {
    my $self = shift;
    my $msg  = shift or return;

    Carp::confess( __PACKAGE__ . $msg ) if $Debug;
}

1;


__END__