use strict;

use warnings;

package inc::latest;

# ABSTRACT: use modules bundled in inc/ if they are newer than installed ones

our $VERSION = '0.500';

package inc::latest;

use Carp;

use File::Basename ();

use File::Spec     ();

use File::Path     ();

use IO::File       ();

use File::Copy     ();

# track and return modules loaded by inc::latest

my @loaded_modules;

sub loaded_modules { @loaded_modules }

# must ultimately "goto" the import routine of the module to be loaded

# so that the calling package is correct when $mod->import() runs.

sub import {

    my ( $package, $mod, @args ) = @_;

    return unless ( defined $mod );

    my $private_path = 'inc/latest/private.pm';

    if ( -e $private_path ) {

        # user mode - delegate work to bundled private module

        require $private_path;

        splice( @_, 0, 1, 'inc::latest::private' );

        goto \&inc::latest::private::import;

    }

    # author mode - just record and load the modules

    push( @loaded_modules, $mod );

    require inc::latest::private;

    goto \&inc::latest::private::_load_module;

}

sub write {

    my $package = shift;

    my ( $where, @preload ) = @_;

    warn "should really be writing in inc/" unless $where =~ /inc$/;

    # write inc/latest.pm

    File::Path::mkpath($where);

    my $fh = IO::File->new( File::Spec->catfile( $where, 'latest.pm' ), "w" );

    print {$fh} "# This stub created by inc::latest $VERSION\n";

    print {$fh} <<'HERE';

package inc::latest;

use strict;

use vars '@ISA';

require inc::latest::private;

@ISA = qw/inc::latest::private/;

HERE

    if (@preload) {

        print {$fh} "\npackage inc::latest::preload;\n";

        for my $mod (@preload) {

            print {$fh} "inc::latest->import('$mod');\n";

        }

    }

    print {$fh} "\n1;\n";

    close $fh;

    # write inc/latest/private;

    require inc::latest::private;

    File::Path::mkpath( File::Spec->catdir( $where, 'latest' ) );

    my $from = $INC{'inc/latest/private.pm'};

    my $to = File::Spec->catfile( $where, 'latest', 'private.pm' );

    File::Copy::copy( $from, $to ) or die "Couldn't copy '$from' to '$to': $!";

    return 1;

}

sub bundle_module {

    my ( $package, $module, $where ) = @_;

    # create inc/inc_$foo

    ( my $dist = $module ) =~ s{::}{-}g;

    my $inc_lib = File::Spec->catdir( $where, "inc_$dist" );

    File::Path::mkpath $inc_lib;

    # get list of files to copy

    require ExtUtils::Installed;

    # workaround buggy EU::Installed check of @INC

    my $inst = ExtUtils::Installed->new( extra_libs => [@INC] );

    my $packlist = $inst->packlist($module) or die "Couldn't find packlist";

    my @files = grep { /\.pm$/ } keys %$packlist;

    # figure out prefix

    my $mod_path = quotemeta $package->_mod2path($module);

    my ($prefix) = grep { /$mod_path$/ } @files;

    $prefix =~ s{$mod_path$}{};

    # copy files

    for my $from (@files) {

        next unless $from =~ /\.pm$/;

        ( my $mod_path = $from ) =~ s{^\Q$prefix\E}{};

        my $to = File::Spec->catfile( $inc_lib, $mod_path );

        File::Path::mkpath( File::Basename::dirname($to) );

        File::Copy::copy( $from, $to ) or die "Couldn't copy '$from' to '$to': $!";

    }

    return 1;

}

# Translate a module name into a directory/file.pm to search for in @INC

sub _mod2path {

    my ( $self, $mod ) = @_;

    my @parts = split /::/, $mod;

    $parts[-1] .= '.pm';

    return $parts[0] if @parts == 1;

    return File::Spec->catfile(@parts);

}

1;

# vim: ts=4 sts=4 sw=4 tw=75 et:

__END__

=pod

=encoding UTF-8

=head1 NAME

inc::latest - use modules bundled in inc/ if they are newer than installed ones

=head1 VERSION

version 0.500

=head1 SYNOPSIS

  # in Makefile.PL or Build.PL

  use inc::latest 'Some::Configure::Prereq';

=head1 DESCRIPTION

B<WARNING -- THIS IS AN EXPERIMENTAL MODULE>.  It was originally bundled

(as an experiment) with L<Module::Build> and has been split out for more

general use.

The C<inc::latest> module helps bootstrap configure-time dependencies for

CPAN distributions.  These dependencies get bundled into the C<inc>

directory within a distribution and are used by F<Makefile.PL> or F<Build.PL>.

Arguments to C<inc::latest> are module names that are checked against both

the current C<@INC> array and against specially-named directories in

C<inc>.  If the bundled version is newer than the installed one (or the

module isn't installed, then, the bundled directory is added to the start

of C<@INC> and the module is loaded from there.

There are actually two variations of C<inc::latest> -- one for authors and

one for the C<inc> directory.  For distribution authors, the C<inc::latest>

installed in the system will record modules loaded via C<inc::latest> and

can be used to create the bundled files in C<inc>, including writing the

second variation as C<inc/latest.pm>.

This second C<inc::latest> is the one that is loaded in a distribution

being installed (e.g. from F<Makefile.PL> or F<Build.PL>).  This bundled

C<inc::latest> is the one that determines which module to load.

=head2 Special notes on bundling

The C<inc::latest> module creates bundled directories based on the packlist

file of an installed distribution.  Even though C<inc::latest> takes module

name arguments, it is better to think of it as bundling and making

available entire I<distributions>.  When a module is loaded through

C<inc::latest>, it looks in all bundled distributions in C<inc/> for a

newer module than can be found in the existing C<@INC> array.

Thus, the module-name provided should usually be the "top-level" module

name of a distribution, though this is not strictly required.

C<inc::latest> has a number of heuristics to discover module names,

allowing users to do things like this:

  use inc::latest 'Devel::AssertOS::Unix';

even though Devel::AssertOS::Unix is contained within the Devel-CheckOS

distribution.

At the current time, packlists are required.  Thus, bundling dual-core

modules may require a 'forced install' over versions in the latest version

of perl in order to create the necessary packlist for bundling.

=head2 Managing dependency chains

Before bundling a distribution you must ensure that all prerequisites are

also bundled and load in the correct order.

For example, if you need C<Wibble>, but C<Wibble> depends on C<Wobble>,

and you have bundled C<Module::Build>, your F<Build.PL> might look like this:

  use inc::latest 'Wobble';

  use inc::latest 'Wibble';

  use inc::latest 'Module::Build';

  Module::Build->new(

    module_name => 'Foo::Bar',

    license => 'perl',

  )->create_build_script;

Authors are strongly suggested to limit the bundling of additional

dependencies if at all possible and to carefully test their distribution

tarballs before uploading to CPAN.

=head1 USAGE

=head2 As bundled in inc/

Using L</Author-mode>, a special stub module will be created in your

distribute directory as F<inc/latest.pm>.  In your F<Makefile.PL> or

F<Build.PL>, you can then load C<inc::latest> to load bundled modules.

When calling C<use>, the bundled C<inc::latest> takes a single module name

and optional arguments to pass to that module's own import method.

  use inc::latest 'Foo::Bar' qw/foo bar baz/;

The implementation is private.  Only the C<import> method is public.

=head2 Author-mode

When you have L<inc::latest> installed from CPAN, then you are in author-mode

if any of the Author-mode methods are available.  For example:

  if ( inc::latest->can('write') ) {

    inc::latest->write('inc');

  }

Using author-mode, you can create the stub F<inc/latest.pm> and bundle

modules into F<inc>.

=over 4

=item loaded_modules()

  my @list = inc::latest->loaded_modules;

This takes no arguments and always returns a list of module names requested

for loading via "use inc::latest 'MODULE'", regardless of whether the load

was successful or not.

=item write()

  inc::latest->write( 'inc' );

This writes the bundled version of inc::latest to the directory name given

as an argument.  It almost all cases, it should be 'C<inc>'.

=item bundle_module()

  for my $mod ( inc::latest->loaded_modules ) {

    inc::latest->bundle_module($mod, $dir);

  }

If $mod corresponds to a packlist, then this function creates a

specially-named directory in $dir and copies all .pm files from the modlist

to the new directory (which almost always should just be 'inc').  For

example, if Foo::Bar is the name of the module, and $dir is 'inc', then the

directory would be 'inc/inc_Foo-Bar' and contain files like this:

  inc/inc_Foo-Bar/Foo/Bar.pm

Currently, $mod B<must> have a packlist.  If this is not the case (e.g. for

a dual-core module), then the bundling will fail.  You may be able to

create a packlist by forced installing the module on top of the version

that came with core Perl.

=back

=for :stopwords cpan testmatrix url annocpan anno bugtracker rt cpants kwalitee diff irc mailto metadata placeholders metacpan

=head1 SUPPORT

=head2 Bugs / Feature Requests

Please report any bugs or feature requests through the issue tracker

at L<https://github.com/dagolden/inc-latest/issues>.

You will be notified automatically of any progress on your issue.

=head2 Source Code

This is open source software.  The code repository is available for

public review and contribution under the terms of the license.

L<https://github.com/dagolden/inc-latest>

  git clone https://github.com/dagolden/inc-latest.git

=head1 AUTHORS

=over 4

=item *

David Golden <dagolden@cpan.org>

=item *

Eric Wilhelm <ewilhelm@cpan.org>

=back

=head1 COPYRIGHT AND LICENSE

This software is Copyright (c) 2009 by David Golden.

This is free software, licensed under:

  The Apache License, Version 2.0, January 2004

=cut