#!/usr/bin/perl
# -*- perl -*-

#
# $Id: mkprereqinst,v 1.7 2002/03/04 08:54:48 eserte Exp $
# Author: Slaven Rezic
#
# Copyright (C) 2002 Slaven Rezic. All rights reserved.
# This package is free software; you can redistribute it and/or
# modify it under the same terms as Perl itself.
#
# Mail: slaven.rezic@berlin.de
# WWW:  http://www.rezic.de/eserte/
#

use Config;
use Getopt::Long;
use strict;
use vars qw($VERSION);
use ExtUtils::MakeMaker;

$VERSION = sprintf("%d.%02d", q$Revision: 1.7 $ =~ /(\d+)\.(\d+)/);

my $v;
my $exec;

if (!GetOptions("v!" => \$v,
		"exec!" => \$exec)) {
    die <<EOF;
usage: $0 [-v] [-exec]
-v:    verbose
-exec: do not create prereqinst but rather exec the generated code
EOF
}

{
    package ExtUtils::MakeMaker;
    use vars qw($Makefile_PL);

    sub WriteMakefile {
	$Makefile_PL = { @_ };
    }
}

do "Makefile.PL"; die $@ if $@;

my $prereq_pm = $ExtUtils::MakeMaker::Makefile_PL->{PREREQ_PM};
if (ref $prereq_pm ne 'HASH') {
    warn "No prerequisites found in Makefile.PL\n";
    exit 0;
}

my $code = "";

$code .= <<EOF;
$Config{startperl}
# -*- perl -*-
#
# DO NOT EDIT, created automatically by $0\n
# on @{[ scalar localtime ]}
#

use Getopt::Long;
EOF

$code .= <<'EOF';
my $require_errors;
my $use = 'cpan';

if (!GetOptions("ppm"  => sub { $use = 'ppm'  },
		"cpan" => sub { $use = 'cpan' },
	       )) {
    die "usage: $0 [-ppm | -cpan]\n";
}

EOF

my(@installs, @ppm_installs, @requires, @modlist);
while(my($mod, $ver) = each %$prereq_pm) {
    my $check_mod = "require $mod";
    if ($ver) {
	$check_mod .= "; $mod->VERSION($ver)";
    }
    push @installs, "install '$mod' if !eval '$check_mod';";
    (my $ppm = $mod) =~ s/::/-/g;
    push @ppm_installs, "do { print STDERR 'Install $ppm'.qq(\\n); PPM::InstallPackage(package => '$ppm') or warn ' (not successful)'.qq(\\n); } if !eval '$check_mod';";
    push @requires, "if (!eval 'require $mod;" . ($ver ? " $mod->VERSION($ver);" : "") . '\') { warn $@; $require_errors++ }';
    push @modlist, $mod . ($ver ? " $ver" : "");
}

$code .= <<EOF;
if (\$use eq 'ppm') {
    require PPM;
@{[ join("\n", map("    $_", @ppm_installs)) ]}
} else {
    use CPAN;
@{[ join("\n", map("    $_", @installs)) ]}
}
EOF

$code .= join("\n", @requires), "\n\n";

$code .= 'warn "Autoinstallation of prerequisites completed\n" if !$require_errors;' . "\n";

if ($exec) {
    package Prereqinst;
    eval $code;
    die $@ if $@;
} else {
    open(F, "> prereqinst") or die "Can't write prereqinst: $!";
    print F $code;
    close F;
    chmod 0755, "prereqinst";
}

if ($v) {
    print STDERR "Dependencies: " . join(", ", @modlist) . "\n";
}

__END__

=head1 NAME

mkprereqinst - create a prereqinst file for perl module distributions

=head1 DESCRIPTION

C<mkprereqinst> creates a C<prereqinst.pl> file. The created file can
be included to perl module and script distributions to help people to
get and install module prerequisites through C<CPAN.pm> or C<PPM.pm>.

The standard installation process of perl distributions with a
prereqinst file will look as following:

    perl Makefile.PL
    (if there are some modules missing then execute the next line)
    perl prereqinst
    make all test install

If the user needs superuser privileges to install something on his
system, then C<perl prereqinst.pl> and C<make install> should be run
as superuser.

ActivePerl users may use

    perl prereqinst.pl -ppm

to fetch the modules through C<PPM> instead of C<CPAN>.

=head2 OPTIONS

C<mkprereqinst> accepts the following options:

=over

=item C<-v>

Be verbose.

=item C<-exec>

Instead of creating the C<prereqinst.pl>, execute the generated code.

=back

=head1 BUGS and TODO

The script does nasty things with C<ExtUtils::MakeMaker> and the
C<WriteMakefile> subroutine.

It is annoying to create the prereqinst.pl file if the Makefile.PL is
interactive.

OS-related or other conditions in C<PREREQ_PM> are not handled.

There are problems with the mapping of perl module names to PPM
package names.

It should be possible to supply -cpan/-ppm with the -exec option.

prereqinst.pl should autodetected whether the system is a CPAN or a
PPM system. With -cpan or -ppm it will be possible to change the
default.


=head1 README

mkprereqinst creates a prereqinst file. The created file can be
included to perl module and script distributions to help people to get
and install module dependecies through CPAN.pm or PPM.pm

=head1 PREREQUISITES

only standard perl modules

=head1 COREQUISITES

none

=head1 OSNAMES

any

=head1 SCRIPT CATEGORIES

CPAN

=head1 SEE ALSO

CPAN(3), PPM(3), ExtUtils::MakeMaker(3).

=cut