#!/usr/bin/perl

=head1 NAME

dh_perl - calculates Perl dependencies and cleans up after MakeMaker

=cut

use strict;
use warnings;
use Config;
use File::Find;
use Debian::Debhelper::Dh_Lib;

=head1 SYNOPSIS

B<dh_perl> [S<I<debhelper options>>] [B<-d>] [S<I<library dirs> ...>]

=head1 DESCRIPTION

B<dh_perl> is a debhelper program that is responsible for generating
the B<${perl:Depends}> substitutions and adding them to substvars files.

The program will look at Perl scripts and modules in your package,
and will use this information to generate a dependency on B<perl> or
B<perlapi>. The dependency will be substituted into your package's F<control>
file wherever you place the token B<${perl:Depends}>.

B<dh_perl> also cleans up empty directories that MakeMaker can generate when
installing Perl modules.

=head1 OPTIONS

=over 4

=item B<-d>

In some specific cases you may want to depend on B<perl-base> rather than the
full B<perl> package. If so, you can pass the -d option to make B<dh_perl> generate
a dependency on the correct base package. This is only necessary for some
packages that are included in the base system.

Note that this flag may cause no dependency on B<perl-base> to be generated at
all. B<perl-base> is Essential, so its dependency can be left out, unless a
versioned dependency is needed.

=item B<-V>

By default, scripts and architecture independent modules don't depend
on any specific version of B<perl>. The B<-V> option causes the current
version of the B<perl> (or B<perl-base> with B<-d>) package to be specified.

=item I<library dirs>

If your package installs Perl modules in non-standard
directories, you can make B<dh_perl> check those directories by passing their
names on the command line. It will only check the F<vendorlib> and F<vendorarch>
directories by default.

=back

=head1 CONFORMS TO

Debian policy, version 3.8.3

Perl policy, version 1.20

=cut

init();

my $vendorlib = substr $Config{vendorlib}, 1;
my $vendorarch = substr $Config{vendorarch}, 1;

# Cleaning the paths given on the command line
foreach (@ARGV) {
	s#/$##;
	s#^/##;
}

my $perl = 'perl';
# If -d is given, then the dependency is on perl-base rather than perl.
$perl .= '-base' if $dh{D_FLAG};

# dependency types
use constant PROGRAM   => 1;
use constant PM_MODULE => 2;
use constant XS_MODULE => 4;
use constant ARCHDEP_MODULE => 8;

foreach my $package (@{$dh{DOPACKAGES}}) {
	my $tmp=tmpdir($package);

	next unless -d $tmp;

	# Check also for alternate locations given on the command line
	my @dirs = grep -d, map "$tmp/$_", $vendorlib, $vendorarch, @ARGV;

	# Look for perl modules and check where they are installed
	my $deps = 0;
	find sub {
		return unless -f;
		$deps |= PM_MODULE if /\.pm$/;
		$deps |= XS_MODULE if /\.so$/;
		$deps |= ARCHDEP_MODULE
			if $File::Find::dir =~ /\Q$vendorarch\E/;
	}, @dirs if @dirs;

	# find scripts
	find sub {
		return unless -f and (-x _ or /\.pl$/);
		return if $File::Find::dir=~/\/usr\/share\/doc\//;

		return unless open(my $fd, '<', $_);
		if (read($fd, local $_, 32) and m%^#!\s*(/usr/bin/perl|/usr/bin/env\s+perl)\s%) {
			$deps |= PROGRAM;
		}
		close($fd);
	}, $tmp;

	if ($deps) {
		my $version="";
		if ($deps & XS_MODULE or $dh{V_FLAG_SET}) {
			($version) = `dpkg -s $perl` =~ /^Version:\s*(\S+)/m
				unless $version;
			$version = ">= $version";
		}

		my $perlarch = $perl;
		$perlarch .= ':any' if $deps == PROGRAM and not $dh{V_FLAG_SET};

		# no need to depend on an un-versioned perl-base -- it's
		# essential
		addsubstvar($package, "perl:Depends", $perlarch, $version)
			unless $perl eq 'perl-base' && ! length($version);

		# add perlapi-<ver> for XS modules and other modules
		# installed into vendorarch
		addsubstvar($package, "perl:Depends",
			"perlapi-" . ($Config{debian_abi} || $Config{version}))
			if $deps & ( XS_MODULE | ARCHDEP_MODULE );
	}

	# MakeMaker always makes lib and share dirs, but typically
	# only one directory is installed into.
	foreach my $dir ("$tmp/$vendorlib", "$tmp/$vendorarch") {
		if (-d $dir) {
			doit("rmdir", "--ignore-fail-on-non-empty", "--parents",
				"$dir");
		}
	}
}

=head1 SEE ALSO

L<debhelper(7)>

This program is a part of debhelper.

=head1 AUTHOR

Brendan O'Dea <bod@debian.org>

=cut

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