#!/usr/bin/env perl

use warnings 'FATAL' => 'all';
use strict;

package Convert;

use Module::CoreList;
use LWP::UserAgent qw();
use YAML::XS qw();
use version qw();

# Match unpredictible package names .
my %OVERRIDE =
	('libwww-perl' => 'perl-libwww',
	'aceperl' => 'perl-ace',
	'mod_perl' => 'mod_perl',
	'glade-perl-two' => 'perl-glade-two',
	'Gnome2-GConf' => 'gconf-perl',
	'Gtk2-GladeXML' => 'glade-perl',
	'Glib' => 'glib-perl',
	'Gnome2' => 'gnome-perl',
	'Gnome2-VFS' => 'gnome-vfs-perl',
	'Gnome2-Canvas' => 'gnomecanvas-perl',
	'Gnome2-GConf' => 'gconf-perl',
	'Gtk2' => 'gtk2-perl',
	'Cairo' => 'cairo-perl',
	'Pango' => 'pango-perl',
	'Perl-Critic' => 'perl-critic',
	'Perl-Tidy' => 'perl-tidy',
	'App-Ack' => 'ack',
	'TermReadKey' => 'perl-term-readkey');

sub dist2pkg
{
	my ($name, $ver) = @_;
	return dist_pkgname($name), dist_pkgver($ver);
}

# Copied from CPANPLUS::Dist::Arch
sub dist_pkgname
{
	my ($distname) = @_;

	return $OVERRIDE{$distname} if(exists($OVERRIDE{$distname}));

	# Package names should be lowercase and consist of alphanumeric
	# characters only (and hyphens!)...
	$distname =  lc($distname);
	$distname =~ tr/_+/--/;
	$distname =~ tr/-a-z0-9//cd; # Delete all other chars
	$distname =~ tr/-/-/s;

	# Delete leading or trailing hyphens...
	$distname =~ s/\A-//;
	$distname =~ s/-\z//;

	die qq{Dist name '$distname' completely violates packaging standards}
		if(length($distname) == 0);

	# Don't prefix the package with perl- if it IS perl...
	$distname = "perl-$distname" unless($distname eq 'perl');

	return $distname;
}

sub dist_pkgver
{
	my ($version) = @_;

	# Remove developer versions because pacman has no special logic
	# to handle comparing them to regular versions such as perl uses.
	$version =~ s/_[^_]+\z//;

	# Package versions should be numbers and decimal points only...
	$version =~ tr/-_/../;
	$version =~ tr/0-9.//cd;

	$version =~ tr/././s;
	$version =~ s/^[.]|[.]$//g;

	return $version;
}

#---HELPER FUNCTION---
# Decide if the dist. is named after the module.
sub _ismainmod
{
	my ($mod_name, $dist_name) = @_;

	$mod_name =~ tr/:/-/s;
	return lc($mod_name) eq lc($dist_name);
}

#---HELPER FUNCTION---
# Merges the right-hand deps into the left-hand deps.
sub _merge
{
	my ($left_deps, $right_deps) = @_;

	MERGE_LOOP:
	while(my ($pkg, $ver) = each(%$right_deps)) {
		if($left_deps->{$pkg}) {
			my $leftver  = version->parse($left_deps->{$pkg});
			my $rightver = version->parse($ver);
			next MERGE_LOOP if $leftver > $rightver;
		}
		$left_deps->{$pkg} = $ver;
	}

	return;
}

#---HELPER FUNCTION---
# Merge duplicate deps into $left always storing the greatest version there.
sub _mergedups
{
	my ($left, $right) = @_;

	for my $name (keys %$left) {
		my $rver = delete($right->{$name}) or next;
		my $lver = $left->{$name};
		my $lvo  = ($lver ? version->parse($lver) : 0);
		my $rvo  = ($rver ? version->parse($rver) : 0);
		$left->{$name} = ($lvo > $rvo ? $lvo : $rvo);
	}

	return;
}

#---HELPER FUNCTION---
sub _yankcheckers
{
	my ($deps_ref) = @_;
	my %checkdeps;

	my @pkgs = keys %$deps_ref;
	for my $testdep (grep { /^perl-pod-coverage$|perl-test-/ } @pkgs){
		my $val = delete($deps_ref->{$testdep});
		$checkdeps{$testdep} = $val if(defined($val));
	}

	return \%checkdeps;
}

#---HELPER FUNCTION---
# Converts a decimal perl version (like $]) into the dotted decimal
# form that the official ArchLinux perl package uses.
sub _perldepver
{
	my ($perlver) = @_;

	# Fix perl-style vstrings which have a leading "v".
	return $perlver if($perlver =~ s/\Av//);
	return $perlver unless($perlver =~ /\A(\d+)[.](\d{3})(\d{1,3})\z/);

	# Re-apply the missing trailing zeroes.
	my $patch = $3;
	$patch .= q{0} x (3 - length($patch));
	return sprintf('%d.%d.%d', $1, $2, $patch);
}

#---PUBLIC FUNCNTION---
# Translates CPAN module dependencies into ArchLinux package dependencies.
sub _reqs2deps
{
	my ($prereqs) = @_;

	my %pkgdeps;
	
	CPAN_DEP_LOOP:
	while(my ($name, $ver) = each(%$prereqs)) {
		# Sometimes a perl version is given as a prerequisite
		if($name eq 'perl') {
			$pkgdeps{'perl'} = _perldepver($ver);
			next CPAN_DEP_LOOP;
		}

# Ideally we could take advantage of the perl package's provides list
# and add dependencies for core modules.

# This is more robust and handles the problem of packages built
# with a different version of perl than the perl that is present
# when the package is installed.

# The problem is that the perl package provides list still needs work.
# While I was trying to generate a provides list I noticed the
# Module::CoreList module had some incorrect version numbers
# as well. So until I get around to reporting these bugs I will
# just go back to not depending on packages provided by perl.

		# 0+$] is needed to force the perl version into number-dom
		# otherwise trailing zeros cause problems
		my $bundled_version = $Module::CoreList::version{0+$]}->{$name};
		if($bundled_version) {
			# Avoid parsing an empty string (causes an error) or 0.
			next CPAN_DEP_LOOP unless($ver);

			# Avoid parsing a bundled version of 0. Is this possible?
			my $bundle_vobj = version->parse($bundled_version);
			my $dep_vobj = version->parse($ver);
			next CPAN_DEP_LOOP if($bundle_vobj >= $dep_vobj);
		}

		my $dist = _distofmod($name);
		my $pkgname = dist_pkgname($dist);

		# If the module is not named after the distribution, ignore its
		# version which might not match the distribution.
		undef $ver unless(_ismainmod($name, $dist));

		# If two module prereqs are in the same CPAN distribution then
		# the version required for the main module will override.
		# (because versions specified for other modules in the dist
		# are 0)
		$pkgdeps{$pkgname} ||= ($ver ? dist_pkgver($ver) : 0);
	}
	
	return \%pkgdeps;
}

sub prereqs
{
	my ($pkgname, $prereqs) = @_;

	# maps perl names for different dependencies to ArchLinux's names
	my %namemap = ('configure' => 'makedepends',
				   'build' => 'makedepends',
				   'test' => 'checkdepends',
				   'runtime' => 'depends');

	my %pkgdeps;
	while (my ($perl, $arch) = each(%namemap)) {
		my $reqs = $prereqs->{$perl}{'requires'};
		my $deps; $deps = _reqs2deps($reqs) if($reqs);

		next unless(keys(%$deps));
		if($pkgdeps{$arch}) { _merge($pkgdeps{$arch}, $deps); }
		else { $pkgdeps{$arch} = $deps; }
	}
	
	# ArchLinux now has a separate array for dependencies that we only
	# need for checking (aka "testing"). Older perl METAs do not
	# have this separated. Force any test modules to be checkdepends.
	if(!$pkgdeps{'checkdepends'} && $pkgname !~ /\Aperl-test-/) {
		my $checkdeps = {};
		my $makedeps = $pkgdeps{'makedepends'};
		_merge($checkdeps, _yankcheckers($makedeps));
		$pkgdeps{'checkdepends'} = $checkdeps;
	}

	# We at least require perl, if nothing else.
	unless(grep { scalar(keys(%$_)) > 0 } values(%pkgdeps)) {
		$pkgdeps{'depends'}{'perl'} = 0;
	}

	_mergedups(@pkgdeps{'makedepends', 'checkdepends'});
	_mergedups(@pkgdeps{'depends', 'makedepends'});

	# Convert all deps into arrays of strings.
	for my $deptype (keys(%pkgdeps)) {
		$pkgdeps{$deptype} = _stringify($pkgdeps{$deptype});
	}

	return \%pkgdeps;
}

#---HELPER FUNCTION---
sub _stringify
{
	my ($deps) = @_;

	my @depstrs;
	for my $pkg (sort(keys(%$deps))) {
		my $ver = $deps->{$pkg};
		my $str = ($ver eq '0' ? $pkg : "$pkg>=$ver");
		push(@depstrs, $str);
	}

	return \@depstrs;
}

my $UA;
sub _distofmod
{
	my ($mod) = @_;

	my $UA ||= LWP::UserAgent->new();
	my $url = "http://cpanmetadb.appspot.com/v1.0/package/$mod";
	my $resp = $UA->get($url);
	die "failed to lookup dist for $mod: " . $resp->status_line
		unless($resp->is_success);

	$resp = YAML::XS::Load($resp->content);
	my $file = $resp->{'distfile'};
	$file =~ s{.*/}{};
	$file =~ s{-[^-]+\z}{};

	return $file;
}

#-----------------------------------------------------------------------------

package main;

use File::Basename qw(basename dirname);
use File::Spec::Functions qw(catfile catdir);
use File::Find qw(find);

use JSON::XS qw(decode_json); # for META.json
use YAML::XS (); # for META.yml
use Pod::Select (); # search POD for description

use Digest::MD5 (); # for md5sums & sha512sums
use Digest::SHA ();

sub main
{
	my $distpath = shift() or die "Usage: perl-dist [path to cpan dist file]\n";
	my $dir  = dirname($distpath);
	my $file = basename($distpath);
	my $info = distinfo($file);

	chsrcdir(catdir($dir, 'src'), $file);
	$dir = extractdist($file);

	my $meta = loadmeta($dir);
	my $desc = $meta->{'abstract'};
	if(!$desc || $desc eq '~') {
		$meta->{'abstract'} = distdesc($dir, $info->{'mod'});
	}

	my ($name, $ver) = Convert::dist2pkg(@{$info}{'name', 'ver'});
	my $deps = Convert::prereqs($name, $meta->{'prereqs'});

	my %pbvars =
		('pkgver'  => $ver,
		 'pkgdesc' => $meta->{'abstract'},
		 'arch' => (xsdist($dir) ? ['i686', 'x86_64'] : 'any'),
		 'md5sums' => md5sums($file),
		 'sha512sums' => sha512sums($file),
		 'distdir' => $dir,
		 %$deps,
		 );

	# Since this is a perl distribution, use the perl-pkg template.
	printf("template\nperl-pkg %s\n\n", (-f "$dir/Build.PL" ? "MB" : "MM"));

	printmeta(\%pbvars);
	return 0;
}

# Create the src/ directory and tarball symlink. Then chdir into it.

sub chsrcdir
{
	my ($srcdir, $distfile) = @_;

	unless(-d $srcdir) {
		mkdir $srcdir or die "mkdir $srcdir: $!";
	}
	chdir($srcdir) or die "chdir $srcdir: $!";
	unless(-f $distfile) {
		symlink(catfile('..', $distfile), $distfile) or die "symlink $distfile: $!";
	}

	return $srcdir;
}

sub distinfo
{
	my ($distfile) = @_;

	my @c = split(/-/, $distfile);
	my $ver = pop(@c);
	my $name = join(q{-}, @c);
	my $mod = $name;
	$mod =~ s/-/::/g;
	return { 'name' => $name, 'ver' => $ver, 'mod' => $mod };
}

sub extractdist
{
	my ($file) = @_;

	system("bsdtar -xf $file");
	die "perl-dist: bsdtar failed to extract $file\n" unless($? == 0);

	opendir(my $srcdir, '.') or die "opendir: $!";
	my @dirs = grep { -d $_ && !/\A[.]/ } readdir($srcdir);
	closedir($srcdir);

	die("perl-dist: many dirs (@dirs) inside the tarball $file\n")
		if(@dirs > 1);
	die("perl-dist: no dirs found in tarball $file\n") if(@dirs == 0);
	return $dirs[0];
}

sub printmeta
{
	my ($pbvars) = @_;
	while(my ($name, $val) = each(%$pbvars)) {
		if(!defined($val) || $val eq q{}) {
			warn("perl-dist: warning: $name is undefined\n");
			$val = q{};
		}
		print($name, "\n");
		print("$_\n") for (ref $val ? @$val : $val);
		print("\n");
	}

	# TODO: autodetect license type
	print("license\n$_\n\n") for (qw/PerlArtistic GPL/);
}

sub loadmeta
{
	my ($distdir) = @_;

	for my $metaext (qw/json yml/) {
		my $path = "$distdir/META.$metaext";
		next unless -f $path;

		open(my $metafh, '<', $path) or die "open: $!";
		my $meta = do { local $/; <$metafh> };
		close($metafh);

		$meta = ($metaext eq 'json' ? decode_json($meta)    :
				 $metaext eq 'yml'  ? YAML::XS::Load($meta) :
				 die "internal error: unknown \$metaext: $metaext");

		upgrademeta($meta);
		return $meta;
	}

	return undef;
}

sub upgrademeta
{
	my ($meta) = @_;

	return if(exists($meta->{'prereqs'}));

	my $prereqs;
	$prereqs->{'configure'}{'requires'} = delete($meta->{'configure_requires'});
	$prereqs->{'build'}{'requires'} = delete($meta->{'build_requires'});
	$prereqs->{'runtime'}{'requires'} = delete($meta->{'requires'});

	$meta->{'prereqs'} = $prereqs;
	return;
}

sub xsdist
{
	my ($dir) = @_;
	my $isxs;
	find({ 'wanted' => sub { $isxs = 1 if(/[.]xs$/) }, 'no_chdir' => 1 }, $dir);
	return $isxs;
}

#-----------------------------------------------------------------------------

sub distdesc
{
	my ($dir, $modname) = @_;
	return _poddesc($dir, $modname) || _readmedesc($dir, $modname);
}

sub _poddesc
{
	my ($dir, $modname) = @_;

	my $podselect = Pod::Select->new;
	$podselect->select('NAME');

	my $modpath = $modname; $modpath =~ s{::}{/}g;
	my $moddir = dirname($modpath);
	my $modfile = basename($modpath);

	# First check under lib/ for a "properly" pathed module, with
	# nested directories. Then search desperately for a .pm file that
	# matches the module's last name component.

	my @possible = glob("$dir/{lib/,}{$moddir/,}$modfile.{pod,pm}");

	PODSEARCH:
	for my $podpath (@possible) {
		next PODSEARCH unless(-f $podpath);

		# Read the NAME section of the POD into a scalar.
		my $namesect = q{};
		open(my $podfile, '<', $podpath) or next PODSEARCH;
		open(my $podout, '>', \$namesect) or die "open: $!";

		$podselect->parse_from_filehandle($podfile, $podout);

		close($podfile);
		close($podout) or die "close: $!";

		next PODSEARCH unless($namesect);

		# Remove formatting codes.
		$namesect =~ s{ [IBCLEFSXZ] <(.*?)> }{$1}gxms;
		$namesect =~ s{ [IBCLEFSXZ] <<(.*?)>> }{$1}gxms;

		# The short desc is on a line beginning with 'Module::Name - '
		return $1 if($namesect =~ / ^ \s* $modname [ -]+ ([^\n]+) /xms);
	}

	return undef;
}

#---HELPER FUNCTION---
sub _readmedesc
{
	my ($dir, $modname) = @_;

	my $path = catfile($dir, 'README');
	return undef unless(-f $path);
	open(my $fh, '<', $path) or die "open: $!";

	while (<$fh>) {
		chomp;
		next unless((/\ANAME/ ... /\A[A-Z]+/)
			&& / \A \s* ${modname} [\s\-]+ (.+) \z /x);
		return $1;
	}

	close $fh;
	return undef;
}

#-----------------------------------------------------------------------------

sub md5sums
{
	return [ map {
		open(my $fh, '<', $_) or die "open: $!";
		my $md5 = Digest::MD5->new()->addfile($fh)->hexdigest;
	} @_ ]
}

sub sha512sums
{
	return [ map {
		my $sha = Digest::SHA->new(512)->addfile($_)->hexdigest;
	} @_ ]
}

exit main(@ARGV);