#!/usr/bin/perl
# apk add perl-libwww perl-json

use strict;
use warnings;
use 5.016;
use feature "switch";
no if $] >= 5.018, warnings => "experimental::smartmatch";

use LWP::UserAgent;
use LWP::ConnCache;
use CPAN::Meta;
use Module::CoreList;
use JSON;

my $license_mappings = {
	"perl_5" => "GPL-1.0-or-later OR Artistic-1.0-Perl",
	"artistic_2" => "Artistic-2.0",
	"gpl_3" => "GPL-3.0-only",
};

my $package_mappings = {
	"LWP" => "perl-libwww",
	"TermReadKey" => "perl-term-readkey",
};
our $packager = "";
my $template = <<'EOF';
# Automatically generated by apkbuild-cpan, template 2
[% authors %]
pkgname=[% pkgname %]
_pkgreal=[% pkgreal %]
pkgver=[% pkgver %]
pkgrel=0
pkgdesc="Perl module for [% pkgreal %]"
url="https://metacpan.org/release/[% pkgreal %]/"
arch="noarch"
license="GPL-1.0-or-later Artistic-1.0-Perl"
cpandepends=""
cpanmakedepends=""
cpancheckdepends=""
depends="$cpandepends"
makedepends="perl-dev $cpanmakedepends"
checkdepends="$cpancheckdepends"
subpackages="$pkgname-doc"
source="[% source %]"
builddir="$srcdir/$_pkgreal-$pkgver"

build() {
	:
}

check() {
	:
}

package() {
	:
}

EOF

our $ua = LWP::UserAgent->new();
our $json = JSON->new;
$ua->env_proxy;
$ua->conn_cache(LWP::ConnCache->new());

sub read_file {
	my ($filename) = @_;
	local $/;
	open my $fh, "<", $filename or die "could not open $filename: $!";
	return <$fh>;
}

sub read_assignments_from_file {
	my ($filename) = @_;
	return () if ( ! -e $filename );
	my $text = read_file($filename);
	my %sline = $text =~ /^(\w+)\s*=\s*([^\"\n]*)$/mg;
	my %mline = $text =~ /^(\w+)\s*=\s*\"([^\"]*)\"$/mg;
	my %hash = ( %sline, %mline );

	my $authors = join("\n", $text =~ /^# Contributor: .*$/mg, $text =~ /^# Maintainer: .*$/mg);
	$hash{'authors'} = $authors if length($authors) > 1;

	return \%hash;
}

sub map_cpan_to_apk {
	my ($cpan_distrib) = @_;
	return $package_mappings->{$cpan_distrib} if exists $package_mappings->{$cpan_distrib};
	# most packages are named according to the
	# distribution name
	return 'perl-' . lc $cpan_distrib;
}

sub read_apkbuild {
	return read_assignments_from_file("APKBUILD");
}

sub write_apkbuild {
	my ($distdata, $authors, $moddata) = @_;

	my $cpanid = $distdata->{id};
	$cpanid = substr($cpanid, 0, 1) . "/" . substr($cpanid, 0, 2) . "/$cpanid";

	my %repl = (
		authors  => ($authors or "# Contributor: $packager\n# Maintainer: $packager"),
		pkgname  => map_cpan_to_apk($moddata->{distribution}),
		pkgreal  => $moddata->{distribution},
		pkgver  => $moddata->{version},
		source   => $moddata->{download_url} =~ s/$moddata->{version}/\$pkgver/r,
		pkgdesc  => $distdata->{abstract},
	);
	$template =~ s/\[% (.*?) %\]/$repl{$1}/g;

	open my $fh, '>', "APKBUILD" or die;
	print $fh $template;
	close $fh;

	say "Wrote $repl{pkgname}/APKBUILD";
}

sub parse_deps {
	my ($reqs) = @_;
	my $distfiles = {};
	my $response;
	my $deps = "";

	for my $module ($reqs->required_modules) {
		if (Module::CoreList->is_core($module)) {
			my $perlver = Module::CoreList->first_release($module);
			say "$module is part of core perl since $perlver.";
			next;
		}
		next if $module eq 'perl';

		# map module name to package name
		$response = $ua->get("https://fastapi.metacpan.org/module/$module");
		$response->is_success or die $response->status_line;
		my $moddata = $json->decode($response->decoded_content);
		$moddata->{error} and die "Error trying to locate $module: $moddata->{error}\n";
		$distfiles->{$moddata->{distribution}} = $moddata;
	}

	# map package names to alpine packages
	foreach ( keys %{ $distfiles } ) {
		$response = $ua->get("https://fastapi.metacpan.org/release/$_");
		$response->is_success or die $response->status_line;
		my $distdata = $json->decode($response->decoded_content);
		$distdata->{error} and die "Error trying to locate $_: $distdata->{error}\n";

		my $pkgname = map_cpan_to_apk($distdata->{name});
		$deps .= "$pkgname ";
	}
	$deps =~ s/\h+/ /g;
	$deps =~ s/ $//;
	return $deps;

}

sub prepare_tree {
	system("abuild checksum unpack prepare") == 0 or
		die "abuild checksum failed";
}

sub update_functions {
	my $apkbuild = read_apkbuild;
	my $metaprefix = "src/" . $apkbuild->{'_pkgreal'} . "-" . $apkbuild->{'pkgver'} . "/";
	my $build_func;
	my $check_func;
	my $package_func;

	my $text = read_file "APKBUILD";
	if (-e "$metaprefix/Build.PL" ) {
		$build_func = <<'EOF';
build() {
	export CFLAGS=$(perl -MConfig -E 'say $Config{ccflags}')
	perl Build.PL installdirs=vendor
	./Build
}
EOF
		$package_func = <<'EOF';
package() {
	./Build install destdir="$pkgdir"
	find "$pkgdir" \( -name perllocal.pod -o -name .packlist \) -delete
}
EOF
		$check_func = <<'EOF';
check() {
	./Build test
}
EOF
	} else {
		$build_func = <<'EOF';
build() {
	export CFLAGS=$(perl -MConfig -E 'say $Config{ccflags}')
	PERL_MM_USE_DEFAULT=1 perl -I. Makefile.PL INSTALLDIRS=vendor
	make
}
EOF
		$package_func = <<'EOF';
package() {
	make DESTDIR="$pkgdir" install
	find "$pkgdir" \( -name perllocal.pod -o -name .packlist \) -delete
}
EOF
		$check_func = <<'EOF';
check() {
	export CFLAGS=$(perl -MConfig -E 'say $Config{ccflags}')
	make test
}
EOF
	}

	$text =~ s/^build\(\) \{.*?^\}\n/$build_func/smg or
		die "Can't replace build function APKBUILD";
	$text =~ s/^package\(\) \{.*?^\}\n/$package_func/smg or
		die "Can't replace package function APKBUILD";
	$text =~ s/^check\(\) \{.*?^\}\n/$check_func/smg or
		die "Can't replace check function APKBUILD";

	open my $fh, '>', "APKBUILD" or die;
	print $fh $text;
	close $fh;
}

sub do_depends {

	my $apkbuild = read_apkbuild;
	my $metaprefix = "src/" . $apkbuild->{'_pkgreal'} . "-" . $apkbuild->{'pkgver'} . "/";
	my $meta;

	foreach my $metafile ("MYMETA.json", "META.json", "MYMETA.yml", "META.yml") {
		if (-e "$metaprefix$metafile") {
			say "Using meta information from $metafile";
			$meta = CPAN::Meta->load_file("$metaprefix$metafile");
			last;
		}
	}
	die "No dependency meta file found" unless $meta;

	my $abstract = $meta->abstract;
	say "Abstract: $abstract";

	my $license = join " ", map {$license_mappings->{$_} or $_} $meta->license;
	say "License: $license";

	my $deps = parse_deps $meta->effective_prereqs->requirements_for('runtime', 'requires');
	say "CPAN deps: $deps";
	say "Recommend: " . parse_deps $meta->effective_prereqs->requirements_for('runtime', 'recommends');

	my $makedeps = parse_deps($meta->effective_prereqs->requirements_for('build', 'requires'), $meta->effective_prereqs->requirements_for('build', 'recommends'));
	say "CPAN build deps: $makedeps";
	say "CPAN requires: " . parse_deps($meta->effective_prereqs->requirements_for('build', 'requires'));
	say "CPAN recommds: " . parse_deps($meta->effective_prereqs->requirements_for('build', 'recommends'));

	my $checkdeps = parse_deps($meta->effective_prereqs->requirements_for('test', 'requires'), $meta->effective_prereqs->requirements_for('test', 'recommends'));
	say "CPAN check deps: $makedeps";

	my $text = read_file "APKBUILD";
	if ($abstract && $abstract ne 'unknown') {
		$text =~ s/^pkgdesc=\"([^\"]*)\"$/pkgdesc=\"$abstract\"/mg or
			die "Can't find cpandepends line in APKBUILD";
	}
	if (length(`find $metaprefix -name '*.xs'`)) {
		$text =~ s/^arch=\"([^\"]*)\"$/arch="all"/mg or
			die "Can't find arch line in APKBUILD";
	}
	if ($license ne 'unknown') {
		$text =~ s/^license=\"([^\"]*)\"$/license=\"$license\"/mg or
			die "Can't find license line in APKBUILD";
	}
	$text =~ s/^cpandepends=\"([^\"]*)\"$/cpandepends=\"$deps\"/mg or
		die "Can't find cpandepends line in APKBUILD";
	$text =~ s/^cpanmakedepends=\"([^\"]*)\"$/cpanmakedepends=\"$makedeps\"/mg or
		die "Can't find cpanmakedepends line in APKBUILD";
	$text =~ s/^cpancheckdepends=\"([^\"]*)\"$/cpancheckdepends=\"$checkdeps\"/mg or
		die "Can't find cpancheckdepends line in APKBUILD";

	open my $fh, '>', "APKBUILD" or die;
	print $fh $text;
	close $fh;
}

sub get_data {
	my $apkbuild = read_apkbuild;
	$apkbuild->{_pkgreal} or die "Not apkbuild-cpan generated APKBUILD";
	my $response = $ua->get("https://fastapi.metacpan.org/release/$apkbuild->{_pkgreal}");
	$response->is_success or die $response->status_line;
	my $distdata = $json->decode($response->decoded_content);
	$distdata->{error} and die "Error trying to locate $apkbuild->{_pkgreal}: $distdata->{error}\n";

	$response = $ua->get("https://fastapi.metacpan.org/module/$distdata->{main_module}");
	$response->is_success or die $response->status_line;
	my $moddata = $json->decode($response->decoded_content);
	$moddata->{error} and die "Error trying to locate $distdata->{main_module}: $moddata->{error}\n";

	return ($apkbuild, $distdata, $moddata);
}

my $abuild_conf = read_assignments_from_file("/etc/abuild.conf");
$packager = $abuild_conf->{PACKAGER} if $abuild_conf->{PACKAGER};

my $user_abuild_conf = read_assignments_from_file($ENV{"HOME"} . "/.abuild/abuild.conf");
$packager = $user_abuild_conf->{PACKAGER} if $user_abuild_conf->{PACKAGER};

given ( $ARGV[0] ) {
	when ("create") {
		my $module = $ARGV[1];
		my $response;
		$module or die "Module name is a mandatory argument";

		$response = $ua->get("https://fastapi.metacpan.org/module/$module");
		$response->is_success or die $response->status_line;
		my $moddata = $json->decode($response->decoded_content);
		$moddata->{error} and die "Error trying to locate $module: $moddata->{error}\n";

		$response = $ua->get("https://fastapi.metacpan.org/release/$moddata->{distribution}");
		$response->is_success or die $response->status_line;
		my $distdata = $json->decode($response->decoded_content);
		$distdata->{error} and die "Error trying to locate $module: $distdata->{error}\n";

		my $apkname = map_cpan_to_apk $distdata->{metadata}{name};
		mkdir $apkname;
		chdir $apkname;
		write_apkbuild($distdata, undef, $moddata);
		prepare_tree;
		update_functions;
		do_depends;
	}
	when ("recreate") {
		my ($apkbuild, $distdata, $moddata) = get_data;
		write_apkbuild($distdata, $apkbuild->{authors}, $moddata);
		prepare_tree;
		update_functions;
		do_depends;
	}
	when ("upgrade") {
		my ($apkbuild, $distdata, $moddata) = get_data;

		my $pkgver = $moddata->{version};
		if ($pkgver != $apkbuild->{pkgver}) {
			say "Upgrading CPAN module from $apkbuild->{pkgver} to $pkgver";

			my $text = read_file "APKBUILD";
			$text =~ s/^pkgver=(.*)$/pkgver=$pkgver/mg or
				die "Can't find pkgver line in APKBUILD";
			$text =~ s/^pkgrel=(.*)$/pkgrel=0/mg;
			open my $fh, '>', "APKBUILD" or die;
			say $fh $text;
			close $fh;

			prepare_tree;
			do_depends;
		} else {
			say "Up-to-data with CPAN";
		}
	}
	when ('check') {
		my ($apkbuild, $distdata, $moddata) = get_data;
		my $pkgver = $moddata->{version};
		say "$apkbuild->{pkgname}: Latest version: $pkgver Packaged version: $apkbuild->{pkgver}";
		if ($pkgver ne $apkbuild->{pkgver}) {
			exit(1);
		}
	}
	when ("update") {
		prepare_tree;
		do_depends;
	}
	default {
		say "Usage: apkbuild-cpan [create <Module::Name> | check | recreate | update | upgrade]";
		exit;
	}
}