#! /usr/bin/perl
# Written by Zack Weinberg <zackw at panix.com> in 2018 and 2020.
# To the extent possible under law, Zack Weinberg has waived all
# copyright and related or neighboring rights to this work.
#
# See https://creativecommons.org/publicdomain/zero/1.0/ for further
# details.

# Using the information in lib/hashes.conf, validate a list of
# selected hashes and hash groups that was supplied as the argument of
# the --enable-hashes option to the configure script, expand all
# the groups, and remove duplicates.
#
# Caution: if you change the format of lib/hashes.conf you will
# probably need to modify gen-crypt-hashes-h as well as this script.

use v5.14;    # implicit use strict, use feature ':5.14'
use warnings FATAL => 'all';
use utf8;
use open qw(:std :utf8);
no  if $] >= 5.022, warnings => 'experimental::re_strict';
use if $] >= 5.022, re       => 'strict';

use FindBin ();
use lib $FindBin::Bin;
use BuildCommon qw(
    parse_hashes_conf
);

sub expand_selected {
    my ($hconf, $selected) = @_;

    if ($selected eq 'all') {
        return keys %{$hconf->hashes};
    } else {
        my %enabled;
        my @errors;
        my $hashes = $hconf->hashes;
        my $groups = $hconf->groups;
        for my $w (split /,/, $selected) {
            if ($w eq 'all') {
                push @errors, "'all' must be used alone\n";
            } elsif (exists $hashes->{$w}) {
                $enabled{$w} = 1;
            } elsif (exists $groups->{$w}) {
                for my $h (@{$groups->{$w}}) {
                    $enabled{$h->name} = 1;
                }
            } else {
                push @errors, "'$w' is not a hash or group name\n";
            }
        }
        if (scalar(%enabled) == 0) {
            push @errors, "no hashes are enabled\n";
        }
        die join q{}, @errors if @errors;
        return keys %enabled;
    }
}

#
# Main
#
if (scalar(@ARGV) != 2) {
    print {*STDERR}
        "usage: ${FindBin::Script} hashes.conf names,of,selected,hashes\n";
    exit 1;
}
exit 0 if eval {
    my ($hashes_conf, $hashes_selected) = @ARGV;
    my $hconf   = parse_hashes_conf($hashes_conf);
    my @enabled = expand_selected($hconf, $hashes_selected);

    print ',', (join ',', sort @enabled), ",\n";
    close STDOUT or die "write error: $!\n";
    1;
};

print {*STDERR} "${FindBin::Script}: $@";
exit 1;