#!/usr/bin/env perl

use strict;
use warnings;
use Digest::SHA qw(sha256);
use FindBin qw($Bin);
use File::Path qw(make_path);
use JSON::PP;
use lib "$Bin";
use LXMF::MessagePack qw(pack_array pack_bin pack_float64 pack_map);

my $output_dir = "$Bin/../examples";
make_path($output_dir);

my $destination_hash = pack("C*", 0x00 .. 0x0f);
my $source_hash = pack("C*", 0x10 .. 0x1f);
my $signature = pack("C*", 0x20 .. 0x5f);
my $stamp = pack("C*", 0xa0 .. 0xbf);

my $timestamp = 1_700_000_000.25;
my $title = "Test title";
my $content = "Deterministic LXMF body";
my $fields = pack_map();

my @required_items = (
    pack_float64($timestamp),
    pack_bin($title),
    pack_bin($content),
    $fields,
);

my $payload = pack_array(@required_items);
my $stamped_payload = pack_array(@required_items, pack_bin($stamp));
my $message_id = sha256($destination_hash . $source_hash . $payload);
my $signed_part = $destination_hash . $source_hash . $payload . $message_id;

my $minimal = $destination_hash . $source_hash . $signature . $payload;
my $stamped = $destination_hash . $source_hash . $signature . $stamped_payload;

write_hex("$output_dir/lxmf_message_minimal.hex", $minimal);
write_hex("$output_dir/lxmf_message_stamped.hex", $stamped);

my $manifest = {
    description => "Deterministic LXMessage packing vectors; signature bytes are placeholders",
    format => "destination_hash || source_hash || signature || msgpack_payload",
    payload_order => [qw(timestamp title content fields optional_stamp)],
    destination_hash_hex => unpack("H*", $destination_hash),
    source_hash_hex => unpack("H*", $source_hash),
    signature_hex => unpack("H*", $signature),
    signature_valid => JSON::PP::false,
    timestamp => $timestamp,
    title_hex => unpack("H*", $title),
    content_hex => unpack("H*", $content),
    fields => {},
    stamp_hex => unpack("H*", $stamp),
    payload_without_stamp_hex => unpack("H*", $payload),
    payload_with_stamp_hex => unpack("H*", $stamped_payload),
    message_id_hex => unpack("H*", $message_id),
    signed_part_hex => unpack("H*", $signed_part),
    minimal_lxmf_hex => unpack("H*", $minimal),
    stamped_lxmf_hex => unpack("H*", $stamped),
};

open my $json_fh, ">:raw", "$output_dir/lxmf_message_vectors.json"
    or die "cannot write vector manifest: $!\n";
print {$json_fh} JSON::PP->new->canonical->pretty->encode($manifest);
close $json_fh;

print "Generated deterministic LXMessage vectors in $output_dir\n";

sub write_hex {
    my ($path, $bytes) = @_;
    open my $fh, ">:raw", $path or die "cannot write $path: $!\n";
    print {$fh} unpack("H*", $bytes), "\n";
    close $fh;
}