webhook_10_currency.psgi

use 5.010;
use strict;

use Data::Dumper;
use JSON;

use Bot;
my $bot = Bot::bot();

return main_app();

sub main_app {
    my $app = sub {
        my $env = shift;

        my $status = 200;
        my $headers = [
            'Content-Type' => 'text/plain',
        ];
        my $body = '';

        my $path = $env->{PATH_INFO};

        my $input = $env->{'psgi.input'};
        my $json = join '', <$input>;

        my $data = from_json($json);
        say Dumper($data);

        process_message($data) if $data->{message};

        return [$status, $headers, [$body]];
    };

    return $app;
}

sub process_message {
    my ($data) = @_;

    my $message = $data->{message};
    my $text = $message->{text};
    my $chat_id = $message->{chat}{id};

    my ($amount, $currency_from, $currency_to) = $text =~ /([\d.]+)\s*(\w+)\s+(?:to|in)\s+(\w+)/;

    $currency_from = uc $currency_from;
    $currency_to = uc $currency_to;

    my %currency = (
        LEI => 1,
        EUR => 4.45621098,
        USD => 3.95439788,
    );

    my $result;
    if ($currency{$currency_from} && $currency{$currency_to}) {
        $result = sprintf '%.2f', $amount * $currency{$currency_from} / $currency{$currency_to};
    }
    else {
        $result = 'Available currencies: ' . join ', ', keys %currency;
        $result .= "\n<i>Example: 25 LEI in EUR</i>";
    }

    $bot->sendMessage({
        chat_id => $chat_id,
        text => $result,
        parse_mode => 'HTML',
    });
}