package Hydra::Math;
use strict;
use warnings;
use List::Util qw(min);
use Exporter 'import';
our @EXPORT_OK = qw(exponential_backoff);
=head2 exponential_backoff
Calculates a number of seconds to wait before reattempting something.
Arguments:
=over 1
=item C<$attempts>
Integer number of attempts made.
=back
=cut
sub exponential_backoff {
    my ($attempt) = @_;
    my $clamp = min(10, $attempt);
    return 2 ** $clamp;
}
1;

use strict;
use warnings;
use Setup;
use Hydra::Math qw(exponential_backoff);
use Test2::V0;
subtest "exponential_backoff" => sub {
    is(exponential_backoff(0), 1);
    is(exponential_backoff(1), 2);
    is(exponential_backoff(2), 4);
    is(exponential_backoff(9), 512);
    is(exponential_backoff(10), 1024);
    is(exponential_backoff(11), 1024, "we're clamped to 1024 seconds");
    is(exponential_backoff(11000), 1024, "we're clamped to 1024 seconds");
};
done_testing;