#!/usr/bin/perl
use strict;
use warnings;
use MIDI::Simple::Drummer::Rock;

# "Is there a drummer in the house?"
my $d = MIDI::Simple::Drummer::Rock->new(
    -bpm     => shift || 100,
    -volume  => shift || 100,
    -phrases => shift || 8,
    -file    => "$0.mid",
);

# Declare beat and fill variables for later use.
my ($beat, $fill) = (0, 0);

# Declare a selection of beat names to use.
my @rotate = qw( 2.1 2.2 2.4 );

# Get 'er started.
$d->count_in;

# Choose a beat and-or fill.
for my $p (1 .. $d->phrases) {
    # Beat 2.3 every other phrase.
    if($p % 2 > 0) {
        $beat = $d->beat(-name => 2.3, -fill => $fill);
        $beat = $d->beat(-name => 2.3);
    }
    # Otherwise rotate the beat.
    else {
        # Choose a random beat name from the selection above.
        $beat = $d->beat(-name => (@rotate)[int(rand @rotate)]);
        # Play an exciting fill (chosen at random without a -name).
        $fill = $d->fill(-last => $fill);
    }
}

# Add and play a custom ending fill.
$d->patterns('end fill' => \&fin);
$d->fill(-name => 'end');
#fin($d); # <- Perfectly reasonable but use the API:

# Write out the MIDI file.
$d->write;

# Declare the end fill.
sub fin {
    my $d = shift;
    $d->accent;
    # Crash and kick, simultaneously.
    $d->note('qn', $d->strike('Crash Cymbal 1', $d->name_of('kick')));
}