encode-files

#!/usr/bin/env perl6

use Tinky;

=begin pod

=head1 NAME

encode-files - watch a directory of files and encode WAV to FLAC

=head1 SYNOPSIS

=begin code

    encode-files [--out-dir=/tmp/flac ] <DIRECTORY>

=end code

=head1 DESCRIPTION

This watches the directory supplied as an argument and when a new WAV file
shows up it will be copied to the output directory (default "/tmp/flac"
but can be specified with the C<--out-dir> parameter, ) and then encoded
as FLAC.

It notifies of state changes to STDERR.

You will of course need the 'flac' program for this to work.

=end pod

my $state-new       =   Tinky::State.new(name   =>  'new');
my $state-ready     =   Tinky::State.new(name   =>  'ready');
my $state-copied    =   Tinky::State.new(name   =>  'copied');
my $state-done      =   Tinky::State.new(name   =>  'done');
my $state-failed    =   Tinky::State.new(name   =>  'failed');

my $ready           =   Tinky::Transition.new(name  =>  'ready', from => $state-new, to => $state-ready);
my $copied          =   Tinky::Transition.new(name  =>  'copied',   from => $state-ready, to => $state-copied);
my $copy-fail       =   Tinky::Transition.new(name  =>  'fail', from => $state-ready, to => $state-failed);
my $encoded         =   Tinky::Transition.new(name  =>  'done', from => $state-copied, to => $state-done);
my $encode-fail     =   Tinky::Transition.new(name  =>  'fail', from => $state-copied, to => $state-failed); 

my @transitions = ( $ready, $copied, $copy-fail, $encoded, $encode-fail);

my $workflow = Tinky::Workflow.new(name => "encoding", :@transitions, initial-state => $state-new);

class ProcessFile does Tinky::Object {
    has Str $.path      is required;
    has Str $.out-dir   is required;
    has Str $.new-path;
    has Str $.flac-file;
    has     @.errors;
    method new-path() returns Str {
        $!new-path //= $!out-dir.IO.child($!path.IO.basename).Str;
    }
    method flac-file() returns Str {
        $!flac-file //= self.new-path.subst(/\.wav$/, '.flac');
        $!flac-file;
    }

}


multi sub MAIN($dir, Str :$out-dir = '/tmp/flac') {
    my ProcessFile @process-files;

    my $watch-supply = IO::Notification.watch-path($dir).grep({ $_.path ~~ /\.wav$/ }).unique(as => { $_.path }, expires => 5);

    say "Watching '$dir'";

    react {
        whenever $watch-supply -> $change {
            if @process-files.grep({ $_.path eq $change.path }) {
                $*ERR.say: "** Already processing '", $change.path, "' **";
            }
            else {
                CATCH {
                    default {
                        say $_;
                    }
                }
                my $pf = ProcessFile.new(path => $change.path, :$out-dir);
                say "Processing '{ $pf.path }'";
                $pf.apply-workflow($workflow);
                @process-files.append: $pf;
                $pf.ready;
            }
        }
        whenever $state-ready.enter-supply -> $pf {
            CATCH {
                default {
                    $pf.fail;
                }
            }
            my $copy = Proc::Async.new('/usr/bin/cp', $pf.path, $pf.new-path, :err);
            whenever $copy.start {
                $pf.copied;
            }
        }
        whenever $state-copied.enter-supply -> $pf {
            CATCH {
                default {
                    $pf.fail;
                }
            }
            my $encode = Proc::Async.new('/usr/bin/flac', $pf.new-path);
            whenever $encode.stdout {
                   # ignored 
            }
            whenever $encode.stderr -> $error {
                $pf.errors.append: $error;
            }
            whenever $encode.start {
                $pf.done;
            }
        }
        whenever $state-done.enter-supply -> $pf {
            say "File '{ $pf.path }' has been processed to '{ $pf.flac-file }'";
        }
        whenever $workflow.transition-supply -> ($trans, $pf ) {
            $*ERR.say("File '{ $pf.path }' went from '{ $trans.from.name }' to '{ $trans.to.name }'");
        }
    }
}

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