#!/usr/bin/perl
use strict;
use warnings;

use File::Find::Rule;
use Path::Class qw( dir file );
use POSIX ":sys_wait_h";

my (@tracks) = File::Find::Rule->file->name('*.flac')->in('./');

my $pid = $$;

sub flac_decode {
  my $writefno = shift;
  my $file     = shift;
  open *STDOUT, '>>&=', $writefno || die "Pipe open failed";
  $|++;
  exec {'flac'} 'flac', '-d', '-c', $file;
}

sub mp3_encode {
  my $readfno = shift;
  my $file    = shift;
  exec {'lame'} 'lame', qw( --verbose --preset insane -V 0 -B 128 -q 0 ), "/proc/$pid/fd/$readfno", $file;
}

for (@tracks) {
  my $file = file($_);
  my $dir  = $file->dir;
  my $base = $file->basename;

  my $out = $base;
  $out =~ s/.flac/.mp3/;

  print "$file => $out\n";

  my ( $readfh, $writefh );
  pipe $readfh, $writefh;

  my ( $flaccer, $mp3er );
  if ( not $flaccer = fork() ) {
    flac_decode( fileno $writefh, "$file" );
  }
  if ( not $mp3er = fork() ) {
    mp3_encode( fileno $readfh, $out );
  }

  waitpid $flaccer, 0;
  waitpid $mp3er,   0;

}