#!/usr/bin/perl
########################
# Jigstar Music Daemon #
########################

#> #> = Temporary comment.

#> Check for lock file to see if another instance of JMD is running.
die "Error: Lock file exists!" if -e "/var/lock/jmd";
open LOCK, ">/var/lock/jmd";
print LOCK $$;
close LOCK;

#> Check to see if ESD is running. If not, start it.
#> Remember, esdctl returns 1 if ESD isn't running.
 system("esdctl serverinfo >> /dev/null") and system("esd -nobeeps &");

#> Exit cleanly when told to do so.
 $SIG{INT} = sub {
  #> Do I need to force my children to die so they won't become zombies?
  unlink "/var/lock/jmd", "/tmp/jmd";
  system("killall esd");
  exit;
};
$SIG{QUIT} = $SIG{INT};

#> Use CHLD to simulate the 'done' thing.

#> Declare subroutines.
 sub Play ($);
 sub Next ();
 sub Pause ();
 sub Resume ();
 sub Stop ();
 sub Debug ();

#> When woken up by JMC, read the input and execute the commands.
$SIG{ALRM} = sub {
 return unless -s "/tmp/jmd";
 open INPUT, "/tmp/jmd";
 chomp($Cmd = <INPUT>);
 close INPUT;
 open INPUT, ">/tmp/jmd";
 print INPUT undef;
 close INPUT;
 $Cmd =~ s/^play // and Play $Cmd if $Cmd =~ m/^play /;
 Next if $Cmd eq "next";
 Status == 1 ? Pause : Resume if $Cmd eq "toggle";
 Pause if $Cmd eq "pause";
 Resume if $Cmd eq "resume";
 Stop if $Cmd eq "stop";
 Debug if $Cmd eq "status";
 $SIG{QUIT}->() if $Cmd eq "quit";
};

our @PIDs;

sub Play ($) {
 my $Args = shift;
 Pause;
 #> Have MPG321 get all files from /root/mp3. Make it configurable later.
 #> Change STDERR receiver.
 if (my $PID = fork()) {
  push @PIDs, $PID;
 } else {
  chdir "/root/mp3/";
  exec("mpg321 -v $Args 2> /dev/tty12 &");
 }
}

sub Next () {
 #> If it's stopped, resume it temporarily to change tracks.
 if (Status() == 2) {
  Resume;
  kill "INT", $PIDs[-1] if @PIDs;
 }
 kill "INT", $PIDs[-1] if @PIDs;
}

sub Pause () {
 kill "STOP", $PIDs[-1] if @PIDs;
}

sub Resume () {
 kill "CONT", $PIDs[-1] if @PIDs;
}

sub Stop () {
 kill 9, $PIDs[-1] if @PIDs;
 pop @PIDs;
}

sub Debug () {
 my $Counter = 0;
 for my $PID (@PIDs) {
  #> Print the ID, the PID, and the status. Don't need to check if nothing is
  #> there, because there has to be.
  print "$Counter: $PID = " . Status($PID) . "\n";
  $Counter++;
 }
}

#> Return status of a PID. 0 = Isn't running, 1 = Playing, & 2 = Paused.
sub Status ($) {
 my $PID = shift || $PIDs[-1];
 my $Line = +(split(/\n/, `ps $PID`))[1];
 if ($Line !~ m/$PID/) {
  return 0;
 } elsif ($Line =~ m/T</) {
  return 2;
 } else {
  return 1;
 }
}

sleep while 1;