#! /usr/bin/perl

sub notify ($$) {
  my ($head, $body) = @_;

  $body =~ s:\&:&:g;
  $body =~ s:\<:&lt;:g;
  $body =~ s:\>:&gt;:g;
  my $kid = fork;
  defined $kid or return;
  if (!$kid) {
    open STDOUT, ">", "/dev/null";
    exec "gdbus", "call", "-e",
      "-d", "org.freedesktop.Notifications",
      "-o", "/org/freedesktop/Notifications",
      "-m", "org.freedesktop.Notifications.Notify", "--",
      "DisOrder", "0", "audio-volume-high",
      $head, $body, "[]", "{}", "5000";
  }
  waitpid $kid, 0;
}

sub cmd (@) {
  my @args = @_;
  open my $f, "-|", "disorder", @args;
  chomp (my @r = <$f>);
  close $f;
  if (wantarray) { return @r; }
  elsif (@r == 1) { return $r[0]; }
  else { return "??? multiple lines"; }
}

sub now_playing (;$) {
  my ($track) = @_;
  if (!defined $track) {
    my @r = cmd "playing";
    if ($r[0] =~ /^track\s+(.*)$/) { $track = $1; }
    else { return; }
  }
  my %p;
  for my $p ("artist", "album", "title")
    { $p{$p} = cmd "part", $track, "display", $p; }
  if ($p{artist} =~ /^[A-Z]$/)
    { $p{artist} = $p{album}; $p{album} = undef; }
  elsif ($p{artist} eq "share" && $p{album} eq "disorder")
    { next LINE; }
  my $r = "$p{artist}: ‘$p{title}’";
  if (defined $p{album}) { $r .= ", from ‘$p{album}’"; }
  notify "DisOrder: now playing", $r;
}

for (;;) {
  open my $log, "-|", "disorder", "log";
  my $startp = 1;
  my $stateinfo = undef;
  LINE: while (<$log>) {
    chomp;
    my @f = ();
    my $q = my $t = undef;
    my $e = 0;
    my $j = -1;
    for (my $i = 0; $i < length $_; $i++) {
      my $ch = substr($_, $i, 1);
      if ($e) {
	if ($ch eq "n") { $ch = "\n"; }
	$t .= $ch; $e = 0;
      } elsif ($ch eq $q) {
	push @f, $t; $q = $t = undef;
      } elsif (defined $q) {
	if ($ch eq "\\") { $e = 1; }
	else { $t .= $ch; }
      } elsif ($ch eq " ") {
	push @f, $t if defined $t; $t = undef;
      } elsif (!defined $t && ($ch eq '"' || $ch eq "'")) {
	$t //= ""; $q = $ch; $j = $i;
      } else {
	$t //= ""; $t .= $ch;
      }
    }
    defined $q and die "unmatched $q (pos $j) in: $_";
    push @f, $t if defined $t;

    my $what = $f[1];
    if ($what eq "volume" && $startp) {
      $startp = 0;
      notify "DisOrder state", "Connected: $startinfo";
      now_playing;
    } elsif ($what eq "state") {
      my $st = $f[2];
      my $msg;
      my $np = 0;
      if ($st eq "disable_random") { $msg = "random play disabled"; }
      elsif ($st eq "enable_random") { $msg = "random play enabled"; }
      elsif ($st eq "disable_play") { $msg = "playing disabled"; }
      elsif ($st eq "enable_play") { $msg = "playing enabled"; }
      elsif ($st eq "pause") { $msg = "paused"; }
      elsif ($st eq "resume") { $msg = "playing"; $np = 1; }
      else { next LINE; }
      if (!$startp) {
	notify "DisOrder state", ucfirst $msg;
	now_playing if $np;
      } else {
	if (defined $startinfo) { $startinfo .= "; " . $msg; }
	else { $startinfo = $msg; }
      }
    } elsif ($what eq "scratched") {
      notify "DisOrder state", "Scratched playing track";
    } elsif ($what eq "playing") {
      now_playing $f[2];
    }
  }
  close $log;
  sleep 5;
}