From f1a45f3dd740c5b55cd44ff09548d49791191863 Mon Sep 17 00:00:00 2001
From: Nick Bowler <nbowler@draconx.ca>
Date: Sat, 23 May 2020 16:33:30 -0400
Subject: [PATCH] mpdreload: Simplify script operation.

This script doesn't need any metadata other than filenames and queue
IDs, so we don't need to store anything else in its data structures.

We can also ask MPD not to send us most unneeded information which
speeds things up a lot.
---
 MPDHacks.pm  | 10 ++++++++++
 mpdreload.pl | 42 +++++++++---------------------------------
 2 files changed, 19 insertions(+), 33 deletions(-)

diff --git a/MPDHacks.pm b/MPDHacks.pm
index 0f5026e..7da3b06 100644
--- a/MPDHacks.pm
+++ b/MPDHacks.pm
@@ -115,4 +115,14 @@ sub exec {
 	print $sock "$cmd\n";
 }
 
+# Submit a command to the MPD server and wait for it to complete.
+# Intended for simple cases where the command output is unneeded.
+sub run {
+	MPD::exec(@_);
+	while (<$sock>) {
+		last if (/^OK/);
+		die($_) if (/^ACK/);
+	}
+}
+
 1;
diff --git a/mpdreload.pl b/mpdreload.pl
index c852a2b..c82353e 100755
--- a/mpdreload.pl
+++ b/mpdreload.pl
@@ -26,8 +26,8 @@ use MPDHacks;
 
 my $sock;
 
-# Returns a hash reference containing all tracks in the current play queue.
-# The hash keys are filenames.
+# Returns a hash reference mapping filenames to an array reference listing
+# the queue IDs for that file in the current play queue.
 sub get_tracks_in_play_queue {
 	my %matches;
 	my $entry;
@@ -39,18 +39,9 @@ sub get_tracks_in_play_queue {
 
 		if (/^(\w+): (.*)$/) {
 			if ($1 eq "file") {
-				if (exists($matches{$2})) {
-					$entry = $matches{$2};
-				} else {
-					$entry = {};
-					$matches{$2} = $entry;
-				}
-			}
-
-			if (exists($entry->{$1})) {
-				$entry->{$1}->{$2} = 1;
-			} else {
-				$entry->{$1} = { $2 => 1 }
+				$entry = $matches{$2} //= [];
+			} elsif ($1 eq "Id") {
+				push @$entry, $2;
 			}
 		}
 	}
@@ -129,19 +120,14 @@ if (@ARGV != 1) {
 $sock = MPD::connect();
 
 # Retrieve the current play queue and target play queue.
+MPD::run("tagtypes", "clear");
 my $current = get_tracks_in_play_queue();
 my $target = get_playlist_files($ARGV[0]);
 
 MPD::exec("command_list_begin");
 for (my $i = 0; $i < @$target; $i++) {
 	my $f = $target->[$i];
-	my $ids = $current->{$f}->{Id};
-
-	my $id = (keys %$ids)[0];
-	delete $ids->{$id};
-
-	# Remove tracks with no unused queue IDs
-	delete $current->{$f} unless (keys %$ids > 0);
+	my $id = shift @{ $current->{$f} };
 
 	if (defined $id) {
 		MPD::exec("moveid", $id, $i);
@@ -151,15 +137,5 @@ for (my $i = 0; $i < @$target; $i++) {
 }
 
 # Remove any tracks left from the old play queue.
-foreach (keys %$current) {
-	my $ids = $current->{$_}->{Id};
-	foreach (keys %$ids) {
-		MPD::exec("deleteid", $_);
-	}
-}
-
-MPD::exec("command_list_end");
-while (<$sock>) {
-	last if /^OK$/;
-	die($_) if /^ACK/;
-}
+MPD::exec("deleteid", $_) foreach (map { @$_ } values %$current);
+MPD::run("command_list_end");
-- 
2.43.2