command/queue: add position parameter to "load"

Another one from https://github.com/MusicPlayerDaemon/MPD/issues/888

NEWS

@@ -6,6 +6,7 @@ ver 0.23 (not yet released)
   - support relative positions in "addid"
   - fix relative positions in "move" and "moveid"
   - add "position" parameter to "findadd" and "searchadd"
+  - add position parameter to "load"
 * database
   - proxy: require MPD 0.20 or later
   - proxy: require libmpdclient 2.11 or later

doc/protocol.rst

@@ -917,11 +917,16 @@ remote playlists (absolute URI with a supported scheme).
 
 .. _command_load:
 
-:command:`load {NAME} [START:END]`
+:command:`load {NAME} [START:END] [POSITION]`
     Loads the playlist into the current queue.  Playlist
     plugins are supported.  A range may be specified to load
     only a part of the playlist.
 
+    The ``POSITION`` parameter specifies where the songs will be
+    inserted into the queue.  (This requires specifying the range as
+    well; the special value `0:` can be used if the whole playlist
+    shall be loaded at a certain queue position.)
+
 .. _command_playlistadd:
 
 :command:`playlistadd {NAME} {URI}`

src/command/AllCommands.cxx

@@ -135,7 +135,7 @@ static constexpr struct command commands[] = {
 	{ "listplaylist", PERMISSION_READ, 1, 1, handle_listplaylist },
 	{ "listplaylistinfo", PERMISSION_READ, 1, 1, handle_listplaylistinfo },
 	{ "listplaylists", PERMISSION_READ, 0, 0, handle_listplaylists },
-	{ "load", PERMISSION_ADD, 1, 2, handle_load },
+	{ "load", PERMISSION_ADD, 1, 3, handle_load },
 	{ "lsinfo", PERMISSION_READ, 0, 1, handle_lsinfo },
 	{ "mixrampdb", PERMISSION_PLAYER, 1, 1, handle_mixrampdb },
 	{ "mixrampdelay", PERMISSION_PLAYER, 1, 1, handle_mixrampdelay },

src/command/PlaylistCommands.cxx

@@ -79,11 +79,16 @@ handle_load(Client &client, Request args, [[maybe_unused]] Response &r)
 					   );
 	RangeArg range = args.ParseOptional(1, RangeArg::All());
 
-	const ScopeBulkEdit bulk_edit(client.GetPartition());
+	auto &partition = client.GetPartition();
+	const ScopeBulkEdit bulk_edit(partition);
 
 	auto &playlist = client.GetPlaylist();
 	const unsigned old_size = playlist.GetLength();
 
+	const unsigned position = args.size > 2
+		? args.ParseUnsigned(2, old_size)
+		: old_size;
+
 	const SongLoader loader(client);
 	playlist_open_into_queue(uri,
 				 range.start, range.end,
@@ -96,6 +101,16 @@ handle_load(Client &client, Request args, [[maybe_unused]] Response &r)
 	for (unsigned i = old_size; i < new_size; ++i)
 		instance.LookupRemoteTag(playlist.queue.Get(i).GetRealURI());
 
+	if (position < old_size) {
+		const RangeArg move_range{old_size, new_size};
+
+		try {
+			partition.MoveRange(move_range, position);
+		} catch (...) {
+			/* ignore - shall we handle it? */
+		}
+	}
+
 	return CommandResult::OK;
 }