osc.lua: cycle tracks when there's only one

When there is 1 audio or sub track, if the command wasn't configured,
make left click select or unselect it directly without opening the
selector. Unfortunately this is awkward to implement with the command
script-opts.

Requested by sfan5.

player/lua/osc.lua

@@ -2,6 +2,9 @@ local assdraw = require 'mp.assdraw'
 local msg = require 'mp.msg'
 local opt = require 'mp.options'
 
+local default_audio_command = "script-binding select/select-aid; script-message-to osc osc-hide"
+local default_sub_command = "script-binding select/select-sid; script-message-to osc osc-hide"
+
 --
 -- Parameters
 --
@@ -94,13 +97,13 @@ local user_opts = {
     chapter_next_mbtn_mid_command = "show-text ${chapter-list} 3000",
     chapter_next_mbtn_right_command = "script-binding select/select-chapter; script-message-to osc osc-hide",
 
-    audio_track_mbtn_left_command = "script-binding select/select-aid; script-message-to osc osc-hide",
+    audio_track_mbtn_left_command = default_audio_command,
     audio_track_mbtn_mid_command = "show-text ${track-list/audio} 3000",
     audio_track_mbtn_right_command = "show-text ${track-list/audio} 3000",
     audio_track_wheel_down_command = "cycle audio",
     audio_track_wheel_up_command = "cycle audio down",
 
-    sub_track_mbtn_left_command = "script-binding select/select-sid; script-message-to osc osc-hide",
+    sub_track_mbtn_left_command = default_sub_command,
     sub_track_mbtn_mid_command = "show-text ${track-list/sub} 3000",
     sub_track_mbtn_right_command = "show-text ${track-list/sub} 3000",
     sub_track_wheel_down_command = "cycle sub",
@@ -1866,7 +1869,13 @@ local function osc_init()
         return ("\238\132\134" .. osc_styles.smallButtonsLlabel .. " " ..
                (mp.get_property_native("aid") or "-") .. "/" .. audio_track_count)
     end
-    ne.eventresponder["mbtn_left_up"] = command_callback(user_opts.audio_track_mbtn_left_command)
+    if audio_track_count == 1 and
+       user_opts.audio_track_mbtn_left_command == default_audio_command then
+        ne.eventresponder["mbtn_left_up"] = command_callback("cycle audio")
+    else
+        ne.eventresponder["mbtn_left_up"] = command_callback(
+            user_opts.audio_track_mbtn_left_command)
+    end
     ne.eventresponder["shift+mbtn_left_up"] = command_callback(
         user_opts.audio_track_mbtn_mid_command)
     ne.eventresponder["mbtn_right_up"] = command_callback(user_opts.audio_track_mbtn_right_command)
@@ -1886,7 +1895,11 @@ local function osc_init()
         return ("\238\132\135" .. osc_styles.smallButtonsLlabel .. " " ..
                (mp.get_property_native("sid") or "-") .. "/" .. sub_track_count)
     end
-    ne.eventresponder["mbtn_left_up"] = command_callback(user_opts.sub_track_mbtn_left_command)
+    if sub_track_count == 1 and user_opts.sub_track_mbtn_left_command == default_sub_command then
+        ne.eventresponder["mbtn_left_up"] = command_callback("cycle sub")
+    else
+        ne.eventresponder["mbtn_left_up"] = command_callback(user_opts.sub_track_mbtn_left_command)
+    end
     ne.eventresponder["shift+mbtn_left_up"] = command_callback(user_opts.sub_track_mbtn_mid_command)
     ne.eventresponder["mbtn_right_up"] = command_callback(user_opts.sub_track_mbtn_right_command)