MusicAppMediaFix: support multiple (user-specified) media apps

Source/MusicAppMediaFix.spoon/init.lua

@@ -1,6 +1,7 @@
 --- === MusicAppMediaFix ===
 ---
---- Override macOS behaviour and send all media keys (play/prev/next) to Music.app
+--- Override macOS behaviour and send all media keys (play/prev/next) to
+--- the last active of a specified list of apps in MusicAppMediaFix.mediaApps
 local obj = { __gc = true }
 --obj.__index = obj
 setmetatable(obj, obj)
@@ -16,6 +17,9 @@ obj.homepage = "https://github.com/Hammerspoon/Spoons"
 obj.license = "MIT - https://opensource.org/licenses/MIT"
 
 obj.eventtap = nil
+obj.appWatcher = nil
+obj.mediaApps = {"Music"}
+obj.currentApp = nil
 
 -- Internal function used to find our location, so we know where to load files from
 local function script_path()
@@ -25,7 +29,9 @@ end
 obj.spoonPath = script_path()
 
 function obj:init()
+    self.currentApp = self.mediaApps[1]
     self.eventtap = hs.eventtap.new({hs.eventtap.event.types.systemDefined}, self.mediaKeyCallback)
+    self.appWatcher = hs.application.watcher.new(self.appWatcherCallback)
 end
 
 function obj.mediaKeyCallback(event)
@@ -38,19 +44,32 @@ function obj.mediaKeyCallback(event)
 
     -- handle action
     if data["down"] == false or data["repeat"] == true then
+        for i, app in pairs(obj.mediaApps) do
+          if app ~= obj.currentApp then
+              hs.osascript.applescript('tell application "' .. app .. '" to pause')
+          end
+        end
         if data["key"] == "PLAY" then
-            hs.applescript('tell application "Music" to playpause')
+            hs.applescript('tell application "' .. obj.currentApp .. '" to playpause')
         elseif data["key"] == "FAST" then
-            hs.applescript('tell application "Music" to next track')
+            hs.applescript('tell application "' .. obj.currentApp .. '" to next track')
         elseif data["key"] == "REWIND" then
-            hs.applescript('tell application "Music" to previous track')
+            hs.applescript('tell application "' .. obj.currentApp .. '" to previous track')
         end
     end
 
     -- consume event
     return true, nil
 end
 
+function obj.appWatcherCallback(appName, eventType, app)
+    if hs.fnutils.contains(obj.mediaApps, appName)
+         and (eventType == hs.application.watcher.activated) then
+       obj.currentApp = appName
+       print("Sending media key events to " .. appName)
+    end
+end
+
 --- MusicAppMediaFix:start()
 --- Method
 --- Starts the hs.eventtap that powers this Spoon
@@ -64,6 +83,7 @@ function obj:start()
     if self.eventtap:isEnabled() ~= true then
         self.eventtap:start()
     end
+    self.appWatcher:start()
     return self
 end
 
@@ -80,6 +100,7 @@ function obj:stop()
     if self.eventtap:isEnabled() then
         self.eventtap:stop()
     end
+    self.appWatcher:stop()
     return self
 end