InputSourceSwitch: add application watcher support for apps window filter can't capture

Some applications (like kitty-quick-access) cannot be detected by
window filter. This adds an optional application watcher mode that
users can configure per-app. Also adds a stop() method and bumps
version to 1.1.

Author: kang8

Source/InputSourceSwitch.spoon/init.lua

@@ -8,7 +8,9 @@
 ---
 --- spoon.InputSourceSwitch:setApplications({
 ---     ["WeChat"] = "Pinyin - Simplified",
----     ["Mail"] = "ABC"
+---     ["Mail"] = "ABC",
+---     -- Use application watcher for apps that window filter can't capture
+---     ["kitty-quick-access"] = { source = "ABC", watcher = "application" }
 --- })
 ---
 --- spoon.InputSourceSwitch:start()
@@ -21,7 +23,7 @@ obj.__index = obj
 
 -- Metadata
 obj.name = "InputSourceSwitch"
-obj.version = "1.0"
+obj.version = "1.1"
 obj.author = "eks5115 <eks5115@gmail.com>"
 obj.homepage = "https://github.com/Hammerspoon/Spoons"
 obj.license = "MIT - https://opensource.org/licenses/MIT"
@@ -52,24 +54,38 @@ local function isMethod(methodName)
     return false
 end
 
-local function setAppInputSource(appName, sourceName, event)
+local function switchInputSource(sourceName, appName)
+    local r = true
+
+    if (isLayout(sourceName)) then
+        r = hs.keycodes.setLayout(sourceName)
+    elseif isMethod(sourceName) then
+        r = hs.keycodes.setMethod(sourceName)
+    else
+        hs.alert.show(string.format('sourceName: %s is not layout or method', sourceName))
+    end
+
+    if (not r) then
+        hs.alert.show(string.format('set %s to %s failure', appName, sourceName))
+    end
+end
+
+local function setAppInputSourceWithWindowFilter(appName, sourceName, event)
     event = event or hs.window.filter.windowFocused
 
     hs.window.filter.new(appName):subscribe(event, function()
-        local r = true
-
-        if (isLayout(sourceName)) then
-            r = hs.keycodes.setLayout(sourceName)
-        elseif isMethod(sourceName) then
-            r = hs.keycodes.setMethod(sourceName)
-        else
-            hs.alert.show(string.format('sourceName: %s is not layout or method', sourceName))
-        end
+        switchInputSource(sourceName, appName)
+    end)
+end
 
-        if (not r) then
-            hs.alert.show(string.format('set %s to %s failure', appName, sourceName))
+local function setAppInputSourceWithAppWatcher(appName, sourceName)
+    local watcher = hs.application.watcher.new(function(name, eventType, appObj)
+        if eventType == hs.application.watcher.activated and name == appName then
+            switchInputSource(sourceName, appName)
         end
-        end)
+    end)
+    watcher:start()
+    return watcher
 end
 
 --- InputSourceSwitch.applicationMap
@@ -83,12 +99,16 @@ obj.applicationsMap = {}
 ---
 --- Parameters:
 ---  * applications - A table containing that mapping the application name to the input source
----     key is the application name and value is the input source name
+---     key is the application name
+---     value can be:
+---       - a string: the input source name (uses window filter, default)
+---       - a table: { source = "input source name", watcher = "window" | "application" }
 ---     example:
 --- ```
 --- {
 ---     ["WeChat"] = "Pinyin - Simplified",
----     ["Mail"] = "ABC"
+---     ["Mail"] = "ABC",
+---     ["kitty-quick-access"] = { source = "ABC", watcher = "application" }
 --- }
 --- ```
 function obj:setApplications(applications)
@@ -104,8 +124,22 @@ end
 --- Parameters:
 ---  * None
 function obj:start()
-    for k,v in pairs(self.applicationsMap) do
-        setAppInputSource(k, v)
+    for appName, config in pairs(self.applicationsMap) do
+        local sourceName, watcherType
+
+        if type(config) == "string" then
+            sourceName = config
+            watcherType = "window"
+        else
+            sourceName = config.source
+            watcherType = config.watcher or "window"
+        end
+
+        if watcherType == "application" then
+            setAppInputSourceWithAppWatcher(appName, sourceName)
+        else
+            setAppInputSourceWithWindowFilter(appName, sourceName)
+        end
     end
     return self
 end