refactor: improve partner customization

app/src/main/java/im/angry/openeuicc/util/Partner.kt

@@ -9,40 +9,43 @@ import im.angry.openeuicc.BuildConfig
 
 class Partner {
     companion object {
-        private val intent = Intent("com.google.android.euicc.action.PARTNER_CUSTOMIZATION")
+        private const val ACTION = "com.google.android.euicc.action.PARTNER_CUSTOMIZATION"
 
-        fun getInstance(context: Context): Partner? {
-            var flags = if (BuildConfig.DEBUG)
+        private val instances = mutableMapOf<String, Partner?>()
+
+        private val packageFlags: Int
+            get() {
+                val flags = if (BuildConfig.DEBUG)
                     PackageManager.MATCH_UNINSTALLED_PACKAGES else
                     PackageManager.MATCH_SYSTEM_ONLY
-            flags = flags or PackageManager.MATCH_DISABLED_COMPONENTS
-            val apps = context.packageManager
-                .queryBroadcastReceivers(intent, flags)
+                return flags or PackageManager.MATCH_DISABLED_COMPONENTS
+            }
+
+        fun getInstance(context: Context, action: String = ACTION) = instances.getOrPut(action) {
+            context.packageManager
+                .queryBroadcastReceivers(Intent(action), packageFlags)
                 .mapNotNull { it.activityInfo?.applicationInfo }
-            for (app in apps) {
+                .firstNotNullOfOrNull {
                     try {
-                    val resources = context.packageManager.getResourcesForApplication(app)
-                    return Partner(resources)
+                        context.packageManager.getResourcesForApplication(it)
                     } catch (_: PackageManager.NameNotFoundException) {
-                    continue
+                        null
                     }
                 }
-            return null
+                ?.let(::Partner)
         }
     }
 
     private val resources: Resources
-    private val ids = mutableMapOf<String, Int>()
 
     private constructor(resources: Resources) {
         this.resources = resources
     }
 
-    private fun getIdentifier(name: String) = ids.getOrPut(name) {
-        resources.getIdentifier(name, null, null)
-    }
+    private fun getIdentifier(name: String) =
+        resources.getIdentifier(name, null, null).takeIf { it != 0 }
 
-    fun getString(name: String) = getIdentifier(name).let(resources::getString)
+    fun getString(name: String) = getIdentifier(name)?.let(resources::getString)
 
-    fun getBoolean(name: String) = getIdentifier(name).let(resources::getBoolean)
+    fun getBoolean(name: String) = getIdentifier(name)?.let(resources::getBoolean)
 }