android: Select default output device based on callIntent

Add comments on existing code
Extracted a specific android controller for isolation and better testing

lint fixes

Fix device update logic and more tests

better typescript

src/controls.ts

@@ -33,12 +33,36 @@ export interface Controls {
   showNativeOutputDevicePicker?: () => void;
 }
 
+/**
+ * Output Audio device when using the controlled audio output mode (mobile).
+ */
 export interface OutputDevice {
   id: string;
   name: string;
+  /**
+   * Reverse engineered:
+   *  - on iOS always true if output is routed to speaker. In other case iOS on declare a `dummy` id device.
+   *    In that case then ElementCalls manually append a earpiece device with id `EARPIECE_CONFIG_ID` anb `{ type: "earpiece" }`
+   *  - on Android this is unused.
+   */
   forEarpiece?: boolean;
+  /**
+   * Reverse engineered:
+   * - on iOS always undefined
+   * - on Android true for the `TYPE_BUILTIN_EARPIECE`
+   */
   isEarpiece?: boolean;
+  /**
+   * Reverse engineered:
+   * - on iOS always true if output is routed to speaker. In other case iOS on declare a `dummy` id device.
+   * - on Android true for the `TYPE_BUILTIN_SPEAKER`
+   */
   isSpeaker?: boolean;
+  /**
+   * Reverse engineered:
+   * - on iOS always undefined.
+   * - on Android true for the `TYPE_BLUETOOTH_SCO`
+   */
   isExternalHeadset?: boolean;
 }
 
@@ -47,8 +71,16 @@ export interface OutputDevice {
  */
 export const setPipEnabled$ = new Subject<boolean>();
 
+/**
+ * Stores the list of available controlled audio output devices.
+ * This is set when the native code calls `setAvailableAudioDevices` with the list of available audio output devices.
+ */
 export const availableOutputDevices$ = new Subject<OutputDevice[]>();
 
+/**
+ * Stores the current audio output device id.
+ * This is set when the native code calls `setAudioDevice`
+ */
 export const outputDevice$ = new Subject<string>();
 
 /**
@@ -80,16 +112,41 @@ window.controls = {
     setPipEnabled$.next(false);
   },
 
+  /**
+   * Reverse engineered:
+   *
+   * - on iOS:
+   *  This always a list of one thing. If current route output is speaker it returns
+   *  the single `{"id":"Speaker","name":"Speaker","forEarpiece":true,"isSpeaker":true}` Notice that EC will
+   *  also manually add a virtual earpiece device with id `EARPIECE_CONFIG_ID` and `{ type: "earpiece" }`.
+   *  If the route output is not speaker then it will be `{id: 'dummy', name: 'dummy'}`
+   *
+   *
+   *  - on Android:
+   *  This is a list of all available output audio devices. The `id` is the Android AudioDeviceInfo.getId()
+   *  and the `name` is based the Android AudioDeviceInfo.productName (mapped to static strings for known types)
+   *  The `isEarpiece`, `isSpeaker` and `isExternalHeadset` are set based on the Android AudioDeviceInfo.type
+   *  matching the corresponding types for earpiece, speaker and bluetooth headset.
+   */
   setAvailableAudioDevices(devices: OutputDevice[]): void {
-    logger.info("setAvailableAudioDevices called from native:", devices);
+    logger.info(
+      "[MediaDevices controls] setAvailableAudioDevices called from native:",
+      devices,
+    );
     availableOutputDevices$.next(devices);
   },
   setAudioDevice(id: string): void {
-    logger.info("setAudioDevice called from native", id);
+    logger.info(
+      "[MediaDevices controls] setAudioDevice called from native",
+      id,
+    );
     outputDevice$.next(id);
   },
   setAudioEnabled(enabled: boolean): void {
-    logger.info("setAudioEnabled called from native:", enabled);
+    logger.info(
+      "[MediaDevices controls] setAudioEnabled called from native:",
+      enabled,
+    );
     if (!setAudioEnabled$.observed)
       throw new Error(
         "Output controls are disabled. No setAudioEnabled$ observer",