add hotspot toggle feature also for for Android pre-Oreo; lower minsdk to 21

Author: pgp

app/build.gradle

@@ -7,7 +7,7 @@ android {
 
     defaultConfig {
         applicationId "it.pgp.currenttoggles"
-        minSdkVersion 24
+        minSdkVersion 21
         targetSdkVersion 28
         versionCode 111220816
         versionName "1.1.1"

app/src/main/java/it/pgp/currenttoggles/MainActivity.java

@@ -26,6 +26,7 @@
 import it.pgp.currenttoggles.utils.RootHandler;
 import it.pgp.currenttoggles.utils.oreoap.MyOnStartTetheringCallback;
 import it.pgp.currenttoggles.utils.oreoap.MyOreoWifiManager;
+import it.pgp.currenttoggles.utils.oreoap.PreOreoWifiManager;
 
 public class MainActivity extends Activity {
 
@@ -239,18 +240,28 @@ public static void toggleEnergySaving(Context context) {
     }
 
     public static void toggleHotspot(Context context) {
-        if (!Settings.System.canWrite(context)) {
+        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && !Settings.System.canWrite(context)) {
             launchWriteSettings(context);
         }
         else {
-            MyOreoWifiManager apManager = new MyOreoWifiManager(context);
-            if(apManager.isTetherActive()) {
-                apManager.stopTethering();
-                Toast.makeText(context, "AP stopped", Toast.LENGTH_SHORT).show();
+            if(Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
+                PreOreoWifiManager apManager = new PreOreoWifiManager(context);
+                boolean targetState = !apManager.isApOn();
+                if(apManager.configApState(targetState))
+                    Toast.makeText(context, "AP "+(targetState?"started":"stopped"), Toast.LENGTH_SHORT).show();
+                else
+                    Toast.makeText(context, "Unable to change AP state", Toast.LENGTH_SHORT).show();
             }
             else {
-                apManager.startTethering(new MyOnStartTetheringCallback());
-                Toast.makeText(context, "AP started", Toast.LENGTH_SHORT).show();
+                MyOreoWifiManager apManager = new MyOreoWifiManager(context);
+                if(apManager.isTetherActive()) {
+                    apManager.stopTethering();
+                    Toast.makeText(context, "AP stopped", Toast.LENGTH_SHORT).show();
+                }
+                else {
+                    apManager.startTethering(new MyOnStartTetheringCallback());
+                    Toast.makeText(context, "AP started", Toast.LENGTH_SHORT).show();
+                }
             }
         }
     }

app/src/main/java/it/pgp/currenttoggles/utils/oreoap/PreOreoWifiManager.java

@@ -0,0 +1,44 @@
+package it.pgp.currenttoggles.utils.oreoap;
+
+import android.content.Context;
+import android.net.wifi.WifiConfiguration;
+import android.net.wifi.WifiManager;
+
+import java.lang.reflect.Method;
+
+public class PreOreoWifiManager {
+    final Context context;
+
+    public PreOreoWifiManager(Context context) {
+        this.context = context;
+    }
+
+    public boolean isApOn() {
+        WifiManager wifimanager = (WifiManager) context.getApplicationContext().getSystemService(Context.WIFI_SERVICE);
+        try {
+            Method method = wifimanager.getClass().getDeclaredMethod("isWifiApEnabled");
+            method.setAccessible(true);
+            return (Boolean) method.invoke(wifimanager);
+        }
+        catch (Throwable ignored) {}
+        return false;
+    }
+
+    // toggle wifi hotspot on or off
+    public boolean configApState(boolean expectedState) {
+        WifiManager wifimanager = (WifiManager) context.getApplicationContext().getSystemService(Context.WIFI_SERVICE);
+        WifiConfiguration wificonfiguration = null;
+        try {
+            // if WiFi is on, turn it off // FIXME isApOn checks ap, not wifi
+            if(isApOn()) wifimanager.setWifiEnabled(false);
+            Method method = wifimanager.getClass().getMethod("setWifiApEnabled", WifiConfiguration.class, boolean.class);
+//            method.invoke(wifimanager, wificonfiguration, !isApOn(context));
+            method.invoke(wifimanager, wificonfiguration, expectedState);
+            return true;
+        }
+        catch (Exception e) {
+            e.printStackTrace();
+        }
+        return false;
+    }
+}