Show confirmation dialog if this is the only app to open the file

app/src/main/AndroidManifest.xml

@@ -12,6 +12,14 @@
         android:maxSdkVersion="29"
         tools:ignore="ScopedStorage" />
 
+    <queries>
+        <!-- Used to check if SaveCopy is the only one to open the file -->
+        <intent>
+            <action android:name="android.intent.action.VIEW" />
+            <data android:scheme="content" />
+        </intent>
+    </queries>
+
     <application
         android:allowBackup="false"
         android:icon="@mipmap/ic_launcher"

app/src/main/java/app/rikka/savecopy/SaveActivity.java

@@ -27,6 +27,23 @@ protected void onCreate(Bundle savedInstanceState) {
 
         getPackageManager().clearPackagePreferredActivities(getPackageName());
 
+        checkConfirmation();
+    }
+
+    private void checkConfirmation() {
+        if (shouldShowConfirmation()) {
+            new AlertDialog.Builder(this, R.style.AppTheme_Dialog_Alert)
+                    .setMessage(R.string.dialog_confirmation_message)
+                    .setNegativeButton(android.R.string.cancel, null)
+                    .setPositiveButton(android.R.string.ok, (dialog, which) -> checkPermission())
+                    .setOnDismissListener(dialog -> finish())
+                    .show();
+            return;
+        }
+        checkPermission();
+    }
+
+    private void checkPermission() {
         if (Build.VERSION.SDK_INT >= 23 && (Build.VERSION.SDK_INT <= 28 || (Build.VERSION.SDK_INT == 29 && Build.VERSION.PREVIEW_SDK_INT == 0))) {
             String[] permissions = new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE};
             if (checkSelfPermission(permissions[0]) != PackageManager.PERMISSION_GRANTED
@@ -35,10 +52,11 @@ protected void onCreate(Bundle savedInstanceState) {
                 return;
             }
         }
-        handleIntent();
+
+        startSave();
     }
 
-    private void handleIntent() {
+    private void startSave() {
         String callingPackage = null;
         Uri referrer = getReferrer();
         if (referrer != null) callingPackage = referrer.getAuthority();
@@ -62,7 +80,7 @@ public void onRequestPermissionsResult(int requestCode, @NonNull String[] permis
                 granted &= grantResult == PackageManager.PERMISSION_GRANTED;
             }
             if (granted) {
-                handleIntent();
+                startSave();
             } else {
                 boolean isNight = (getResources().getConfiguration().uiMode & Configuration.UI_MODE_NIGHT_YES) > 0;
                 int theme = isNight ? android.R.style.Theme_DeviceDefault_Dialog_Alert : android.R.style.Theme_DeviceDefault_Light_Dialog_Alert;
@@ -81,4 +99,15 @@ public void onRequestPermissionsResult(int requestCode, @NonNull String[] permis
             }
         }
     }
+
+    private boolean shouldShowConfirmation() {
+        try {
+            Intent intentForTest = new Intent(getIntent());
+            intentForTest.setComponent(null);
+            intentForTest.setPackage(null);
+            return getPackageManager().queryIntentActivities(intentForTest, PackageManager.MATCH_DEFAULT_ONLY).size() <= 1;
+        } catch (Throwable e) {
+            return true;
+        }
+    }
 }

app/src/main/java/app/rikka/savecopy/SaveService.java

@@ -73,7 +73,6 @@ public void onCreate() {
         });
 
         mNotificationManager = getSystemService(NotificationManager.class);
-        //noinspection ConstantConditions
         onCreateNotificationChannel(mNotificationManager);
 
         startForeground(NOTIFICATION_ID_PROGRESS, onStartForeground());

app/src/main/res/values-zh-rCN/strings.xml

@@ -17,4 +17,5 @@
     <string name="settings_prefer_app_folder">偏好应用文件夹</string>
     <string name="settings_prefer_app_folder_summary">将副本保存至 Download/&lt;应用名称&gt;。</string>
     <string name="introduction">此应用将“%1$s”加入至“打开方式”菜单。当您使用“%1$s”打开文件时，文件的副本将被保存至“Download”文件夹。\n\n删除原始文件要求原始应用允许写入，但几乎没有允许写入的。因此我们没有提供此功能。\n\n为了保持主屏幕整洁，此应用不会在主屏幕应用中显示（Android 10 除外）。要卸载，请进入系统设置。</string>
-</resources>
+    <string name="dialog_confirmation_message">是否要保存此文件的副本？</string>
+</resources>

app/src/main/res/values-zh-rTW/strings.xml

@@ -17,4 +17,5 @@
     <string name="settings_prefer_app_folder">偏好應用程式資料夾</string>
     <string name="settings_prefer_app_folder_summary">將副本儲存至 Download/&lt;應用程式名稱&gt;。</string>
     <string name="introduction">此程式將「%1$s」加入至「開啟方式」選單。當您使用「%1$s」開啟檔案時，檔案的副本將被儲存至「Download」資料夾。\n\n刪除原始檔案要求原始程式允許寫入，但幾乎沒有允許寫入的。因此我們沒有提供此功能。\n\n為了保持主螢幕整潔，此程式不會在主螢幕程式中顯示（Android 10 除外）。要解除安裝，請進入系統設定。</string>
-</resources>
+    <string name="dialog_confirmation_message">是否要儲存此檔案的副本？</string>
+</resources>

app/src/main/res/values/strings.xml

@@ -17,4 +17,5 @@
     <string name="settings_prefer_app_folder">Prefer app folder</string>
     <string name="settings_prefer_app_folder_summary">Save the copy to Download/&lt;app name&gt;.</string>
     <string name="introduction">This app adds the \"%1$s\" action to \"Open with\" menus. When you open a file with \"%1$s\", a copy of the file will be saved to the \"Download\" folder.\n\nDelete original file requires the original app to allow writing, but almost no one does. Therefore we did not provide this feature.\n\nIn order to keep your home clean, this app does not show in the home app (except Android 10). To uninstall, please go to system settings.</string>
-</resources>
+    <string name="dialog_confirmation_message">Save a copy for this file?</string>
+</resources>

app/src/main/res/values/theme.xml

@@ -5,6 +5,8 @@
         <item name="android:windowDrawsSystemBarBackgrounds">true</item>
         <item name="android:statusBarColor">@android:color/transparent</item>
         <item name="android:navigationBarColor">@android:color/transparent</item>
+        <item name="android:enforceNavigationBarContrast">false</item>
+        <item name="android:enforceStatusBarContrast">false</item>
     </style>
 
     <style name="Theme.NoDisplay" parent="Theme.Translucent.NoTitleBar" />
@@ -19,4 +21,4 @@
         <item name="android:windowActionBar">false</item>
     </style>
 
-</resources>
+</resources>