Try harder to determine backup file extension

app/src/main/java/org/tasks/dialogs/ImportTasksDialog.java

@@ -2,13 +2,10 @@ package org.tasks.dialogs;
 
 import android.app.Dialog;
 import android.app.ProgressDialog;
-import android.content.ContentResolver;
 import android.content.Context;
 import android.net.Uri;
 import android.os.Bundle;
-import android.webkit.MimeTypeMap;
 import com.todoroo.astrid.backup.TasksXmlImporter;
-import java.io.IOException;
 import javax.inject.Inject;
 import org.tasks.analytics.Tracker;
 import org.tasks.analytics.Tracking;
@@ -16,21 +13,25 @@ import org.tasks.backup.TasksJsonImporter;
 import org.tasks.injection.ForApplication;
 import org.tasks.injection.InjectingNativeDialogFragment;
 import org.tasks.injection.NativeDialogFragmentComponent;
-import timber.log.Timber;
+import org.tasks.ui.Toaster;
 
 public class ImportTasksDialog extends InjectingNativeDialogFragment {
 
   private static final String EXTRA_URI = "extra_uri";
+  private static final String EXTRA_EXTENSION = "extra_extension";
+
   @Inject TasksXmlImporter xmlImporter;
   @Inject TasksJsonImporter jsonImporter;
   @Inject DialogBuilder dialogBuilder;
   @Inject Tracker tracker;
   @Inject @ForApplication Context context;
+  @Inject Toaster toaster;
 
-  public static ImportTasksDialog newImportTasksDialog(Uri data) {
+  public static ImportTasksDialog newImportTasksDialog(Uri data, String extension) {
     ImportTasksDialog importTasksDialog = new ImportTasksDialog();
     Bundle args = new Bundle();
     args.putParcelable(EXTRA_URI, data);
+    args.putString(EXTRA_EXTENSION, extension);
     importTasksDialog.setArguments(args);
     return importTasksDialog;
   }
@@ -39,35 +40,26 @@ public class ImportTasksDialog extends InjectingNativeDialogFragment {
   public Dialog onCreateDialog(Bundle savedInstanceState) {
     Bundle arguments = getArguments();
     Uri data = arguments.getParcelable(EXTRA_URI);
+    String extension = arguments.getString(EXTRA_EXTENSION);
     ProgressDialog progressDialog = dialogBuilder.newProgressDialog();
     progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
     progressDialog.setCancelable(false);
     progressDialog.setIndeterminate(true);
     progressDialog.show();
     setCancelable(false);
-    try {
-      String extension =
-          data.getScheme().equals(ContentResolver.SCHEME_CONTENT)
-              ? MimeTypeMap.getSingleton()
-                  .getExtensionFromMimeType(context.getContentResolver().getType(data))
-              : MimeTypeMap.getFileExtensionFromUrl(data.getPath());
-      switch (extension) {
-        case "json":
-          jsonImporter.importTasks(getActivity(), data, progressDialog);
-          tracker.reportEvent(Tracking.Events.IMPORT_JSON);
-          break;
-        case "xml":
-          xmlImporter.importTasks(getActivity(), data, progressDialog);
-          tracker.reportEvent(Tracking.Events.IMPORT_XML);
-          break;
-        default:
-          throw new IOException("Invalid file type: " + extension);
-      }
-      return progressDialog;
-    } catch (IOException e) {
-      Timber.e(e);
+    switch (extension) {
+      case "json":
+        jsonImporter.importTasks(getActivity(), data, progressDialog);
+        tracker.reportEvent(Tracking.Events.IMPORT_JSON);
+        break;
+      case "xml":
+        xmlImporter.importTasks(getActivity(), data, progressDialog);
+        tracker.reportEvent(Tracking.Events.IMPORT_XML);
+        break;
+      default:
+        throw new RuntimeException("Invalid extension: " + extension);
     }
-    return null;
+    return progressDialog;
   }
 
   @Override

app/src/main/java/org/tasks/files/FileHelper.java

@@ -24,6 +24,7 @@ import android.webkit.MimeTypeMap;
 import android.widget.Toast;
 import androidx.annotation.Nullable;
 import androidx.documentfile.provider.DocumentFile;
+import com.google.common.base.Strings;
 import com.google.common.io.ByteStreams;
 import com.google.common.io.Files;
 import java.io.File;
@@ -144,6 +145,24 @@ public class FileHelper {
     return null;
   }
 
+  public static String getExtension(Context context, Uri uri) {
+    if (uri.getScheme().equals(ContentResolver.SCHEME_CONTENT)) {
+      String extension =
+          MimeTypeMap.getSingleton()
+              .getExtensionFromMimeType(context.getContentResolver().getType(uri));
+      if (!Strings.isNullOrEmpty(extension)) {
+        return extension;
+      }
+    }
+
+    String extension = MimeTypeMap.getFileExtensionFromUrl(uri.getPath());
+    if (!Strings.isNullOrEmpty(extension)) {
+      return extension;
+    }
+
+    return Files.getFileExtension(getFilename(context, uri));
+  }
+
   public static String getMimeType(Context context, Uri uri) {
     String filename = getFilename(context, uri);
     String extension = Files.getFileExtension(filename);

app/src/main/java/org/tasks/preferences/BasicPreferences.java

@@ -443,8 +443,14 @@ public class BasicPreferences extends InjectingPreferenceActivity
       }
     } else if (requestCode == REQUEST_PICKER) {
       if (resultCode == RESULT_OK) {
-        newImportTasksDialog(data.getData()).show(getFragmentManager(), FRAG_TAG_IMPORT_TASKS);
-        result.putBoolean(AppearancePreferences.EXTRA_RESTART, true);
+        Uri uri = data.getData();
+        String extension = FileHelper.getExtension(this, uri);
+        if (!("json".equalsIgnoreCase(extension) || "xml".equalsIgnoreCase(extension))) {
+          toaster.longToast(R.string.invalid_backup_file);
+        } else {
+          newImportTasksDialog(uri, extension).show(getFragmentManager(), FRAG_TAG_IMPORT_TASKS);
+          result.putBoolean(AppearancePreferences.EXTRA_RESTART, true);
+        }
       }
     } else if (requestCode == RC_DRIVE_BACKUP) {
       boolean success = resultCode == RESULT_OK;

app/src/main/java/org/tasks/ui/Toaster.java

@@ -21,6 +21,10 @@ public class Toaster {
     this.locale = locale;
   }
 
+  public void longToast(@StringRes int resId, String arg) {
+    longToast(context.getString(resId, arg));
+  }
+
   public void longToast(@StringRes int resId, int number) {
     longToast(context.getString(resId, locale.formatNumber(number)));
   }

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

@@ -886,4 +886,5 @@ File %1$s contained %2$s.\n\n
   <string name="third_party_licenses">Third-party licenses</string>
   <string name="changelog">Changelog</string>
   <string name="version_string">Version %s</string>
+  <string name="invalid_backup_file">Invalid backup file</string>
 </resources>