Android: Show warning after picking file with wrong extension

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/settings/ui/SettingsActivity.java

@@ -175,12 +175,14 @@ public final class SettingsActivity extends AppCompatActivity implements Setting
       if (requestCode == MainPresenter.REQUEST_SD_FILE)
       {
         Uri uri = canonicalizeIfPossible(result.getData());
-
         int takeFlags = result.getFlags() &
                 (Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
-        getContentResolver().takePersistableUriPermission(uri, takeFlags);
 
-        getFragment().getAdapter().onFilePickerConfirmation(uri.toString());
+        FileBrowserHelper.runAfterExtensionCheck(this, uri, FileBrowserHelper.RAW_EXTENSION, () ->
+        {
+          getContentResolver().takePersistableUriPermission(uri, takeFlags);
+          getFragment().getAdapter().onFilePickerConfirmation(uri.toString());
+        });
       }
       else
       {

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/ui/main/MainActivity.java

@@ -205,7 +205,9 @@ public final class MainActivity extends AppCompatActivity implements MainView
           break;
 
         case MainPresenter.REQUEST_WAD_FILE:
-          mPresenter.installWAD(result.getData().toString());
+          FileBrowserHelper.runAfterExtensionCheck(this, result.getData(),
+                  FileBrowserHelper.WAD_EXTENSION,
+                  () -> mPresenter.installWAD(result.getData().toString()));
           break;
       }
     }

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/ui/main/TvMainActivity.java

@@ -229,7 +229,9 @@ public final class TvMainActivity extends FragmentActivity implements MainView
           break;
 
         case MainPresenter.REQUEST_WAD_FILE:
-          mPresenter.installWAD(result.getData().toString());
+          FileBrowserHelper.runAfterExtensionCheck(this, result.getData(),
+                  FileBrowserHelper.WAD_EXTENSION,
+                  () -> mPresenter.installWAD(result.getData().toString()));
           break;
       }
     }

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/utils/ContentHandler.java

@@ -1,8 +1,13 @@
 package org.dolphinemu.dolphinemu.utils;
 
 import android.content.ContentResolver;
+import android.database.Cursor;
 import android.net.Uri;
 import android.provider.DocumentsContract;
+import android.provider.DocumentsContract.Document;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 import org.dolphinemu.dolphinemu.DolphinApplication;
 
@@ -14,8 +19,7 @@ public class ContentHandler
   {
     try
     {
-      return DolphinApplication.getAppContext().getContentResolver()
+      return getContentResolver().openFileDescriptor(Uri.parse(uri), mode).detachFd();
-              .openFileDescriptor(Uri.parse(uri), mode).detachFd();
     }
     // Some content providers throw IllegalArgumentException for invalid modes,
     // despite the documentation saying that invalid modes result in a FileNotFoundException
@@ -29,8 +33,7 @@ public class ContentHandler
   {
     try
     {
-      ContentResolver resolver = DolphinApplication.getAppContext().getContentResolver();
+      return DocumentsContract.deleteDocument(getContentResolver(), Uri.parse(uri));
-      return DocumentsContract.deleteDocument(resolver, Uri.parse(uri));
     }
     catch (FileNotFoundException e)
     {
@@ -38,4 +41,24 @@ public class ContentHandler
       return true;
     }
   }
+
+  @Nullable
+  public static String getDisplayName(@NonNull Uri uri)
+  {
+    final String[] projection = new String[]{Document.COLUMN_DISPLAY_NAME};
+    try (Cursor cursor = getContentResolver().query(uri, projection, null, null, null))
+    {
+      if (cursor != null && cursor.moveToFirst())
+      {
+        return cursor.getString(0);
+      }
+    }
+
+    return null;
+  }
+
+  private static ContentResolver getContentResolver()
+  {
+    return DolphinApplication.getAppContext().getContentResolver();
+  }
 }

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/utils/FileBrowserHelper.java

@@ -1,23 +1,28 @@
 package org.dolphinemu.dolphinemu.utils;
 
+import android.content.Context;
 import android.content.Intent;
 import android.net.Uri;
 import android.os.Environment;
 
 import androidx.annotation.Nullable;
+import androidx.appcompat.app.AlertDialog;
 import androidx.fragment.app.FragmentActivity;
 
 import com.nononsenseapps.filepicker.FilePickerActivity;
 import com.nononsenseapps.filepicker.Utils;
 
+import org.dolphinemu.dolphinemu.R;
 import org.dolphinemu.dolphinemu.activities.CustomFilePickerActivity;
 import org.dolphinemu.dolphinemu.ui.main.MainPresenter;
 
 import java.io.File;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 public final class FileBrowserHelper
 {
@@ -27,6 +32,9 @@ public final class FileBrowserHelper
   public static final HashSet<String> RAW_EXTENSION = new HashSet<>(Collections.singletonList(
           "raw"));
 
+  public static final HashSet<String> WAD_EXTENSION = new HashSet<>(Collections.singletonList(
+          "wad"));
+
   public static void openDirectoryPicker(FragmentActivity activity, HashSet<String> extensions)
   {
     Intent i = new Intent(activity, CustomFilePickerActivity.class);
@@ -85,4 +93,72 @@ public final class FileBrowserHelper
 
     return null;
   }
+
+  public static void runAfterExtensionCheck(Context context, Uri uri, Set<String> validExtensions,
+          Runnable runnable)
+  {
+    String extension = null;
+
+    String path = uri.getLastPathSegment();
+    if (path != null)
+      extension = getExtension(new File(path).getName());
+
+    if (extension == null)
+      extension = getExtension(ContentHandler.getDisplayName(uri));
+
+    if (extension != null && validExtensions.contains(extension))
+    {
+      runnable.run();
+      return;
+    }
+
+    String message;
+    if (extension == null)
+    {
+      message = context.getString(R.string.no_file_extension);
+    }
+    else
+    {
+      int messageId = validExtensions.size() == 1 ?
+              R.string.wrong_file_extension_single : R.string.wrong_file_extension_multiple;
+
+      ArrayList<String> extensionsList = new ArrayList<>(validExtensions);
+      Collections.sort(extensionsList);
+
+      message = context.getString(messageId, extension, join(", ", extensionsList));
+    }
+
+    new AlertDialog.Builder(context, R.style.DolphinDialogBase)
+            .setMessage(message)
+            .setPositiveButton(R.string.yes, (dialogInterface, i) -> runnable.run())
+            .setNegativeButton(R.string.no, null)
+            .show();
+  }
+
+  @Nullable
+  private static String getExtension(@Nullable String fileName)
+  {
+    if (fileName == null)
+      return null;
+
+    int dotIndex = fileName.lastIndexOf(".");
+    return dotIndex != -1 ? fileName.substring(dotIndex + 1) : null;
+  }
+
+  // TODO: Replace this with String.join once we can use Java 8
+  private static String join(CharSequence delimiter, Iterable<? extends CharSequence> elements)
+  {
+    StringBuilder sb = new StringBuilder();
+
+    boolean first = true;
+    for (CharSequence element : elements)
+    {
+      if (!first)
+        sb.append(delimiter);
+      first = false;
+      sb.append(element);
+    }
+
+    return sb.toString();
+  }
 }

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

@@ -427,6 +427,11 @@ It can efficiently compress both junk data and encrypted Wii data.
 
     <string name="select_dir">Select This Directory</string>
 
+    <!-- File Pickers -->
+    <string name="no_file_extension">The selected file does not appear to have a file name extension.\n\nContinue anyway?</string>
+    <string name="wrong_file_extension_single">The selected file has the file name extension \"%1$s\", but \"%2$s\" was expected.\n\nContinue anyway?</string>
+    <string name="wrong_file_extension_multiple">The selected file has the file name extension \"%1$s\", but one of these extensions was expected: %2$s\n\nContinue anyway?</string>
+
     <!-- Misc -->
     <string name="pitch">Total Pitch</string>
     <string name="yaw">Total Yaw</string>