bugs fixes

* fix storage warning dialogs created on invalid contexts
* implement mkdirs in StoredDirectoryHelper

app/src/main/java/org/schabi/newpipe/download/DownloadDialog.java

@@ -217,6 +217,32 @@ public class DownloadDialog extends DialogFragment implements RadioGroup.OnCheck
                 okButton.setEnabled(true);
 
                 context.unbindService(this);
+
+                // check of download paths are defined
+                if (!askForSavePath) {
+                    String msg = "";
+                    if (mainStorageVideo == null) msg += getString(R.string.download_path_title);
+                    if (mainStorageAudio == null)
+                        msg += getString(R.string.download_path_audio_title);
+
+                    if (!msg.isEmpty()) {
+                        String title;
+                        if (mainStorageVideo == null && mainStorageAudio == null) {
+                            title = getString(R.string.general_error);
+                            msg = getString(R.string.no_available_dir) + ":\n" + msg;
+                        } else {
+                            title = msg;
+                            msg = getString(R.string.no_available_dir);
+                        }
+
+                        new AlertDialog.Builder(context)
+                                .setPositiveButton(android.R.string.ok, null)
+                                .setTitle(title)
+                                .setMessage(msg)
+                                .create()
+                                .show();
+                    }
+                }
             }
 
             @Override
@@ -520,6 +546,7 @@ public class DownloadDialog extends DialogFragment implements RadioGroup.OnCheck
 
     private void showFailedDialog(@StringRes int msg) {
         new AlertDialog.Builder(context)
+                .setTitle(R.string.general_error)
                 .setMessage(msg)
                 .setNegativeButton(android.R.string.ok, null)
                 .create()
@@ -631,6 +658,12 @@ public class DownloadDialog extends DialogFragment implements RadioGroup.OnCheck
                     // This part is called if:
                     // * the filename is not used in a pending/finished download
                     // * the file does not exists, create
+
+                    if (!mainStorage.mkdirs()) {
+                        showFailedDialog(R.string.error_path_creation);
+                        return;
+                    }
+
                     storage = mainStorage.createFile(filename, mime);
                     if (storage == null || !storage.canWrite()) {
                         showFailedDialog(R.string.error_file_creation);

app/src/main/java/org/schabi/newpipe/fragments/detail/VideoDetailFragment.java

@@ -1195,7 +1195,7 @@ public class VideoDetailFragment
                 downloadDialog.setSelectedVideoStream(selectedVideoStreamIndex);
                 downloadDialog.setSubtitleStreams(currentInfo.getSubtitles());
 
-                downloadDialog.show(activity.getSupportFragmentManager(), "downloadDialog");
+                downloadDialog.show(getActivity().getSupportFragmentManager(), "downloadDialog");
             } catch (Exception e) {
                 ErrorActivity.ErrorInfo info = ErrorActivity.ErrorInfo.make(UserAction.UI_ERROR,
                         ServiceList.all()

app/src/main/java/us/shandian/giga/io/StoredDirectoryHelper.java

@@ -144,6 +144,52 @@ public class StoredDirectoryHelper {
         return docTree == null ? ioTree.exists() : docTree.exists();
     }
 
+    /**
+     * Indicates whatever if is possible access using the {@code java.io} API
+     *
+     * @return {@code true} for Java I/O API, otherwise, {@code false} for Storage Access Framework
+     */
+    public boolean isDirect() {
+        return docTree == null;
+    }
+
+    /**
+     * Only using Java I/O. Creates the directory named by this abstract pathname, including any
+     * necessary but nonexistent parent directories.  Note that if this
+     * operation fails it may have succeeded in creating some of the necessary
+     * parent directories.
+     *
+     * @return <code>true</code> if and only if the directory was created,
+     * along with all necessary parent directories or already exists; <code>false</code>
+     * otherwise
+     */
+    public boolean mkdirs() {
+        if (docTree == null) {
+            return ioTree.exists() || ioTree.mkdirs();
+        }
+
+        if (docTree.exists()) return true;
+
+        try {
+            DocumentFile parent;
+            String child = docTree.getName();
+
+            while (true) {
+                parent = docTree.getParentFile();
+                if (parent == null || child == null) break;
+                if (parent.exists()) return true;
+
+                parent.createDirectory(child);
+
+                child = parent.getName();// for the next iteration
+            }
+        } catch (Exception e) {
+            // no more parent directories or unsupported by the storage provider
+        }
+
+        return false;
+    }
+
     public String getTag() {
         return tag;
     }

app/src/main/java/us/shandian/giga/service/DownloadManagerService.java

@@ -270,33 +270,6 @@ public class DownloadManagerService extends Service {
             Toast.makeText(this, "Permission denied (write)", Toast.LENGTH_SHORT).show();
         }
 
-        // Check download save paths
-
-        String msg = "";
-        if (mManager.mMainStorageVideo == null)
-            msg += getString(R.string.download_path_title);
-        else if (mManager.mMainStorageAudio == null)
-            msg += getString(R.string.download_path_audio_title);
-
-        if (!msg.isEmpty()) {
-            String title;
-            if (mManager.mMainStorageVideo == null && mManager.mMainStorageAudio == null) {
-                title = getString(R.string.general_error);
-                msg = getString(R.string.no_available_dir) + ":\n" + msg;
-            } else {
-                title = msg;
-                msg = getString(R.string.no_available_dir);
-            }
-
-            new AlertDialog.Builder(this)
-                    .setPositiveButton(android.R.string.ok, null)
-                    .setTitle(title)
-                    .setMessage(msg)
-                    .create()
-                    .show();
-        }
-
-
         return mBinder;
     }