app: Add support for local sync provider

app/src/main/AndroidManifest.xml

@@ -8,6 +8,12 @@
     <!-- 运行前台服务 -->
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
 
+    <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"
+        tools:ignore="ScopedStorage" />
+
+    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+
     <!--
         Fix the problem that notifications cannot be allowed on Android 13
         https://github.com/siyuan-note/siyuan/issues/7960

app/src/main/java/org/b3log/siyuan/AndroidFileUtils.java

@@ -0,0 +1,33 @@
+package org.b3log.siyuan;
+
+import android.content.Context;
+import android.net.Uri;
+import android.os.Environment;
+import android.provider.DocumentsContract;
+
+public class AndroidFileUtils {
+    public static String getPath(final Context context, final Uri uri) {
+        if (DocumentsContract.isDocumentUri(context, uri)) {
+            if (isExternalStorageDocument(uri)) {
+                final String docId = DocumentsContract.getDocumentId(uri);
+                final String[] split = docId.split(":");
+                if (split.length != 2) return null;
+
+                final String type = split[0];
+
+                if ("primary".equalsIgnoreCase(type))
+                    return Environment.getExternalStorageDirectory() + "/" + split[1];
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * @param uri The Uri to check.
+     * @return Whether the Uri authority is ExternalStorageProvider.
+     */
+    public static boolean isExternalStorageDocument(Uri uri) {
+        return "com.android.externalstorage.documents".equals(uri.getAuthority());
+    }
+}

app/src/main/java/org/b3log/siyuan/JSAndroid.java

@@ -199,6 +199,13 @@ public void changeStatusBarColor(final String color, final int appearanceMode) {
         });
     }
 
+    @JavascriptInterface
+    public String getLocalFileSystemPath() {
+        activity.getStoragePermissions();
+        activity.pickLocalFileSystemFolder();
+        return activity.getLocalSyncPath();
+    }
+
     private int parseColor(String str) {
         try {
             str = str.trim();

app/src/main/java/org/b3log/siyuan/MainActivity.java

@@ -23,17 +23,21 @@
 import android.content.ClipData;
 import android.content.ContentValues;
 import android.content.Intent;
+import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
 import android.graphics.Bitmap;
 import android.graphics.Color;
 import android.net.Uri;
 import android.os.Build;
 import android.os.Bundle;
+import android.os.Environment;
 import android.os.Handler;
 import android.os.LocaleList;
 import android.os.Looper;
 import android.os.Message;
+import android.provider.DocumentsContract;
 import android.provider.MediaStore;
+import android.provider.Settings;
 import android.util.Log;
 import android.view.DragEvent;
 import android.view.View;
@@ -105,6 +109,7 @@ public class MainActivity extends AppCompatActivity implements com.blankj.utilco
     private ValueCallback<Uri[]> uploadMessage;
     private static final int REQUEST_SELECT_FILE = 100;
     private static final int REQUEST_CAMERA = 101;
+    private static final int LOCAL_SYNC_FOLDER_CODE = 200;
 
     @Override
     public void onNewIntent(final Intent intent) {
@@ -156,6 +161,32 @@ protected void onCreate(final Bundle savedInstanceState) {
         AndroidBug5497Workaround.assistActivity(this);
     }
 
+    public String getLocalSyncPath() {
+        SharedPreferences prefs = getSharedPreferences("app_prefs", MODE_PRIVATE);
+        return prefs.getString("localSyncPath", null);
+    }
+
+    public void getStoragePermissions() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R && !Environment.isExternalStorageManager()) {
+            Intent intent = new Intent(Settings.ACTION_MANAGE_APP_ALL_FILES_ACCESS_PERMISSION);
+            Uri uri = Uri.fromParts("package", getPackageName(), null);
+            intent.setData(uri);
+            startActivity(intent);
+        }
+    }
+
+    public void pickLocalFileSystemFolder() {
+        Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
+        startActivityForResult(intent, LOCAL_SYNC_FOLDER_CODE);
+    }
+
+    private void saveLocalSyncPath(String path) {
+        SharedPreferences prefs = getSharedPreferences("app_prefs", MODE_PRIVATE);
+        SharedPreferences.Editor editor = prefs.edit();
+        editor.putString("localSyncPath", path);
+        editor.apply();
+    }
+
     private void initUIElements() {
         bootLogo = findViewById(R.id.bootLogo);
         bootProgressBar = findViewById(R.id.progressBar);
@@ -573,8 +604,22 @@ private void openCamera() {
 
     @Override
     protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
+        super.onActivityResult(requestCode, resultCode, intent);
+        if (requestCode == LOCAL_SYNC_FOLDER_CODE && resultCode == RESULT_OK) {
+            if (intent != null) {
+                Uri treeUri = intent.getData();
+                Uri docUri = DocumentsContract.buildDocumentUriUsingTree(treeUri,
+                        DocumentsContract.getTreeDocumentId(treeUri));
+                String path = AndroidFileUtils.getPath(this, docUri);
+                if (path == null || path.isEmpty())
+                    Toast.makeText(this, "Error with selected directory",
+                            Toast.LENGTH_LONG).show();
+                else
+                    saveLocalSyncPath(path);
+            }
+        }
+
         if (null == uploadMessage) {
-            super.onActivityResult(requestCode, resultCode, intent);
             return;
         }