Use DnD for tags and builtin filter subtasks

app/src/main/java/com/todoroo/astrid/adapter/AstridTaskAdapter.java

@@ -40,13 +40,14 @@ public final class AstridTaskAdapter extends TaskAdapter {
 
   @Override
   public boolean canMove(ViewHolder source, ViewHolder target) {
-    return true;
+    return !updater.isDescendantOf(target.task.getUuid(), source.task.getUuid());
   }
 
-  public boolean canIndent(int position, TaskContainer task) {
-    String parentUuid = getItemUuid(position - 1);
-    int parentIndent = updater.getIndentForTask(parentUuid);
-    return getIndent(task) <= parentIndent;
+  @Override
+  public int maxIndent(int previousPosition, TaskContainer task) {
+    TaskContainer previous = getTask(previousPosition);
+    String parentUuid = previous.getUuid();
+    return updater.getIndentForTask(parentUuid) + 1;
   }
 
   @Override
@@ -56,11 +57,8 @@ public final class AstridTaskAdapter extends TaskAdapter {
 
   @Override
   public void moved(int from, int to, int indent) {
-    String targetTaskId = getItemUuid(from);
-    if (!Task.isValidUuid(targetTaskId)) {
-      return; // This can happen with gestures on empty parts of the list (e.g. extra space below
-      // tasks)
-    }
+    TaskContainer source = getTask(from);
+    String targetTaskId = source.getUuid();
 
     try {
       if (to >= getCount()) {
@@ -69,6 +67,11 @@ public final class AstridTaskAdapter extends TaskAdapter {
         String destinationTaskId = getItemUuid(to);
         updater.moveTo(list, filter, targetTaskId, destinationTaskId);
       }
+      int currentIndent = updater.getIndentForTask(targetTaskId);
+      int delta = indent - currentIndent;
+      for (int i = 0 ; i < Math.abs(delta) ; i++) {
+        updater.indent(list, filter, targetTaskId, delta);
+      }
     } catch (Exception e) {
       Timber.e(e);
     }

app/src/main/java/com/todoroo/astrid/adapter/GoogleTaskAdapter.java

@@ -56,8 +56,8 @@ public final class GoogleTaskAdapter extends TaskAdapter {
   }
 
   @Override
-  public int maxIndent(int position, TaskContainer task) {
-    return position == 0 || task.hasChildren() ? 0 : 1;
+  public int maxIndent(int previousPosition, TaskContainer task) {
+    return task.hasChildren() ? 0 : 1;
   }
 
   @Override

app/src/main/java/com/todoroo/astrid/adapter/TaskAdapter.java

@@ -60,7 +60,7 @@ public class TaskAdapter {
     return false;
   }
 
-  public int maxIndent(int position, TaskContainer task) {
+  public int maxIndent(int previousPosition, TaskContainer task) {
     return 0;
   }
 

app/src/main/java/com/todoroo/astrid/subtasks/SubtasksFilterUpdater.java

@@ -391,6 +391,10 @@ public class SubtasksFilterUpdater {
     applyToFilter(filter);
   }
 
+  public boolean isDescendantOf(String desc, String parent) {
+    return isDescendantOf(idToNode.get(desc), idToNode.get(parent));
+  }
+
   // Returns true if desc is a descendant of parent
   private boolean isDescendantOf(Node desc, Node parent) {
     Node curr = desc;

app/src/main/java/org/tasks/tasklist/ItemTouchHelperCallback.java

@@ -9,7 +9,6 @@ import android.graphics.Canvas;
 import androidx.annotation.NonNull;
 import androidx.recyclerview.widget.ItemTouchHelper;
 import androidx.recyclerview.widget.RecyclerView;
-import com.todoroo.astrid.activity.TaskListFragment;
 import com.todoroo.astrid.adapter.TaskAdapter;
 import com.todoroo.astrid.utility.Flags;
 import org.tasks.data.TaskContainer;
@@ -17,7 +16,6 @@ import org.tasks.data.TaskContainer;
 public class ItemTouchHelperCallback extends ItemTouchHelper.Callback {
   private final TaskAdapter adapter;
   private final TaskListRecyclerAdapter recyclerAdapter;
-  private final TaskListFragment taskList;
   private final Runnable onClear;
   private int from = -1;
   private int to = -1;
@@ -25,13 +23,9 @@ public class ItemTouchHelperCallback extends ItemTouchHelper.Callback {
   private boolean swiping;
 
   ItemTouchHelperCallback(
-      TaskAdapter adapter,
-      TaskListRecyclerAdapter recyclerAdapter,
-      TaskListFragment taskList,
-      Runnable onClear) {
+      TaskAdapter adapter, TaskListRecyclerAdapter recyclerAdapter, Runnable onClear) {
     this.adapter = adapter;
     this.recyclerAdapter = recyclerAdapter;
-    this.taskList = taskList;
     this.onClear = onClear;
   }
 
@@ -85,7 +79,7 @@ public class ItemTouchHelperCallback extends ItemTouchHelper.Callback {
         to == 0 || to == recyclerAdapter.getItemCount() - 1
             ? 0
             : adapter.minIndent(from <= to ? to + 1 : to, task));
-    source.setMaxIndent(adapter.maxIndent(to, task));
+    source.setMaxIndent(to == 0 ? 0 : adapter.maxIndent(from >= to ? to - 1 : to, task));
   }
 
   @Override
@@ -175,7 +169,6 @@ public class ItemTouchHelperCallback extends ItemTouchHelper.Callback {
     int delta = direction == ItemTouchHelper.RIGHT ? 1 : -1;
     int position = viewHolder.getAdapterPosition();
     recyclerAdapter.swiped(position, delta);
-    taskList.loadTaskListContent();
   }
 
   boolean isDragging() {

app/src/main/java/org/tasks/tasklist/TaskListRecyclerAdapter.java

@@ -59,7 +59,7 @@ public class TaskListRecyclerAdapter extends RecyclerView.Adapter<ViewHolder>
     this.actionModeProvider = actionModeProvider;
     this.list = list;
     itemTouchHelperCallback =
-        new ItemTouchHelperCallback(adapter, this, taskList, this::drainQueue);
+        new ItemTouchHelperCallback(adapter, this, this::drainQueue);
     isGoogleTaskList = taskList.getFilter() instanceof GtasksFilter;
     Pair<List<TaskContainer>, DiffResult> initial = Pair.create(list, null);
     disposables.add(
@@ -262,6 +262,7 @@ public class TaskListRecyclerAdapter extends RecyclerView.Adapter<ViewHolder>
     adapter.moved(from, to, indent);
     TaskContainer task = list.remove(from);
     list.add(from < to ? to - 1 : to, task);
+    taskList.loadTaskListContent();
   }
 
   void swiped(int position, int delta) {