Wrote some helper functions to convert subtask trees between local and remote ids (could be useful for syncing)

astrid/plugin-src/com/todoroo/astrid/subtasks/AstridOrderedListUpdater.java

@@ -31,7 +31,7 @@ public abstract class AstridOrderedListUpdater<LIST> {
     }
 
     public static class Node {
-        public final long taskId;
+        public long taskId;
         public Node parent;
         public int indent;
         public final ArrayList<Node> children = new ArrayList<Node>();
@@ -63,7 +63,12 @@ public abstract class AstridOrderedListUpdater<LIST> {
     }
 
     public void initializeFromSerializedTree(LIST list, Filter filter, String serializedTree) {
-        treeRoot = buildTreeModel(serializedTree);
+        treeRoot = buildTreeModel(serializedTree, new JSONTreeModelBuilder() {
+            @Override
+            public void afterAddNode(Node node) {
+                idToNode.put(node.taskId, node);
+            }
+        });
         verifyTreeModel(list, filter);
     }
 
@@ -303,44 +308,54 @@ public abstract class AstridOrderedListUpdater<LIST> {
         applyToFilter(filter);
     }
 
-    private Node buildTreeModel(String serializedTree) {
+    private interface JSONTreeModelBuilder {
+        void afterAddNode(Node node);
+    }
+
+    public static Node buildTreeModel(String serializedTree, JSONTreeModelBuilder callback) {
         Node root = new Node(-1, null, -1);
         try {
             JSONArray tree = new JSONArray(serializedTree);
-            recursivelyBuildChildren(root, tree);
+            recursivelyBuildChildren(root, tree, callback);
         } catch (JSONException e) {
             Log.e("OrderedListUpdater", "Error building tree model", e);  //$NON-NLS-1$//$NON-NLS-2$
         }
         return root;
     }
 
-    private void recursivelyBuildChildren(Node node, JSONArray children) throws JSONException {
+    private static void recursivelyBuildChildren(Node node, JSONArray children, JSONTreeModelBuilder callback) throws JSONException {
         for (int i = 1; i < children.length(); i++) {
             JSONArray subarray = children.optJSONArray(i);
             if (subarray == null) {
                 Long id = children.getLong(i);
                 Node child = new Node(id, node, node.indent + 1);
                 node.children.add(child);
-                idToNode.put(id, child);
+                if (callback != null)
+                    callback.afterAddNode(child);
             } else {
                 Long id = subarray.getLong(0);
                 Node child = new Node(id, node, node.indent + 1);
-                recursivelyBuildChildren(child, subarray);
+                recursivelyBuildChildren(child, subarray, callback);
                 node.children.add(child);
-                idToNode.put(id, child);
+                if (callback != null)
+                    callback.afterAddNode(child);
             }
         }
     }
 
     protected String serializeTree() {
+        return serializeTree(treeRoot);
+    }
+
+    public static String serializeTree(Node root) {
         JSONArray tree = new JSONArray();
-        if (treeRoot == null) {
+        if (root == null) {
             return tree.toString();
         }
 
         try {
             tree.put(-1L);
-            recursivelySerialize(treeRoot, tree);
+            recursivelySerialize(root, tree);
         } catch (JSONException e) {
             Log.e("OrderedListUpdater", "Error serializing tree model", e);  //$NON-NLS-1$//$NON-NLS-2$
         }

astrid/plugin-src/com/todoroo/astrid/subtasks/SubtasksHelper.java

@@ -1,13 +1,16 @@
 package com.todoroo.astrid.subtasks;
 
 import java.util.ArrayList;
+import java.util.HashMap;
 
 import android.content.SharedPreferences;
 import android.text.TextUtils;
 import android.util.Log;
 
+import com.todoroo.andlib.data.TodorooCursor;
 import com.todoroo.andlib.service.ContextManager;
 import com.todoroo.andlib.sql.Criterion;
+import com.todoroo.andlib.sql.Query;
 import com.todoroo.andlib.utility.Preferences;
 import com.todoroo.astrid.actfm.TagViewFragment;
 import com.todoroo.astrid.api.Filter;
@@ -18,6 +21,7 @@ import com.todoroo.astrid.core.SortHelper;
 import com.todoroo.astrid.dao.TaskDao.TaskCriteria;
 import com.todoroo.astrid.data.TagData;
 import com.todoroo.astrid.data.Task;
+import com.todoroo.astrid.subtasks.AstridOrderedListUpdater.Node;
 import com.todoroo.astrid.utility.AstridPreferences;
 
 public class SubtasksHelper {
@@ -75,12 +79,11 @@ public class SubtasksHelper {
         else
             serialized = Preferences.getStringValue(SubtasksUpdater.ACTIVE_TASKS_ORDER);
 
-        ArrayList<Long> ids = getIdArray(serialized);
+        return AstridOrderedListUpdater.buildOrderString(getIdArray(serialized));
-        return AstridOrderedListUpdater.buildOrderString(ids.toArray(new Long[ids.size()]));
     }
 
     @SuppressWarnings("nls")
-    private static ArrayList<Long> getIdArray(String serializedTree) {
+    public static Long[] getIdArray(String serializedTree) {
         ArrayList<Long> ids = new ArrayList<Long>();
         String[] digitsOnly = serializedTree.split("\\D+");
         for (String idString : digitsOnly) {
@@ -91,7 +94,74 @@ public class SubtasksHelper {
                 Log.e("widget-subtasks", "error parsing id " + idString, e);
             }
         }
-        return ids;
+        return ids.toArray(new Long[ids.size()]);
+    }
+
+    public static String convertTreeToRemoteIds(String localTree) {
+        return convertIdTree(localTree, true);
+    }
+
+    public static String convertTreeToLocalIds(String remoteTree) {
+        return convertIdTree(remoteTree, false);
+    }
+
+    private static String convertIdTree(String treeString, boolean localToRemote) {
+        Long[] ids = getIdArray(treeString);
+        HashMap<Long, Long> idMap = buildIdMap(ids, localToRemote);
+
+        Node tree = AstridOrderedListUpdater.buildTreeModel(treeString, null);
+        remapTree(tree, idMap);
+        return AstridOrderedListUpdater.serializeTree(tree);
+    }
+
+    private static void remapTree(Node root, HashMap<Long, Long> idMap) {
+        ArrayList<Node> children = root.children;
+        for (int i = 0; i < children.size(); i++) {
+            Node child = children.get(i);
+            Long remoteId = idMap.get(child.taskId);
+            if (remoteId == null || remoteId <= 0) {
+                children.remove(i);
+                i--;
+            } else {
+                child.taskId = remoteId;
+                remapTree(child, idMap);
+            }
+        }
+    }
+
+    private static HashMap<Long, Long> buildIdMap(Long[] localIds, boolean localToRemote) { // If localToRemote is true, keys are local ids. If false. keys are remtoe ids
+        HashMap<Long, Long> map = new HashMap<Long, Long>();
+        Criterion criterion;
+        if (localToRemote)
+            criterion = Task.ID.in(localIds);
+        else
+            criterion = Task.REMOTE_ID.in(localIds);
+
+        TodorooCursor<Task> tasks = PluginServices.getTaskService().query(Query.select(Task.ID, Task.REMOTE_ID).where(criterion));
+        try {
+            Task t = new Task();
+            for (tasks.moveToFirst(); !tasks.isAfterLast(); tasks.moveToNext()) {
+                t.clear();
+                t.readFromCursor(tasks);
+
+                if (t.containsNonNullValue(Task.REMOTE_ID)) {
+                    Long key;
+                    Long value;
+                    if (localToRemote) {
+                        key = t.getId();
+                        value = t.getValue(Task.REMOTE_ID);
+                    } else {
+                        key = t.getValue(Task.REMOTE_ID);
+                        value = t.getId();
+                    }
+
+                    map.put(key, value);
+                }
+            }
+        } finally {
+            tasks.close();
+        }
+        return map;
     }
 
 }