/**
     * 功能：syncType分类，addLocalNode，addRemoteNode，deleteNode，updateLocalNode，updateRemoteNode
     * @author TTS
     * @param syncType
     * @param node
     * @param c
     * @throws NetworkFailureException
     */
    private void doContentSync(int syncType, Node node, Cursor c) throws NetworkFailureException {
        if (mCancelled) {
            return;
        }
 
        MetaData meta;
        switch (syncType) {
            case Node.SYNC_ACTION_ADD_LOCAL:
                addLocalNode(node);
                break;
            case Node.SYNC_ACTION_ADD_REMOTE:
                addRemoteNode(node, c);
                break;
            case Node.SYNC_ACTION_DEL_LOCAL:
                meta = mMetaHashMap.get(c.getString(SqlNote.GTASK_ID_COLUMN));
                if (meta != null) {
                    GTaskClient.getInstance().deleteNode(meta);
                }
                mLocalDeleteIdMap.add(c.getLong(SqlNote.ID_COLUMN));
                break;
            case Node.SYNC_ACTION_DEL_REMOTE:
                meta = mMetaHashMap.get(node.getGid());
                if (meta != null) {
                    GTaskClient.getInstance().deleteNode(meta);
                }
                GTaskClient.getInstance().deleteNode(node);
                break;
            case Node.SYNC_ACTION_UPDATE_LOCAL:
                updateLocalNode(node, c);
                break;
            case Node.SYNC_ACTION_UPDATE_REMOTE:
                updateRemoteNode(node, c);
                break;
            case Node.SYNC_ACTION_UPDATE_CONFLICT:
                // merging both modifications maybe a good idea
                // right now just use local update simply
                updateRemoteNode(node, c);
                break;
            case Node.SYNC_ACTION_NONE:
                break;
            case Node.SYNC_ACTION_ERROR:
            default:
                throw new ActionFailureException("unkown sync action type");
        }
    }
 
    /**
     * 功能：本地增加Node
     * @author TTS
     * @param node
     * @throws NetworkFailureException
     */
    private void addLocalNode(Node node) throws NetworkFailureException {
        if (mCancelled) {
            return;
        }
 
        SqlNote sqlNote;
        if (node instanceof TaskList) {
            if (node.getName().equals(
                    GTaskStringUtils.MIUI_FOLDER_PREFFIX + GTaskStringUtils.FOLDER_DEFAULT)) {
                sqlNote = new SqlNote(mContext, Notes.ID_ROOT_FOLDER);
            } else if (node.getName().equals(
                    GTaskStringUtils.MIUI_FOLDER_PREFFIX + GTaskStringUtils.FOLDER_CALL_NOTE)) {
                sqlNote = new SqlNote(mContext, Notes.ID_CALL_RECORD_FOLDER);
            } else {
                sqlNote = new SqlNote(mContext);
                sqlNote.setContent(node.getLocalJSONFromContent());
                sqlNote.setParentId(Notes.ID_ROOT_FOLDER);
            }
        } else {
            sqlNote = new SqlNote(mContext);
            JSONObject js = node.getLocalJSONFromContent();
            try {
                if (js.has(GTaskStringUtils.META_HEAD_NOTE)) {
                    JSONObject note = js.getJSONObject(GTaskStringUtils.META_HEAD_NOTE);
                    if (note.has(NoteColumns.ID)) {
                        long id = note.getLong(NoteColumns.ID);
                        if (DataUtils.existInNoteDatabase(mContentResolver, id)) {
                            // the id is not available, have to create a new one
                            note.remove(NoteColumns.ID);
                        }
                    }
                }
 
                if (js.has(GTaskStringUtils.META_HEAD_DATA)) {
                    JSONArray dataArray = js.getJSONArray(GTaskStringUtils.META_HEAD_DATA);
                    for (int i = 0; i < dataArray.length(); i++) {
                        JSONObject data = dataArray.getJSONObject(i);
                        if (data.has(DataColumns.ID)) {
                            long dataId = data.getLong(DataColumns.ID);
                            if (DataUtils.existInDataDatabase(mContentResolver, dataId)) {
                                // the data id is not available, have to create
                                // a new one
                                data.remove(DataColumns.ID);
                            }
                        }
                    }
 
                }
            } catch (JSONException e) {
                Log.w(TAG, e.toString());
                e.printStackTrace();
            }
            sqlNote.setContent(js);
 
            Long parentId = mGidToNid.get(((Task) node).getParent().getGid());
            if (parentId == null) {
                Log.e(TAG, "cannot find task's parent id locally");
                throw new ActionFailureException("cannot add local node");
            }
            sqlNote.setParentId(parentId.longValue());
        }
 
        // create the local node
        sqlNote.setGtaskId(node.getGid());
        sqlNote.commit(false);
 
        // update gid-nid mapping
        mGidToNid.put(node.getGid(), sqlNote.getId());
        mNidToGid.put(sqlNote.getId(), node.getGid());
 
        // update meta
        updateRemoteMeta(node.getGid(), sqlNote);
    }
 
    /**
     * 功能：update本地node
     * @author TTS
     * @param node
     * ----同步操作的基础数据类型
     * @param c
     * ----Cursor
     * @throws NetworkFailureException
     */
    private void updateLocalNode(Node node, Cursor c) throws NetworkFailureException {
        if (mCancelled) {
            return;
        }
 
        SqlNote sqlNote;
        // update the note locally
        sqlNote = new SqlNote(mContext, c);
        sqlNote.setContent(node.getLocalJSONFromContent());
 
        Long parentId = (node instanceof Task) ? mGidToNid.get(((Task) node).getParent().getGid())
                : new Long(Notes.ID_ROOT_FOLDER);
        if (parentId == null) {
            Log.e(TAG, "cannot find task's parent id locally");
            throw new ActionFailureException("cannot update local node");
        }
        sqlNote.setParentId(parentId.longValue());
        sqlNote.commit(true);
 
        // update meta info
        updateRemoteMeta(node.getGid(), sqlNote);
    }
 
    /**
     * 功能：远程增加Node
     * 需要updateRemoteMeta
     * @author TTS
     * @param node
     * ----同步操作的基础数据类型
     * @param c
     * --Cursor
     * @throws NetworkFailureException
     */
    private void addRemoteNode(Node node, Cursor c) throws NetworkFailureException {
        if (mCancelled) {
            return;
        }
 
        SqlNote sqlNote = new SqlNote(mContext, c);     //从本地mContext中获取内容
        Node n;
 
        // update remotely
        if (sqlNote.isNoteType()) {
            Task task = new Task();
            task.setContentByLocalJSON(sqlNote.getContent());
 
            String parentGid = mNidToGid.get(sqlNote.getParentId());
            if (parentGid == null) {
                Log.e(TAG, "cannot find task's parent tasklist");           //调试信息
                throw new ActionFailureException("cannot add remote task");
            }
            mGTaskListHashMap.get(parentGid).addChildTask(task);            //在本地生成的GTaskList中增加子结点
 
            //登录远程服务器，创建Task
            GTaskClient.getInstance().createTask(task); 
            n = (Node) task;
 
            // add meta
            updateRemoteMeta(task.getGid(), sqlNote);
        } else {
            TaskList tasklist = null;
 
            // we need to skip folder if it has already existed
            String folderName = GTaskStringUtils.MIUI_FOLDER_PREFFIX;
            if (sqlNote.getId() == Notes.ID_ROOT_FOLDER)
                folderName += GTaskStringUtils.FOLDER_DEFAULT;
            else if (sqlNote.getId() == Notes.ID_CALL_RECORD_FOLDER)
                folderName += GTaskStringUtils.FOLDER_CALL_NOTE;
            else
                folderName += sqlNote.getSnippet();
 
            //iterator迭代器，通过统一的接口迭代所有的map元素
            Iterator<Map.Entry<String, TaskList>> iter = mGTaskListHashMap.entrySet().iterator(); 
            while (iter.hasNext()) {
                Map.Entry<String, TaskList> entry = iter.next();
                String gid = entry.getKey();
                TaskList list = entry.getValue();
 
                if (list.getName().equals(folderName)) {
                    tasklist = list;
                    if (mGTaskHashMap.containsKey(gid)) {
                        mGTaskHashMap.remove(gid);
                    }
                    break;
                }
            }
 
            // no match we can add now
            if (tasklist == null) {
                tasklist = new TaskList();
                tasklist.setContentByLocalJSON(sqlNote.getContent());
                GTaskClient.getInstance().createTaskList(tasklist);
                mGTaskListHashMap.put(tasklist.getGid(), tasklist);
            }
            n = (Node) tasklist;
        }
 
        // update local note
        sqlNote.setGtaskId(n.getGid());
        sqlNote.commit(false);
        sqlNote.resetLocalModified();
        sqlNote.commit(true);
 
        // gid-id mapping                                             //创建id间的映射
        mGidToNid.put(n.getGid(), sqlNote.getId());
        mNidToGid.put(sqlNote.getId(), n.getGid());
    }