/*
* Copyright (C) 2011 Red Hat, Inc. and/or its affiliates.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jboss.errai.enterprise.client.jaxrs;
import static org.jboss.errai.common.client.protocols.SerializationParts.ENCODED_TYPE;
import static org.jboss.errai.common.client.protocols.SerializationParts.ENUM_STRING_VALUE;
import static org.jboss.errai.common.client.protocols.SerializationParts.NUMERIC_VALUE;
import static org.jboss.errai.common.client.protocols.SerializationParts.OBJECT_ID;
import static org.jboss.errai.common.client.protocols.SerializationParts.QUALIFIED_VALUE;
import java.util.HashMap;
import java.util.Map;
import org.jboss.errai.common.client.protocols.SerializationParts;
import com.google.gwt.json.client.JSONArray;
import com.google.gwt.json.client.JSONNumber;
import com.google.gwt.json.client.JSONObject;
import com.google.gwt.json.client.JSONParser;
import com.google.gwt.json.client.JSONString;
import com.google.gwt.json.client.JSONValue;
/**
* Utility to transform Errai's JSON to a Jackson compatible JSON and vice versa.
* <p>
* Limitations:
* <ul>
* <li>Fields with nested parameterized types are not supported (e.g. List<List<String>>)</li>
* </ul>
*
* @author Christian Sadilek <csadilek@redhat.com>
*/
public class JacksonTransformer {
private JacksonTransformer() {};
/**
* Transforms Errai JSON into a Jackson compatible JSON.
*
* @param erraiJson
* JSON generated by Errai
* @return jackson compatible JSON
*/
public static String toJackson(String erraiJson) {
JSONValue val = JSONParser.parseStrict(erraiJson);
val = toJackson(val, null, null, new HashMap<String, JSONValue>());
return val.toString();
}
/**
* The transformation from Errai JSON to Jackson's JSON contains the following steps:
* <ul>
* <li>For all JSON objects, recursively remove the Errai specific OBJECT_ID and ENCODED_TYPE
* values</li>
* <li>Keep a reference to the removed OBJECT_IDs, so back-references can be resolved</li>
* <li>If an array is encountered, process all its elements, then remove the Errai specific
* QUALIFIED_VALUE key, by associating its actual value with the object's key directly: "list":
* {"^Value": ["e1","e2"]} becomes "list": ["e1","e2"]</li>
* <li>If an enum is encountered, remove the Errai specific ENUM_STRING_VALUE key, by associating
* its actual value with the object's key directly: "gender": {"^EnumStringValue": "MALE"} becomes
* "gender": "MALE"</li>
* <li>If a number is encountered, remove the Errai specific NUMERIC_VALUE key, by associating its
* actual value with the object's key directly: "id": {"^NumValue": "1"} becomes "id": "1"</li>
* <li>If a date is encountered, remove the Errai specific QUALIFIED_VALUE key, by associating its
* actual value with the object's key directly and turning it into a JSON number</li>
* <li>If EMBEDDED_JSON is encountered, turn in into standard json</li>
* </ul>
*
* @param val
* the JSON value to transform
* @param key
* the key of the JSON value to transform
* @param parent
* the parent object of the current value
* @param objectCache
* a cache for removed objects, that is used to resolve backreferences
* @return the modified JSON value
*/
private static JSONValue toJackson(JSONValue val, String key, JSONObject parent, Map<String, JSONValue> objectCache) {
JSONObject obj;
if ((obj = val.isObject()) != null) {
JSONValue encType = obj.get(ENCODED_TYPE);
JSONValue objectIdVal = obj.get(OBJECT_ID);
if (objectIdVal != null && encType != null) {
String objectId = objectIdVal.isString().stringValue();
String cacheKey = objectId + "/" + encType.isString().stringValue();
if (!objectId.equals("-1")) {
JSONValue backRef = objectCache.get(cacheKey);
if (backRef != null) {
if (parent != null) {
obj = backRef.isObject();
parent.put(key, obj);
}
else {
return backRef.isObject();
}
}
else {
objectCache.put(cacheKey, obj);
}
}
}
obj.put(OBJECT_ID, null);
obj.put(ENCODED_TYPE, null);
for (String k : obj.keySet()) {
JSONArray arr;
if ((arr = obj.get(k).isArray()) != null) {
for (int i = 0; i < arr.size(); i++) {
if (arr.get(i).isObject() != null && arr.get(i).isObject().get(NUMERIC_VALUE) != null) {
arr.set(i, arr.get(i).isObject().get(NUMERIC_VALUE));
}
else if (arr.get(i).isObject() != null) {
arr.set(i, toJackson(arr.get(i), null, null, objectCache));
}
}
if (k.equals(QUALIFIED_VALUE)) {
if (parent != null) {
parent.put(key, arr);
}
else {
return arr;
}
}
}
else if (k.equals(ENUM_STRING_VALUE) || k.equals(NUMERIC_VALUE)) {
if (parent != null) {
parent.put(key, obj.get(k));
}
return toJackson(obj.get(k), k, obj, objectCache);
}
else if (k.equals(QUALIFIED_VALUE)) {
if (parent != null) {
if (encType.isString().stringValue().equals("java.util.Date")) {
String dateValue = obj.get(k).isString().stringValue();
parent.put(key, new JSONNumber(Double.parseDouble(dateValue)));
}
else {
parent.put(key, obj.get(k));
}
}
}
else if (k.startsWith(SerializationParts.EMBEDDED_JSON)) {
final JSONValue newKey = JSONParser.parseStrict((k.substring(SerializationParts.EMBEDDED_JSON.length())));
JSONValue value = obj.get(k);
JSONObject tmpObject = new JSONObject();
toJackson(newKey, QUALIFIED_VALUE, tmpObject, objectCache);
String embeddedKey = null;
JSONValue qualVal = tmpObject.get(QUALIFIED_VALUE);
if (qualVal.isString() != null) {
embeddedKey = qualVal.isString().stringValue();
}
else {
embeddedKey = qualVal.toString();
}
obj.put(embeddedKey, value);
}
toJackson(obj.get(k), k, obj, objectCache);
}
}
return (obj != null) ? cleanUpEmbeddedJson(obj) : val;
}
private static JSONObject cleanUpEmbeddedJson(JSONObject obj) {
if (obj != null) {
for (String k : obj.keySet()) {
if (k.startsWith(SerializationParts.EMBEDDED_JSON)) {
obj.put(k, null);
}
}
}
return obj;
}
/**
* Transforms Jackson generated JSON into Errai compatible JSON.
*
* @param jackson
* JSON generated by Jackson
* @return Errai compatible JSON
*/
public static String fromJackson(String jackson) {
JSONValue val = JSONParser.parseStrict(jackson);
val = fromJackson(val, null, null, new int[1]);
return val.toString();
}
/**
* The transformation from Jackson's JSON to Errai JSON contains the following steps:
* <ul>
* <li>Recursively add an incremented OBJECT_ID to every JSON object</li>
* <li>If a number is encountered, wrap it in a new JSON object with an OBJECT_ID and
* NUMERIC_VALUE property</li>
* <li>If an array is encountered, wrap it in a new JSON object with an OBJECT_ID and
* QUALIFIED_VALUE property</li>
* </ul>
*
* @param val
* the JSON value to transform
* @param key
* the key of the JSON value to transform
* @param parent
* the parent object of the current value
* @param objectId
* last used object id
* @return modified JSON value
*/
private static JSONValue fromJackson(JSONValue val, String key, JSONObject parent, int[] objectId) {
JSONObject obj;
JSONNumber num;
JSONArray arr;
if ((obj = val.isObject()) != null) {
obj.put(OBJECT_ID, new JSONString(new Integer(++objectId[0]).toString()));
for (String k : obj.keySet()) {
fromJackson(obj.get(k), k, obj, objectId);
}
}
else if ((num = val.isNumber()) != null) {
JSONObject numObject = new JSONObject();
numObject.put(OBJECT_ID, new JSONString(new Integer(++objectId[0]).toString()));
numObject.put(NUMERIC_VALUE, num);
if (parent != null) {
parent.put(key, numObject);
}
else {
val = numObject;
}
}
else if ((arr = val.isArray()) != null) {
JSONObject arrayObject = new JSONObject();
arrayObject.put(OBJECT_ID, new JSONString(new Integer(++objectId[0]).toString()));
arrayObject.put(QUALIFIED_VALUE, arr);
if (parent != null) {
parent.put(key, arrayObject);
}
else {
val = arrayObject;
}
for (int i = 0; i < arr.size(); i++) {
arr.set(i, fromJackson(arr.get(i), QUALIFIED_VALUE, null, objectId));
}
}
return val;
}
}