Move transform acl (#2021)

* Move ACL transforming into Parse Server

For the database adapters, it will be more performant and easier to work with _rperm and _wperm than with the ACL object. This way we can type it as an array and so on, and once we have stronger validations in Parse Server, we can type it as an array containing strings of length < x, which will be much much better in sql databases.

* Use destructuring

src/Adapters/Storage/Mongo/MongoTransform.js

@@ -273,11 +273,12 @@ const parseObjectKeyValueToMongoObjectKeyValue = (className, restKey, restValue,
 
 // Main exposed method to create new objects.
 // restCreate is the "create" clause in REST API form.
-function parseObjectToMongoObjectForCreate(className, restCreate, schema) {
+const parseObjectToMongoObjectForCreate = (className, restCreate, schema) => {
   if (className == '_User') {
      restCreate = transformAuthData(restCreate);
   }
-  var mongoCreate = transformACL(restCreate);
+  restCreate = addLegacyACL(restCreate);
+  let mongoCreate = {}
   for (let restKey in restCreate) {
     let { key, value } = parseObjectKeyValueToMongoObjectKeyValue(
       className,
@@ -298,18 +299,18 @@ const transformUpdate = (className, restUpdate, parseFormatSchema) => {
     restUpdate = transformAuthData(restUpdate);
   }
 
-  var mongoUpdate = {};
-  var acl = transformACL(restUpdate);
-  if (acl._rperm || acl._wperm || acl._acl) {
-    mongoUpdate['$set'] = {};
+  let mongoUpdate = {};
+  let acl = addLegacyACL(restUpdate)._acl;
+  if (acl) {
+    mongoUpdate.$set = {};
     if (acl._rperm) {
-      mongoUpdate['$set']['_rperm'] = acl._rperm;
+      mongoUpdate.$set._rperm = acl._rperm;
     }
     if (acl._wperm) {
-      mongoUpdate['$set']['_wperm'] = acl._wperm;
+      mongoUpdate.$set._wperm = acl._wperm;
     }
     if (acl._acl) {
-      mongoUpdate['$set']['_acl'] = acl._acl;
+      mongoUpdate.$set._acl = acl._acl;
     }
   }
   for (var restKey in restUpdate) {
@@ -347,66 +348,34 @@ function transformAuthData(restObject) {
   return restObject;
 }
 
-// Transforms a REST API formatted ACL object to our two-field mongo format.
-// This mutates the restObject passed in to remove the ACL key.
-function transformACL(restObject) {
-  var output = {};
-  if (!restObject['ACL']) {
-    return output;
-  }
-  var acl = restObject['ACL'];
-  var rperm = [];
-  var wperm = [];
-  var _acl = {}; // old format
+// Add the legacy _acl format.
+const addLegacyACL = restObject => {
+  let restObjectCopy = {...restObject};
+  let _acl = {};
 
-  for (var entry in acl) {
-    if (acl[entry].read) {
-      rperm.push(entry);
-      _acl[entry] = _acl[entry] || {};
-      _acl[entry]['r'] = true;
-    }
-    if (acl[entry].write) {
-      wperm.push(entry);
-      _acl[entry] = _acl[entry] || {};
-      _acl[entry]['w'] = true;
-    }
+  if (restObject._wperm) {
+    restObject._wperm.forEach(entry => {
+      _acl[entry] = { w: true };
+    });
   }
-  output._rperm = rperm;
-  output._wperm = wperm;
-  output._acl = _acl;
-  delete restObject.ACL;
-  return output;
+
+  if (restObject._rperm) {
+    restObject._rperm.forEach(entry => {
+      if (!(entry in _acl)) {
+        _acl[entry] = { r: true };
+      } else {
+        _acl[entry].r = true;
+      }
+    });
+  }
+
+  if (Object.keys(_acl).length > 0) {
+    restObjectCopy._acl = _acl;
+  }
+
+  return restObjectCopy;
 }
 
-// Transforms a mongo format ACL to a REST API format ACL key
-// This mutates the mongoObject passed in to remove the _rperm/_wperm keys
-function untransformACL(mongoObject) {
-  var output = {};
-  if (!mongoObject['_rperm'] && !mongoObject['_wperm']) {
-    return output;
-  }
-  var acl = {};
-  var rperm = mongoObject['_rperm'] || [];
-  var wperm = mongoObject['_wperm'] || [];
-  rperm.map((entry) => {
-    if (!acl[entry]) {
-      acl[entry] = {read: true};
-    } else {
-      acl[entry]['read'] = true;
-    }
-  });
-  wperm.map((entry) => {
-    if (!acl[entry]) {
-      acl[entry] = {write: true};
-    } else {
-      acl[entry]['write'] = true;
-    }
-  });
-  output['ACL'] = acl;
-  delete mongoObject._rperm;
-  delete mongoObject._wperm;
-  return output;
-}
 
 // A sentinel value that helper transformations return when they
 // cannot perform a transformation
@@ -752,7 +721,14 @@ const mongoObjectToParseObject = (className, mongoObject, schema) => {
       return BytesCoder.databaseToJSON(mongoObject);
     }
 
-    var restObject = untransformACL(mongoObject);
+    let restObject = {};
+    if (mongoObject._rperm || mongoObject._wperm) {
+      restObject._rperm = mongoObject._rperm || [];
+      restObject._wperm = mongoObject._wperm || [];
+      delete mongoObject._rperm;
+      delete mongoObject._wperm;
+    }
+
     for (var key in mongoObject) {
       switch(key) {
       case '_id':