Security rules based on quickstart-ios firestore (#167)

Author: barcellos

firestore/firestore.rules

@@ -1,7 +1,18 @@
 service cloud.firestore {
   match /databases/{database}/documents {
-    match /{document=**} {
-      allow read, write: if auth != null;
+    match /restaurants/{restaurant} {
+      match /ratings/{rating} {
+        allow read: if request.auth != null;
+        allow write: if request.auth.uid == request.resource.userId;
+      }
+
+      allow read: if request.auth != null;
+      allow create: if request.auth != null;
+      allow update: if request.auth != null
+                    && request.resource.name == resource.name
+                    && request.resource.city == resource.city
+                    && request.resource.price == resource.price
+                    && request.resource.category == resource.category;
     }
   }
 }