From eb67d86163fc54bc015fbb049ef6cc25a50cfdd0 Mon Sep 17 00:00:00 2001
From: Chi Vinh Le <vinh@wikiwi.io>
Date: Tue, 29 Aug 2017 18:57:20 +0700
Subject: [PATCH] Implement UserConnection on the graph

---
 graph/loaders/users.js  | 42 ++++++++++++++++++++++++++++++++---------
 graph/resolvers/user.js |  5 +++--
 graph/typeDefs.graphql  | 18 +++++++++++++++++-
 3 files changed, 53 insertions(+), 12 deletions(-)

diff --git a/graph/loaders/users.js b/graph/loaders/users.js
index 999ad1938..3d48bafd7 100644
--- a/graph/loaders/users.js
+++ b/graph/loaders/users.js
@@ -26,12 +26,12 @@ const genUserByIDs = async (context, ids) => {
  * @param  {Object} context   graph context
  * @param  {Object} query     query terms to apply to the users query
  */
-const getUsersByQuery = ({user}, {ids, limit, cursor, statuses = null, sortOrder}) => {
+const getUsersByQuery = async ({user}, {ids, limit, cursor, statuses = null, sortOrder}) => {
 
-  let users = UserModel.find();
+  let query = UserModel.find();
 
   if (ids) {
-    users = users.find({
+    query = query.find({
       id: {
         $in: ids
       }
@@ -39,7 +39,7 @@ const getUsersByQuery = ({user}, {ids, limit, cursor, statuses = null, sortOrder
   }
 
   if (statuses != null) {
-    users = users.where({
+    query = query.where({
       status: {
         $in: statuses
       }
@@ -48,13 +48,13 @@ const getUsersByQuery = ({user}, {ids, limit, cursor, statuses = null, sortOrder
 
   if (cursor) {
     if (sortOrder === 'DESC') {
-      users = users.where({
+      query = query.where({
         created_at: {
           $lt: cursor
         }
       });
     } else {
-      users = users.where({
+      query = query.where({
         created_at: {
           $gt: cursor
         }
@@ -62,9 +62,33 @@ const getUsersByQuery = ({user}, {ids, limit, cursor, statuses = null, sortOrder
     }
   }
 
-  return users
-    .sort({created_at: sortOrder === 'DESC' ? -1 : 1})
-    .limit(limit);
+  // Apply the limit.
+  if (limit) {
+    query = query.limit(limit + 1);
+  }
+
+  const nodes = await query.exec();
+
+  // The hasNextPage is always handled the same (ask for one more than we need,
+  // if there is one more, than there is more).
+  let hasNextPage = false;
+  if (limit && nodes.length > limit) {
+
+    // There was one more than we expected! Set hasNextPage = true and remove
+    // the last item from the array that we requested.
+    hasNextPage = true;
+    nodes.splice(limit, 1);
+  }
+
+  const startCursor = nodes.length ? nodes[0].created_at : null;
+  const endCursor = nodes.length ? nodes[nodes.length - 1].created_at : null;
+
+  return {
+    startCursor,
+    endCursor,
+    hasNextPage,
+    nodes,
+  };
 };
 
 /**
diff --git a/graph/resolvers/user.js b/graph/resolvers/user.js
index 57601c269..e5c5746ca 100644
--- a/graph/resolvers/user.js
+++ b/graph/resolvers/user.js
@@ -51,7 +51,7 @@ const User = {
 
     return tokens;
   },
-  ignoredUsers({id}, args, {user, loaders: {Users}}) {
+  async ignoredUsers({id}, args, {user, loaders: {Users}}) {
 
     // Only allow a logged in user that is either the current user or is a staff
     // member to access the ignoredUsers of a given user.
@@ -64,7 +64,8 @@ const User = {
       return [];
     }
 
-    return Users.getByQuery({ids: user.ignoresUsers});
+    const connection = await Users.getByQuery({ids: user.ignoresUsers});
+    return connection.nodes;
   },
   roles({id, roles}, _, {user}) {
 
diff --git a/graph/typeDefs.graphql b/graph/typeDefs.graphql
index 4dff623fd..5bebb7e76 100644
--- a/graph/typeDefs.graphql
+++ b/graph/typeDefs.graphql
@@ -121,6 +121,22 @@ type User {
   suspension: SuspensionInfo
 }
 
+# UserConnection represents a paginable subset of a user list.
+type UserConnection {
+
+  # Indicates that there are more users after this subset.
+  hasNextPage: Boolean!
+
+  # Cursor of first user in subset.
+  startCursor: Cursor
+
+  # Cursor of last user in subset.
+  endCursor: Cursor
+
+  # Subset of users.
+  nodes: [User!]!
+}
+
 # UsersQuery allows the ability to query users by a specific fields.
 input UsersQuery {
   action_type: ACTION_TYPE
@@ -731,7 +747,7 @@ type RootQuery {
   me: User
 
   # Users returned based on a query.
-  users(query: UsersQuery): [User]
+  users(query: UsersQuery!): UserConnection
 
   # a single User by id
   user(id: ID!): User