Added staff user limit

refs: https://github.com/TryGhost/Team/issues/510

- In the case that host config is provided, keep staff users within the limiti
- The definition of a staff user is a user with a role other than Contributor, and whose status is not inactive
   - Contributors don't count
   - Suspended (status inactive) users don't count
   - Locked users DO count
   - Invited users DO count
- You can't invite more staff users whilst there are pending invites
- You can't unsuspend a user, or change the role on a user in such a way as will take you over your limit
- You can't import staff users - all imported users are automatically set to Contributors
- As part of this work, we are changing the default Ghost user to a Contributor otherwise it uses up a staff user

Note: there is one known active bug with this commit.
- Assume you have one remaining user within your limit. You send an invite, this works.
- You cannot "resend" that invite, it will think you're sending a new invite and hit the limit
- You must "revoke" that invite first, and create a new one
- This bug exists because the resend function uses the add endpoint & does a delete+add, but this hits the permission check before the delete

core/server/data/importer/importers/data/users.js

@@ -2,6 +2,7 @@ const debug = require('ghost-ignition').debug('importer:users');
 const _ = require('lodash');
 const BaseImporter = require('./base');
 const models = require('../../../../models');
+const limitService = require('../../../../services/limits');
 
 class UsersImporter extends BaseImporter {
     constructor(allDataFromFile) {
@@ -58,6 +59,14 @@ class UsersImporter extends BaseImporter {
                 role = {name: 'Author'};
             }
 
+            // If this site has any sort of staff limit, set all imported users to contributors
+            // Any other sort of logic for counting staff users would be too complex in this scenario
+            // So we essentially don't allow importing staff users
+            // The roles can be changed afterwards if the limit permits
+            if (limitService.isLimited('staff')) {
+                role = {name: 'Contributor'};
+            }
+
             _.each(this.dataToImport, (obj) => {
                 if (attachedRole.user_id === obj.id) {
                     if (!_.isArray(obj.roles)) {

core/server/data/schema/fixtures/fixtures.json

@@ -470,7 +470,7 @@
                     "name": "Ghost",
                     "email": "ghost-author@example.com",
                     "status": "active",
-                    "roles": ["Author"],
+                    "roles": ["Contributor"],
                     "twitter": "ghost",
                     "facebook": "ghost",
                     "location": "The Internet",

core/server/models/invite.js

@@ -5,6 +5,7 @@ const errors = require('@tryghost/errors');
 const constants = require('@tryghost/constants');
 const security = require('@tryghost/security');
 const settingsCache = require('../services/settings/cache');
+const limitService = require('../services/limits');
 const ghostBookshelf = require('./base');
 
 let Invite;
@@ -43,9 +44,15 @@ Invite = ghostBookshelf.Model.extend({
         return ghostBookshelf.Model.add.call(this, data, options);
     },
 
-    permissible(inviteModel, action, context, unsafeAttrs, loadedPermissions, hasUserPermission, hasApiKeyPermission) {
+    async permissible(inviteModel, action, context, unsafeAttrs, loadedPermissions, hasUserPermission, hasApiKeyPermission) {
         const isAdd = (action === 'add');
 
+        if (isAdd && limitService.isLimited('staff')) {
+            // CASE: if your site is limited to a certain number of staff users
+            // Inviting a new user requires we check we won't go over the limit
+            await limitService.errorIfWouldGoOverLimit('staff');
+        }
+
         if (!isAdd) {
             if (hasUserPermission && hasApiKeyPermission) {
                 return Promise.resolve();

core/server/models/user.js

@@ -4,6 +4,7 @@ const validator = require('validator');
 const ObjectId = require('bson-objectid');
 const ghostBookshelf = require('./base');
 const baseUtils = require('./base/utils');
+const limitService = require('../services/limits');
 const {i18n} = require('../lib/common');
 const errors = require('@tryghost/errors');
 const security = require('@tryghost/security');
@@ -655,7 +656,7 @@ User = ghostBookshelf.Model.extend({
         });
     },
 
-    permissible: function permissible(userModelOrId, action, context, unsafeAttrs, loadedPermissions, hasUserPermission, hasApiKeyPermission) {
+    permissible: async function permissible(userModelOrId, action, context, unsafeAttrs, loadedPermissions, hasUserPermission, hasApiKeyPermission) {
         const self = this;
         const userModel = userModelOrId;
         let origArgs;
@@ -687,6 +688,11 @@ User = ghostBookshelf.Model.extend({
             });
         }
 
+        // If we have a staff user limit & the user is being unsuspended
+        if (limitService.isLimited('staff') && action === 'edit' && unsafeAttrs.status && unsafeAttrs.status === 'active' && userModel.get('status') === 'inactive') {
+            await limitService.errorIfWouldGoOverLimit('staff');
+        }
+
         if (action === 'edit') {
             // Users with the role 'Editor', 'Author', and 'Contributor' have complex permissions when the action === 'edit'
             // We now have all the info we need to construct the permissions
@@ -741,6 +747,13 @@ User = ghostBookshelf.Model.extend({
                 }));
             }
 
+            if (limitService.isLimited('staff') && userModel.hasRole('Contributor') && role.name !== 'Contributor') {
+                // CASE: if your site is limited to a certain number of staff users
+                // Trying to change the role of a contributor, who doesn't count towards the limit, to any other role requires a limit check
+                // To check if it's OK to add one more staff user
+                await limitService.errorIfWouldGoOverLimit('staff');
+            }
+
             return User.getOwnerUser()
                 .then((owner) => {
                     // CASE: owner can assign role to any user
@@ -765,6 +778,7 @@ User = ghostBookshelf.Model.extend({
                         // CASE: you are trying to change a role, but you are not owner
                         // @NOTE: your role is not the same than the role you try to change (!)
                         // e.g. admin can assign admin role to a user, but not owner
+
                         return permissions.canThis(context).assign.role(role)
                             .then(() => {
                                 if (hasUserPermission && hasApiKeyPermission) {

test/unit/data/schema/integrity_spec.js

@@ -33,7 +33,7 @@ const defaultSettings = require('../../../../core/server/data/schema/default-set
 describe('DB version integrity', function () {
     // Only these variables should need updating
     const currentSchemaHash = '559cdbb49a7eeb5758caf0c6e3bf790d';
-    const currentFixturesHash = '370d0da0ab7c45050b2ff30bce8896ba';
+    const currentFixturesHash = '5f6f69931811c407dff01da9ef9667f4';
     const currentSettingsHash = 'e1f85186a7c7ed76064b6026f68c6321';
     const currentRoutesHash = '3d180d52c663d173a6be791ef411ed01';