Koenig - Show alert for unsupported browsers

refs https://github.com/TryGhost/Ghost/issues/9724
- add `ember-useragent` package so that we can check the user agent screen for known-incompatible browsers/devices
- show alerts for Edge, mobile browsers, and IE11 when accessing the editor with Koenig enabled

ghost/admin/app/routes/editor.js

@@ -2,16 +2,53 @@ import $ from 'jquery';
 import AuthenticatedRoute from 'ghost-admin/routes/authenticated';
 import ShortcutsRoute from 'ghost-admin/mixins/shortcuts-route';
 import ctrlOrCmd from 'ghost-admin/utils/ctrl-or-cmd';
+import {htmlSafe} from '@ember/string';
 import {run} from '@ember/runloop';
+import {inject as service} from '@ember/service';
 
 let generalShortcuts = {};
 generalShortcuts[`${ctrlOrCmd}+shift+p`] = 'publish';
 
 export default AuthenticatedRoute.extend(ShortcutsRoute, {
+    feature: service(),
+    notifications: service(),
+    userAgent: service(),
+
     classNames: ['editor'],
     shortcuts: generalShortcuts,
     titleToken: 'Editor',
 
+    setupController() {
+        this._super(...arguments);
+
+        // display a warning if we detect an unsupported browser
+        if (this.feature.koenigEditor) {
+            // IE is definitely not supported and will not work at all in Ghost 2.0
+            if (this.userAgent.browser.isIE) {
+                this.notifications.showAlert(
+                    htmlSafe('Internet Explorer is not supported in Koenig and will no longer work in Ghost 2.0. Please switch to <a href="https://ghost.org/downloads/" target="_blank" rel="noopener">Ghost Desktop</a> or a recent version of Chrome/Firefox/Safari.'),
+                    {type: 'info', key: 'koenig.browserSupport'}
+                );
+            }
+
+            // edge has known issues
+            if (this.userAgent.browser.isEdge) {
+                this.notifications.showAlert(
+                    htmlSafe('Microsoft Edge is not currently supported in Koenig. Please switch to <a href="https://ghost.org/downloads/" target="_blank" rel="noopener">Ghost Desktop</a> or a recent version of Chrome/Firefox/Safari.'),
+                    {type: 'info', key: 'koenig.browserSupport'}
+                );
+            }
+
+            // mobile browsers are not currently supported
+            if (this.userAgent.device.isMobile || this.userAgent.device.isTablet) {
+                this.notifications.showAlert(
+                    htmlSafe('Mobile editing is not currently supported in Koenig. Please use a desktop browser or <a href="https://ghost.org/downloads/" target="_blank" rel="noopener">Ghost Desktop</a>.'),
+                    {type: 'info', key: 'koenig.browserSupport'}
+                );
+            }
+        }
+    },
+
     actions: {
         save() {
             this._blurAndScheduleAction(function () {

ghost/admin/package.json

@@ -93,6 +93,7 @@
     "ember-svg-jar": "1.2.0",
     "ember-test-selectors": "1.0.0",
     "ember-truth-helpers": "2.0.0",
+    "ember-useragent": "0.6.1",
     "ember-wormhole": "0.5.4",
     "emberx-file-input": "1.2.1",
     "eslint": "4.19.1",

ghost/admin/yarn.lock

@@ -4153,6 +4153,17 @@ ember-truth-helpers@2.0.0, ember-truth-helpers@^2.0.0:
   dependencies:
     ember-cli-babel "^6.8.2"
 
+ember-useragent@0.6.1:
+  version "0.6.1"
+  resolved "https://registry.yarnpkg.com/ember-useragent/-/ember-useragent-0.6.1.tgz#0854b3c11acf0fdd98a165fba9bf5dc76eace804"
+  dependencies:
+    broccoli-debug "^0.6.3"
+    broccoli-funnel "^2.0.1"
+    broccoli-merge-trees "^3.0.0"
+    ember-cli-babel "^6.6.0"
+    fastboot-transform "^0.1.2"
+    ua-parser-js "^0.7.14"
+
 ember-weakmap@^3.0.0:
   version "3.2.0"
   resolved "https://registry.yarnpkg.com/ember-weakmap/-/ember-weakmap-3.2.0.tgz#663871d7a8bb085c5b1cedcb3fb183857990343f"
@@ -4771,6 +4782,13 @@ fast-sourcemap-concat@^1.0.1:
     source-map-url "^0.3.0"
     sourcemap-validator "^1.0.5"
 
+fastboot-transform@^0.1.2:
+  version "0.1.3"
+  resolved "https://registry.yarnpkg.com/fastboot-transform/-/fastboot-transform-0.1.3.tgz#7dea0b117594afd8772baa6c9b0919644e7f7dcd"
+  dependencies:
+    broccoli-stew "^1.5.0"
+    convert-source-map "^1.5.1"
+
 faye-websocket@~0.10.0:
   version "0.10.0"
   resolved "https://registry.yarnpkg.com/faye-websocket/-/faye-websocket-0.10.0.tgz#4e492f8d04dfb6f89003507f6edbf2d501e7c6f4"
@@ -9901,6 +9919,10 @@ typedarray@^0.0.6, typedarray@~0.0.5:
   version "0.0.6"
   resolved "https://registry.yarnpkg.com/typedarray/-/typedarray-0.0.6.tgz#867ac74e3864187b1d3d47d996a78ec5c8830777"
 
+ua-parser-js@^0.7.14:
+  version "0.7.18"
+  resolved "https://registry.yarnpkg.com/ua-parser-js/-/ua-parser-js-0.7.18.tgz#a7bfd92f56edfb117083b69e31d2aa8882d4b1ed"
+
 uc.micro@^1.0.1, uc.micro@^1.0.5:
   version "1.0.5"
   resolved "https://registry.yarnpkg.com/uc.micro/-/uc.micro-1.0.5.tgz#0c65f15f815aa08b560a61ce8b4db7ffc3f45376"