Fix Unsupported Block Editor on account created prior to December 2018

RELEASE-NOTES.txt

@@ -6,6 +6,7 @@
 * [*] Improved large text support in the blog details header in My Sites. [#16521]
 * [***] Block Editor: New Block: Reusable block. [https://github.com/wordpress-mobile/gutenberg-mobile/pull/3490]
 * [***] Block Editor: Add reusable blocks to the block inserter menu. [https://github.com/wordpress-mobile/gutenberg-mobile/pull/3054]
+* [*] Fixed a bug where the web version of the editor did not load when using an account created before December 2018. [#16586]
 
 17.4
 -----

WordPress/Classes/ViewRelated/Gutenberg/GutenbergViewController.swift

@@ -1063,7 +1063,7 @@ extension GutenbergViewController: GutenbergBridgeDataSource {
         let blog = post.blog
         let isJetpackSSOEnabled = (blog.jetpack?.isConnected ?? false) && (blog.settings?.jetpackSSOEnabled ?? false)
 
-        return blog.isHostedAtWPcom || (isJetpackSSOEnabled && blog.webEditor == .gutenberg)
+        return blog.isHostedAtWPcom || isJetpackSSOEnabled
     }
 }
 

WordPress/Classes/ViewRelated/Gutenberg/GutenbergWeb/GutenbergWebViewController.swift

@@ -2,7 +2,7 @@ import UIKit
 import WebKit
 import Gutenberg
 
-class GutenbergWebViewController: GutenbergWebSingleBlockViewController, WebKitAuthenticatable {
+class GutenbergWebViewController: GutenbergWebSingleBlockViewController, WebKitAuthenticatable, NoResultsViewHost {
     enum GutenbergWebError: Error {
         case wrongEditorUrl(String?)
     }
@@ -11,6 +11,7 @@ class GutenbergWebViewController: GutenbergWebSingleBlockViewController, WebKitA
     private let url: URL
     private let progressView = WebProgressView()
     private let userId: String
+    let gutenbergReadySemaphore = DispatchSemaphore(value: 0)
 
     init(with post: AbstractPost, block: Block) throws {
         authenticator = GutenbergRequestAuthenticator(blog: post.blog)
@@ -35,8 +36,10 @@ class GutenbergWebViewController: GutenbergWebSingleBlockViewController, WebKitA
     override func viewDidLoad() {
         super.viewDidLoad()
         addNavigationBarElements()
+        showLoadingMessage()
         addProgressView()
         startObservingWebView()
+        waitForGutenbergToLoad(fallback: showTroubleshootingInstructions)
     }
 
     deinit {
@@ -82,6 +85,10 @@ class GutenbergWebViewController: GutenbergWebSingleBlockViewController, WebKitA
     override func onGutenbergReady() {
         super.onGutenbergReady()
         navigationItem.rightBarButtonItem?.isEnabled = true
+        DispatchQueue.main.async { [weak self] in
+            self?.hideNoResults()
+            self?.gutenbergReadySemaphore.signal()
+        }
     }
 
     private func loadCustomScript(named name: String, with argument: String? = nil) -> WKUserScript? {
@@ -104,6 +111,31 @@ class GutenbergWebViewController: GutenbergWebSingleBlockViewController, WebKitA
         navigationItem.rightBarButtonItem?.isEnabled = false
     }
 
+    private func showLoadingMessage() {
+        let title = NSLocalizedString("Loading the block editor.", comment: "Loading message shown while the Unsupported Block Editor is loading.")
+        let subtitle = NSLocalizedString("Please ensure the block editor is enabled on your site. If it is not enabled, it will not load.", comment: "Message asking users to make sure that the block editor is enabled on their site in order for the Unsupported Block Editor to load properly.")
+        configureAndDisplayNoResults(on: view, title: title, subtitle: subtitle, accessoryView: NoResultsViewController.loadingAccessoryView())
+    }
+
+    private func waitForGutenbergToLoad(fallback: @escaping () -> Void) {
+        DispatchQueue.global(qos: .background).async { [weak self] in
+            let timeout: TimeInterval = 15
+            // blocking call
+            if self?.gutenbergReadySemaphore.wait(timeout: .now() + timeout) == .timedOut {
+                DispatchQueue.main.async {
+                    fallback()
+                }
+            }
+        }
+    }
+
+    private func showTroubleshootingInstructions() {
+        let title = NSLocalizedString("Unable to load the block editor right now.", comment: "Title message shown when the Unsupported Block Editor fails to load.")
+        let subtitle = NSLocalizedString("Please ensure the block editor is enabled on your site and try again.", comment: "Subtitle message shown when the Unsupported Block Editor fails to load. It asks users to verify that the block editor is enabled on their site before trying again.")
+        // This does nothing if the "no results" screen is not currently displayed, which is the intended behavior
+        updateNoResults(title: title, subtitle: subtitle, image: "cloud")
+    }
+
     private func startObservingWebView() {
         webView.addObserver(self, forKeyPath: #keyPath(WKWebView.estimatedProgress), options: [.new], context: nil)
     }
@@ -123,6 +155,7 @@ extension GutenbergWebViewController {
     override func webView(_ webView: WKWebView, didCommit navigation: WKNavigation!) {
         super.webView(webView, didCommit: navigation)
         if webView.url?.absoluteString.contains("reauth=1") ?? false {
+            hideNoResults()
             removeCoverViewAnimated()
         }
     }