Add new methods to WPAuthenticatorDelegate to allow host apps to handle errors

WordPressAuthenticator.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name          = "WordPressAuthenticator"
-  s.version       = "1.31.0-beta.1"
+  s.version       = "1.31.0-beta.2"
   s.summary       = "WordPressAuthenticator implements an easy and elegant way to authenticate your WordPress Apps."
 
   s.description   = <<-DESC

WordPressAuthenticator/Authenticator/WordPressAuthenticatorDelegateProtocol.swift

@@ -68,6 +68,14 @@ public protocol WordPressAuthenticatorDelegate: class {
     ///
     func shouldPresentLoginEpilogue(isJetpackLogin: Bool) -> Bool
 
+    /// Indicates the Host app wants to handle and display a given error.
+    ///
+    func shouldHandleError(_ error: Error) -> Bool
+
+    /// Signals the Host app that there is an error that needs to be handled.
+    ///
+    func handleError(_ error: Error, onCompletion: @escaping (UIViewController) -> Void)
+
     /// Indicates if the Signup Epilogue should be displayed.
     ///
     func shouldPresentSignupEpilogue() -> Bool

WordPressAuthenticator/Signin/LoginViewController.swift

@@ -189,7 +189,6 @@ open class LoginViewController: NUXViewController, LoginFacadeDelegate {
     /// Overridden here to direct these errors to the login screen's error label
     dynamic open func displayRemoteError(_ error: Error) {
         configureViewLoading(false)
-
         let err = error as NSError
         guard err.code != 403 else {
             let message = LocalizedText.loginError

WordPressAuthenticator/Unified Auth/View Related/Site Address/SiteAddressViewController.swift

@@ -140,6 +140,17 @@ final class SiteAddressViewController: LoginViewController {
         }
     }
 
+    override func displayRemoteError(_ error: Error) {
+        guard authenticationDelegate.shouldHandleError(error) else {
+            super.displayRemoteError(error)
+            return
+        }
+
+        authenticationDelegate.handleError(error) { customUI in
+            self.navigationController?.pushViewController(customUI, animated: true)
+        }
+    }
+
     /// Reload the tableview and show errors, if any.
     ///
     override func displayError(message: String, moveVoiceOverFocus: Bool = false) {
@@ -351,6 +362,19 @@ private extension SiteAddressViewController {
         }
     }
 
+    /// Push a custom view controller, provided by a host app, to the navigation stack
+    func pushCustomUI(_ customUI: UIViewController) {
+        /// Assign the help button of the newly injected UI to the same help button we are currently displaying
+        /// We are making a somewhat big assumption here: the chrome of the new UI we insert would look like the UI
+        /// WPAuthenticator is already displaying. Which is risky, but also kind of makes sense, considering
+        /// we are also pushing that injected UI to the current navigation controller.
+        if WordPressAuthenticator.shared.delegate?.supportActionEnabled == true {
+            customUI.navigationItem.rightBarButtonItems = self.navigationItem.rightBarButtonItems
+        }
+
+        self.navigationController?.pushViewController(customUI, animated: true)
+    }
+
     // MARK: - Private Constants
 
     /// Rows listed in the order they were created.
@@ -419,6 +443,16 @@ private extension SiteAddressViewController {
 
                 let err = self.originalErrorOrError(error: error as NSError)
 
+                /// Check if the host app wants to provide custom UI to handle the error.
+                /// If it does, insert the custom UI provided by the host app and exit early
+                if self.authenticationDelegate.shouldHandleError(err) {
+                    self.authenticationDelegate.handleError(err) { customUI in
+                        self.pushCustomUI(customUI)
+                    }
+
+                    return
+                }
+
                 if let xmlrpcValidatorError = err as? WordPressOrgXMLRPCValidatorError {
                     self.displayError(message: xmlrpcValidatorError.localizedDescription, moveVoiceOverFocus: true)
 
@@ -480,14 +514,7 @@ private extension SiteAddressViewController {
 
                 self.showWPUsernamePassword()
             case let .injectViewController(customUI):
-                /// Assign the help button of the newly injected UI to the same help button we are currently displaying
-                /// We are making a somewhat big assumption here: the chrome of the new UI we insert would look like the UI
-                /// WPAuthenticator is already displaying. Which is risky, but also kind of makes sense, considering
-                /// we are also pushing that injected UI to the current navigation controller.
-                if WordPressAuthenticator.shared.delegate?.supportActionEnabled == true {
-                    customUI.navigationItem.rightBarButtonItems = self.navigationItem.rightBarButtonItems
-                }
-                self.navigationController?.pushViewController(customUI, animated: true)
+                self.pushCustomUI(customUI)
             }
         })
     }