Fix auto-enqueuing for authenticated visitor

Previously, if an authenticated visitor has chat history, enqueuing was postponed until a visitor sends a message. This behaviour was broken after adding LO acknowledge.
This commit fixes it.
So now:
- unauthenticated visitors, if LO acknowledge is enabled, will be enqueued once they accept LO acknowledge
- unauthenticated visitors, if LO acknowledge is disabled, will be automatically enqueued
- authenticated visitors, if they do not have chat history and LO acknowledge is disabled, will be enqueued automatically
- authenticated visitors, if they do not have chat history and if LO acknowledge is enabled, will be enqueued once they accept LO acknowledge
- authenticated visitors, if LO acknowledge is enabled and if they have chat history, will be enqueued only after sending a message and accepting LO acknowledge
- authenticated visitors, if LO acknowledge is disabled and if they have chat history, will be enqueued after sending a message

MOB- 3442

GliaWidgets/Sources/Coordinators/EngagementCoordinator/EngagementCoordinator.swift

@@ -71,7 +71,6 @@ class EngagementCoordinator: SubFlowCoordinator, FlowCoordinator {
                 showsCallBubble: false
             )
             engagement = .chat(chatViewController)
-            interactor.state = .enqueueing(.text)
             navigationPresenter.setViewControllers(
                 [chatViewController],
                 animated: false

GliaWidgets/Sources/ViewModel/Chat/ChatViewModel.swift

@@ -166,7 +166,18 @@ class ChatViewModel: EngagementViewModel {
 
     override func start() {
         super.start()
-        loadHistory()
+
+        loadHistory { [weak self] history in
+            guard let self = self else { return }
+            // We only proceed to considering enqueue flow if `startAction` is about starting of engagement.
+            guard case .startEngagement = self.startAction else { return }
+            // We enqueue eagerly in case if this is the first engagement for visitor (by  evaluating previous chat history)
+            // or in case if engagement has been restored.
+
+            if history.isEmpty || self.environment.getCurrentEngagement() != nil {
+                self.interactor.state = .enqueueing(.text)
+            }
+        }
     }
 
     override func update(for state: InteractorState) {
@@ -366,7 +377,7 @@ extension ChatViewModel {
 // MARK: History
 
 extension ChatViewModel {
-    private func loadHistory() {
+    private func loadHistory(_ completion: @escaping ([ChatMessage]) -> Void) {
         environment.fetchChatHistory { [weak self] result in
             guard let self else { return }
             let messages = (try? result.get()) ?? []
@@ -389,6 +400,7 @@ extension ChatViewModel {
             self.historySection.set(items)
             self.action?(.refreshSection(self.historySection.index))
             self.action?(.scrollToBottom(animated: false))
+            completion(messages)
         }
     }
 }
@@ -489,7 +501,7 @@ extension ChatViewModel {
 
         case .enqueueing, .ended, .none:
             handle(pendingMessage: outgoingMessage)
-            enqueue(mediaType: .text)
+            interactor.state = .enqueueing(.text)
         }
 
         messageText = ""

GliaWidgetsTests/Sources/Coordinators/EngagementCoordinator/EngagementCoordinatorTests.swift

@@ -47,7 +47,7 @@ final class EngagementCoordinatorTests: XCTestCase {
 
         coordinator.start()
 
-        XCTAssertEqual(coordinator.interactor.state, .enqueueing(.text))
+        XCTAssertEqual(coordinator.interactor.state, .none)
         let viewController = coordinator.navigationPresenter.viewControllers.first as? ChatViewController
         XCTAssertNotNil(viewController)
         XCTAssertNotNil(coordinator.gliaViewController)
@@ -169,7 +169,6 @@ final class EngagementCoordinatorTests: XCTestCase {
 
     func test_chatCoordinatorBackOnInteractorStateNone() {
         coordinator.start()
-        coordinator.interactor.state = .none
 
         XCTAssertNotEqual(coordinator.coordinators.count, 0)
 
@@ -190,6 +189,8 @@ final class EngagementCoordinatorTests: XCTestCase {
 
         coordinator.start()
 
+        coordinator.interactor.state = .enqueueing(.text)
+
         let chatCoordinator = coordinator.coordinators.last as? ChatCoordinator
         chatCoordinator?.delegate?(.back)