Add loading view

RiotSwiftUI/Modules/Room/PollHistory/Service/MatrixSDK/PollHistoryService.swift

@@ -22,6 +22,7 @@ final class PollHistoryService: PollHistoryServiceProtocol {
     private let room: MXRoom
     private let pollsSubject: PassthroughSubject<TimelinePollDetails, Never> = .init()
     private let errorSubject: PassthroughSubject<Error, Never> = .init()
+    private let isFetchingSubject: PassthroughSubject<Bool, Never> = .init()
     
     private var listner: Any?
     private var timeline: MXEventTimeline?
@@ -36,12 +37,16 @@ final class PollHistoryService: PollHistoryServiceProtocol {
         errorSubject.eraseToAnyPublisher()
     }
     
+    var isFetching: AnyPublisher<Bool, Never> {
+        isFetchingSubject.eraseToAnyPublisher()
+    }
+    
     init(room: MXRoom) {
         self.room = room
         self.targetTimestamp = Date().addingTimeInterval(-TimeInterval(Constants.daysToSync) * Constants.oneDayInSeconds)
     }
     
-    func startFetching() {
+    func next() {
         guard timeline == nil else {
             paginate()
             return
@@ -81,12 +86,14 @@ private extension PollHistoryService {
             return
         }
         
-        #warning("to be removed probably?")
         timeline.resetPagination()
         
+        isFetchingSubject.send(true)
         timeline.paginate(Constants.pageSize,
                           direction: .backwards,
-                          onlyFromStore: false) { response in
+                          onlyFromStore: false) { [weak self] response in
+            self?.isFetchingSubject.send(false)
+            
             switch response {
             case .success:
                 #warning("Go on with pagination...")

RiotSwiftUI/Modules/Room/PollHistory/Service/Mock/MockPollHistoryService.swift

@@ -27,11 +27,15 @@ final class MockPollHistoryService: PollHistoryServiceProtocol {
         Empty().eraseToAnyPublisher()
     }
 
-    func startFetching() {
+    func next() {
         for poll in activePollsData + pastPollsData {
             polls.send(poll)
         }
     }
+    
+    var isFetching: AnyPublisher<Bool, Never> {
+        Just(false).eraseToAnyPublisher()
+    }
 
     var activePollsData: [TimelinePollDetails] = (1..<10)
         .map { index in

RiotSwiftUI/Modules/Room/PollHistory/Service/PollHistoryServiceProtocol.swift

@@ -17,8 +17,17 @@
 import Combine
 
 protocol PollHistoryServiceProtocol {
+    /// Publishes poll data as soon they are found in the timeline.
+    /// Updates are also published here, so clients needs to address duplicates.
     var pollHistory: AnyPublisher<TimelinePollDetails, Never> { get }
+    
+    /// Publishes whatever errors produced during the sync.
     var error: AnyPublisher<Error, Never> { get }
     
-    func startFetching()
+    /// Ask to fetch the next batch of polls.
+    /// Concrete implementations can decide what a batch is.
+    func next()
+    
+    /// Inform the whenever a new batch of polls starts or ends.
+    var isFetching: AnyPublisher<Bool, Never> { get }
 }