Handle number of batches / last batch

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

@@ -50,6 +50,10 @@ final class PollHistoryService: PollHistoryServiceProtocol {
     func nextBatch() -> AnyPublisher<TimelinePollDetails, Error> {
         currentBatchSubject?.eraseToAnyPublisher() ?? startPagination()
     }
+    
+    var hasNextBatch: Bool {
+        timeline.canPaginate(.backwards)
+    }
 }
 
 private extension PollHistoryService {

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

@@ -17,6 +17,15 @@
 import Combine
 
 final class MockPollHistoryService: PollHistoryServiceProtocol {
+    lazy var nextBatchPublisher: AnyPublisher<TimelinePollDetails, Error> = (activePollsData + pastPollsData)
+        .publisher
+        .setFailureType(to: Error.self)
+        .eraseToAnyPublisher()
+    
+    func nextBatch() -> AnyPublisher<TimelinePollDetails, Error> {
+        nextBatchPublisher
+    }
+    
     var updatesPublisher: AnyPublisher<TimelinePollDetails, Never> = Empty().eraseToAnyPublisher()
     var updates: AnyPublisher<TimelinePollDetails, Never> {
         updatesPublisher
@@ -27,14 +36,7 @@ final class MockPollHistoryService: PollHistoryServiceProtocol {
         pollErrorPublisher
     }
     
-    lazy var nextBatchPublisher: AnyPublisher<TimelinePollDetails, Error> = (activePollsData + pastPollsData)
-        .publisher
-        .setFailureType(to: Error.self)
-        .eraseToAnyPublisher()
-    
-    func nextBatch() -> AnyPublisher<TimelinePollDetails, Error> {
-        nextBatchPublisher
-    }
+    var hasNextBatch: Bool = true
 }
 
 private extension MockPollHistoryService {

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

@@ -27,4 +27,8 @@ protocol PollHistoryServiceProtocol {
     /// Publishes errors regarding poll aggregations.
     /// Note: `nextBatch()` will continue to publish new polls even if some poll isn't being aggregated correctly.
     var pollErrors: AnyPublisher<Error, Never> { get }
+    
+    /// Returns true every time the service can fetch another batch.
+    /// There is no guarantee the `nextBatch()` returned publisher will publish something anyway.
+    var hasNextBatch: Bool { get }
 }