[#1055] Implement retry timer to state machine CBP

Closes #1055

Sources/ZcashLightClientKit/Block/CompactBlockProcessorNG.swift

@@ -7,7 +7,7 @@
 
 import Foundation
 
-class CompactBlockProcessorNG {
+actor CompactBlockProcessorNG {
     // It would be better to use Combine here but Combine doesn't work great with async. When this runs regularly only one closure is stored here
     // and that is one provided by `SDKSynchronizer`. But while running tests more "subscribers" is required here. Therefore it's required to handle
     // more closures here.
@@ -31,6 +31,8 @@ class CompactBlockProcessorNG {
     private let storage: CompactBlockRepository
     private let transactionRepository: TransactionRepository
 
+    private(set) var config: Configuration
+
     private var retryAttempts: Int = 0
     private var backoffTimer: Timer?
     private var consecutiveChainValidationErrors: Int = 0
@@ -345,6 +347,10 @@ extension CompactBlockProcessorNG {
         await context.update(state: .validateServer)
         await syncStarted()
 
+        if backoffTimer == nil {
+            await setTimer()
+        }
+
         // Try to find action for state.
         while true {
             guard let action = actions[await context.state] else {
@@ -439,7 +445,7 @@ extension CompactBlockProcessorNG {
 
         // don't set a new timer if there are no more attempts.
         if hasRetryAttempt() {
-//            await self.setTimer()
+            await self.setTimer()
         }
     }
 }
@@ -447,6 +453,42 @@ extension CompactBlockProcessorNG {
 // MARK: - Utils
 
 extension CompactBlockProcessorNG {
+    private func setTimer() async {
+        let interval = config.blockPollInterval
+        self.backoffTimer?.invalidate()
+        let timer = Timer(
+            timeInterval: interval,
+            repeats: true,
+            block: { [weak self] _ in
+                Task { [weak self] in
+                    guard let self else { return }
+                    switch await context.state {
+                    case .stopped, .failed, .finished, .validateServer:
+                        if await self.canStartSync() {
+                            self.logger.debug(
+                                """
+                                Timer triggered: Starting compact Block processor!.
+                                Processor State: \(await self.context.state)
+                                latestHeight: \(try await self.transactionRepository.lastScannedHeight())
+                                attempts: \(await self.retryAttempts)
+                                """
+                            )
+                            await self.start()
+                        } else if await hasRetryAttempt() {
+                            await self.failure(ZcashError.compactBlockProcessorMaxAttemptsReached(self.config.retries))
+                        }
+                    case .computeSyncRanges, .checksBeforeSync, .download, .validate, .scan, .enhance, .fetchUTXO, .handleSaplingParams, .clearCache,
+                            .scanDownloaded, .clearAlreadyScannedBlocks:
+                        await self.latestBlocksDataProvider.updateBlockData()
+                    }
+                }
+            }
+        )
+        RunLoop.main.add(timer, forMode: .default)
+
+        self.backoffTimer = timer
+    }
+
     func canStartSync() async -> Bool {
         switch await context.state {
         case .stopped, .failed, .finished, .validateServer: