From 4a78b4bd16dd8442786be5006d0cfac2590d5ed7 Mon Sep 17 00:00:00 2001
From: Lukas Korba <lukas.korba@seznam.cz>
Date: Tue, 1 Aug 2023 13:04:50 +0200
Subject: [PATCH] [#1167] Step 3 - Download chain tip metadata from
 lightwalletd

- update chain tip action added

[#1167] Step 3 - Download chain tip metadata from lightwalletd

- roots removed from the ActionContext

[#1167] Step 3 - Download chain tip metadata from lightwalletd

- fallback to linear sync until next step is implemented

[#1167] Step 3 - Download chain tip metadata from lightwalletd

- offline tests fixed
---
 .../Block/Actions/Action.swift                |  1 +
 .../Block/Actions/UpdateChainTipAction.swift  | 39 +++++++++++++++++++
 .../Actions/UpdateSubtreeRootsAction.swift    |  4 +-
 .../Block/CompactBlockProcessor.swift         |  4 ++
 4 files changed, 45 insertions(+), 3 deletions(-)
 create mode 100644 Sources/ZcashLightClientKit/Block/Actions/UpdateChainTipAction.swift

diff --git a/Sources/ZcashLightClientKit/Block/Actions/Action.swift b/Sources/ZcashLightClientKit/Block/Actions/Action.swift
index c643166f..de822fda 100644
--- a/Sources/ZcashLightClientKit/Block/Actions/Action.swift
+++ b/Sources/ZcashLightClientKit/Block/Actions/Action.swift
@@ -35,6 +35,7 @@ enum CBPState: CaseIterable {
     case migrateLegacyCacheDB
     case validateServer
     case updateSubtreeRoots
+    case updateChainTip
     case computeSyncControlData
     case download
     case scan
diff --git a/Sources/ZcashLightClientKit/Block/Actions/UpdateChainTipAction.swift b/Sources/ZcashLightClientKit/Block/Actions/UpdateChainTipAction.swift
new file mode 100644
index 00000000..03e1d476
--- /dev/null
+++ b/Sources/ZcashLightClientKit/Block/Actions/UpdateChainTipAction.swift
@@ -0,0 +1,39 @@
+//
+//  UpdateChainTipAction.swift
+//  
+//
+//  Created by Lukáš Korba on 01.08.2023.
+//
+
+import Foundation
+
+final class UpdateChainTipAction {
+    let rustBackend: ZcashRustBackendWelding
+    let service: LightWalletService
+    let logger: Logger
+    
+    init(container: DIContainer) {
+        service = container.resolve(LightWalletService.self)
+        rustBackend = container.resolve(ZcashRustBackendWelding.self)
+        logger = container.resolve(Logger.self)
+    }
+}
+
+extension UpdateChainTipAction: Action {
+    var removeBlocksCacheWhenFailed: Bool { false }
+
+    func run(with context: ActionContext, didUpdate: @escaping (CompactBlockProcessor.Event) async -> Void) async throws -> ActionContext {
+        let latestBlockHeight = try await service.latestBlockHeight()
+        
+        logger.info("Latest block height is \(latestBlockHeight)")
+        try await rustBackend.updateChainTip(height: Int32(latestBlockHeight))
+        
+        // TODO: [#1169] Switching back to linear sync for now before step 5 & 6 are implemented
+        // https://github.com/zcash/ZcashLightClientKit/issues/1169
+        await context.update(state: .computeSyncControlData)
+
+        return context
+    }
+
+    func stop() async { }
+}
diff --git a/Sources/ZcashLightClientKit/Block/Actions/UpdateSubtreeRootsAction.swift b/Sources/ZcashLightClientKit/Block/Actions/UpdateSubtreeRootsAction.swift
index efb7d035..c5703760 100644
--- a/Sources/ZcashLightClientKit/Block/Actions/UpdateSubtreeRootsAction.swift
+++ b/Sources/ZcashLightClientKit/Block/Actions/UpdateSubtreeRootsAction.swift
@@ -52,9 +52,7 @@ extension UpdateSubtreeRootsAction: Action {
             do {
                 try await rustBackend.putSaplingSubtreeRoots(startIndex: UInt64(request.startIndex), roots: roots)
                 
-                // TODO: [#1167] Switching back to linear sync for now before step 3 & 4 are implemented
-                // https://github.com/zcash/ZcashLightClientKit/issues/1167
-                await context.update(state: .computeSyncControlData)
+                await context.update(state: .updateChainTip)
             } catch {
                 logger.debug("putSaplingSubtreeRoots failed with error \(error.localizedDescription)")
                 throw ZcashError.compactBlockProcessorPutSaplingSubtreeRoots(error)
diff --git a/Sources/ZcashLightClientKit/Block/CompactBlockProcessor.swift b/Sources/ZcashLightClientKit/Block/CompactBlockProcessor.swift
index 95972243..12f2da76 100644
--- a/Sources/ZcashLightClientKit/Block/CompactBlockProcessor.swift
+++ b/Sources/ZcashLightClientKit/Block/CompactBlockProcessor.swift
@@ -216,6 +216,8 @@ actor CompactBlockProcessor {
                 action = ValidateServerAction(container: container, configProvider: configProvider)
             case .updateSubtreeRoots:
                 action = UpdateSubtreeRootsAction(container: container)
+            case .updateChainTip:
+                action = UpdateChainTipAction(container: container)
             case .computeSyncControlData:
                 action = ComputeSyncControlDataAction(container: container, configProvider: configProvider)
             case .download:
@@ -589,6 +591,8 @@ extension CompactBlockProcessor {
             break
         case .updateSubtreeRoots:
             break
+        case .updateChainTip:
+            break
         case .computeSyncControlData:
             break
         case .download: