From 75a9e3622e671f619969b78f89d5081ae12a7838 Mon Sep 17 00:00:00 2001
From: Michal Fousek <chlup@chlup.info>
Date: Thu, 11 May 2023 13:28:43 +0200
Subject: [PATCH] [#1042] Implement ComputeSyncRangesAction

Closes #1042
---
 .../Block/Actions/Action.swift                |  7 +-
 .../Actions/ComputeSyncRangesAction.swift     | 71 ++++++++++++++++++-
 2 files changed, 73 insertions(+), 5 deletions(-)

diff --git a/Sources/ZcashLightClientKit/Block/Actions/Action.swift b/Sources/ZcashLightClientKit/Block/Actions/Action.swift
index ff4636bf..a0484ff7 100644
--- a/Sources/ZcashLightClientKit/Block/Actions/Action.swift
+++ b/Sources/ZcashLightClientKit/Block/Actions/Action.swift
@@ -10,15 +10,16 @@ import Foundation
 actor ActionContext {
     var state: CBPState
     var syncRanges: SyncRanges
+    var totalProgressRange: CompactBlockRange = 0...0
 
     init(state: CBPState) {
         self.state = state
         syncRanges = SyncRanges.empty
     }
 
-    func update(state: CBPState) async {
-        self.state = state
-    }
+    func update(state: CBPState) async { self.state = state }
+    func update(syncRanges: SyncRanges) async { self.syncRanges = syncRanges }
+    func update(totalProgressRange: CompactBlockRange) async { self.totalProgressRange = totalProgressRange }
 }
 
 enum CBPState: CaseIterable {
diff --git a/Sources/ZcashLightClientKit/Block/Actions/ComputeSyncRangesAction.swift b/Sources/ZcashLightClientKit/Block/Actions/ComputeSyncRangesAction.swift
index 30a5874b..0e8f6f66 100644
--- a/Sources/ZcashLightClientKit/Block/Actions/ComputeSyncRangesAction.swift
+++ b/Sources/ZcashLightClientKit/Block/Actions/ComputeSyncRangesAction.swift
@@ -8,7 +8,34 @@
 import Foundation
 
 class ComputeSyncRangesAction {
-    init(container: DIContainer) { }
+    let config: CompactBlockProcessorNG.Configuration
+    let downloaderService: BlockDownloaderService
+    let internalSyncProgress: InternalSyncProgress
+    let latestBlocksDataProvider: LatestBlocksDataProvider
+    let logger: Logger
+    init(container: DIContainer, config: CompactBlockProcessorNG.Configuration) {
+        self.config = config
+        downloaderService = container.resolve(BlockDownloaderService.self)
+        internalSyncProgress = container.resolve(InternalSyncProgress.self)
+        latestBlocksDataProvider = container.resolve(LatestBlocksDataProvider.self)
+        logger = container.resolve(Logger.self)
+    }
+
+    /// It may happen that sync process start with syncing blocks that were downloaded but not synced in previous run of the sync process. This
+    /// methods analyses what must be done and computes range that should be used to compute reported progress.
+    private func computeTotalProgressRange(from syncRanges: SyncRanges) -> CompactBlockRange {
+        guard syncRanges.downloadedButUnscannedRange != nil || syncRanges.downloadAndScanRange != nil else {
+            // In this case we are sure that no downloading or scanning happens so this returned range won't be even used. And it's easier to return
+            // this "fake" range than to handle nil.
+            return 0...0
+        }
+
+        // Thanks to guard above we can be sure that one of these two ranges is not nil.
+        let lowerBound = syncRanges.downloadedButUnscannedRange?.lowerBound ?? syncRanges.downloadAndScanRange?.lowerBound ?? 0
+        let upperBound = syncRanges.downloadAndScanRange?.upperBound ?? syncRanges.downloadedButUnscannedRange?.upperBound ?? 0
+
+        return lowerBound...upperBound
+    }
 }
 
 extension ComputeSyncRangesAction: Action {
@@ -16,7 +43,47 @@ extension ComputeSyncRangesAction: Action {
         // call internalSyncProgress and compute sync ranges and store them in context
         // if there is nothing sync just switch to finished state
 
-        await context.update(state: .checksBeforeSync)
+        let latestDownloadHeight = try await downloaderService.lastDownloadedBlockHeight()
+
+        await internalSyncProgress.migrateIfNeeded(latestDownloadedBlockHeightFromCacheDB: latestDownloadHeight)
+
+        await latestBlocksDataProvider.updateScannedData()
+        await latestBlocksDataProvider.updateBlockData()
+
+        let nextState = await internalSyncProgress.computeNextState(
+            latestBlockHeight: latestBlocksDataProvider.latestBlockHeight,
+            latestScannedHeight: latestBlocksDataProvider.latestScannedHeight,
+            walletBirthday: config.walletBirthday
+        )
+
+        switch nextState {
+        case .finishProcessing:
+            await context.update(state: .finished)
+        case .processNewBlocks(let ranges):
+            let totalProgressRange = computeTotalProgressRange(from: ranges)
+            await context.update(totalProgressRange: totalProgressRange)
+            await context.update(syncRanges: ranges)
+            await context.update(state: .checksBeforeSync)
+
+            logger.debug("""
+            Syncing with ranges:
+            downloaded but not scanned: \
+            \(ranges.downloadedButUnscannedRange?.lowerBound ?? -1)...\(ranges.downloadedButUnscannedRange?.upperBound ?? -1)
+            download and scan:          \(ranges.downloadAndScanRange?.lowerBound ?? -1)...\(ranges.downloadAndScanRange?.upperBound ?? -1)
+            enhance range:              \(ranges.enhanceRange?.lowerBound ?? -1)...\(ranges.enhanceRange?.upperBound ?? -1)
+            fetchUTXO range:            \(ranges.fetchUTXORange?.lowerBound ?? -1)...\(ranges.fetchUTXORange?.upperBound ?? -1)
+            total progress range:       \(totalProgressRange.lowerBound)...\(totalProgressRange.upperBound)
+            """)
+
+        case let .wait(latestHeight, latestDownloadHeight):
+            // Lightwalletd might be syncing
+            logger.info(
+                "Lightwalletd might be syncing: latest downloaded block height is: \(latestDownloadHeight) " +
+                "while latest blockheight is reported at: \(latestHeight)"
+            )
+            await context.update(state: .finished)
+        }
+
         return context
     }