From 11be3e78b3de891a56749aa6f73fc3b7f47d9b5e Mon Sep 17 00:00:00 2001
From: Christoph Hagen <github@christophhagen.de>
Date: Fri, 8 Sep 2023 10:09:51 +0200
Subject: [PATCH] Add metric migration

---
 Package.swift               |   2 +
 Sources/App/configure.swift | 109 ++++++++++++++++++++++++++++++++++++
 Sources/Run/main.swift      |   8 +++
 3 files changed, 119 insertions(+)

diff --git a/Package.swift b/Package.swift
index 79fd2cb..ae59f79 100755
--- a/Package.swift
+++ b/Package.swift
@@ -11,6 +11,7 @@ let package = Package(
         .package(url: "https://github.com/christophhagen/Clairvoyant", from: "0.9.0"),
         .package(url: "https://github.com/christophhagen/ClairvoyantVapor", from: "0.2.0"),
         .package(url: "https://github.com/christophhagen/ClairvoyantBinaryCodable", from: "0.3.0"),
+        .package(url:"https://github.com/christophhagen/CBORCoding", from: "1.0.0"),
     ],
     targets: [
         .target(name: "App",
@@ -19,6 +20,7 @@ let package = Package(
                     .product(name: "Clairvoyant", package: "Clairvoyant"),
                     .product(name: "ClairvoyantVapor", package: "ClairvoyantVapor"),
                     .product(name: "ClairvoyantBinaryCodable", package: "ClairvoyantBinaryCodable"),
+                    .product(name: "CBORCoding", package: "CBORCoding"),
                 ],
                 swiftSettings: [
                     // Enable better optimizations when building in Release configuration. Despite the use of
diff --git a/Sources/App/configure.swift b/Sources/App/configure.swift
index 93bb7cb..512a783 100755
--- a/Sources/App/configure.swift
+++ b/Sources/App/configure.swift
@@ -54,3 +54,112 @@ func log(_ message: String) {
     }
     observer.log(message)
 }
+
+import CBORCoding
+
+public func migrate(folder: URL) throws {
+    try migrateMetric("caps.log", containing: String.self, in: folder)
+    try migrateMetric("caps.status", containing: ServerStatus.self, in: folder)
+    try migrateMetric("caps.count", containing: Int.self, in: folder)
+    try migrateMetric("caps.images", containing: Int.self, in: folder)
+    try migrateMetric("caps.classifier", containing: Int.self, in: folder)
+}
+
+private func migrateMetric<T>(_ id: String, containing type: T.Type, in folder: URL) throws where T: MetricValue {
+    print("Processing metric \(id)")
+    let file = id.hashed()
+    let url = folder.appendingPathComponent(file)
+
+    let files = try FileManager.default.contentsOfDirectory(at: url, includingPropertiesForKeys: nil)
+        .filter { Int($0.lastPathComponent) != nil }
+    print("Found \(files.count) files for \(id)")
+
+    let all: [Timestamped<T>] = try files.map(readElements(from:))
+        .reduce([], +)
+        .sorted { $0.timestamp < $1.timestamp }
+
+    print("Found \(all.count) items for \(id)")
+
+    try FileManager.default.removeItem(at: url)
+
+    print("Removed log folder")
+
+    // TODO: Write values back to disk
+    let observer = MetricObserver(logFileFolder: folder, logMetricId: "sesame.migration")
+    let metric: Metric<T> = observer.addMetric(id: id)
+    let semaphore = DispatchSemaphore(value: 0)
+    Task {
+        try await metric.update(all)
+        print("Saved all values for metric \(id)")
+        semaphore.signal()
+    }
+    semaphore.wait()
+    print("Finished metric \(id)")
+}
+
+private func readElements<T>(from url: URL) throws -> [Timestamped<T>] where T: MetricValue {
+    let data = try Data(contentsOf: url)
+    let file = url.lastPathComponent
+    print("File \(file): Loaded \(data.count) bytes")
+
+
+
+    let decoder = CBORDecoder()
+    let timestampLength = 9
+    let byteCountLength = 2
+
+    var result: [Timestamped<T>] = []
+    var currentIndex = data.startIndex
+    var skippedValues = 0
+    while currentIndex < data.endIndex {
+        let startIndexOfTimestamp = currentIndex + byteCountLength
+        guard startIndexOfTimestamp <= data.endIndex else {
+            print("File \(file): Only \(data.endIndex - currentIndex) bytes, needed \(byteCountLength) for byte count")
+            throw MetricError.logFileCorrupted
+        }
+        guard let byteCount = UInt16(fromData: data[currentIndex..<startIndexOfTimestamp]) else {
+            print("File \(file): Invalid byte count")
+            throw MetricError.logFileCorrupted
+        }
+        let nextIndex = startIndexOfTimestamp + Int(byteCount)
+        guard nextIndex <= data.endIndex else {
+            print("File \(file): Needed \(byteCountLength + Int(byteCount)) for timestamped value, has \(data.endIndex - startIndexOfTimestamp)")
+            throw MetricError.logFileCorrupted
+        }
+        guard byteCount >= timestampLength else {
+            print("File \(file): Only \(byteCount) bytes, needed \(timestampLength) for timestamp")
+            throw MetricError.logFileCorrupted
+        }
+        let timestampData = data[startIndexOfTimestamp..<startIndexOfTimestamp+timestampLength]
+        let timestamp = try decoder.decode(Double.self, from: timestampData)
+        let date = Date(timeIntervalSince1970: timestamp)
+        let elementData = data[startIndexOfTimestamp+timestampLength..<nextIndex]
+        do {
+            let element: T = try decoder.decode(from: elementData)
+            result.append(.init(value: element, timestamp: date))
+        } catch {
+            skippedValues += 1
+        }
+        currentIndex = nextIndex
+        if result.count % 100 == 1 {
+            print("File \(file): \(result.count) entries loaded (\(currentIndex)/\(data.endIndex) bytes)")
+        }
+    }
+    print("Loaded \(result.count) data points (\(skippedValues) skipped)")
+    return result
+}
+
+extension UInt16 {
+
+    func toData() -> Data {
+        Data([UInt8(self >> 8 & 0xFF), UInt8(self & 0xFF)])
+    }
+
+    init?<T: DataProtocol>(fromData data: T) {
+        guard data.count == 2 else {
+            return nil
+        }
+        let bytes = Array(data)
+        self = UInt16(UInt32(bytes[0]) << 8 | UInt32(bytes[1]))
+    }
+}
diff --git a/Sources/Run/main.swift b/Sources/Run/main.swift
index 05937c6..400ecf7 100755
--- a/Sources/Run/main.swift
+++ b/Sources/Run/main.swift
@@ -6,6 +6,13 @@ try LoggingSystem.bootstrap(from: &env)
 let app = Application(env)
 defer { app.shutdown() }
 
+let storageFolder = URL(fileURLWithPath: app.directory.resourcesDirectory)
+let logFolder = storageFolder.appendingPathComponent("logs")
+print("Starting migration")
+try migrate(folder: logFolder)
+print("Finished migration")
+/*
+ 
 private let semaphore = DispatchSemaphore(value: 0)
 Task {
     try await configure(app)
@@ -13,3 +20,4 @@ Task {
 }
 semaphore.wait()
 try app.run()
+*/