Implement Milestone 7.2 offline audio downloads

2026-05-30 07:11:20 +02:00
parent 6e73c1878e
commit 56f030e651
19 changed files with 1822 additions and 31 deletions
@@ -0,0 +1,209 @@
+import CryptoKit
+import Foundation
+
+public enum OfflineAudioFileStoreError: LocalizedError, Equatable, Sendable {
+    case emptyAudioData
+    case sha256Mismatch(expected: String, actual: String)
+    case missingLocalFile(path: String)
+
+    public var errorDescription: String? {
+        switch self {
+        case .emptyAudioData:
+            return "The downloaded audio file was empty."
+        case let .sha256Mismatch(expected, actual):
+            return "The downloaded audio file hash did not match. Expected \(expected), received \(actual)."
+        case let .missingLocalFile(path):
+            return "The local audio file is missing: \(path)"
+        }
+    }
+}
+
+public protocol OfflineAudioFileStore: Actor {
+    func saveAudioFile(
+        _ data: Data,
+        assetId: String,
+        sha256: String?
+    ) async throws -> String
+    func readAudioFile(at localFilePath: String) async throws -> Data
+    func fileExists(at localFilePath: String) async -> Bool
+    func resolveLocalFilePath(
+        persistedLocalFilePath: String,
+        assetId: String
+    ) async -> String?
+}
+
+public actor FileOfflineAudioFileStore: OfflineAudioFileStore {
+    private let baseDirectoryURL: URL
+    private let fileManager: FileManager
+
+    public init(
+        baseDirectoryURL: URL? = nil,
+        fileManager: FileManager = .default
+    ) throws {
+        self.fileManager = fileManager
+        if let baseDirectoryURL {
+            self.baseDirectoryURL = baseDirectoryURL
+        } else {
+            self.baseDirectoryURL = try Self.defaultBaseDirectoryURL(fileManager: fileManager)
+        }
+    }
+
+    public func saveAudioFile(
+        _ data: Data,
+        assetId: String,
+        sha256: String?
+    ) async throws -> String {
+        guard !data.isEmpty else {
+            throw OfflineAudioFileStoreError.emptyAudioData
+        }
+
+        try fileManager.createDirectory(
+            at: baseDirectoryURL,
+            withIntermediateDirectories: true
+        )
+
+        let fileURL = localFileURL(for: assetId)
+        try data.write(to: fileURL, options: .atomic)
+
+        let storedData = try Data(contentsOf: fileURL)
+        guard !storedData.isEmpty else {
+            try? fileManager.removeItem(at: fileURL)
+            throw OfflineAudioFileStoreError.emptyAudioData
+        }
+
+        if let sha256 {
+            let actualHash = Self.sha256Hex(for: storedData)
+            if actualHash != sha256 {
+                try? fileManager.removeItem(at: fileURL)
+                throw OfflineAudioFileStoreError.sha256Mismatch(
+                    expected: sha256,
+                    actual: actualHash
+                )
+            }
+        }
+
+        return fileURL.standardizedFileURL.path
+    }
+
+    public func readAudioFile(at localFilePath: String) async throws -> Data {
+        guard let resolvedLocalFilePath = await resolveLocalFilePath(
+            persistedLocalFilePath: localFilePath,
+            assetId: URL(fileURLWithPath: localFilePath).deletingPathExtension().lastPathComponent
+        ) else {
+            throw OfflineAudioFileStoreError.missingLocalFile(path: localFilePath)
+        }
+
+        return try Data(contentsOf: URL(fileURLWithPath: resolvedLocalFilePath))
+    }
+
+    public func fileExists(at localFilePath: String) async -> Bool {
+        let resolvedLocalFilePath = URL(fileURLWithPath: localFilePath).standardizedFileURL.path
+        return fileManager.fileExists(atPath: resolvedLocalFilePath)
+    }
+
+    public func resolveLocalFilePath(
+        persistedLocalFilePath: String,
+        assetId: String
+    ) async -> String? {
+        let trimmedPersistedPath = persistedLocalFilePath
+            .trimmingCharacters(in: .whitespacesAndNewlines)
+        if !trimmedPersistedPath.isEmpty {
+            let persistedURL = URL(fileURLWithPath: trimmedPersistedPath).standardizedFileURL
+            if fileManager.fileExists(atPath: persistedURL.path) {
+                return persistedURL.path
+            }
+        }
+
+        let currentFileURL = localFileURL(for: assetId).standardizedFileURL
+        guard fileManager.fileExists(atPath: currentFileURL.path) else {
+            return nil
+        }
+
+        return currentFileURL.path
+    }
+
+    private static func defaultBaseDirectoryURL(fileManager: FileManager) throws -> URL {
+        guard let applicationSupportURL = fileManager.urls(
+            for: .applicationSupportDirectory,
+            in: .userDomainMask
+        ).first else {
+            throw CocoaError(.fileNoSuchFile)
+        }
+
+        return applicationSupportURL
+            .appendingPathComponent("Velody", isDirectory: true)
+            .appendingPathComponent("audio", isDirectory: true)
+    }
+
+    private func localFileURL(for assetId: String) -> URL {
+        baseDirectoryURL.appendingPathComponent("\(assetId).mp3")
+    }
+
+    private static func sha256Hex(for data: Data) -> String {
+        SHA256.hash(data: data).map { String(format: "%02x", $0) }.joined()
+    }
+}
+
+public actor InMemoryOfflineAudioFileStore: OfflineAudioFileStore {
+    private var files: [String: Data]
+
+    public init(files: [String: Data] = [:]) {
+        self.files = files
+    }
+
+    public func saveAudioFile(
+        _ data: Data,
+        assetId: String,
+        sha256: String?
+    ) async throws -> String {
+        guard !data.isEmpty else {
+            throw OfflineAudioFileStoreError.emptyAudioData
+        }
+
+        if let sha256 {
+            let actualHash = SHA256.hash(data: data)
+                .map { String(format: "%02x", $0) }
+                .joined()
+            if actualHash != sha256 {
+                throw OfflineAudioFileStoreError.sha256Mismatch(
+                    expected: sha256,
+                    actual: actualHash
+                )
+            }
+        }
+
+        let localFilePath = "/in-memory/\(assetId).mp3"
+        files[localFilePath] = data
+        return localFilePath
+    }
+
+    public func readAudioFile(at localFilePath: String) async throws -> Data {
+        guard let data = files[localFilePath] else {
+            throw OfflineAudioFileStoreError.missingLocalFile(path: localFilePath)
+        }
+
+        return data
+    }
+
+    public func fileExists(at localFilePath: String) async -> Bool {
+        files[localFilePath] != nil
+    }
+
+    public func resolveLocalFilePath(
+        persistedLocalFilePath: String,
+        assetId: String
+    ) async -> String? {
+        let trimmedPersistedPath = persistedLocalFilePath
+            .trimmingCharacters(in: .whitespacesAndNewlines)
+        if files[trimmedPersistedPath] != nil {
+            return trimmedPersistedPath
+        }
+
+        let fallbackLocalFilePath = "/in-memory/\(assetId).mp3"
+        guard files[fallbackLocalFilePath] != nil else {
+            return nil
+        }
+
+        return fallbackLocalFilePath
+    }
+}
@@ -0,0 +1,93 @@
+import Foundation
+import VelodyDomain
+
+public protocol RemoteTrackDownloadStateStore: Actor {
+    func loadDownloadStates() async throws -> [RemoteTrackDownloadState]
+    func saveDownloadStates(_ states: [RemoteTrackDownloadState]) async throws
+}
+
+public extension RemoteTrackDownloadStateStore {
+    func saveDownloadState(_ state: RemoteTrackDownloadState) async throws {
+        var states = try await loadDownloadStates()
+
+        if let existingIndex = states.firstIndex(where: { $0.remoteTrackId == state.remoteTrackId }) {
+            states[existingIndex] = state
+        } else {
+            states.append(state)
+        }
+
+        try await saveDownloadStates(states)
+    }
+}
+
+public actor FileRemoteTrackDownloadStateStore: RemoteTrackDownloadStateStore {
+    private let fileURL: URL
+    private let fileManager: FileManager
+    private let encoder = JSONEncoder()
+    private let decoder = JSONDecoder()
+
+    public init(
+        fileURL: URL? = nil,
+        fileManager: FileManager = .default
+    ) throws {
+        self.fileManager = fileManager
+        if let fileURL {
+            self.fileURL = fileURL
+        } else {
+            self.fileURL = try Self.defaultFileURL(fileManager: fileManager)
+        }
+        encoder.dateEncodingStrategy = .iso8601
+        decoder.dateDecodingStrategy = .iso8601
+    }
+
+    public func loadDownloadStates() async throws -> [RemoteTrackDownloadState] {
+        guard fileManager.fileExists(atPath: fileURL.path) else {
+            return []
+        }
+
+        let data = try Data(contentsOf: fileURL)
+        return try decoder.decode([RemoteTrackDownloadState].self, from: data)
+    }
+
+    public func saveDownloadStates(_ states: [RemoteTrackDownloadState]) async throws {
+        try fileManager.createDirectory(
+            at: fileURL.deletingLastPathComponent(),
+            withIntermediateDirectories: true
+        )
+
+        let sortedStates = states.sorted { lhs, rhs in
+            lhs.remoteTrackId.localizedCaseInsensitiveCompare(rhs.remoteTrackId) == .orderedAscending
+        }
+        let data = try encoder.encode(sortedStates)
+        try data.write(to: fileURL, options: .atomic)
+    }
+
+    private static func defaultFileURL(fileManager: FileManager) throws -> URL {
+        guard let applicationSupportURL = fileManager.urls(
+            for: .applicationSupportDirectory,
+            in: .userDomainMask
+        ).first else {
+            throw CocoaError(.fileNoSuchFile)
+        }
+
+        return applicationSupportURL
+            .appendingPathComponent("Velody", isDirectory: true)
+            .appendingPathComponent("remote-download-states.json")
+    }
+}
+
+public actor InMemoryRemoteTrackDownloadStateStore: RemoteTrackDownloadStateStore {
+    private var states: [RemoteTrackDownloadState]
+
+    public init(states: [RemoteTrackDownloadState] = []) {
+        self.states = states
+    }
+
+    public func loadDownloadStates() async throws -> [RemoteTrackDownloadState] {
+        states
+    }
+
+    public func saveDownloadStates(_ states: [RemoteTrackDownloadState]) async throws {
+        self.states = states
+    }
+}
@@ -0,0 +1,133 @@
+import CryptoKit
+import Foundation
+import XCTest
+@testable import VelodyPersistence
+
+final class OfflineAudioFileStoreTests: XCTestCase {
+    func testFileOfflineAudioFileStoreWritesAndReadsAudioData() async throws {
+        let fileManager = FileManager.default
+        let tempDirectory = fileManager.temporaryDirectory.appendingPathComponent(
+            UUID().uuidString,
+            isDirectory: true
+        )
+
+        defer {
+            try? fileManager.removeItem(at: tempDirectory)
+        }
+
+        let store = try FileOfflineAudioFileStore(baseDirectoryURL: tempDirectory)
+        let bytes = sampleMp3Data(seed: "offline-audio")
+
+        let localFilePath = try await store.saveAudioFile(
+            bytes,
+            assetId: "asset-123",
+            sha256: sha256Hex(bytes)
+        )
+        let storedBytes = try await store.readAudioFile(at: localFilePath)
+        let fileExists = await store.fileExists(at: localFilePath)
+
+        XCTAssertEqual(storedBytes, bytes)
+        XCTAssertTrue(fileExists)
+    }
+
+    func testFileOfflineAudioFileStoreRejectsEmptyAudioData() async throws {
+        let store = try FileOfflineAudioFileStore(
+            baseDirectoryURL: FileManager.default.temporaryDirectory
+                .appendingPathComponent(UUID().uuidString, isDirectory: true)
+        )
+
+        await XCTAssertThrowsErrorAsync {
+            _ = try await store.saveAudioFile(
+                Data(),
+                assetId: "asset-123",
+                sha256: nil
+            )
+        } assertion: { error in
+            XCTAssertEqual(error as? OfflineAudioFileStoreError, .emptyAudioData)
+        }
+    }
+
+    func testFileOfflineAudioFileStoreRejectsShaMismatch() async throws {
+        let fileManager = FileManager.default
+        let tempDirectory = fileManager.temporaryDirectory.appendingPathComponent(
+            UUID().uuidString,
+            isDirectory: true
+        )
+
+        defer {
+            try? fileManager.removeItem(at: tempDirectory)
+        }
+
+        let store = try FileOfflineAudioFileStore(baseDirectoryURL: tempDirectory)
+        let bytes = sampleMp3Data(seed: "sha-mismatch")
+
+        await XCTAssertThrowsErrorAsync {
+            _ = try await store.saveAudioFile(
+                bytes,
+                assetId: "asset-123",
+                sha256: String(repeating: "f", count: 64)
+            )
+        } assertion: { error in
+            guard case .sha256Mismatch = error as? OfflineAudioFileStoreError else {
+                return XCTFail("Expected a sha256Mismatch error.")
+            }
+        }
+    }
+
+    func testFileOfflineAudioFileStoreResolvesCurrentBaseDirectoryWhenPersistedPathIsStale() async throws {
+        let fileManager = FileManager.default
+        let tempDirectory = fileManager.temporaryDirectory.appendingPathComponent(
+            UUID().uuidString,
+            isDirectory: true
+        )
+        let firstAudioDirectory = tempDirectory.appendingPathComponent("audio-v1", isDirectory: true)
+        let secondAudioDirectory = tempDirectory.appendingPathComponent("audio-v2", isDirectory: true)
+        let bytes = sampleMp3Data(seed: "path-repair")
+
+        defer {
+            try? fileManager.removeItem(at: tempDirectory)
+        }
+
+        let staleFilePath = firstAudioDirectory
+            .appendingPathComponent("asset-123.mp3")
+            .standardizedFileURL
+            .path
+        let secondStore = try FileOfflineAudioFileStore(baseDirectoryURL: secondAudioDirectory)
+        let currentFilePath = try await secondStore.saveAudioFile(
+            bytes,
+            assetId: "asset-123",
+            sha256: sha256Hex(bytes)
+        )
+
+        let resolvedFilePath = await secondStore.resolveLocalFilePath(
+            persistedLocalFilePath: staleFilePath,
+            assetId: "asset-123"
+        )
+
+        XCTAssertEqual(resolvedFilePath, currentFilePath)
+    }
+}
+
+private func sampleMp3Data(seed: String) -> Data {
+    Data([
+        0x49, 0x44, 0x33, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x21,
+    ] + Array(seed.utf8))
+}
+
+private func sha256Hex(_ data: Data) -> String {
+    SHA256.hash(data: data).map { String(format: "%02x", $0) }.joined()
+}
+
+private func XCTAssertThrowsErrorAsync(
+    _ expression: @escaping () async throws -> Void,
+    assertion: (Error) -> Void,
+    file: StaticString = #filePath,
+    line: UInt = #line
+) async {
+    do {
+        try await expression()
+        XCTFail("Expected expression to throw an error.", file: file, line: line)
+    } catch {
+        assertion(error)
+    }
+}
@@ -0,0 +1,38 @@
+import Foundation
+import XCTest
+import VelodyDomain
+@testable import VelodyPersistence
+
+final class RemoteTrackDownloadStateStoreTests: XCTestCase {
+    func testFileDownloadStateStorePersistsAcrossInstances() async throws {
+        let fileManager = FileManager.default
+        let tempDirectory = fileManager.temporaryDirectory.appendingPathComponent(
+            UUID().uuidString,
+            isDirectory: true
+        )
+        let fileURL = tempDirectory.appendingPathComponent("remote-download-states.json")
+
+        defer {
+            try? fileManager.removeItem(at: tempDirectory)
+        }
+
+        let firstStore = try FileRemoteTrackDownloadStateStore(fileURL: fileURL)
+        let states = [
+            RemoteTrackDownloadState(
+                remoteTrackId: "track-123",
+                assetId: "asset-456",
+                localFilePath: "/tmp/asset-456.mp3",
+                downloadedAt: Date(timeIntervalSince1970: 1_000),
+                downloadStatus: .downloaded,
+                lastDownloadError: nil
+            ),
+        ]
+
+        try await firstStore.saveDownloadStates(states)
+
+        let secondStore = try FileRemoteTrackDownloadStateStore(fileURL: fileURL)
+        let restoredStates = try await secondStore.loadDownloadStates()
+
+        XCTAssertEqual(restoredStates, states)
+    }
+}