DataManager.swift

#if canImport(CloudKit) && canImport(CryptoKit)
  import CryptoKit
  import Dependencies
  import Foundation

  @available(macOS 13, iOS 16, tvOS 16, watchOS 9, *)
  package protocol DataManager: Sendable {
    func load(_ url: URL) throws -> Data
    func save(_ data: Data, to url: URL) throws
    func sha256(of fileURL: URL) -> Data?
    var temporaryDirectory: URL { get }
  }

  @available(macOS 13, iOS 16, tvOS 16, watchOS 9, *)
  struct LiveDataManager: DataManager {
    func load(_ url: URL) throws -> Data {
      try Data(contentsOf: url)
    }
    func save(_ data: Data, to url: URL) throws {
      try data.write(to: url)
    }
    func sha256(of fileURL: URL) -> Data? {
      do {
        let fileHandle = try FileHandle(forReadingFrom: fileURL)
        defer { try? fileHandle.close() }
        var hasher = SHA256()
        while true {
          let finished = try autoreleasepool {
            guard
              let data = try fileHandle.read(upToCount: 1024 * 1024),
              !data.isEmpty
            else { return true }
            hasher.update(data: data)
            return false
          }
          guard !finished
          else { break }
        }
        let digest = hasher.finalize()
        return Data(digest)
      } catch {
        return nil
      }
    }
    var temporaryDirectory: URL {
      URL(fileURLWithPath: NSTemporaryDirectory())
    }
  }

  @available(macOS 13, iOS 16, tvOS 16, watchOS 9, *)
  package struct InMemoryDataManager: DataManager {
    package let storage = LockIsolated<[URL: Data]>([:])

    package init() {}

    package func load(_ url: URL) throws -> Data {
      try storage.withValue { storage in
        guard let data = storage[url]
        else {
          struct FileNotFound: Error {}
          throw FileNotFound()
        }
        return data
      }
    }

    package func save(_ data: Data, to url: URL) throws {
      storage.withValue { $0[url] = data }
    }

    package func sha256(of fileURL: URL) -> Data? {
      storage.withValue {
        $0[fileURL].map {
          Data(SHA256.hash(data: $0))
        }
      }
    }

    package var temporaryDirectory: URL {
      URL(fileURLWithPath: "/tmp")
    }
  }

  @available(macOS 13, iOS 16, tvOS 16, watchOS 9, *)
  private enum DataManagerKey: DependencyKey {
    static var liveValue: any DataManager {
      LiveDataManager()
    }
    static var previewValue: any DataManager {
      InMemoryDataManager()
    }
    static var testValue: any DataManager {
      InMemoryDataManager()
    }
  }

  @available(macOS 13, iOS 16, tvOS 16, watchOS 9, *)
  extension DependencyValues {
    package var dataManager: DataManager {
      get { self[DataManagerKey.self] }
      set { self[DataManagerKey.self] = newValue }
    }
  }
#endif