以 SwiftData 之道，重塑 Core Data 开发

@Model
public final class Item {
    public var name: String = ""
    public var height: Double?
    public init(name: String, height: Double? = nil) {
        self.name = name
        self.height = height
    }
}

// 初步声明
public final class Item {
    public var name: String = ""
    public var height: Double?
}

@objc(Item)
public final class Item: NSManagedObject {}

extension Item {
    @NSManaged
    public var name: String
    @NSManaged
    public var height: Double? // Property cannot be marked @NSManaged because its type cannot be represented in Objective-C
}

@objc(Note)
public final class Item: NSManagedObject {}

extension Item {
    @NSManaged
    public var name: String

    public var height: Double? {
        get {
            heightValueNumber?.doubleValue
        }
        set {
            heightValueNumber = newValue as NSNumber?
        }
    }

    @NSManaged
    var heightValueNumber: NSNumber? // 没有添加 public 权限
}

extension Item {
    ...
    public var valueDisplayMode: DataDisplayMode {
        get {
            DataDisplayMode(rawValue: valueDisplayModeRaw) ?? .average
        }
        set {
            valueDisplayModeRaw = newValue.rawValue
        }
    }
}

public enum DataDisplayMode: Int16, Sendable, Equatable {
    case sum = 1
    case average = 2
}

extension Item {
		...
    public var options: [ItemOption]? {
        get {
            guard let data = optionsData else { return nil }
            return try? JSONDecoder().decode([ItemOption].self, from: data)
        }
        set {
            optionsData = try? JSONEncoder().encode(newValue)
        }
    }
    
    @NSManaged var optionsData: Data?
}

extension Item {
    @NSManaged public var note: Note?

    @NSManaged public var datas: Set<ItemData>? // 用 Set 替换 NSSet
  
    @objc(addDatasObject:)
    @NSManaged public func addToDatas(_ value: ItemData)

    @objc(removeDatasObject:)
    @NSManaged public func removeFromDatas(_ value: ItemData)

    @objc(addDatas:)
    @NSManaged public func addToDatas(_ values: NSSet)

    @objc(removeDatas:)
    @NSManaged public func removeFromDatas(_ values: NSSet)
}

let item = Item(context:context)
item.name = "hello"
...
// 给其他属性赋值

extension Item {
    public convenience init(
        name: String,
        height: Double? = nil,
        valueDisplayMode: DataDisplayMode = .sum,
        options: [ItemOption]? = nil
    ) {
        self.init(entity: Self.entity(), insertInto: nil)
        self.name = name
        self.height = height
        self.valueDisplayMode = valueDisplayMode
        self.options = options
    }
}

let item = Item(name: "fat")
context.insert(item) // 显式插入上下文

let note = Note(name: "note1")
context.insert(note)
let item = Item(name: "fat")
context.insert(item)
item.note = note

@preconcurrency import CoreData

public enum DBModelConfiguration {
    public nonisolated static let objectModel: NSManagedObjectModel = {
        guard let modelURL = Bundle.module.url(forResource: "CareLog", withExtension: "momd") else {
            fatalError("Couldn't find the CareLog.momd file in the module bundle.")
        }
        guard let model = NSManagedObjectModel(contentsOf: modelURL) else {
            fatalError("Couldn't load the CareLog.momd file in the module bundle.")
        }
        return model
    }()
}

@NSModelActor
public actor DataHandler {}

extension DataHandler {
    // 公开方法
    public func deleteItemData(
        for itemDataID: PersistentObjectID,
        saveImmediately: Bool
    ) throws(DataHandlerError) { ... }

    public func deleteItemDatas(
        for itemDataIDs: [PersistentObjectID],
        saveImmediately: Bool
    ) throws(DataHandlerError) { ... }

    public func createItemData(
        with viewModel: ItemDataVM,
        saveImmediately: Bool = true
    ) throws(DataHandlerError) -> PersistentObjectID { ... }
  
    public func updateItemData(
        with viewModel: ItemDataVM,
        saveImmediately: Bool = true
    ) throws(DataHandlerError) { ... }

    // 内部方法
    func createItemDataObject(
        with itemDataVM: ItemDataVM,
        in item: Item,
        saveImmediately: Bool = true
    ) throws(DataHandlerError) -> ItemData { ... }

    func updateItemDataObject(
        for itemData: ItemData,
        with itemDataVM: ItemDataVM,
        saveImmediately: Bool = true
    ) throws(DataHandlerError) { ... }
}

@Test
func createRootNoteTest() async throws {
    let container = PersistentController.createTestContainer(#function)
    let handler = DataHandler(container: container)
    // 创建数据
    try await handler.createRootNote(with: NoteVM.sample2)
    // 验证结果
    ...
}

extension DataHandler {
    public func perform<T>(_ action: (NSManagedObjectContext) throws -> T) throws -> T where T: Sendable {
        try action(modelContext)
    }
}

@Test
func createRootNoteTest() async throws {
    let container = PersistentController.createTestContainer(#function)
    let handler = DataHandler(container: container)
    // 创建数据
    try await handler.createRootNote(with: NoteVM.sample2)
    // 验证结果
    let query = Note.query(for: .allRootNotes(sortBy: nil))
    // 在 Actor 中运行判断代码
    try await handler.perform { context in
        #expect(try context.count(for: query) == 1)
    }
}

extension PersistentController {
    /// 创建一个用来测试的 NSPersistentContainer( 只包含特定的 Configuration 中的实体 )
    static func createTestContainer(
        _ name: String,
        enablePHT: Bool = false,
        configurationName: String = DBModelConfiguration.privateConfigurationName,
        subDirectory: String = "DBCoreDataTestTemp"
    ) -> NSPersistentContainer {
        let tempURL = URL.temporaryDirectory
        // 如果 tempURL 中没有 subDirectory 就创建
        if !FileManager.default.fileExists(atPath: tempURL.appendingPathComponent(subDirectory).path) {
            try? FileManager.default
                .createDirectory(at: tempURL.appendingPathComponent(subDirectory), withIntermediateDirectories: true)
        }
        let url = tempURL.appendingPathComponent(subDirectory).appendingPathComponent(
            name + ".sqlite"
        )
        // 删除原本的数据库文件，保证每次测试数据环境都是全新的
        if FileManager.default.fileExists(atPath: url.path) {
            try? FileManager.default.removeItem(at: url)
        }
        let container = NSPersistentContainer(name: name, managedObjectModel: model)
        let description = NSPersistentStoreDescription(url: url)
        description.configuration = configurationName
        description.shouldAddStoreAsynchronously = false
        // 开启 Persistent History Tracking
        if enablePHT {
            description.setOption(true as NSNumber, forKey: NSPersistentHistoryTrackingKey)
            description.setOption(true as NSNumber, forKey: NSPersistentStoreRemoteChangeNotificationPostOptionKey)
        }
        container.persistentStoreDescriptions = [description]
        container.loadPersistentStores { _, error in
            if let error {
                fatalError("加载 Persistent Store 失败: \(error)")
            }
        }
        return container
    }
}