import Foundation
import WatchConnectivity
import WidgetKit

/// 手表端会话管理：激活 WCSession、传录音文件到 iPhone、维护今日速记数并刷新复杂功能。
@MainActor
final class WatchSessionManager: NSObject, ObservableObject, WCSessionDelegate {
    static let todayCountKey = "yujiTodayCount"
    static let todayDateKey = "yujiTodayDate"

    @Published var transferState = ""
    @Published var todayCount = 0

    private var completions: [String: (Result<Void, Error>) -> Void] = [:]

    override init() {
        super.init()
        todayCount = Self.loadTodayCount()
        if WCSession.isSupported() {
            let session = WCSession.default
            session.delegate = self
            session.activate()
        }
    }

    /// 今日速记数：按自然日归零，存在手表本地 UserDefaults
    static func loadTodayCount() -> Int {
        let defaults = UserDefaults.standard
        let today = Calendar.current.startOfDay(for: Date())
        if let saved = defaults.object(forKey: todayDateKey) as? Date,
           Calendar.current.isDate(saved, inSameDayAs: today) {
            return defaults.integer(forKey: todayCountKey)
        }
        defaults.set(today, forKey: todayDateKey)
        defaults.set(0, forKey: todayCountKey)
        return 0
    }

    private func bumpTodayCount() {
        todayCount = Self.loadTodayCount() + 1
        UserDefaults.standard.set(todayCount, forKey: todayCountKey)
        WidgetCenter.shared.reloadAllTimelines()
    }

    /// 传录音文件到 iPhone，完成后回调（成功时今日数 +1 并刷新复杂功能）
    func transfer(url: URL, completion: @escaping (Result<Void, Error>) -> Void) {
        guard WCSession.isSupported(), WCSession.default.activationState == .activated else {
            completion(.failure(NSError(domain: "YuJiWatch", code: 1, userInfo: [NSLocalizedDescriptionKey: "手表与 iPhone 未连接，录音先存在手表上，连上后会自动重传。"])))
            return
        }
        let transfer = WCSession.default.transferFile(url, metadata: ["createdAt": Date().timeIntervalSince1970])
        completions[transfer.file.fileURL.lastPathComponent] = completion
        transferState = "正在传到 iPhone…"
    }

    // MARK: - WCSessionDelegate

    func session(_ session: WCSession, activationDidCompleteWith activationState: WCSessionActivationState, error: Error?) {
        // 激活完成即可传文件，无需额外处理
    }

    func session(_ session: WCSession, didFinish fileTransfer: WCSessionFileTransfer, error: Error?) {
        let key = fileTransfer.file.fileURL.lastPathComponent
        guard let completion = completions.removeValue(forKey: key) else { return }
        if let error {
            transferState = "传输失败：\(error.localizedDescription)"
            completion(.failure(error))
        } else {
            transferState = "已传到 iPhone"
            bumpTodayCount()
            completion(.success(()))
        }
    }
}