import Foundation

// 控件专用设备会话：主 app 经 /api/auth/device-session 给控制中心控件代铸的独立委派会话
// （独立 refresh，不与引擎抢轮换）。存 App Group 共享文件，控件读取后自行调 /api/clipboard、
// 401 即自刷并写回；refresh 被拒则清空，待主 app 下次启动重铸。
struct WidgetSession: Codable
{
    var accessToken: String
    var refreshToken: String
    let userId: String
}

enum WidgetSessionStore
{
    private static func fileURL() -> URL?
    {
        guard let base = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: AppGroup.identifier)
        else { return nil }
        return base.appendingPathComponent("widget_session.json")
    }

    static func load() -> WidgetSession?
    {
        guard let url = fileURL(), let data = try? Data(contentsOf: url) else { return nil }
        return try? JSONDecoder().decode(WidgetSession.self, from: data)
    }

    static func save(_ session: WidgetSession)
    {
        guard let url = fileURL(), let data = try? JSONEncoder().encode(session) else { return }
        // 首次解锁后即可读（含再次锁屏后）：控制中心控件可从锁屏触发，用 .completeFileProtection
        // 会在锁屏时读不到 → 控件静默失效。UntilFirstUserAuthentication 仍加密、又覆盖锁屏调用。
        try? data.write(to: url, options: [ .atomic, .completeFileProtectionUntilFirstUserAuthentication ])
    }

    static func clear()
    {
        guard let url = fileURL() else { return }
        try? FileManager.default.removeItem(at: url)
    }

    // refreshAccess：用控件会话自身的 refresh token 换新 access（POST /api/auth/refresh），轮换后写回。
    // 供主 app 在 content-available 后台唤醒 / 回前台时调用，使关闭态剪贴板会话保持可用——与引擎主会话
    // 完全隔离，绝不触碰主 refresh，故不会致引擎令牌失同步而重登（#7）。无会话则 no-op。CAS-before-clear：
    // 仅当刷新被明确拒绝（401）且磁盘上仍是本次所用 refresh 时才清，避免误删并发轮换出的新会话。
    static func refreshAccess() async
    {
        guard let session = load() else { return }
        var req = URLRequest(url: URL(string: CDropAPI.base + "/api/auth/refresh")!)
        req.httpMethod = "POST"
        req.setValue("application/json", forHTTPHeaderField: "Content-Type")
        req.httpBody = try? JSONSerialization.data(withJSONObject: [ "refresh_token": session.refreshToken ])
        guard let (data, resp) = try? await URLSession.shared.data(for: req) else { return }
        let code = (resp as? HTTPURLResponse)?.statusCode ?? 0
        if code == 200,
           let obj = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
           let access = obj["access_token"] as? String
        {
            let newRefresh = (obj["refresh_token"] as? String) ?? session.refreshToken
            save(WidgetSession(accessToken: access, refreshToken: newRefresh, userId: session.userId))
        }
        else if code == 401, load()?.refreshToken == session.refreshToken
        {
            clear()
        }
    }
}