import Foundation

// MARK: - 防火墙呈现、wrapper 观测与系统代理门禁

extension ProxyRuntimeController {
  func presentFirewallStatus(for document: SslocalRuntimeDocument) async {
    guard document.listen.listenerMode.exposesNetworkInterfaces else {
      state = .running
      return
    }
    if let blocked = await blockedFirewallExecutable() {
      presentFirewallBlocked(blocked)
      return
    }
    state = .running
    observeFirewall(generation: flowGeneration)
  }

  private func blockedFirewallExecutable() async -> URL? {
    for executableURL in firewallExecutableURLs {
      let status = await firewallStatus(for: executableURL)
      if status == .blocked { return executableURL }
    }
    return nil
  }

  private func presentFirewallBlocked(_ executableURL: URL) {
    let name = executableURL.lastPathComponent
    state = .firewallBlocked(FirewallBlockedFacts(executableName: name))
  }

  private func observeFirewall(generation: Int) {
    firewallObservationTask?.cancel()
    let interval = firewallPollIntervalNanoseconds
    firewallObservationTask = Task { @MainActor [weak self] in
      while !Task.isCancelled {
        try? await Task.sleep(nanoseconds: interval)
        guard !Task.isCancelled, let self, generation == flowGeneration else { return }
        if let blocked = await blockedFirewallExecutable() {
          presentFirewallBlocked(blocked)
          firewallObservationTask = nil
          return
        }
      }
    }
  }

  func cancelFirewallObservation() {
    firewallObservationTask?.cancel()
    firewallObservationTask = nil
  }

  private func firewallStatus(for executableURL: URL) async -> FirewallBlockStatus {
    let checker = firewallChecker
    return await Task.detached(priority: .utility) {
      checker.status(for: executableURL)
    }.value
  }

  func probeAsync(
    host: String, port: Int, timeout: TimeInterval
  ) async -> EndpointHealthProbe.Outcome {
    let probe = probe
    return await Task.detached(priority: .utility) {
      probe.probe(host: host, port: port, timeout: timeout)
    }.value
  }

  /// 显式停止协议次序（D2）：注销（SIGTERM wrapper → wrapper 停 sslocal 并
  /// 等待）完成后才允许后续删文件动作。最多等 5 秒，超时也继续（launchd 会
  /// 兜底结束进程）。
  func waitForWrapperExit() async {
    let deadline = Date().addingTimeInterval(5)
    while wrapperState() != .notRunning && Date() < deadline {
      try? await Task.sleep(nanoseconds: 100_000_000)
    }
  }

  func wrapperState() -> WrapperProcessState {
    guard
      let data = try? Data(contentsOf: runtimeFileStore.pidFileURL),
      let text = String(data: data, encoding: .utf8)?.trimmingCharacters(
        in: .whitespacesAndNewlines),
      let pid = Int32(text)
    else { return .notRunning }
    guard sendSignal(pid, 0) == 0 else { return .notRunning }
    return .running(pid: pid)
  }

  // MARK: - 目录同步

  /// Re-expands one command-start snapshot; a concurrently published catalog
  /// is intentionally observed by the next command, not halfway through this one.
  func reexpand(in catalog: ConfigurationCatalog) -> ActivationEffect? {
    let effect = machine.catalogDidCommit(
      catalog, credentials: credentials, plugins: plugins,
      options: settings.runtimeDocumentOptions)
    activeTargetID = machine.activeTargetID
    switch effect {
    case .deployed(let configuration):
      skippedServers = configuration.skippedServers
    case .clearedAndStopped:
      skippedServers = []
    case nil:
      break
    }
    return effect
  }

  func describe(_ error: Error) -> String {
    String(describing: error)
  }

  // MARK: - 系统代理门禁（issue #60/#71）

  /// 系统代理收敛：helper 可用 + agent 健康 + 所选模式具备可用出口才经特权
  /// helper 应用；任一条件关闭时意图保持待应用、系统设置保持原样，条件恢复
  /// 后自动重写。收敛路径永不清理（issue #71）。
  func convergeSystemProxy() async {
    guard settings.systemProxyEnabled else { return }
    guard await ensureHelperAvailableForApply() else {
      systemProxyState = .pending
      return
    }
    guard systemProxyExitAvailable, let document = lastDocument else {
      systemProxyState = .pending
      return
    }
    do {
      let configuration = try proxyMode.systemProxyConfiguration(
        for: document, exceptions: settings.proxyExceptionList)
      let outcome = try await systemProxy.apply(configuration)
      if outcome == .unchanged {
        // 值语义等价的零写入路径：事件行供排障回答「这次为何没有授权弹窗」。
        RuntimeLog.emit(.systemProxyUnchanged)
      }
      systemProxyState = .applied
    } catch {
      // 错误细节进日志：状态呈现走 facts，XPC/ helper 层失败原因只有这里可查。
      RuntimeLog.emit(.systemProxyWriteFailed(detail: describe(error)))
      systemProxyState = .failed(systemProxyFacts(for: error))
    }
  }

  /// helper 可用性门禁（issue #71）：已批准即通过——仅当 LaunchDaemon 清单
  /// 与上次注册时的指纹漂移（app 更新改过清单）才注销重注刷新 launchd 的
  /// job 定义；未注册则尝试注册（注册本身不弹授权框，成功即记指纹）；待批准
  /// 或注册失败时置位批准路径并保持待应用。
  private func ensureHelperAvailableForApply() async -> Bool {
    switch systemProxyHelper.status {
    case .approved:
      if helperRegistrationDrifted() {
        do {
          try systemProxyHelper.unregister()
          // launchd 对节流中（spawn scheduled）job 的移除是异步的：立即重注
          // 会命中尚未移除的旧定义（实测注销重注后定义不变）。等过 minimum
          // runtime（10s）节流窗再重注；间隔内收敛以旧定义失败呈超时。
          try? await Task.sleep(nanoseconds: helperRefreshDelayNanoseconds)
          try systemProxyHelper.register()
          storeHelperRegistrationStamp()
        } catch {
          // 刷新失败不记指纹，下次启动重试；状态退回后由下方分支接手。
          RuntimeLog.emit(.systemProxyHelperRegisterFailed(detail: describe(error)))
        }
      }
      if systemProxyHelper.status == .approved {
        systemProxyApprovalRequired = false
        return true
      }
    case .notRegistered:
      do {
        try systemProxyHelper.register()
        storeHelperRegistrationStamp()
      } catch {
        RuntimeLog.emit(.systemProxyHelperRegisterFailed(detail: describe(error)))
      }
      if systemProxyHelper.status == .approved {
        systemProxyApprovalRequired = false
        return true
      }
    case .requiresApproval:
      break
    }
    systemProxyApprovalRequired = true
    return false
  }

  private func helperRegistrationDrifted(defaults: UserDefaults = .standard) -> Bool {
    SystemProxyHelperRegistrationStamp.drifted(
      plistData: SystemProxyHelperIdentity.launchDaemonPlistData(in: appBundle),
      storedStamp: defaults.string(forKey: SystemProxyHelperRegistrationStamp.defaultsKey))
  }

  private func storeHelperRegistrationStamp(defaults: UserDefaults = .standard) {
    guard let plistData = SystemProxyHelperIdentity.launchDaemonPlistData(in: appBundle) else {
      return
    }
    defaults.set(
      SystemProxyHelperRegistrationStamp.stamp(plistData),
      forKey: SystemProxyHelperRegistrationStamp.defaultsKey)
  }

  /// 登录项批准路径（issue #71）：打开系统设置的登录项面板并立即重试收敛；
  /// 批准完成前意图保持待应用、系统设置不变。
  func openSystemProxyHelperApproval() async {
    systemProxyHelper.openApprovalPath()
    await convergeSystemProxy()
  }

  /// 出口可用 = agent 入站健康（回环入口可用，含防火墙仅阻主机态的情形）
  /// 且模式有出口；直连不依赖活动服务器目标。
  private var systemProxyExitAvailable: Bool {
    switch state {
    case .running, .firewallBlocked:
      return proxyMode == .direct || activeTargetID != nil
    case .off, .starting, .launchFailed, .requiresApproval, .serviceFailed:
      return false
    }
  }

  /// 门禁关闭（issue #71）：健康/出口/目标变化不撤回已写入的系统设置，
  /// 意图保持待应用等恢复；意图关闭则为空闲。
  func holdSystemProxyIntent() {
    systemProxyApprovalRequired = false
    systemProxyState = settings.systemProxyEnabled ? .pending : .idle
  }

  /// 无条件清除全部系统代理配置（issue #71）：typed 失败原样呈现，不重试。
  func clearSystemProxyOutcome() async -> SystemProxyControlState {
    do {
      try await systemProxy.clear()
      return .idle
    } catch {
      return .failed(systemProxyFacts(for: error))
    }
  }

  func startEnabledSystemProxyObservation() {
    guard systemProxyObservationMode != .enabled else { return }
    systemProxyObservationMode = .enabled
    systemProxyNetworkChangeMonitor.start { [weak self] change in
      self?.handleSystemProxyNetworkChange(change)
    }
  }

  func clearAndStopSystemProxyObservation() async -> SystemProxyControlState {
    if let systemProxyCleanupTask { return await systemProxyCleanupTask.value }
    let task = Task { @MainActor [weak self] in
      guard let self else { return SystemProxyControlState.idle }
      return await performSystemProxyCleanupUntilQuiet()
    }
    systemProxyCleanupTask = task
    let result = await task.value
    systemProxyCleanupTask = nil
    return result
  }

  private func performSystemProxyCleanupUntilQuiet() async -> SystemProxyControlState {
    if systemProxyObservationMode != .enabled {
      systemProxyObservationMode = .cleanup
      systemProxyNetworkChangeMonitor.start { [weak self] change in
        self?.handleSystemProxyNetworkChange(change)
      }
    } else {
      systemProxyObservationMode = .cleanup
    }

    var outcome: SystemProxyControlState = .idle
    repeat {
      systemProxyCleanupRescanRequested = false
      outcome = await clearSystemProxyOutcome()
      // Let queued SystemConfiguration notifications reach the main actor. Any
      // location/service/proxy change during this cleanup starts another full scan.
      try? await Task.sleep(nanoseconds: 100_000_000)
      await Task.yield()
    } while systemProxyCleanupRescanRequested

    systemProxyNetworkChangeMonitor.stop()
    systemProxyObservationMode = .stopped
    return outcome
  }

  private func handleSystemProxyNetworkChange(_ change: SystemProxyNetworkChange) {
    switch systemProxyObservationMode {
    case .stopped:
      return
    case .cleanup:
      if !change.isDisjoint(with: [.networkConfiguration, .proxyConfiguration]) {
        systemProxyCleanupRescanRequested = true
      }
    case .enabled:
      guard settings.systemProxyEnabled else { return }
      // Proxy-only changes are deliberately ignored while enabled: competing proxy
      // software must not create a write loop. Location/service/path changes reapply.
      guard !change.isDisjoint(with: [.networkConfiguration, .networkPath]) else {
        return
      }
      guard !systemProxyConvergenceScheduled else { return }
      systemProxyConvergenceScheduled = true
      Task { @MainActor [weak self] in
        await Task.yield()
        guard let self else { return }
        self.systemProxyConvergenceScheduled = false
        await self.convergeSystemProxy()
      }
    }
  }

  func systemProxyFacts(for error: Error) -> SystemProxyFailureFacts {
    if let error = error as? SystemProxyError {
      return Self.systemProxyFacts(for: error)
    }
    if let error = error as? ProxyModeError {
      return .mode(error)
    }
    return .unknown
  }

  // 显式映射保持与错误族一一对应；错误带关联值，无法用字典键穷举。
  // swiftlint:disable:next cyclomatic_complexity
  private static func systemProxyFacts(
    for error: SystemProxyError
  ) -> SystemProxyFailureFacts {
    switch error {
    case .preferencesUnavailable: return .operation(.preferencesUnavailable)
    case .preferencesBusy: return .operation(.preferencesBusy)
    case .noCurrentNetworkSet: return .operation(.noCurrentNetworkSet)
    case .noProxyServices: return .operation(.noProxyServices)
    case .unreadableService: return .operation(.unreadableService)
    case .invalidStoredConfiguration: return .operation(.invalidStoredConfiguration)
    case .cannotWriteService: return .operation(.cannotWriteService)
    case .commitFailed: return .operation(.commitFailed)
    case .applyFailed: return .operation(.applyFailed)
    case .noNetworkLocations: return .operation(.noNetworkLocations)
    case .invalidRequest: return .operation(.invalidRequest)
    case .helperUnavailable: return .operation(.helperUnavailable)
    }
  }
}