// StatsClient.swift — 主 App 侧实时统计生产者
//
// iOS 的隧道跑在独立的 PacketTunnel 扩展进程里，扩展已 LibboxSetup 到 App Group 容器
// 并起了 LibboxCommandServer。要拿实时上/下行 + 延迟，主 App 用 LibboxCommandClient
// 连接「同一个 group 容器路径」下的 CommandServer socket，订阅 status/group 命令——
// 对齐 sing-box-for-apple(SFI) 与 Android 的 StatsHandler 模型。
//
// CommandServer 会按 statusInterval 自动向已连接的 client 广播 box 统计；client 的
// writeStatus/writeGroups 回调拿到数据后映射成 pangolin/vpn/stats 契约字典
// (见 lib/bridge/vpn_bridge.dart)，经 VpnStatsStreamHandler 推到 Dart 侧。
//
// 生命周期：VPN 进入 connected → start()；断开/失效 → stop()。由 VpnManager 驱动。

import Foundation
import Libbox

/// 把 LibboxCommandClient 的实时回调映射成 stats 契约字典并推到 EventChannel。
final class StatsClient: NSObject {

    static let shared = StatsClient()

    // iOS App Group：必须与 PacketTunnelProvider 的 setup 路径一致。
    private let appGroup = "group.com.pangolin.pangolinVpn"

    private let queue = DispatchQueue(label: "pangolin.stats.client")
    private var client: LibboxCommandClient?
    private var started = false
    // libbox 全局 setup 每进程一次即可。
    private static var didSetup = false

    /// 缓存最近一次 writeGroups 解析出的 urltest 延迟(tag → delayMs)，
    /// 在 writeStatus 时一并打包(对齐 Android：status 与 group 是两个命令流)。
    private var latestUrltest: [(tag: String, delayMs: Int)] = []

    /// writeGroups 捕获的出口组 tag（如 urltest 的 "auto"），用于主动触发延迟探测。
    private var groupTags: [String] = []
    /// 周期主动 urltest：sing-box urltest 默认惰性探测(首个 interval 前 history 为空)，
    /// 这里每 12s 主动触发一次，让延迟稳定、及时刷新。
    private var urlTestTimer: DispatchSourceTimer?

    // ── 生命周期 ────────────────────────────────────────────────

    /// 隧道已连接后调用：建立并连接 CommandClient。幂等。
    func start() {
        queue.async { [weak self] in
            guard let self, !self.started else { return }
            guard self.ensureSetup() else { return }

            let options = LibboxCommandClientOptions()
            options.statusInterval = 1_000_000_000 // 1s（纳秒）
            options.addCommand(LibboxCommandStatus) // 实时上/下行 + 累计
            options.addCommand(LibboxCommandGroup)  // 出口组 → urltest 延迟

            guard let c = LibboxNewCommandClient(self, options) else {
                NSLog("StatsClient: LibboxNewCommandClient returned nil")
                return
            }
            // CommandServer 在扩展刚起时可能还没 ready，连不上时重试几次。
            for attempt in 0..<10 {
                do {
                    try c.connect()
                    self.client = c
                    self.started = true
                    NSLog("StatsClient: connected (attempt %d)", attempt + 1)
                    self.startUrlTestTimer()
                    return
                } catch {
                    NSLog("StatsClient: connect failed (attempt %d): %@", attempt + 1,
                          error.localizedDescription)
                    Thread.sleep(forTimeInterval: 0.5)
                }
            }
            NSLog("StatsClient: gave up connecting after retries")
        }
    }

    /// 隧道断开后调用：断开并释放 CommandClient。幂等。
    /// 周期主动触发 urltest 探测（在 queue 上）。
    private func startUrlTestTimer() {
        urlTestTimer?.cancel()
        let timer = DispatchSource.makeTimerSource(queue: queue)
        timer.schedule(deadline: .now() + 2, repeating: 12)
        timer.setEventHandler { [weak self] in
            guard let self, let c = self.client else { return }
            for tag in self.groupTags {
                try? c.urlTest(tag)
            }
        }
        timer.resume()
        urlTestTimer = timer
    }

    func stop() {
        queue.async { [weak self] in
            guard let self else { return }
            self.urlTestTimer?.cancel()
            self.urlTestTimer = nil
            if let c = self.client {
                try? c.disconnect()
            }
            self.client = nil
            self.started = false
            self.latestUrltest = []
            self.groupTags = []
            // 断开后清零，避免 UI 残留上一次连接的速率。
            VpnStatsStreamHandler.shared.push([
                "uploadBytes": 0, "downloadBytes": 0,
                "uploadSpeed": 0.0, "downloadSpeed": 0.0,
                "urltestResults": [[String: Any]](),
            ])
        }
    }

    // ── libbox 全局 setup（与扩展同一 group 容器路径）─────────────

    private func ensureSetup() -> Bool {
        if Self.didSetup { return true }
        guard let base = FileManager.default
            .containerURL(forSecurityApplicationGroupIdentifier: appGroup) else {
            NSLog("StatsClient: no app group container")
            return false
        }
        let work = base.appendingPathComponent("work", isDirectory: true)
        let setup = LibboxSetupOptions()
        setup.basePath = base.path
        setup.workingPath = work.path
        setup.tempPath = NSTemporaryDirectory()
        var err: NSError?
        LibboxSetup(setup, &err)
        if let err {
            NSLog("StatsClient: LibboxSetup failed: %@", err.localizedDescription)
            return false
        }
        Self.didSetup = true
        return true
    }
}

// ── LibboxCommandClientHandler：实时回调 ─────────────────────────────
extension StatsClient: LibboxCommandClientHandlerProtocol {
    func connected() { NSLog("StatsClient: server connected") }
    func disconnected(_ message: String?) { NSLog("StatsClient: server disconnected: %@", message ?? "") }
    func clearLogs() {}
    func writeLogs(_ messageList: (any LibboxLogIteratorProtocol)?) {}
    func setDefaultLogLevel(_ level: Int32) {}
    func initializeClashMode(_ modeList: (any LibboxStringIteratorProtocol)?, currentMode: String?) {}
    func updateClashMode(_ newMode: String?) {}
    func write(_ events: LibboxConnectionEvents?) {}

    func writeStatus(_ message: LibboxStatusMessage?) {
        guard let m = message else { return }
        let stats: [String: Any] = [
            "uploadBytes": m.uplinkTotal,
            "downloadBytes": m.downlinkTotal,
            "uploadSpeed": Double(m.uplink),
            "downloadSpeed": Double(m.downlink),
            "urltestResults": latestUrltest.map { ["tag": $0.tag, "delayMs": $0.delayMs] },
        ]
        VpnStatsStreamHandler.shared.push(stats)
    }

    func writeGroups(_ message: (any LibboxOutboundGroupIteratorProtocol)?) {
        guard let groups = message else { return }
        var urltest: [(tag: String, delayMs: Int)] = []
        var tags: [String] = []
        while groups.hasNext() {
            guard let group = groups.next() else { break }
            tags.append(group.tag)
            guard let items = group.getItems() else { continue }
            while items.hasNext() {
                guard let item = items.next() else { break }
                urltest.append((tag: item.tag, delayMs: Int(item.urlTestDelay)))
            }
        }
        latestUrltest = urltest
        queue.async { [weak self] in self?.groupTags = tags }
    }
}