import Darwin
import Foundation
import NetworkExtension
import os.log

class PacketTunnelProvider: NEPacketTunnelProvider {
    private let log = Logger(subsystem: "win.evilfox.navis.tunnel", category: "tunnel")
    private let store = ProfileStore()
    private var hevQueue: DispatchQueue?
    private var coreKind: String?

    override func startTunnel(options: [String: NSObject]?, completionHandler: @escaping (Error?) -> Void) {
        log.info("startTunnel")
        store.setTunnelStatus("starting")

        let resolved = resolveEndpoint(options: options)
        let name = resolved.name
        let uri = resolved.uri
        if uri.isEmpty {
            fail(TunnelError.message("нет URI — выберите сервер и Подключить снова"), completionHandler)
            return
        }

        // Persist what we actually use (helps UI + next start).
        store.writeTunnelConfig(name: name, uri: uri)

        let proto = Proto.detect(uri)
        switch proto {
        case .vless, .vmess, .trojan:
            break
        case .hy2:
            fail(TunnelError.message("Hysteria2 на iOS пока недоступен — выберите VLESS/VMess/Trojan"), completionHandler)
            return
        case .naive:
            fail(TunnelError.message("NaiveProxy на iOS недоступен (Chromium-ядро)"), completionHandler)
            return
        case .awg:
            fail(TunnelError.message("AmneziaWG на iOS — следующим этапом"), completionHandler)
            return
        case .unknown:
            fail(TunnelError.message("Неизвестный протокол"), completionHandler)
            return
        }

        // Critical order: start local SOCKS core BEFORE installing full tunnel routes.
        // Otherwise traffic to the proxy server is sucked into utun and never reaches the internet.
        DispatchQueue.global(qos: .userInitiated).async { [weak self] in
            guard let self else {
                completionHandler(TunnelError.message("tunnel deallocated"))
                return
            }
            do {
                try self.startCore(uri: uri, proto: proto)
                try self.waitLocalPort(1080, timeoutMs: 15_000)

                let serverHost = LinkParser.hostOf(uri)
                let serverIP = Self.resolveIPv4(serverHost)
                let settings = Self.makeNetworkSettings(excludeHostOrIP: serverIP ?? serverHost)

                let lock = DispatchSemaphore(value: 0)
                var settingsError: Error?
                self.setTunnelNetworkSettings(settings) { err in
                    settingsError = err
                    lock.signal()
                }
                lock.wait()
                if let settingsError {
                    throw settingsError
                }

                try self.startHev()
                self.store.setTunnelStatus("connected")
                self.log.info("tunnel up name=\(name, privacy: .public) proto=\(proto.label, privacy: .public) uriHost=\(serverHost, privacy: .public)")
                completionHandler(nil)
            } catch {
                self.log.error("start failed: \(error.localizedDescription, privacy: .public)")
                self.teardownCore()
                self.store.setTunnelStatus("error", error: error.localizedDescription)
                completionHandler(error)
            }
        }
    }

    override func stopTunnel(with reason: NEProviderStopReason, completionHandler: @escaping () -> Void) {
        log.info("stopTunnel reason=\(String(describing: reason), privacy: .public)")
        teardownCore()
        store.setTunnelStatus("stopped")
        store.clearTunnelConfig()
        completionHandler()
    }

    /// Prefer: start options → providerConfiguration → App Group file/defaults.
    private func resolveEndpoint(options: [String: NSObject]?) -> (name: String, uri: String) {
        if let uri = options?["uri"] as? String, !uri.isEmpty {
            let name = (options?["name"] as? String).flatMap { $0.isEmpty ? nil : $0 } ?? "Navis"
            return (name, uri)
        }
        if let proto = protocolConfiguration as? NETunnelProviderProtocol,
           let cfg = proto.providerConfiguration
        {
            let uri = (cfg["uri"] as? String) ?? ""
            if !uri.isEmpty {
                let name = (cfg["name"] as? String).flatMap { $0.isEmpty ? nil : $0 } ?? "Navis"
                return (name, uri)
            }
        }
        if let file = store.readTunnelConfigFile() {
            return (file.name, file.uri)
        }
        if let cfg = store.readTunnelConfig() {
            return (cfg.name, cfg.uri)
        }
        return ("Navis", "")
    }

    private func startCore(uri: String, proto: Proto) throws {
        let work = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: AppConstants.appGroupID)
            ?? FileManager.default.temporaryDirectory
        let runtime = work.appendingPathComponent("runtime", isDirectory: true)
        try FileManager.default.createDirectory(at: runtime, withIntermediateDirectories: true)

        switch proto {
        case .vless, .vmess, .trojan:
            let json = try XrayConfigBuilder.buildJSON(uri: uri, socksPort: 1080, httpPort: 1081)
            let cfgURL = runtime.appendingPathComponent("xray.json")
            try json.write(to: cfgURL, atomically: true, encoding: .utf8)
            // Stop any previous instance before starting.
            LibXrayCore.stop()
            try LibXrayCore.runFile(cfgURL.path)
            coreKind = "xray"
        case .hy2:
            let yaml = try Hy2ConfigBuilder.buildYAML(uri: uri)
            let cfgURL = runtime.appendingPathComponent("hy2.yaml")
            try yaml.write(to: cfgURL, atomically: true, encoding: .utf8)
            try Hy2CoreRunner.start(configPath: cfgURL.path, workDir: runtime.path)
            coreKind = "hy2"
        default:
            throw TunnelError.message("протокол не поддержан в tunnel")
        }
    }

    private func startHev() throws {
        let work = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: AppConstants.appGroupID)
            ?? FileManager.default.temporaryDirectory
        let runtime = work.appendingPathComponent("runtime", isDirectory: true)
        try FileManager.default.createDirectory(at: runtime, withIntermediateDirectories: true)

        guard let tunFd = resolveTunnelFileDescriptor(), tunFd >= 0 else {
            throw TunnelError.message("не удалось получить utun fd для hev")
        }

        let hevCfg = runtime.appendingPathComponent("hev.yml")
        try HevBridge.writeConfig(to: hevCfg)

        let queue = DispatchQueue(label: "win.evilfox.navis.hev", qos: .userInitiated)
        hevQueue = queue
        queue.async {
            _ = HevBridge.runBlocking(configPath: hevCfg.path, tunFd: tunFd)
        }
        Thread.sleep(forTimeInterval: 0.35)
    }

    private func teardownCore() {
        HevBridge.quit()
        switch coreKind {
        case "xray":
            LibXrayCore.stop()
        case "hy2":
            Hy2CoreRunner.stop()
        default:
            LibXrayCore.stop()
            Hy2CoreRunner.stop()
        }
        coreKind = nil
    }

    private func fail(_ error: Error, _ completionHandler: @escaping (Error?) -> Void) {
        store.setTunnelStatus("error", error: error.localizedDescription)
        completionHandler(error)
    }

    private func waitLocalPort(_ port: Int, timeoutMs: Int) throws {
        let deadline = Date().addingTimeInterval(Double(timeoutMs) / 1000.0)
        while Date() < deadline {
            if tcpConnectOK(port: port) { return }
            Thread.sleep(forTimeInterval: 0.15)
        }
        throw TunnelError.message("локальный SOCKS :\(port) не поднялся (проверьте ссылку VLESS/Trojan)")
    }

    private func tcpConnectOK(port: Int) -> Bool {
        let fd = socket(AF_INET, SOCK_STREAM, 0)
        guard fd >= 0 else { return false }
        defer { close(fd) }
        var addr = sockaddr_in()
        addr.sin_len = UInt8(MemoryLayout<sockaddr_in>.size)
        addr.sin_family = sa_family_t(AF_INET)
        addr.sin_port = in_port_t(UInt16(port).bigEndian)
        addr.sin_addr = in_addr(s_addr: inet_addr("127.0.0.1"))
        let result = withUnsafePointer(to: &addr) {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
                connect(fd, $0, socklen_t(MemoryLayout<sockaddr_in>.size))
            }
        }
        return result == 0
    }

    private static func makeNetworkSettings(excludeHostOrIP: String) -> NEPacketTunnelNetworkSettings {
        let settings = NEPacketTunnelNetworkSettings(tunnelRemoteAddress: "127.0.0.1")
        let ipv4 = NEIPv4Settings(addresses: ["10.8.0.2"], subnetMasks: ["255.255.255.255"])
        ipv4.includedRoutes = [NEIPv4Route.default()]

        var excluded: [NEIPv4Route] = [
            NEIPv4Route(destinationAddress: "127.0.0.0", subnetMask: "255.0.0.0"),
            // Private LAN — do not claim (and avoid eating the tunnel address space unnecessarily).
            NEIPv4Route(destinationAddress: "10.0.0.0", subnetMask: "255.0.0.0"),
            NEIPv4Route(destinationAddress: "172.16.0.0", subnetMask: "255.240.0.0"),
            NEIPv4Route(destinationAddress: "192.168.0.0", subnetMask: "255.255.0.0"),
        ]
        // Keep path to proxy server outside the tunnel (prevents routing loop).
        if !excludeHostOrIP.isEmpty, looksLikeIPv4(excludeHostOrIP) {
            excluded.append(NEIPv4Route(destinationAddress: excludeHostOrIP, subnetMask: "255.255.255.255"))
        }
        ipv4.excludedRoutes = excluded
        settings.ipv4Settings = ipv4
        settings.dnsSettings = NEDNSSettings(servers: ["1.1.1.1", "8.8.8.8"])
        settings.mtu = 1400
        return settings
    }

    private static func looksLikeIPv4(_ s: String) -> Bool {
        var addr = in_addr()
        return s.withCString { inet_pton(AF_INET, $0, &addr) == 1 }
    }

    private static func resolveIPv4(_ host: String) -> String? {
        let trimmed = host.trimmingCharacters(in: .whitespacesAndNewlines)
        if trimmed.isEmpty { return nil }
        if looksLikeIPv4(trimmed) { return trimmed }

        var hints = addrinfo(
            ai_flags: AI_ADDRCONFIG,
            ai_family: AF_INET,
            ai_socktype: SOCK_STREAM,
            ai_protocol: 0,
            ai_addrlen: 0,
            ai_canonname: nil,
            ai_addr: nil,
            ai_next: nil
        )
        var res: UnsafeMutablePointer<addrinfo>?
        let rc = getaddrinfo(trimmed, nil, &hints, &res)
        guard rc == 0, let first = res else { return nil }
        defer { freeaddrinfo(res) }
        var addr = first.pointee.ai_addr.withMemoryRebound(to: sockaddr_in.self, capacity: 1) { $0.pointee }
        var buf = [CChar](repeating: 0, count: Int(INET_ADDRSTRLEN))
        guard inet_ntop(AF_INET, &addr.sin_addr, &buf, socklen_t(INET_ADDRSTRLEN)) != nil else { return nil }
        return String(cString: buf)
    }
}

enum TunnelError: LocalizedError {
    case message(String)
    var errorDescription: String? {
        switch self {
        case .message(let s): return s
        }
    }
}