import Foundation
import Libbox
import NetworkExtension
import os
#if os(iOS)
    import FileProvider
#endif

private let logger = Logger(category: "ExtensionProfile")

@MainActor
public class ExtensionProfile: ObservableObject {
    public static let controlKind = AppConfiguration.widgetControlKind

    private let manager: NEVPNManager?
    private var connection: NEVPNConnection?
    private var observer: Any?
    private let isMock: Bool

    @Published public var status: NEVPNStatus
    @Published public var connectedDate: Date?

    public init(_ manager: NEVPNManager) {
        self.manager = manager
        connection = manager.connection
        status = manager.connection.status
        connectedDate = manager.connection.connectedDate
        isMock = false
    }

    private init(mockStatus: NEVPNStatus, mockConnectedDate: Date?) {
        manager = nil
        connection = nil
        status = mockStatus
        connectedDate = mockConnectedDate
        isMock = true
    }

    private static var _mock: ExtensionProfile?

    public static var mock: ExtensionProfile {
        if _mock == nil {
            _mock = ExtensionProfile(mockStatus: .connected, mockConnectedDate: Date().addingTimeInterval(-3600))
        }
        return _mock!
    }

    public func register() {
        guard !isMock, let manager else { return }
        observer = NotificationCenter.default.addObserver(
            forName: NSNotification.Name.NEVPNStatusDidChange,
            object: manager.connection,
            queue: nil
        ) { [weak self] notification in
            guard let connection = notification.object as? NEVPNConnection else {
                return
            }
            Task { @MainActor in
                guard let self else {
                    return
                }
                self.connection = connection
                self.status = connection.status
                self.connectedDate = connection.connectedDate
                #if os(iOS)
                    if #available(iOS 16.0, *) {
                        if connection.status == .connected || connection.status == .disconnected {
                            Self.signalFileProviderChanges()
                        }
                    }
                #endif
            }
        }
    }

    #if os(iOS)
        @available(iOS 16.0, *)
        private static func signalFileProviderChanges() {
            Task.detached {
                guard let domain = try? await NSFileProviderManager.domains()
                    .first(where: { $0.identifier.rawValue == AppConfiguration.fileProviderDomainID }),
                    let manager = NSFileProviderManager(for: domain)
                else {
                    return
                }
                try? await manager.signalEnumerator(for: .workingSet)
            }
        }
    #endif

    nonisolated deinit {
        if let observer {
            NotificationCenter.default.removeObserver(observer)
        }
    }

    private static func makeDefaultOnDemandRules() -> [NEOnDemandRule] {
        let rule = NEOnDemandRuleConnect()
        rule.interfaceTypeMatch = .any
        rule.probeURL = URL(string: "http://captive.apple.com")
        return [rule]
    }

    private func setOnDemandRules(useDefaultRules: Bool) async {
        guard let manager else { return }
        if useDefaultRules {
            manager.onDemandRules = Self.makeDefaultOnDemandRules()
        } else {
            let rules = await SharedPreferences.onDemandRules.get()
            manager.onDemandRules = rules.isEmpty ? Self.makeDefaultOnDemandRules() : rules.map { $0.toNERule() }
        }
    }

    public func updateOnDemand(enabled: Bool, useDefaultRules: Bool) async throws {
        guard let manager else { return }
        manager.isOnDemandEnabled = enabled
        await setOnDemandRules(useDefaultRules: useDefaultRules)
        try await manager.saveToPreferences()
    }

    @available(iOS 16.0, macOS 13.0, tvOS 17.0, *)
    public func fetchLastDisconnectError() async throws {
        guard let connection else { return }
        try await connection.fetchLastDisconnectError()
    }

    public func start() async throws {
        if isMock {
            status = .connecting
            try await Task.sleep(nanoseconds: 500_000_000)
            status = .connected
            connectedDate = Date()
            return
        }
        guard let manager else { return }
        try await fetchProfile()
        manager.isEnabled = true
        let alwaysOn = await SharedPreferences.alwaysOn.get()
        let onDemandEnabled = await SharedPreferences.onDemandEnabled.get()
        if alwaysOn || onDemandEnabled {
            manager.isOnDemandEnabled = true
            await setOnDemandRules(useDefaultRules: alwaysOn)
        }
        #if !os(tvOS)
            if let protocolConfiguration = manager.protocolConfiguration {
                let includeAllNetworks = await SharedPreferences.includeAllNetworks.get()
                protocolConfiguration.includeAllNetworks = includeAllNetworks
                if #available(iOS 16.4, macOS 13.3, *) {
                    protocolConfiguration.excludeCellularServices = !includeAllNetworks
                }
            }
        #endif
        try await manager.saveToPreferences()
        let options = try await prepareStartOptions()
        try manager.connection.startVPNTunnel(options: options)
    }

    public func reloadService() async throws {
        if isMock { return }
        let options = try await prepareStartOptions()
        let data = try ExtensionStartOptions.encode(options)
        guard let session = connection as? NETunnelProviderSession else {
            throw NSError(domain: "ExtensionStartOptions", code: -1, userInfo: [
                NSLocalizedDescriptionKey: "Tunnel session unavailable",
            ])
        }
        let response = try await withCheckedThrowingContinuation { continuation in
            do {
                try session.sendProviderMessage(data) { response in
                    continuation.resume(returning: response)
                }
            } catch {
                continuation.resume(throwing: error)
            }
        }
        if let response, !response.isEmpty {
            let message = String(data: response, encoding: .utf8) ?? "Unknown error"
            throw NSError(domain: "ExtensionStartOptions", code: -1, userInfo: [
                NSLocalizedDescriptionKey: message,
            ])
        }
    }

    private func prepareStartOptions() async throws -> [String: NSObject] {
        var options: [String: NSObject] = [
            "manualStart": NSNumber(value: true),
        ]

        let profileID = await SharedPreferences.selectedProfileID.get()
        guard let profile = try await ProfileManager.get(profileID) else {
            throw NSError(domain: "ExtensionProfile", code: -1, userInfo: [
                NSLocalizedDescriptionKey: "Missing selected profile",
            ])
        }

        let configContent = try await profile.readAsync()
        options["configContent"] = NSString(string: configContent)

        #if !os(macOS)
            options["ignoreMemoryLimit"] = await NSNumber(value: SharedPreferences.ignoreMemoryLimit.get())
        #endif
        options["systemProxyEnabled"] = await NSNumber(value: SharedPreferences.systemProxyEnabled.get())
        options["excludeDefaultRoute"] = await NSNumber(value: SharedPreferences.excludeDefaultRoute.get())
        options["autoRouteUseSubRangesByDefault"] = await NSNumber(value: SharedPreferences.autoRouteUseSubRangesByDefault.get())
        options["excludeAPNsRoute"] = await NSNumber(value: SharedPreferences.excludeAPNsRoute.get())

        #if !os(tvOS)
            options["includeAllNetworks"] = await NSNumber(value: SharedPreferences.includeAllNetworks.get())
        #endif

        #if os(tvOS)
            options["commandServerPort"] = await NSNumber(value: SharedPreferences.commandServerPort.get())
            options["commandServerSecret"] = await NSString(string: SharedPreferences.commandServerSecret.get())
        #endif

        return options
    }

    public func fetchProfile() async throws {
        let profileID = await SharedPreferences.selectedProfileID.get()
        if let profile = try await ProfileManager.get(profileID), profile.type == .icloud {
            _ = try await profile.readAsync()
        }
    }

    public func stop() async throws {
        if isMock {
            status = .disconnecting
            try await Task.sleep(nanoseconds: 300_000_000)
            status = .disconnected
            connectedDate = nil
            return
        }
        guard let manager else { return }
        if manager.isOnDemandEnabled {
            manager.isOnDemandEnabled = false
            try await manager.saveToPreferences()
        }
        do {
            try await Task.detached(priority: .userInitiated) {
                try LibboxNewStandaloneCommandClient()!.serviceClose()
            }.value
        } catch {
            logger.debug("serviceClose error: \(error.localizedDescription)")
        }
        manager.connection.stopVPNTunnel()
    }

    public func restart() async throws {
        try await stop()
        var waitSeconds = 0
        while status != .disconnected {
            try await Task.sleep(nanoseconds: NSEC_PER_SEC)
            waitSeconds += 1
            if waitSeconds >= 5 {
                throw NSError(domain: "ExtensionProfile", code: 0, userInfo: [NSLocalizedDescriptionKey: String(localized: "Restart service timeout")])
            }
        }
        try await start()
    }

    public static func load() async throws -> ExtensionProfile? {
        let managers = try await NETunnelProviderManager.loadAllFromPreferences()
        if managers.isEmpty {
            return nil
        }
        return ExtensionProfile(managers[0])
    }

    public static func install() async throws {
        let manager = NETunnelProviderManager()
        manager.localizedDescription = Variant.applicationName
        let tunnelProtocol = NETunnelProviderProtocol()
        if Variant.useSystemExtension {
            tunnelProtocol.providerBundleIdentifier = AppConfiguration.systemExtensionBundleID
        } else {
            tunnelProtocol.providerBundleIdentifier = AppConfiguration.extensionBundleID
        }
        tunnelProtocol.serverAddress = "sing-box"
        manager.protocolConfiguration = tunnelProtocol
        manager.isEnabled = true
        try await manager.saveToPreferences()
    }
}