using System.Collections.Generic;
using System.Linq;
using System.Net.NetworkInformation;
using System.Net.Sockets;
using NetTool.Client.Models;

namespace NetTool.Client.Services;

public sealed class NetworkAdapterService
{
    public IReadOnlyList<AdapterInfo> GetAdapters()
    {
        return NetworkInterface
            .GetAllNetworkInterfaces()
            .Select(BuildAdapterInfo)
            .OrderByDescending(adapter => adapter.RecommendationScore)
            .ThenBy(adapter => adapter.Name)
            .ToList();
    }

    public AdapterInfo? GetRecommendedAdapter(IReadOnlyList<AdapterInfo> adapters)
    {
        return adapters
            .OrderByDescending(adapter => adapter.RecommendationScore)
            .ThenBy(adapter => adapter.Name)
            .FirstOrDefault();
    }

    private static AdapterInfo BuildAdapterInfo(NetworkInterface adapter)
    {
        var ipv4Address = adapter
            .GetIPProperties()
            .UnicastAddresses
            .FirstOrDefault(address => address.Address.AddressFamily == AddressFamily.InterNetwork)
            ?.Address
            .ToString() ?? string.Empty;

        var score = GetRecommendationScore(adapter, ipv4Address);
        var (label, reason) = GetRecommendation(score, adapter, ipv4Address);

        return AdapterInfo.FromNetworkInterface(adapter, ipv4Address, score, label, reason);
    }

    private static int GetRecommendationScore(NetworkInterface adapter, string ipv4Address)
    {
        var score = 0;
        var description = adapter.Description;
        var isVirtual = IsVirtualAdapter(description);

        if (adapter.NetworkInterfaceType is NetworkInterfaceType.Ethernet or NetworkInterfaceType.GigabitEthernet)
        {
            score += 50;
        }

        if (adapter.OperationalStatus == OperationalStatus.Up)
        {
            score += 40;
        }

        if (ipv4Address.StartsWith("169.254.", System.StringComparison.Ordinal))
        {
            score += 30;
        }

        if (!isVirtual)
        {
            score += 20;
        }

        if (description.Contains("Intel", System.StringComparison.OrdinalIgnoreCase)
            || description.Contains("Realtek", System.StringComparison.OrdinalIgnoreCase)
            || description.Contains("Broadcom", System.StringComparison.OrdinalIgnoreCase))
        {
            score += 10;
        }

        if (isVirtual)
        {
            score -= 40;
        }

        return score;
    }

    private static (string Label, string Reason) GetRecommendation(int score, NetworkInterface adapter, string ipv4Address)
    {
        if (score >= 90)
        {
            if (ipv4Address.StartsWith("169.254.", System.StringComparison.Ordinal))
            {
                return ("推荐", "已连接且当前 IPv4 为 169.254 网段，最像初始化直连网卡。");
            }

            return ("推荐", "已检测到已连接的网卡，适合作为初始化连接口。");
        }

        if (score >= 40)
        {
            return ("可选", "该网卡可用，但不是最优候选，请确认是否为实际直连接口。");
        }

        return ("不建议", "该网卡更像虚拟或非直连接口，通常不建议用于设备初始化。");
    }

    private static bool IsVirtualAdapter(string description)
    {
        return description.Contains("VMware", System.StringComparison.OrdinalIgnoreCase)
            || description.Contains("Virtual", System.StringComparison.OrdinalIgnoreCase)
            || description.Contains("Hyper-V", System.StringComparison.OrdinalIgnoreCase)
            || description.Contains("TAP", System.StringComparison.OrdinalIgnoreCase)
            || description.Contains("VPN", System.StringComparison.OrdinalIgnoreCase)
            || description.Contains("Loopback", System.StringComparison.OrdinalIgnoreCase);
    }
}