using System.Text.Json;
using System.Text.Json.Serialization;

using MeWeb.Core.Net;

namespace MeWeb.Core.Knowledge;

public class ProviderFact
{
  public string Value { get; set; }
  public decimal? Price { get; set; }
  public string Currency { get; set; }
  public string Basis { get; set; }
  public string Source { get; set; }
  public string Date { get; set; }
}

public class ProviderProfile
{
  public string Name { get; set; }
  public string Country { get; set; }
  public List<uint> Asns { get; set; } = [];
  public string Sheet { get; set; }
  public ProviderFact Ipv4 { get; set; }
  public ProviderFact PublicAddress { get; set; }
  public ProviderFact Ipv6 { get; set; }
  public ProviderFact Port25 { get; set; }
}

[JsonSourceGenerationOptions(JsonSerializerDefaults.Web)]
[JsonSerializable(typeof(ProviderProfile))]
[JsonSerializable(typeof(List<Carrier>))]
[JsonSerializable(typeof(List<ObservedNetwork>))]
public partial class KnowledgeJsonContext : JsonSerializerContext
{
}

public sealed class KnowledgeBase(IPlatform platform)
{
  readonly Lazy<AsnTable> asn = new(LoadAsn);
  readonly Lazy<List<ProviderProfile>> providers = new(LoadProviders);
  readonly Lazy<NetworkTable> networks = new(LoadNetworks);
  readonly Lazy<RegistryTable> registry = new(() => LoadRegistry(platform));
  readonly Lazy<Dictionary<string, string>> carriers = new(LoadCarriers);
  readonly Lazy<List<ObservedNetwork>> observed = new(LoadObserved);

  public bool HasAsnTable => typeof(KnowledgeBase).Assembly.GetManifestResourceInfo("ip2asn.bin") is not null;

  public AsnTable Asn => asn.Value;

  public IReadOnlyList<ProviderProfile> Providers => providers.Value;

  public RegistryTable Registry => registry.Value;

  public ProviderProfile ProviderFor(uint number) => number == 0 ? null : Providers.FirstOrDefault(p => p.Asns.Contains(number));

  public ObservedNetwork ObservedFor(uint number, bool mobile) =>
      number == 0 ? null : observed.Value.FirstOrDefault(o => o.Asn == number && o.Line == (mobile ? ObservedNetwork.Mobile : ObservedNetwork.Home));

  public NetworkInfo NetworkFor(uint number) => number == 0 ? null : networks.Value?.Find(number);

  public string CarrierFor(string mccMnc) => string.IsNullOrEmpty(mccMnc) ? null : carriers.Value.GetValueOrDefault(mccMnc);

  public string NameOf(uint number) => NetworkFor(number)?.Organisation ?? Asn?.Find(number)?.Name;

  static NetworkTable LoadNetworks()
  {
    using var stream = typeof(KnowledgeBase).Assembly.GetManifestResourceStream("networks.bin");
    return stream is null ? null : NetworkTable.Read(stream);
  }

  static RegistryTable LoadRegistry(IPlatform platform)
  {
    var stream = platform.OpenRegistry();
    if (stream is null) return null;
    try
    {
      return RegistryTable.Open(stream);
    }
    catch (Exception ex) when (ex is IOException or InvalidDataException or EndOfStreamException)
    {
      stream.Dispose();
      return null;
    }
  }

  static Dictionary<string, string> LoadCarriers()
  {
    using var stream = typeof(KnowledgeBase).Assembly.GetManifestResourceStream("carriers.json");
    if (stream is null) return [];
    var list = JsonSerializer.Deserialize(stream, KnowledgeJsonContext.Default.ListCarrier) ?? [];
    return list.Where(c => c.MccMnc is not null && c.Name is not null).GroupBy(c => c.MccMnc).ToDictionary(g => g.Key, g => g.First().Name);
  }

  static List<ObservedNetwork> LoadObserved()
  {
    using var stream = typeof(KnowledgeBase).Assembly.GetManifestResourceStream("observed.json");
    return stream is null ? [] : JsonSerializer.Deserialize(stream, KnowledgeJsonContext.Default.ListObservedNetwork) ?? [];
  }

  static AsnTable LoadAsn()
  {
    using var stream = typeof(KnowledgeBase).Assembly.GetManifestResourceStream("ip2asn.bin");
    return stream is null ? null : AsnTable.Read(stream);
  }

  static List<ProviderProfile> LoadProviders()
  {
    var assembly = typeof(KnowledgeBase).Assembly;
    var list = new List<ProviderProfile>();
    foreach (var name in assembly.GetManifestResourceNames().Where(n => n.StartsWith("isp.", StringComparison.Ordinal)).Order(StringComparer.Ordinal))
    {
      using var stream = assembly.GetManifestResourceStream(name);
      var profile = JsonSerializer.Deserialize(stream, KnowledgeJsonContext.Default.ProviderProfile);
      if (profile is not null) list.Add(profile);
    }
    return list;
  }
}