63 lines
2.3 KiB
C#
63 lines
2.3 KiB
C#
 
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using System.IO.Compression;
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using System.Text;
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namespace MeWeb.Core.Knowledge;
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public class NetworkInfo
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{
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public uint Number { get; set; }
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public string Organisation { get; set; }
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public List<uint> Upstreams { get; set; } = [];
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}
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public sealed class NetworkTable
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{
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const uint Magic = 0x324B574D;
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readonly Dictionary<uint, NetworkInfo> networks = [];
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public DateTimeOffset BuiltAt { get; private set; }
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public int Count => networks.Count;
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public NetworkInfo Find(uint number) => networks.GetValueOrDefault(number);
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public static NetworkTable Read(Stream compressed)
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{
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using var brotli = new BrotliStream(compressed, CompressionMode.Decompress);
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using var reader = new BinaryReader(brotli, Encoding.UTF8);
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if (reader.ReadUInt32() != Magic) throw new InvalidDataException("not a me-web? network table");
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var table = new NetworkTable { BuiltAt = DateTimeOffset.FromUnixTimeSeconds(reader.ReadInt64()) };
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var count = reader.Read7BitEncodedInt();
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var previous = 0u;
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for (var i = 0; i < count; i++)
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{
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previous += (uint)reader.Read7BitEncodedInt64();
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var info = new NetworkInfo { Number = previous, Organisation = reader.ReadString() };
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var upstreams = reader.Read7BitEncodedInt();
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for (var u = 0; u < upstreams; u++) info.Upstreams.Add((uint)reader.Read7BitEncodedInt64());
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if (info.Organisation.Length == 0) info.Organisation = null;
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table.networks[info.Number] = info;
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}
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return table;
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}
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public static void Write(Stream output, DateTimeOffset builtAt, IEnumerable<NetworkInfo> networks)
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{
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var list = networks.Where(n => n.Number != 0).OrderBy(n => n.Number).ToList();
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using var brotli = new BrotliStream(output, CompressionLevel.SmallestSize, leaveOpen: true);
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using var writer = new BinaryWriter(brotli, Encoding.UTF8);
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writer.Write(Magic);
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writer.Write(builtAt.ToUnixTimeSeconds());
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writer.Write7BitEncodedInt(list.Count);
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var previous = 0u;
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foreach (var info in list)
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{
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writer.Write7BitEncodedInt64(info.Number - previous);
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writer.Write(info.Organisation ?? "");
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writer.Write7BitEncodedInt(info.Upstreams.Count);
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foreach (var upstream in info.Upstreams) writer.Write7BitEncodedInt64(upstream);
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previous = info.Number;
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}
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}
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}
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