using System.Text.Json;
using FinalFactory.Rendezvous.Client;
using FinalFactory.Rendezvous.Contracts;

namespace FinalFactory.Rendezvous.Tests.Contracts;

public sealed class TraversalTokenCodecTests
{
    [Fact]
    public void IntroductionTokenBindsAttemptAndRedactsTheFixedTicket()
    {
        JoinAttemptId attemptId = new(Guid.Parse("00000000-0000-0000-0000-000000000301"));
        string authenticator = Credential('T');

        string encoded = NatIntroductionTokenCodec.Encode(attemptId, authenticator);

        Assert.Equal(NatIntroductionTokenCodec.EncodedLength, encoded.Length);
        Assert.True(encoded.Length <= ContractLimits.LiteNetLibNatTokenMaxCharacters);
        Assert.True(NatIntroductionTokenCodec.TryDecode(encoded, out NatIntroductionToken? decoded));
        Assert.NotNull(decoded);
        Assert.Equal(attemptId, decoded.AttemptId);
        Assert.Equal(encoded, decoded.ConnectionTicket);
        Assert.DoesNotContain(encoded, decoded.ToString(), StringComparison.Ordinal);
    }

    [Fact]
    public void ConnectionTicketMatchesTheVersionedV1Vector()
    {
        using JsonDocument vector = JsonDocument.Parse(ContractTestFiles.Read("connection-ticket.json"));
        JsonElement root = vector.RootElement;
        JoinAttemptId attemptId = new(Guid.Parse(root.GetProperty("attemptId").GetString()!));
        string authenticator = root.GetProperty("derivedAuthenticator").GetString()!;

        string ticket = NatIntroductionTokenCodec.Encode(attemptId, authenticator);

        Assert.Equal(root.GetProperty("connectionTicket").GetString(), ticket);
        Assert.Equal(root.GetProperty("digest").GetString(), NatIntroductionTokenCodec.ComputeDigest(ticket));
    }

    [Fact]
    public void IntroductionTokenRejectsNonCanonicalOrAlteredFields()
    {
        string valid = NatIntroductionTokenCodec.Encode(
            new JoinAttemptId(Guid.Parse("abcdef00-0000-0000-0000-000000000302")),
            Credential('T'));

        Assert.False(NatIntroductionTokenCodec.TryDecode(null, out _));
        Assert.False(NatIntroductionTokenCodec.TryDecode(valid[..^1], out _));
        Assert.False(NatIntroductionTokenCodec.TryDecode(valid[..^1] + "!", out _));
        Assert.False(NatIntroductionTokenCodec.TryDecode(new string('A', 43), out _));
    }

    [Fact]
    public void DirectConnectionRequestRoundTripsFixedBoundedPayloadAndRedactsTicket()
    {
        JoinAttemptId attemptId = new(Guid.Parse("00000000-0000-0000-0000-000000000303"));
        string ticket = Credential('D');

        byte[] encoded = DirectConnectionRequestCodec.Encode(attemptId, ticket);

        Assert.Equal(DirectConnectionRequestCodec.EncodedLength, encoded.Length);
        Assert.True(DirectConnectionRequestCodec.TryDecode(encoded, out DirectConnectionRequest? decoded));
        Assert.NotNull(decoded);
        Assert.Equal(attemptId, decoded.AttemptId);
        Assert.Equal(ticket, decoded.ConnectionTicket);
        Assert.DoesNotContain(ticket, decoded.ToString(), StringComparison.Ordinal);

        encoded[0] ^= 0xff;
        Assert.False(DirectConnectionRequestCodec.TryDecode(encoded, out _));
        Assert.False(DirectConnectionRequestCodec.TryDecode(encoded.AsSpan(1), out _));
    }

    private static string Credential(char value) => new(value, ContractLimits.DerivedCredentialCharacters);
}