using System.Runtime.InteropServices;
using NucleicProtocol.Interop;

namespace NucleicApp.Tests;

internal sealed class FakeNativeProtocol : INativeProtocol
{
    private NativeProtocolCallback? eventCallback;
    private NativeProtocolCallback? stateCallback;
    private nint context;

    public string? ConfigurationJson { get; private set; }
    public string? RendezvousJson { get; private set; }
    public List<string> Intents { get; } = [];
    public bool Closed { get; private set; }
    public string ProjectionResult { get; set; } = "{\"splices\":[],\"version\":1}";

    public nint ClientCreate(string configurationJson)
    {
        ConfigurationJson = configurationJson;
        return 11;
    }

    public void ClientSetCallbacks(
        nint handle, NativeProtocolCallback? eventCallback,
        NativeProtocolCallback? stateCallback, nint context)
    {
        this.eventCallback = eventCallback;
        this.stateCallback = stateCallback;
        this.context = context;
    }

    public int ClientConnectLocal(nint handle, string rendezvousJson)
    {
        RendezvousJson = rendezvousJson;
        return 0;
    }

    public int ClientConnectRemote(nint handle, string endpointJson) => 0;
    public int ClientPair(nint handle, string pairingCode) => 0;
    public int ClientSendIntent(nint handle, string clientMessageJson)
    {
        Intents.Add(clientMessageJson);
        return 0;
    }

    public void ClientClose(nint handle) => Closed = true;
    public nint ProjectionCreate() => 22;
    public nint ProjectionApply(nint projection, string hostMessageJson) =>
        Marshal.StringToCoTaskMemUTF8(ProjectionResult);
    public void ProjectionFree(nint projection) { }
    public string CopyAndFreeString(nint value)
    {
        try { return Marshal.PtrToStringUTF8(value)!; }
        finally { Marshal.FreeCoTaskMem(value); }
    }

    public void EmitEvent(string json) => Emit(eventCallback, json);
    public void EmitState(string json) => Emit(stateCallback, json);

    private void Emit(NativeProtocolCallback? callback, string json)
    {
        var pointer = Marshal.StringToCoTaskMemUTF8(json);
        try { callback?.Invoke(context, pointer); }
        finally { Marshal.FreeCoTaskMem(pointer); }
    }
}

internal sealed class FakeProtocolClient : IProtocolClient
{
    public event Action<string>? MessageJsonReceived;
    public event Action<string>? StateJsonReceived;
    public HostdRendezvous? Rendezvous { get; private set; }
    public List<string> Intents { get; } = [];
    public Queue<ProtocolResult> ConnectLocalResults { get; } = [];
    public int ConnectLocalCount { get; private set; }
    public bool Disposed { get; private set; }

    public ProtocolResult ConnectLocal(HostdRendezvous rendezvous)
    {
        ConnectLocalCount++;
        Rendezvous = rendezvous;
        return ConnectLocalResults.TryDequeue(out var result) ? result : ProtocolResult.Ok;
    }
    public ProtocolResult ConnectRemote(string endpointJson) => ProtocolResult.Ok;
    public ProtocolResult Pair(string pairingCode) => ProtocolResult.Ok;
    public ProtocolResult SendIntent(string clientMessageJson)
    {
        Intents.Add(clientMessageJson);
        return ProtocolResult.Ok;
    }
    public void Dispose() => Disposed = true;
    public void EmitMessage(string json) => MessageJsonReceived?.Invoke(json);
    public void EmitState(string json) => StateJsonReceived?.Invoke(json);
}

internal sealed class FakeProtocolClientFactory(FakeProtocolClient client) : IProtocolClientFactory
{
    public ProtocolClientConfiguration? Configuration { get; private set; }
    public IProtocolClient Create(ProtocolClientConfiguration configuration)
    {
        Configuration = configuration;
        return client;
    }
}

internal static class TestRepository
{
    public static string Root
    {
        get
        {
            var current = new DirectoryInfo(AppContext.BaseDirectory);
            while (current is not null)
            {
                if (Directory.Exists(Path.Combine(current.FullName, "fixtures", "protocol-abi")))
                    return current.FullName;
                current = current.Parent;
            }
            throw new DirectoryNotFoundException("could not locate repository fixtures");
        }
    }

    public static string Fixture(string side, string name) => File.ReadAllText(
        Path.Combine(Root, "fixtures", "protocol-abi", "v1", side, name + ".json"));
}