using OpenAC.MosswartMassacre.Backend;
using OpenAC.MosswartMassacre.Tests.Fakes;

namespace OpenAC.MosswartMassacre.Tests.Backend;

public sealed class BackendClientTests
{
    private static readonly DateTime Connected = new(2026, 9, 25, 8, 30, 15, DateTimeKind.Utc);

    [Fact]
    public async Task Connect_sends_the_secret_header_then_registers_first()
    {
        using var server = new TestSocketServer();
        using var client = new BackendClient(new RecordingLogger());

        client.Start(server.Uri, "s3cret", "Mossy", () => Connected);

        Assert.Equal("{\"type\":\"register\",\"player_name\":\"Mossy\"}", server.NextFrame());
        Assert.True(server.Secrets.TryPeek(out string? secret));
        Assert.Equal("s3cret", secret);
        Assert.True(await WaitAsync(() => client.TryTakeConnection(out _)));
    }

    [Fact]
    public async Task Frames_sent_after_connect_arrive_in_order()
    {
        using var server = new TestSocketServer();
        using var client = new BackendClient(new RecordingLogger());
        client.Start(server.Uri, "", "Mossy", () => Connected);
        server.NextFrame();
        Assert.True(await WaitAsync(() => client.IsConnected));

        client.Send("{\"n\":1}");
        client.Send("{\"n\":2}");

        Assert.Equal("{\"n\":1}", server.NextFrame());
        Assert.Equal("{\"n\":2}", server.NextFrame());
    }

    [Fact]
    public void A_frame_sent_while_disconnected_is_dropped()
    {
        using var client = new BackendClient(new RecordingLogger());
        Assert.False(client.Send("{}"));
    }

    [Fact]
    public async Task A_frame_larger_than_one_receive_buffer_is_reassembled()
    {
        using var server = new TestSocketServer();
        using var client = new BackendClient(new RecordingLogger());
        client.Start(server.Uri, "", "Mossy", () => Connected);
        server.NextFrame();
        Assert.True(await WaitAsync(() => client.IsConnected));

        string big = "{\"type\":\"share_vital_update\",\"pad\":\"" + new string('x', 20000) + "\"}";
        await server.PushAsync("  " + big + "\n");

        string? received = null;
        Assert.True(await WaitAsync(() => client.TryReceive(out received)));
        Assert.Equal(big, received);
    }

    [Fact]
    public async Task A_dropped_socket_reconnects_and_registers_again()
    {
        using var server = new TestSocketServer();
        using var client = new BackendClient(new RecordingLogger());
        client.Start(server.Uri, "", "Mossy", () => Connected);
        server.NextFrame();
        Assert.True(await WaitAsync(() => client.IsConnected));

        await server.DropAsync();

        Assert.Equal("{\"type\":\"register\",\"player_name\":\"Mossy\"}", server.NextFrame(8000));
        Assert.Equal(2, server.Connections);
    }

    [Fact]
    public async Task Stop_closes_and_stops_reconnecting()
    {
        using var server = new TestSocketServer();
        using var client = new BackendClient(new RecordingLogger());
        client.Start(server.Uri, "", "Mossy", () => Connected);
        server.NextFrame();
        Assert.True(await WaitAsync(() => client.IsConnected));

        client.Stop();

        Assert.False(client.IsRunning);
        Assert.False(client.IsConnected);
        await Task.Delay(2500);
        Assert.Equal(1, server.Connections);
    }

    [Fact]
    public async Task Stop_sends_what_was_queued_before_it_closes_without_blocking()
    {
        using var server = new TestSocketServer();
        using var client = new BackendClient(new RecordingLogger());
        client.Start(server.Uri, "", "Mossy", () => Connected);
        server.NextFrame();
        Assert.True(await WaitAsync(() => client.IsConnected));

        string big = "{\"type\":\"full_inventory\",\"pad\":\"" + new string('x', 400_000) + "\"}";
        client.Send(big);
        client.Send("{\"type\":\"share_unsubscribe\"}");
        var watch = System.Diagnostics.Stopwatch.StartNew();
        client.Stop();
        Assert.True(watch.ElapsedMilliseconds < 200, $"Stop blocked for {watch.ElapsedMilliseconds} ms");

        Assert.Equal(big, server.NextFrame());
        Assert.Equal("{\"type\":\"share_unsubscribe\"}", server.NextFrame());
        await client.LastStop.WaitAsync(TimeSpan.FromSeconds(15));
    }

    [Fact]
    public async Task A_new_start_right_after_stop_hears_only_its_own_connection()
    {
        using var server = new TestSocketServer();
        using var client = new BackendClient(new RecordingLogger());
        client.Start(server.Uri, "", "Mossy", () => Connected);
        server.NextFrame();
        Assert.True(await WaitAsync(() => client.IsConnected));
        client.Stop();

        client.Start(server.Uri, "", "Horan", () => Connected);

        Assert.Equal("{\"type\":\"register\",\"player_name\":\"Horan\"}", server.NextFrame(8000));
        Assert.True(await WaitAsync(() => client.TryTakeConnection(out _)));
        Assert.False(client.TryTakeConnection(out _));
    }

    internal static async Task<bool> WaitAsync(Func<bool> condition, int timeoutMs = 5000)
    {
        for (int waited = 0; waited < timeoutMs; waited += 20)
        {
            if (condition())
                return true;
            await Task.Delay(20);
        }
        return condition();
    }
}