using System.Text;
using NATS.Server.JetStream;
using NATS.Server.JetStream.Api;
using NATS.Server.JetStream.Consumers;
using NATS.Server.JetStream.Models;
using NATS.Server.JetStream.Publish;

namespace NATS.Server.Tests;

internal sealed class JetStreamApiFixture : IAsyncDisposable
{
    private static readonly StreamManager SharedStreamManager = new();
    private static readonly ConsumerManager SharedConsumerManager = new();
    private static readonly JetStreamApiRouter SharedRouter = new(SharedStreamManager, SharedConsumerManager);

    private readonly StreamManager _streamManager;
    private readonly ConsumerManager _consumerManager;
    private readonly JetStreamApiRouter _router;
    private readonly JetStreamPublisher _publisher;

    private JetStreamApiFixture()
    {
        _streamManager = new StreamManager();
        _consumerManager = new ConsumerManager();
        _router = new JetStreamApiRouter(_streamManager, _consumerManager);
        _publisher = new JetStreamPublisher(_streamManager);
    }

    public static Task<JetStreamApiResponse> RequestAsync(string subject, string payload)
    {
        return Task.FromResult(SharedRouter.Route(subject, Encoding.UTF8.GetBytes(payload)));
    }

    public static async Task<JetStreamApiFixture> StartWithStreamAsync(string streamName, string subject, int maxMsgs = 0)
    {
        var fixture = new JetStreamApiFixture();
        var payload = $"{{\"name\":\"{streamName}\",\"subjects\":[\"{subject}\"],\"max_msgs\":{maxMsgs}}}";
        _ = await fixture.RequestLocalAsync($"$JS.API.STREAM.CREATE.{streamName}", payload);
        return fixture;
    }

    public static async Task<JetStreamApiFixture> StartWithPullConsumerAsync()
    {
        var fixture = await StartWithStreamAsync("ORDERS", "orders.*");
        _ = await fixture.CreateConsumerAsync("ORDERS", "PULL", "orders.created");
        return fixture;
    }

    public static async Task<JetStreamApiFixture> StartWithPushConsumerAsync()
    {
        var fixture = await StartWithStreamAsync("ORDERS", "orders.*");
        _ = await fixture.CreateConsumerAsync("ORDERS", "PUSH", "orders.created", push: true, heartbeatMs: 25);
        return fixture;
    }

    public Task<PubAck> PublishAndGetAckAsync(string subject, string payload, string? msgId = null, bool expectError = false)
    {
        if (_publisher.TryCapture(subject, Encoding.UTF8.GetBytes(payload), msgId, out var ack))
        {
            if (ack.ErrorCode == null && _streamManager.TryGet(ack.Stream, out var streamHandle))
            {
                var stored = streamHandle.Store.LoadAsync(ack.Seq, default).GetAwaiter().GetResult();
                if (stored != null)
                    _consumerManager.OnPublished(ack.Stream, stored);
            }

            return Task.FromResult(ack);
        }

        if (expectError)
            return Task.FromResult(new PubAck { ErrorCode = 404 });

        throw new InvalidOperationException($"No stream matched subject '{subject}'.");
    }

    public Task<JetStreamApiResponse> RequestLocalAsync(string subject, string payload)
    {
        return Task.FromResult(_router.Route(subject, Encoding.UTF8.GetBytes(payload)));
    }

    public Task<StreamState> GetStreamStateAsync(string streamName)
    {
        return _streamManager.GetStateAsync(streamName, default).AsTask();
    }

    public Task<JetStreamApiResponse> CreateConsumerAsync(string stream, string durableName, string filterSubject, bool push = false, int heartbeatMs = 0)
    {
        var payload = $@"{{""durable_name"":""{durableName}"",""filter_subject"":""{filterSubject}"",""push"":{push.ToString().ToLowerInvariant()},""heartbeat_ms"":{heartbeatMs}}}";
        return RequestLocalAsync($"$JS.API.CONSUMER.CREATE.{stream}.{durableName}", payload);
    }

    public async Task<JetStreamConsumerInfo> GetConsumerInfoAsync(string stream, string durableName)
    {
        var response = await RequestLocalAsync($"$JS.API.CONSUMER.INFO.{stream}.{durableName}", "{}");
        return response.ConsumerInfo ?? throw new InvalidOperationException("Consumer not found.");
    }

    public Task<PullFetchBatch> FetchAsync(string stream, string durableName, int batch)
    {
        return _consumerManager.FetchAsync(stream, durableName, batch, _streamManager, default).AsTask();
    }

    public Task<PushFrame> ReadPushFrameAsync(string stream = "ORDERS", string durableName = "PUSH")
    {
        var frame = _consumerManager.ReadPushFrame(stream, durableName);
        if (frame == null)
            throw new InvalidOperationException("No push frame available.");
        return Task.FromResult(frame);
    }

    public ValueTask DisposeAsync() => ValueTask.CompletedTask;
}