using FieldLogger.Sync;

namespace FieldLogger.Sync.Tests;

/// <summary>
/// In-memory stand-in for the broker. Records published payloads, lets a test toggle
/// connectivity, force publish failures, and inject application-level acks — so the engine's
/// durability/ack/backoff behaviour is exercised without MQTTnet or a live broker.
/// </summary>
public sealed class FakeMqttTransport : IMqttTransport
{
    public bool IsConnected { get; set; } = true;
    public bool FailNextPublish { get; set; }
    public List<(string Topic, byte[] Payload)> Published { get; } = new();

    public event Func<AckBatch, Task>? AckReceived;

    public Task ConnectAsync(string ackTopic, CancellationToken ct = default)
    {
        IsConnected = true;
        return Task.CompletedTask;
    }

    public Task DisconnectAsync()
    {
        IsConnected = false;
        return Task.CompletedTask;
    }

    public Task PublishAsync(string topic, byte[] payload, string schemaVersion, CancellationToken ct = default)
    {
        if (!IsConnected) throw new InvalidOperationException("not connected");
        if (FailNextPublish)
        {
            FailNextPublish = false;
            throw new InvalidOperationException("simulated broker publish failure");
        }
        Published.Add((topic, payload));
        return Task.CompletedTask;
    }

    /// <summary>Simulate the cloud emitting an application-level ack for these pointIds.</summary>
    public async Task InjectAckAsync(params AckItem[] items)
    {
        if (AckReceived is { } handlers)
        {
            var batch = new AckBatch { Results = items.ToList() };
            foreach (Func<AckBatch, Task> handler in handlers.GetInvocationList())
                await handler(batch);
        }
    }

    public Task InjectAcceptAsync(string pointId) =>
        InjectAckAsync(new AckItem { PointId = pointId, Outcome = AckOutcome.ACCEPTED });

    public Task InjectDuplicateAsync(string pointId) =>
        InjectAckAsync(new AckItem { PointId = pointId, Outcome = AckOutcome.DUPLICATE });

    public Task InjectRejectAsync(string pointId, string reasonCode) =>
        InjectAckAsync(new AckItem { PointId = pointId, Outcome = AckOutcome.REJECTED, ReasonCode = reasonCode });
}