using System.Collections.Generic;
using Svrnty.CQRS.Events.Abstractions.EventStore;
using System.Threading;
using System.Threading.Tasks;

namespace Svrnty.CQRS.Events.Abstractions.EventStore;

/// <summary>
/// Service for emitting events from command handlers.
/// Events are stored and delivered to subscribers based on their subscriptions.
/// </summary>
public interface IEventEmitter
{
    /// <summary>
    /// Emit an event with the specified correlation ID.
    /// </summary>
    /// <param name="event">The event to emit.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>The sequence number assigned to this event.</returns>
    Task<long> EmitAsync(ICorrelatedEvent @event, CancellationToken cancellationToken = default);

    /// <summary>
    /// Emit multiple events with the same correlation ID in a batch.
    /// </summary>
    /// <param name="events">The events to emit.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>Dictionary mapping event IDs to their sequence numbers.</returns>
    Task<Dictionary<string, long>> EmitBatchAsync(IEnumerable<ICorrelatedEvent> events, CancellationToken cancellationToken = default);
}