using System.Threading;
using Svrnty.CQRS.Events.Abstractions.EventStore;
using Svrnty.CQRS.Events.Abstractions.Context;
using System.Threading.Tasks;

namespace Svrnty.CQRS.Events.Abstractions.EventHandlers;

/// <summary>
/// Command handler that can emit strongly-typed correlated events.
/// The framework automatically manages correlation IDs and event emission.
/// </summary>
/// <typeparam name="TCommand">The command type to handle.</typeparam>
/// <typeparam name="TResult">The result type returned by the command.</typeparam>
/// <typeparam name="TEvents">The base type or marker interface for events this command can emit.</typeparam>
public interface ICommandHandlerWithEvents<in TCommand, TResult, TEvents>
    where TCommand : class
    where TEvents : ICorrelatedEvent
{
    /// <summary>
    /// Handle the command and emit events using the provided event context.
    /// The framework will automatically assign correlation IDs and emit the events.
    /// </summary>
    /// <param name="command">The command to handle.</param>
    /// <param name="eventContext">Context for emitting events with automatic correlation ID management.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>The command result.</returns>
    Task<TResult> HandleAsync(TCommand command, IEventContext<TEvents> eventContext, CancellationToken cancellationToken = default);
}

/// <summary>
/// Command handler that emits events but returns no result.
/// </summary>
/// <typeparam name="TCommand">The command type to handle.</typeparam>
/// <typeparam name="TEvents">The base type or marker interface for events this command can emit.</typeparam>
public interface ICommandHandlerWithEvents<in TCommand, TEvents>
    where TCommand : class
    where TEvents : ICorrelatedEvent
{
    /// <summary>
    /// Handle the command and emit events using the provided event context.
    /// The framework will automatically assign correlation IDs and emit the events.
    /// </summary>
    /// <param name="command">The command to handle.</param>
    /// <param name="eventContext">Context for emitting events with automatic correlation ID management.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    Task HandleAsync(TCommand command, IEventContext<TEvents> eventContext, CancellationToken cancellationToken = default);
}

/// <summary>
/// Command handler that emits events and returns the result with correlation ID.
/// Use this variant when you need to return the correlation ID to the caller (e.g., for multi-step workflows).
/// </summary>
/// <typeparam name="TCommand">The command type to handle.</typeparam>
/// <typeparam name="TResult">The result type returned by the command.</typeparam>
/// <typeparam name="TEvents">The base type or marker interface for events this command can emit.</typeparam>
public interface ICommandHandlerWithEventsAndCorrelation<in TCommand, TResult, TEvents>
    where TCommand : class
    where TEvents : ICorrelatedEvent
{
    /// <summary>
    /// Handle the command and emit events using the provided event context.
    /// The framework will automatically assign correlation IDs and emit the events.
    /// Returns the result wrapped with the correlation ID for use in follow-up commands.
    /// </summary>
    /// <param name="command">The command to handle.</param>
    /// <param name="eventContext">Context for emitting events with automatic correlation ID management.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>The command result wrapped with the correlation ID.</returns>
    Task<TResult> HandleAsync(TCommand command, IEventContext<TEvents> eventContext, CancellationToken cancellationToken = default);
}