using System;
using System.Threading;
using System.Threading.Tasks;

namespace Svrnty.CQRS.Events.Abstractions.Sagas;

/// <summary>
/// Orchestrates saga execution with compensation logic.
/// </summary>
public interface ISagaOrchestrator
{
    /// <summary>
    /// Start a new saga instance.
    /// </summary>
    /// <typeparam name="TSaga">The saga type.</typeparam>
    /// <param name="correlationId">Correlation ID for this saga.</param>
    /// <param name="initialData">Optional initial saga data.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>The saga ID.</returns>
    Task<string> StartSagaAsync<TSaga>(
        string correlationId,
        ISagaData? initialData = null,
        CancellationToken cancellationToken = default)
        where TSaga : ISaga;

    /// <summary>
    /// Resume a paused saga.
    /// </summary>
    /// <param name="sagaId">The saga ID to resume.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    Task ResumeSagaAsync(string sagaId, CancellationToken cancellationToken = default);

    /// <summary>
    /// Cancel a running saga (triggers compensation).
    /// </summary>
    /// <param name="sagaId">The saga ID to cancel.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    Task CancelSagaAsync(string sagaId, CancellationToken cancellationToken = default);

    /// <summary>
    /// Get saga status.
    /// </summary>
    /// <param name="sagaId">The saga ID.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>Saga status information.</returns>
    Task<SagaStatus> GetStatusAsync(string sagaId, CancellationToken cancellationToken = default);
}

/// <summary>
/// Status information for a saga instance.
/// </summary>
public sealed record SagaStatus
{
    /// <summary>
    /// Saga instance ID.
    /// </summary>
    public required string SagaId { get; init; }

    /// <summary>
    /// Correlation ID.
    /// </summary>
    public required string CorrelationId { get; init; }

    /// <summary>
    /// Saga type name.
    /// </summary>
    public required string SagaName { get; init; }

    /// <summary>
    /// Current state.
    /// </summary>
    public SagaState State { get; init; }

    /// <summary>
    /// Current step index being executed.
    /// </summary>
    public int CurrentStep { get; init; }

    /// <summary>
    /// Total number of steps.
    /// </summary>
    public int TotalSteps { get; init; }

    /// <summary>
    /// When the saga started.
    /// </summary>
    public DateTimeOffset StartedAt { get; init; }

    /// <summary>
    /// When the saga last updated.
    /// </summary>
    public DateTimeOffset LastUpdated { get; init; }

    /// <summary>
    /// When the saga completed (if completed).
    /// </summary>
    public DateTimeOffset? CompletedAt { get; init; }

    /// <summary>
    /// Error message (if failed).
    /// </summary>
    public string? ErrorMessage { get; init; }

    /// <summary>
    /// Saga data.
    /// </summary>
    public System.Collections.Generic.IDictionary<string, object>? Data { get; init; }
}