dotnet-cqrs/Svrnty.CQRS.Events.Abstractions/Models/CommandResultWithEvents.cs

using System;
using Svrnty.CQRS.Events.Abstractions.EventStore;
using System.Collections.Generic;
using System.Linq;

namespace Svrnty.CQRS.Events.Abstractions.Models;

/// <summary>
/// Wraps a command result with events to be emitted.
/// The framework automatically handles correlation ID assignment and event emission.
/// </summary>
/// <typeparam name="TResult">The type of the command result.</typeparam>
public sealed class CommandResultWithEvents<TResult>
{
    private readonly List<ICorrelatedEvent> _events = new();

    /// <summary>
    /// The result of the command execution.
    /// </summary>
    public TResult Result { get; }

    /// <summary>
    /// Events to be emitted with automatic correlation ID management.
    /// </summary>
    public IReadOnlyList<ICorrelatedEvent> Events => _events.AsReadOnly();

    /// <summary>
    /// Correlation ID assigned by the framework.
    /// Available after the command is processed.
    /// This setter is public for framework use but should not be set by application code.
    /// </summary>
    public string? CorrelationId { get; set; }

    public CommandResultWithEvents(TResult result)
    {
        Result = result;
    }

    public CommandResultWithEvents(TResult result, params ICorrelatedEvent[] events)
    {
        Result = result;
        _events.AddRange(events);
    }

    public CommandResultWithEvents(TResult result, IEnumerable<ICorrelatedEvent> events)
    {
        Result = result;
        _events.AddRange(events);
    }

    /// <summary>
    /// Add an event to be emitted. The correlation ID will be automatically assigned.
    /// </summary>
    public CommandResultWithEvents<TResult> AddEvent(ICorrelatedEvent @event)
    {
        _events.Add(@event);
        return this;
    }

    /// <summary>
    /// Add multiple events to be emitted. Correlation IDs will be automatically assigned.
    /// </summary>
    public CommandResultWithEvents<TResult> AddEvents(params ICorrelatedEvent[] events)
    {
        _events.AddRange(events);
        return this;
    }

    /// <summary>
    /// Add multiple events to be emitted. Correlation IDs will be automatically assigned.
    /// </summary>
    public CommandResultWithEvents<TResult> AddEvents(IEnumerable<ICorrelatedEvent> events)
    {
        _events.AddRange(events);
        return this;
    }

    /// <summary>
    /// Method used by the framework to assign correlation IDs to all events.
    /// This method is public for framework use but should not be called by application code.
    /// </summary>
    public void AssignCorrelationIds(string correlationId)
    {
        CorrelationId = correlationId;

        foreach (var @event in _events)
        {
            // Use reflection to set the correlation ID
            var correlationIdProperty = @event.GetType().GetProperty(nameof(ICorrelatedEvent.CorrelationId));
            if (correlationIdProperty != null && correlationIdProperty.CanWrite)
            {
                correlationIdProperty.SetValue(@event, correlationId);
            }
            else if (correlationIdProperty != null && correlationIdProperty.GetSetMethod(nonPublic: true) != null)
            {
                // Handle init-only properties
                correlationIdProperty.GetSetMethod(nonPublic: true)!.Invoke(@event, new object[] { correlationId });
            }
        }
    }
}

/// <summary>
/// Wraps events to be emitted for commands that don't return a result.
/// The framework automatically handles correlation ID assignment and event emission.
/// </summary>
public sealed class CommandResultWithEvents
{
    private readonly List<ICorrelatedEvent> _events = new();

    /// <summary>
    /// Events to be emitted with automatic correlation ID management.
    /// </summary>
    public IReadOnlyList<ICorrelatedEvent> Events => _events.AsReadOnly();

    /// <summary>
    /// Correlation ID assigned by the framework.
    /// Available after the command is processed.
    /// This setter is public for framework use but should not be set by application code.
    /// </summary>
    public string? CorrelationId { get; set; }

    public CommandResultWithEvents()
    {
    }

    public CommandResultWithEvents(params ICorrelatedEvent[] events)
    {
        _events.AddRange(events);
    }

    public CommandResultWithEvents(IEnumerable<ICorrelatedEvent> events)
    {
        _events.AddRange(events);
    }

    /// <summary>
    /// Add an event to be emitted. The correlation ID will be automatically assigned.
    /// </summary>
    public CommandResultWithEvents AddEvent(ICorrelatedEvent @event)
    {
        _events.Add(@event);
        return this;
    }

    /// <summary>
    /// Add multiple events to be emitted. Correlation IDs will be automatically assigned.
    /// </summary>
    public CommandResultWithEvents AddEvents(params ICorrelatedEvent[] events)
    {
        _events.AddRange(events);
        return this;
    }

    /// <summary>
    /// Add multiple events to be emitted. Correlation IDs will be automatically assigned.
    /// </summary>
    public CommandResultWithEvents AddEvents(IEnumerable<ICorrelatedEvent> events)
    {
        _events.AddRange(events);
        return this;
    }

    /// <summary>
    /// Method used by the framework to assign correlation IDs to all events.
    /// This method is public for framework use but should not be called by application code.
    /// </summary>
    public void AssignCorrelationIds(string correlationId)
    {
        CorrelationId = correlationId;

        foreach (var @event in _events)
        {
            // Use reflection to set the correlation ID
            var correlationIdProperty = @event.GetType().GetProperty(nameof(ICorrelatedEvent.CorrelationId));
            if (correlationIdProperty != null && correlationIdProperty.CanWrite)
            {
                correlationIdProperty.SetValue(@event, correlationId);
            }
            else if (correlationIdProperty != null && correlationIdProperty.GetSetMethod(nonPublic: true) != null)
            {
                // Handle init-only properties
                correlationIdProperty.GetSetMethod(nonPublic: true)!.Invoke(@event, new object[] { correlationId });
            }
        }
    }
}