KArtSell.Aegis/docs/Design/kbx-foundation-v52-fe-operational-navigation-screen-anatomy/backend/Shared/Workflow/WorkflowGuard.cs

namespace KBX.Shared.Workflow;

public sealed record WorkflowTransition(string Id, IReadOnlySet<string> From, string To, string? Permission = null, bool ReasonRequired = false);

public static class WorkflowGuard
{
    public static WorkflowTransition RequireTransition(IEnumerable<WorkflowTransition> transitions, string transitionId, string currentState, string? reason = null)
    {
        var transition = transitions.FirstOrDefault(x => string.Equals(x.Id, transitionId, StringComparison.OrdinalIgnoreCase))
            ?? throw new InvalidOperationException($"Unknown transition: {transitionId}");
        if (!transition.From.Contains(currentState)) throw new InvalidOperationException($"Transition {transitionId} is not allowed from {currentState}.");
        if (transition.ReasonRequired && string.IsNullOrWhiteSpace(reason)) throw new InvalidOperationException("A reason is required for this transition.");
        return transition;
    }
}