public async Task <TState> Execute()
{
var previousState = StatedEntity.State;
if (TransitionToInvoke == null)
{
throw new TransitionNotSpecifiedException();
}
try
{
var transition = GetRequestedTransition;
IStateHandler <TEntity> transitionHandler = transition?.OnTransitioning?.Invoke();
var validationResult = await IsPreconditionOk().ConfigureAwait(false);
if (validationResult is TransitionValidationFailed failedResult && transitionHandler != null)
{
StatedEntity.State.InitFailedTransitionResult(
previousState,
TransitionToInvoke,
failedResult);
if (transitionHandler is IPrevalidation <TEntity> pv)
{
await pv.OnValidationFailed(StatedEntity, failedResult).ConfigureAwait(false);
}
return(StatedEntity.State);
}
ITransitionExecutionResult transitionResult = null;
Exception transitionException = null;
if (transition.OnTransitioning != null)
{
try
{
transitionHandler = transition.OnTransitioning.Invoke();
if (transitionHandler is IBeforeTransition <TEntity> bth)
{
await bth.OnPrepareTransition(StatedEntity).ConfigureAwait(false);
}
transitionResult = await transitionHandler.ExecuteTransition(StatedEntity).ConfigureAwait(false);
}
catch (Exception e)
{
transitionException = e;
IsTransitionSuccessful = false;
transitionResult = CreateFailedResult(previousState, TransitionToInvoke, "TransitionFailed", e);
}
}
if (transitionResult is TransitionSuccessful successfulResult)
{
StatedEntity.State = transition.StateTransitionOnSuccess.Compile()(StatedEntity.State);
if (transitionHandler is IAfterSuccessfulTransition <TEntity> ast)
{
await ast.OnSuccessfulTransition(StatedEntity, successfulResult).ConfigureAwait(false);
}
StatedEntity.State.InitSuccessfulTransitionResult(successfulResult);
ActionOnSuccess?.Invoke(StatedEntity, StatedEntity.State);
await StateEngine.NotifyStateChange(StatedEntity).ConfigureAwait(false);
return(StatedEntity.State);
}
if (transitionHandler is IAfterFailedTransition <TEntity> aft)
{
await aft.OnFailedTransition(StatedEntity, transitionResult as TransitionFailed).ConfigureAwait(false);
}
if (transition.OnTransitionFailed == null)
{
throw new TransitionFailedException(transition.StateTransitionOnSuccess.TransitionName <TState, TStateEnum>(),
$"{previousState}", transitionException);
}
throw new TransitionRollbackFailedException(
transition.StateTransitionOnFailed?.TransitionName <TState, TStateEnum>()
?? "[rollback undefined]", $"{previousState}", transitionException);
}
catch (Exception ex)
{
StatedEntity.State.InitFailedTransitionResult(previousState, TransitionToInvoke, "TransitionExecutionFailed", ex);
StatedEntity.State.TransitionResult.AddMessageArg("", "");
ActionOnError?.Invoke(StatedEntity, StatedEntity.State);
return(StatedEntity.State);
}
}