internal static async Task FireCoreAsync <TState, TTrigger>(TTrigger trigger,
                                                                    RawAwaitableStateMachineBase <TState, TTrigger> machine, bool raiseInvalidStateOrTrigger = true)
        {
            var currentStateRepresentation = machine.CurrentStateRepresentation;


            var triggerRep =
                await
                AwaitableDiagnosticsHelper.FindAndEvaluateTriggerRepresentationAsync(trigger, machine,
                                                                                     raiseInvalidStateOrTrigger);

            if (triggerRep == null)
            {
                return;
            }

            // Catch invalid paramters before execution.

            Action <Transition <TState, TTrigger> >    triggerAction = null;
            Func <Transition <TState, TTrigger>, Task> triggerFunc   = null;

            if (AwaitableStateConfigurationHelper.CheckFlag(triggerRep.AwaitableTransitionFlags,
                                                            AwaitableTransitionFlag.TriggerActionReturnsTask))
            {
                try
                {
                    triggerFunc = (Func <Transition <TState, TTrigger>, Task>)triggerRep.OnTriggerAction;
                }
                catch (InvalidCastException)
                {
                    if (raiseInvalidStateOrTrigger)
                    {
                        machine.RaiseInvalidTrigger(trigger);
                    }
                    return;
                }
            }
            else
            {
                try
                {
                    triggerAction = (Action <Transition <TState, TTrigger> >)triggerRep.OnTriggerAction;
                }
                catch (InvalidCastException)
                {
                    if (raiseInvalidStateOrTrigger)
                    {
                        machine.RaiseInvalidTrigger(trigger);
                    }
                    return;
                }
            }

            AwaitableStateRepresentation <TState, TTrigger> nextStateRep = null;

            if (AwaitableStateConfigurationHelper.CheckFlag(triggerRep.AwaitableTransitionFlags,
                                                            AwaitableTransitionFlag.DynamicState))
            {
                var dynamicState = await AwaitableDiagnosticsHelper.GetValidatedDynamicTransition <TState, TTrigger>(triggerRep);

                if (dynamicState == null)
                {
                    return;
                }

                var state = dynamicState.Value.ResultingState;

                nextStateRep =
                    AwaitableStateConfigurationHelper.FindStateRepresentation(state,
                                                                              machine.Representations);
                if (nextStateRep == null)
                {
                    if (raiseInvalidStateOrTrigger)
                    {
                        machine.RaiseInvalidState(state);
                    }
                    return;
                }
            }
            else
            {
                nextStateRep =
                    (AwaitableStateRepresentation <TState, TTrigger>)triggerRep.NextStateRepresentationWrapper;
            }


            var transition = new Transition <TState, TTrigger>(currentStateRepresentation.State, nextStateRep.State);

            machine.RaiseTransitionStarted(nextStateRep.State);

            // Current exit

            if (
                AwaitableStateConfigurationHelper.CheckFlag(
                    currentStateRepresentation.AwaitableTransitionFlags,
                    AwaitableTransitionFlag.ExitReturnsTask))
            {
                var exit = (Func <Transition <TState, TTrigger>, Task>)currentStateRepresentation.OnExitAction;
                if (exit != null)
                {
                    await exit(transition);
                }
            }
            else
            {
                var exit = (Action <Transition <TState, TTrigger> >)currentStateRepresentation.OnExitAction;
                exit?.Invoke(transition);
            }

            // Trigger entry

            if (triggerAction != null)
            {
                triggerAction(transition);
            }
            else if (triggerFunc != null)
            {
                await triggerFunc(transition);
            }

            // Next entry

            if (
                AwaitableStateConfigurationHelper.CheckFlag(
                    nextStateRep.AwaitableTransitionFlags, AwaitableTransitionFlag.EntryReturnsTask))
            {
                var entry = (Func <Transition <TState, TTrigger>, Task>)nextStateRep.OnEntryAction;
                if (entry != null)
                {
                    await entry(transition);
                }
            }
            else
            {
                var entry = (Action <Transition <TState, TTrigger> >)nextStateRep.OnEntryAction;
                entry?.Invoke(transition);
            }

            var pastState = machine.CurrentState;

            machine.CurrentStateRepresentation = nextStateRep;
            machine.RaiseTransitionExecuted(pastState);
        }
        internal static async Task MoveToStateCoreAsync <TState, TTrigger>(TState state, StateTransitionOption option,
                                                                           RawAwaitableStateMachineBase <TState, TTrigger> machine, bool raiseInvalidStates = true)
        {
            AwaitableStateRepresentation <TState, TTrigger> targetRep;

            if (machine.Representations.TryGetValue(state, out targetRep))
            {
                var currentRep = machine.CurrentStateRepresentation;


                machine.RaiseTransitionStarted(targetRep.State);

                var transition = new Transition <TState, TTrigger>(currentRep.State, state);

                if ((option & StateTransitionOption.CurrentStateExitTransition) ==
                    StateTransitionOption.CurrentStateExitTransition)
                {
                    if (
                        AwaitableStateConfigurationHelper.CheckFlag(
                            currentRep.AwaitableTransitionFlags, AwaitableTransitionFlag.ExitReturnsTask))
                    {
                        var action = currentRep.OnExitAction as Func <Transition <TState, TTrigger>, Task>;
                        if (action != null)
                        {
                            await action(transition);
                        }
                    }
                    else
                    {
                        var action = currentRep.OnExitAction as Action <Transition <TState, TTrigger> >;
                        action?.Invoke(transition);
                    }
                }
                if ((option & StateTransitionOption.NewStateEntryTransition) ==
                    StateTransitionOption.NewStateEntryTransition)
                {
                    if (AwaitableStateConfigurationHelper.CheckFlag(
                            targetRep.AwaitableTransitionFlags, AwaitableTransitionFlag.EntryReturnsTask))
                    {
                        var action = targetRep.OnEntryAction as Func <Transition <TState, TTrigger>, Task>;
                        if (action != null)
                        {
                            await action(transition);
                        }
                    }
                    else
                    {
                        var action = targetRep.OnEntryAction as Action <Transition <TState, TTrigger> >;
                        action?.Invoke(transition);
                    }
                }

                var pastState = currentRep.State;
                machine.CurrentStateRepresentation = targetRep;
                machine.RaiseTransitionExecuted(pastState);
            }
            else
            {
                if (raiseInvalidStates)
                {
                    machine.RaiseInvalidState(state);
                }
            }
        }