public async Task <ICommandResult> Execute(Command command)
{
if (command == null)
{
throw new ArgumentNullException(nameof(command));
}
var iterator = new CommandIterator(command);
var currentController = (CommandController <TContext>)Activator.CreateInstance(typeof(TMainController), _context, iterator);
while (true)
{
ICommandResult result;
if (iterator.HasNext)
{
result = await ExecuteControllerMethod(currentController, iterator, iterator.GetNext()).ConfigureAwait(false);
}
else
{
result = await ExecuteControllerMethod(currentController, iterator).ConfigureAwait(false);
}
if (result is ForwardResult forwardResult)
{
var args = new List <object>();
args.Add(_context);
args.Add(iterator);
args.AddRange(forwardResult.ControllerArgs);
currentController = (CommandController <TContext>)Activator.CreateInstance(forwardResult.ControllerType, args.ToArray());
}
else
{
return(result);
}
}
throw new IncompleteCommandException("Command iterator reached end but execution chain goes on.");
}
private Task <ICommandResult> ExecuteControllerMethod(CommandController <TContext> controller, CommandIterator commandIterator, string methodName = default)
{
MethodInfo method;
if (methodName == default)
{
method = controller.GetType().GetMethods().FirstOrDefault(m => m.GetCustomAttribute <DefaultCommandAttribute>(true) != null);
if (method == null)
{
throw new InvalidCommandException($"Controller {controller} has no default command handler.");
}
}
else
{
method = controller.GetType().GetMethods().FirstOrDefault(m => m.GetCustomAttribute <CommandAttribute>(true)?.Command == methodName);
if (method == null)
{
throw new InvalidCommandException($"Controller {controller} has no handler for the {methodName} command.");
}
}
var args = new List <object>();
foreach (ParameterInfo parameter in method.GetParameters())
{
if (!commandIterator.HasNext)
{
throw new IncompleteCommandException("Command iterator reached end but command method requires argument.");
}
args.Add(commandIterator.GetNext(parameter.ParameterType));
}
return((Task <ICommandResult>)method.Invoke(controller, args.ToArray()));
}
protected CommandController(TContext context, CommandIterator commandIterator)
{
Context = context ?? throw new ArgumentNullException(nameof(context));
CommandIterator = commandIterator ?? throw new ArgumentNullException(nameof(commandIterator));
}