public static FacetRequest CreateFrom(
string facetName,
string methodName,
JsonArray jsonArguments,
IEnumerable <Type> typesToSearch
)
{
var request = new FacetRequest {
FacetName = facetName,
MethodName = methodName,
JsonArguments = jsonArguments,
FacetType = Facet.FindFacetTypeByName(
facetName,
typesToSearch
)
};
request.Method = Facet.FindMethodByName(
request.FacetType,
methodName
);
request.Arguments = Facet.DeserializeArguments(
request.Method,
jsonArguments
);
request.Facet = Facet.CreateInstance(request.FacetType);
return(request);
}
/// <summary>
/// Extracts and sorts middleware layers from a facet request
/// </summary>
private static List <Layer> ObtainMiddlewareLayers(
Application app,
IEnumerable <MiddlewareAttribute> globalMiddleware,
FacetRequest request
)
{
var globalLayers = globalMiddleware
.Select(attr => new Layer(app, attr))
.OrderBy(l => l.order);
var classLayers = request.FacetType
.GetCustomAttributes <MiddlewareAttribute>(inherit: true)
.Select(attr => new Layer(app, attr))
.OrderBy(l => l.order);
var methodLayers = request.Method
.GetCustomAttributes <MiddlewareAttribute>(inherit: true)
.Select(attr => new Layer(app, attr))
.OrderBy(l => l.order);
return(globalLayers
.Concat(classLayers)
.Concat(methodLayers)
.ToList());
}
private FacetResponse Next(FacetRequest request)
{
if (currentLayerIndex >= layers.Count)
{
return(finalAction.Invoke(request));
}
var currentLayer = layers[currentLayerIndex];
currentLayerIndex++;
var response = currentLayer.middleware
.Handle(request, Next, currentLayer.parameters);
// make sure null wasn't returned
if (response == null)
{
throw new NullReferenceException(
$"Middleware {currentLayer.middleware.GetType()} has "
+ $"returned null when calling {request.FacetName}."
+ $"{request.MethodName} Returning null from "
+ "middleware is not allowed."
);
}
return(response);
}
/// <summary>
/// Executes provided closure inside all middleware layers
/// </summary>
public static FacetResponse ExecuteMiddlewareStack(
Application app,
IEnumerable <MiddlewareAttribute> globalMiddleware,
FacetRequest request,
Func <FacetRequest, FacetResponse> action
)
{
List <Layer> layers = ObtainMiddlewareLayers(
app,
globalMiddleware,
request
);
LayerIterator iterator = new LayerIterator(
layers,
action
);
return(iterator.Iterate(request));
}
/// <summary>
/// Handles a request, passes it to the next layer
/// and returns the response
/// </summary>
public abstract FacetResponse Handle(
FacetRequest request,
Func <FacetRequest, FacetResponse> next,
string[] parameters
);
public FacetResponse Iterate(FacetRequest request)
{
currentLayerIndex = 0;
return(Next(request));
}
