/*
* Default JSON handler, simply returning a JsonResult to caller.
*/
internal static IActionResult JsonHandler(MagicResponse response)
{
// Checking if JSON is already converted into a string, at which point we return it as such.
if (response.Content is string strContent)
{
return new ContentResult {
Content = strContent, StatusCode = response.Result
}
}
;
// Strongly typed JSON object, hence returning as such.
return(new JsonResult(response.Content as JToken)
{
StatusCode = response.Result
});
}
}
/*
* Transforms from our internal HttpResponse wrapper to an ActionResult
*/
IActionResult HandleResponse(MagicResponse response)
{
// Decorating envelope of response which returns Content-Type to us.
var contentType = DecorateResponseEnvelope(response);
// If empty result, we return nothing.
if (response.Content == null)
{
return(new StatusCodeResult(response.Result));
}
/*
* Figuring out how to return response, which depends upon its Content-Type, and
* whether or not we have a registered handler for specified Content-Type or not.
*/
if (_responseHandlers.TryGetValue(contentType, out var functor))
{
return(functor(response));
}
else
{
// Generic handler for everything except specialised handlers registered for different content types.
if (response.Content is string strResponse)
{
return new ContentResult {
Content = strResponse, StatusCode = response.Result
}
}
;
if (response.Content is byte[] bytesResponse)
{
return(new FileContentResult(bytesResponse, Response.ContentType));
}
if (response.Content is Stream streamResponse)
{
return(new FileStreamResult(streamResponse, Response.ContentType));
}
throw new HyperlambdaException($"Unsupported return value from Hyperlambda, returning objects of type '{response.Content.GetType().FullName}' is not supported");
}
}
/*
* Responsible for decorating envlope of HTTP response.
*/
string DecorateResponseEnvelope(MagicResponse response)
{
// Making sure we attach any explicitly added HTTP headers to the response.
foreach (var idx in response.Headers)
{
Response.Headers.Add(idx.Key, idx.Value);
}
// Making sure we attach all cookies.
foreach (var idx in response.Cookies)
{
var options = new CookieOptions
{
Secure = idx.Secure,
Expires = idx.Expires,
HttpOnly = idx.HttpOnly,
Domain = idx.Domain,
Path = idx.Path,
};
if (!string.IsNullOrEmpty(idx.SameSite))
{
options.SameSite = (SameSiteMode)Enum.Parse(typeof(SameSiteMode), idx.SameSite, true);
}
Response.Cookies.Append(idx.Name, idx.Value, options);
}
// Unless explicitly overridden by service, we default Content-Type to JSON / UTF8.
if (!response.Headers.ContainsKey("Content-Type") || string.IsNullOrEmpty(response.Headers["Content-Type"]))
{
Response.ContentType = "application/json; char-set=utf-8";
return("application/json");
}
else
{
// Figuring out Content-Type (minus arguments).
return(Response.ContentType
.Split(';')
.Select(x => x.Trim())
.FirstOrDefault()
.ToLowerInvariant());
}
}
#endregion
}
/// <inheritdoc/>
public async Task <MagicResponse> ExecuteAsync(MagicRequest request)
{
// Sanity checking invocation
if (string.IsNullOrEmpty(request.URL))
{
return new MagicResponse {
Result = 404
}
}
;
// Making sure we never resolve to anything outside of "modules/" and "system/" folder.
if (!request.URL.StartsWith("modules/") && !request.URL.StartsWith("system/"))
{
return new MagicResponse {
Result = 401
}
}
;
// Figuring out file to execute, and doing some basic sanity checking.
var path = Utilities.GetEndpointFilePath(_rootResolver, request.URL, request.Verb);
if (!await _fileService.ExistsAsync(path))
{
return new MagicResponse {
Result = 404
}
}
;
// Creating our lambda object by loading Hyperlambda file.
var lambda = HyperlambdaParser.Parse(await _fileService.LoadAsync(path));
// Applying interceptors.
lambda = await ApplyInterceptors(lambda, request.URL);
// Attaching arguments.
_argumentsHandler.Attach(lambda, request.Query, request.Payload);
// Invoking method responsible for actually executing lambda object.
return(await ExecuteAsync(lambda, request));
}
#region [ -- Private helper methods -- ]
/*
* Applies interceptors to specified Node/Lambda object.
*/
async Task <Node> ApplyInterceptors(Node result, string url)
{
// Checking to see if interceptors exists recursively upwards in folder hierarchy.
var splits = url.Split(new char [] { '/' }, StringSplitOptions.RemoveEmptyEntries);
// Stripping away last entity (filename) of invocation.
var folders = splits.Take(splits.Length - 1);
// Iterating as long as we have more entities in list of folders.
while (true)
{
// Checking if "current-folder/interceptor.hl" file exists.
var current = _rootResolver.AbsolutePath(string.Join("/", folders) + "/interceptor.hl");
if (_fileService.Exists(current))
{
result = await ApplyInterceptor(result, current);
}
// Checking if we're done, and at root folder, at which point we break while loop.
if (!folders.Any())
{
break; // We're done, no more interceptors!
}
// Traversing upwards in hierarchy to be able to nest interceptors upwards in hierarchy.
folders = folders.Take(folders.Count() - 1);
}
// Returning result to caller.
return(result);
}
/*
* Applies the specified interceptor and returns the transformed Node/Lambda result.
*/
async Task <Node> ApplyInterceptor(Node lambda, string interceptorFile)
{
// Getting interceptor lambda.
var interceptNode = HyperlambdaParser.Parse(await _fileService.LoadAsync(interceptorFile));
// Moving [.arguments] from endpoint lambda to the top of interceptor lambda if existing.
var args = lambda
.Children
.Where(x =>
x.Name == ".arguments" ||
x.Name == ".description" ||
x.Name == ".type" ||
x.Name == "auth.ticket.verify" ||
x.Name.StartsWith("validators."));
// Notice, reversing arguments nodes makes sure we apply arguments in order of appearance.
foreach (var idx in args.Reverse().ToList())
{
interceptNode.Insert(0, idx); // Notice, will detach the argument from its original position!
}
// Moving endpoint Lambda to position before any [.interceptor] node found in interceptor lambda.
foreach (var idxLambda in new Expression("**/.interceptor").Evaluate(interceptNode).ToList())
{
// Iterating through each node in current result and injecting before currently iterated [.lambda] node.
foreach (var idx in lambda.Children)
{
// This logic ensures we keep existing order without any fuzz.
// By cloning node we also support having multiple [.interceptor] nodes.
idxLambda.InsertBefore(idx.Clone());
}
// Removing currently iterated [.interceptor] node in interceptor lambda object.
idxLambda.Parent.Remove(idxLambda);
}
// Returning interceptor Node/Lambda which is now the root of the execution Lambda object.
return(interceptNode);
}
/*
* Method responsible for actually executing lambda object after file has been loaded,
* interceptors and arguments have been applied, and transforming result of invocation
* to a MagicResponse.
*/
async Task <MagicResponse> ExecuteAsync(Node lambda, MagicRequest request)
{
// Creating our result wrapper, wrapping whatever the endpoint wants to return to the client.
var result = new Node();
var response = new MagicResponse();
try
{
await _signaler.ScopeAsync("http.request", request, async() =>
{
await _signaler.ScopeAsync("http.response", response, async() =>
{
await _signaler.ScopeAsync("slots.result", result, async() =>
{
await _signaler.SignalAsync("eval", lambda);
});
});
});
response.Content = GetReturnValue(response, result);
return(response);
}
catch
{
if (result.Value is IDisposable disposable)
{
disposable.Dispose();
}
if (response.Content is IDisposable disposable2 && !object.ReferenceEquals(response.Content, result.Value))
{
disposable2.Dispose();
}
throw;
}
}
/*
* Creates a returned payload of some sort and returning to caller.
*/
object GetReturnValue(MagicResponse httpResponse, Node lambda)
{
/*
* An endpoint can return either a Node/Lambda hierarchy or a simple value.
* First we check if endpoint returned a simple value, at which point we convert it to
* a string. Notice, we're prioritising simple values, implying if return node has a
* simple value, none of its children nodes will be returned.
*/
if (lambda.Value != null)
{
// IDisposables (Streams e.g.) are automatically disposed by ASP.NET Core.
if (lambda.Value is IDisposable || lambda.Value is byte[])
{
return(lambda.Value);
}
return(lambda.Get <string>());
}
else if (lambda.Children.Any())
{
// Checking if we should return content as Hyperlambda.
if (httpResponse.Headers.TryGetValue("Content-Type", out var val) && val == "application/x-hyperlambda")
{
return(HyperlambdaGenerator.GetHyperlambda(lambda.Children));
}
// Defaulting to returning content as JSON by converting from Lambda to JSON.
var convert = new Node();
convert.AddRange(lambda.Children.ToList());
_signaler.Signal(".lambda2json-raw", convert);
return(convert.Value);
}
return(null); // No content
}
#endregion
}
}
