files tree made better.

src/Yavsc/AuthorizationServer/RequiredScopesMiddleware.cs

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+using Microsoft.AspNet.Builder;
+using Microsoft.AspNet.Http;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Claims;
+using System.Threading.Tasks;
+
+namespace Api
+{
+    public class RequiredScopesMiddleware
+    {
+        private readonly RequestDelegate _next;
+        private readonly IEnumerable<string> _requiredScopes;
+
+        public RequiredScopesMiddleware(RequestDelegate next, IList<string> requiredScopes)
+        {
+            _next = next;
+            _requiredScopes = requiredScopes;
+        }
+
+        public async Task Invoke(HttpContext context)
+        {
+            if (context.User.Identity.IsAuthenticated)
+            {
+                if (!ScopePresent(context.User))
+                {
+                    context.Response.OnCompleted(Send403, context);
+                    return;
+                }
+            }
+
+            await _next(context);
+        }
+
+        private bool ScopePresent(ClaimsPrincipal principal)
+        {
+            foreach (var scope in principal.FindAll("scope"))
+            {
+                if (_requiredScopes.Contains(scope.Value))
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        private Task Send403(object contextObject)
+        {
+            var context = contextObject as HttpContext;
+            context.Response.StatusCode = 403;
+
+            return Task.FromResult(0);
+        }
+    }
+}
+