Refactoring in OpenApiReferencableExtensions to reduce duplicated code

Author: simon-pearson-lmk

src/Microsoft.OpenApi/Extensions/OpenApiReferencableExtensions.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. 
 
-using System;
 using System.Collections.Generic;
 using System.Linq;
 using Microsoft.OpenApi.Exceptions;
@@ -25,20 +24,29 @@ public static class OpenApiReferencableExtensions
         public static IOpenApiReferenceable ResolveReference(this IOpenApiReferenceable element, string jsonPointer)
         {
             if (jsonPointer == "/")
+            {
                 return element;
+            }
+            if (string.IsNullOrEmpty(jsonPointer))
+            {
+                throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
+            }
+            var jsonPointerTokens = jsonPointer.Split('/');
+            var propertyName = jsonPointerTokens.ElementAtOrDefault(1);
+            var mapKey = jsonPointerTokens.ElementAtOrDefault(2);
             try
             {
                 if (element.GetType() == typeof(OpenApiHeader))
                 {
-                    return ResolveReferenceOnHeaderElement((OpenApiHeader)element, jsonPointer);
+                    return ResolveReferenceOnHeaderElement((OpenApiHeader)element, propertyName, mapKey, jsonPointer);
                 }
                 if (element.GetType() == typeof(OpenApiParameter))
                 {
-                    return ResolveReferenceOnParameterElement((OpenApiParameter)element, jsonPointer);
+                    return ResolveReferenceOnParameterElement((OpenApiParameter)element, propertyName, mapKey, jsonPointer);
                 }
                 if (element.GetType() == typeof(OpenApiResponse))
                 {
-                    return ResolveReferenceOnResponseElement((OpenApiResponse)element, jsonPointer);
+                    return ResolveReferenceOnResponseElement((OpenApiResponse)element, propertyName, mapKey, jsonPointer);
                 }
             }
             catch (KeyNotFoundException)
@@ -48,78 +56,52 @@ public static IOpenApiReferenceable ResolveReference(this IOpenApiReferenceable
             throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
         }
 
-        private static IOpenApiReferenceable ResolveReferenceOnHeaderElement(OpenApiHeader headerElement, string jsonPointer)
+        private static IOpenApiReferenceable ResolveReferenceOnHeaderElement(
+            OpenApiHeader headerElement,
+            string propertyName,
+            string mapKey,
+            string jsonPointer)
         {
-            if (string.IsNullOrEmpty(jsonPointer))
-            {
-                throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
-            }
-            var jsonPointerTokens = jsonPointer.Split('/');
-            var propertyName = jsonPointerTokens.ElementAtOrDefault(1);
             switch (propertyName)
             {
                 case OpenApiConstants.Schema:
                     return headerElement.Schema;
-                case OpenApiConstants.Examples:
-                    {
-                        if (jsonPointerTokens.Length < 3)
-                            throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
-                        var mapKey = jsonPointerTokens.ElementAtOrDefault(2);
-                        return headerElement.Examples[mapKey];
-                    }
+                case OpenApiConstants.Examples when mapKey != null:
+                    return headerElement.Examples[mapKey];
                 default:
                     throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
             }
         }
 
-        private static IOpenApiReferenceable ResolveReferenceOnParameterElement(OpenApiParameter parameterElement, string jsonPointer)
+        private static IOpenApiReferenceable ResolveReferenceOnParameterElement(
+            OpenApiParameter parameterElement,
+            string propertyName,
+            string mapKey,
+            string jsonPointer)
         {
-            if (string.IsNullOrEmpty(jsonPointer))
-            {
-                throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
-            }
-            var jsonPointerTokens = jsonPointer.Split('/');
-            var propertyName = jsonPointerTokens.ElementAtOrDefault(1);
             switch (propertyName)
             {
                 case OpenApiConstants.Schema:
                     return parameterElement.Schema;
-                case OpenApiConstants.Examples:
-                    {
-                        if (jsonPointerTokens.Length < 3)
-                            throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
-                        var mapKey = jsonPointerTokens.ElementAtOrDefault(2);
-                        return parameterElement.Examples[mapKey];
-                    }
+                case OpenApiConstants.Examples when mapKey != null:
+                    return parameterElement.Examples[mapKey];
                 default:
                     throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
             }
         }
 
-        private static IOpenApiReferenceable ResolveReferenceOnResponseElement(OpenApiResponse responseElement, string jsonPointer)
+        private static IOpenApiReferenceable ResolveReferenceOnResponseElement(
+            OpenApiResponse responseElement,
+            string propertyName,
+            string mapKey,
+            string jsonPointer)
         {
-            if (string.IsNullOrEmpty(jsonPointer))
-            {
-                throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
-            }
-            var jsonPointerTokens = jsonPointer.Split('/');
-            var propertyName = jsonPointerTokens.ElementAtOrDefault(1);
             switch (propertyName)
             {
-                case OpenApiConstants.Headers:
-                    {
-                        if (jsonPointerTokens.Length < 3)
-                            throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
-                        var mapKey = jsonPointerTokens.ElementAtOrDefault(2);
-                        return responseElement.Headers[mapKey];
-                    }
-                case OpenApiConstants.Links:
-                    {
-                        if (jsonPointerTokens.Length < 3)
-                            throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
-                        var mapKey = jsonPointerTokens.ElementAtOrDefault(2);
-                        return responseElement.Links[mapKey];
-                    }
+                case OpenApiConstants.Headers when mapKey != null:
+                    return responseElement.Headers[mapKey];
+                case OpenApiConstants.Links when mapKey != null:
+                    return responseElement.Links[mapKey];
                 default:
                     throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
             }