From ed5b550e8a19be250952371c60e1c1f3d2864a1e Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Sun, 23 Aug 2020 16:12:33 +0800
Subject: Add error code to swagger description.

---
 Timeline/Startup.cs                                |  5 +-
 .../DocumentDescriptionDocumentProcessor.cs        | 55 ++++++++++++++++++++++
 2 files changed, 58 insertions(+), 2 deletions(-)
 create mode 100644 Timeline/Swagger/DocumentDescriptionDocumentProcessor.cs

diff --git a/Timeline/Startup.cs b/Timeline/Startup.cs
index 86bdaf54..cbca01d0 100644
--- a/Timeline/Startup.cs
+++ b/Timeline/Startup.cs
@@ -104,6 +104,7 @@ namespace Timeline
                 document.DocumentName = "Timeline";
                 document.Title = "Timeline REST API Reference";
                 document.Version = typeof(Startup).Assembly.GetName().Version?.ToString() ?? "unknown version";
+                document.DocumentProcessors.Add(new DocumentDescriptionDocumentProcessor());
                 document.DocumentProcessors.Add(
                     new SecurityDefinitionAppender("JWT",
                     new OpenApiSecurityScheme
@@ -111,7 +112,7 @@ namespace Timeline
                         Type = OpenApiSecuritySchemeType.ApiKey,
                         Name = "Authorization",
                         In = OpenApiSecurityApiKeyLocation.Header,
-                        Description = "Type into the textbox: Bearer {your JWT token}."
+                        Description = "Create token via `/api/token/create` ."
                     }));
                 document.OperationProcessors.Add(new AspNetCoreOperationSecurityScopeProcessor("JWT"));
                 document.OperationProcessors.Add(new DefaultDescriptionOperationProcessor());
@@ -153,7 +154,7 @@ namespace Timeline
             }
 
             app.UseOpenApi();
-            app.UseSwaggerUi3();
+            app.UseReDoc();
 
             app.UseAuthentication();
             app.UseAuthorization();
diff --git a/Timeline/Swagger/DocumentDescriptionDocumentProcessor.cs b/Timeline/Swagger/DocumentDescriptionDocumentProcessor.cs
new file mode 100644
index 00000000..dc5ddd96
--- /dev/null
+++ b/Timeline/Swagger/DocumentDescriptionDocumentProcessor.cs
@@ -0,0 +1,55 @@
+using NSwag.Generation.Processors;
+using NSwag.Generation.Processors.Contexts;
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using System.Threading.Tasks;
+using Timeline.Models.Http;
+
+namespace Timeline.Swagger
+{
+    public class DocumentDescriptionDocumentProcessor : IDocumentProcessor
+    {
+        private static Dictionary<string, int> GetAllErrorCodes()
+        {
+            var errorCodes = new Dictionary<string, int>();
+
+            void RecursiveCheckErrorCode(Type type)
+            {
+                foreach (var field in type.GetFields(BindingFlags.Public | BindingFlags.Static | BindingFlags.FlattenHierarchy)
+                    .Where(fi => fi.IsLiteral && !fi.IsInitOnly && fi.FieldType == typeof(int)))
+                {
+                    var name = (type.FullName + "." + field.Name).Remove(0, typeof(ErrorCodes).FullName!.Length + 1).Replace("+", ".", StringComparison.OrdinalIgnoreCase);
+                    int value = (int)field.GetRawConstantValue()!;
+                    errorCodes.Add(name, value);
+                }
+
+                foreach (var nestedType in type.GetNestedTypes())
+                {
+                    RecursiveCheckErrorCode(nestedType);
+                }
+            }
+
+            RecursiveCheckErrorCode(typeof(ErrorCodes));
+
+            return errorCodes;
+        }
+
+        public void Process(DocumentProcessorContext context)
+        {
+            StringBuilder description = new StringBuilder();
+            description.AppendLine("# Error Codes");
+            description.AppendLine("name | value");
+            description.AppendLine("---- | -----");
+            foreach (var (name, value) in GetAllErrorCodes())
+            {
+                description.AppendLine($"`{name}` | `{value}`");
+            }
+
+            context.Document.Info.Description = description.ToString();
+        }
+    }
+}
-- 
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