Compute hash of OpenApi document

src/Microsoft.OpenApi.Hidi/OpenApiService.cs

@@ -356,57 +356,7 @@ public static OpenApiDocument FixReferences(OpenApiDocument document)
 
             return doc;
         }
-
-        private static async Task<Stream> GetStream(string input, ILogger logger)
-        {
-            var stopwatch = new Stopwatch();
-            stopwatch.Start();
-
-            Stream stream;
-            if (input.StartsWith("http"))
-            {
-                try
-                {
-                    var httpClientHandler = new HttpClientHandler()
-                    {
-                        SslProtocols = System.Security.Authentication.SslProtocols.Tls12,
-                    };
-                    using var httpClient = new HttpClient(httpClientHandler)
-                    {
-                      DefaultRequestVersion = HttpVersion.Version20
-                    };
-                    stream = await httpClient.GetStreamAsync(input);
-                }
-                catch (HttpRequestException ex)
-                {
-                    logger.LogError($"Could not download the file at {input}, reason{ex}");
-                    return null;
-                }
-            }
-            else 
-            {
-                try
-                {
-                    var fileInput = new FileInfo(input);
-                    stream = fileInput.OpenRead();
-                }
-                catch (Exception ex) when (ex is FileNotFoundException ||
-                    ex is PathTooLongException ||
-                    ex is DirectoryNotFoundException ||
-                    ex is IOException ||
-                    ex is UnauthorizedAccessException ||
-                    ex is SecurityException ||
-                    ex is NotSupportedException)
-                {
-                    logger.LogError($"Could not open the file at {input}, reason: {ex.Message}");
-                    return null;
-                }
-            }
-            stopwatch.Stop();
-            logger.LogTrace("{timestamp}ms: Read file {input}", stopwatch.ElapsedMilliseconds, input);
-            return stream;
-        }
-
+
         /// <summary>
         /// Takes in a file stream, parses the stream into a JsonDocument and gets a list of paths and Http methods
         /// </summary>
@@ -462,34 +412,6 @@ private static Dictionary<string, List<string>> EnumerateJsonDocument(JsonElemen
             return paths;
         }
 
-        /// <summary>
-        /// Fixes the references in the resulting OpenApiDocument.
-        /// </summary>
-        /// <param name="document"> The converted OpenApiDocument.</param>
-        /// <returns> A valid OpenApiDocument instance.</returns>
-        // private static OpenApiDocument FixReferences2(OpenApiDocument document)
-        // {
-        //     // This method is only needed because the output of ConvertToOpenApi isn't quite a valid OpenApiDocument instance.
-        //     // So we write it out, and read it back in again to fix it up.
-
-        //     OpenApiDocument document;
-        //     logger.LogTrace("Parsing the OpenApi file");
-        //     var result = await new OpenApiStreamReader(new OpenApiReaderSettings
-        //     {
-        //         RuleSet = ValidationRuleSet.GetDefaultRuleSet(),
-        //         BaseUrl = new Uri(openapi)
-        //     }
-        //     ).ReadAsync(stream);
-
-        //     document = result.OpenApiDocument;
-        //     var context = result.OpenApiDiagnostic;
-        //     var sb = new StringBuilder();
-        //     document.SerializeAsV3(new OpenApiYamlWriter(new StringWriter(sb)));
-        //     var doc = new OpenApiStringReader().Read(sb.ToString(), out _);
-
-        //     return doc;
-        // }
-
         /// <summary>
         /// Reads stream from file system or makes HTTP request depending on the input string
         /// </summary>

src/Microsoft.OpenApi.Readers/OpenApiYamlDocumentReader.cs

@@ -79,7 +79,6 @@ public OpenApiDocument Read(YamlDocument input, out OpenApiDiagnostic diagnostic
                 {
                     diagnostic.Warnings.Add(item);
                 }
-
             }
 
             return document;

src/Microsoft.OpenApi/Models/OpenApiDocument.cs

@@ -1,9 +1,12 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
+// Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. 
 
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
 using Microsoft.OpenApi.Exceptions;
 using Microsoft.OpenApi.Interfaces;
 using Microsoft.OpenApi.Services;
@@ -62,6 +65,11 @@ public class OpenApiDocument : IOpenApiSerializable, IOpenApiExtensible
         /// </summary>
         public IDictionary<string, IOpenApiExtension> Extensions { get; set; } = new Dictionary<string, IOpenApiExtension>();
 
+        /// <summary>
+        /// The unique hash code of the generated OpenAPI document
+        /// </summary>
+        public string HashCode => GenerateHashValue(this);
+
         /// <summary>
         /// Parameter-less constructor
         /// </summary>
@@ -375,6 +383,40 @@ public IOpenApiReferenceable ResolveReference(OpenApiReference reference)
             return ResolveReference(reference, false);
         }
 
+        /// <summary>
+        /// Takes in an OpenApi document instance and generates its hash value 
+        /// </summary>
+        /// <param name="doc">The OpenAPI description to hash.</param>
+        /// <returns>The hash value.</returns>
+        public static string GenerateHashValue(OpenApiDocument doc)
+        {
+            using HashAlgorithm sha = SHA512.Create();
+            using var cryptoStream = new CryptoStream(Stream.Null, sha, CryptoStreamMode.Write);
+            using var streamWriter = new StreamWriter(cryptoStream);
+
+            var openApiJsonWriter = new OpenApiJsonWriter(streamWriter, new OpenApiJsonWriterSettings { Terse = true });
+            doc.SerializeAsV3(openApiJsonWriter);
+            openApiJsonWriter.Flush();
+
+            cryptoStream.FlushFinalBlock();
+            var hash = sha.Hash;
+
+            return ConvertByteArrayToString(hash);
+        }
+
+        private static string ConvertByteArrayToString(byte[] hash)
+        {
+            // Build the final string by converting each byte
+            // into hex and appending it to a StringBuilder
+            StringBuilder sb = new StringBuilder();
+            for (int i = 0; i < hash.Length; i++)
+            {
+                sb.Append(hash[i].ToString("X2"));
+            }
+
+            return sb.ToString();
+        }
+
         /// <summary>
         /// Load the referenced <see cref="IOpenApiReferenceable"/> object from a <see cref="OpenApiReference"/> object
         /// </summary>

test/Microsoft.OpenApi.Readers.Tests/Microsoft.OpenApi.Readers.Tests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
     <PropertyGroup>
         <TargetFrameworks>net6.0</TargetFrameworks>
         <GeneratePackageOnBuild>false</GeneratePackageOnBuild>

test/Microsoft.OpenApi.Readers.Tests/V2Tests/OpenApiDocumentTests.cs

@@ -208,7 +208,7 @@ public void ShouldParseProducesInAnyOrder()
                     {
                         Type = ReferenceType.Schema,
                         Id = "Error",
-                        HostDocument= doc
+                        HostDocument = doc
                     },
                     Properties = new Dictionary<string, OpenApiSchema>()
                                                     {
@@ -407,7 +407,7 @@ public void ShouldAssignSchemaToAllResponses()
                 {
                     Id = "Error",
                     Type = ReferenceType.Schema,
-                    HostDocument= document
+                    HostDocument = document
                 }
             };
             var responses = document.Paths["/items"].Operations[OperationType.Get].Responses;

test/Microsoft.OpenApi.Readers.Tests/V3Tests/OpenApiDocumentTests.cs

@@ -34,8 +34,10 @@ public T Clone<T>(T element) where T : IOpenApiSerializable
             {
                 IOpenApiWriter writer;
                 var streamWriter = new FormattingStreamWriter(stream, CultureInfo.InvariantCulture);
-                writer = new OpenApiJsonWriter(streamWriter, new OpenApiJsonWriterSettings() {
-                InlineLocalReferences = true});
+                writer = new OpenApiJsonWriter(streamWriter, new OpenApiJsonWriterSettings()
+                {
+                    InlineLocalReferences = true
+                });
                 element.SerializeAsV3(writer);
                 writer.Flush();
                 stream.Position = 0;
@@ -48,7 +50,7 @@ public T Clone<T>(T element) where T : IOpenApiSerializable
             }
         }
 
-        public OpenApiSecurityScheme CloneSecurityScheme(OpenApiSecurityScheme element) 
+        public OpenApiSecurityScheme CloneSecurityScheme(OpenApiSecurityScheme element)
         {
             using (var stream = new MemoryStream())
             {

test/Microsoft.OpenApi.Readers.Tests/V3Tests/OpenApiSchemaTests.cs

@@ -423,7 +423,7 @@ public void ParseBasicSchemaWithReferenceShouldSucceed()
                                 }
                             }
                         }
-                    },options => options.Excluding(m => m.Name == "HostDocument"));
+                    }, options => options.Excluding(m => m.Name == "HostDocument"));
             }
         }
 

test/Microsoft.OpenApi.Tests/Microsoft.OpenApi.Tests.csproj

@@ -36,6 +36,20 @@
   </ItemGroup>
 
   <ItemGroup>
+    <EmbeddedResource Include="Models\Samples\sampleDocument.yaml">
+    <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </EmbeddedResource>
+    <EmbeddedResource Include="Models\Samples\sampleDocumentWithWhiteSpaces.yaml">
+        <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </EmbeddedResource>
+  </ItemGroup>
+
+  <ItemGroup>
+
     <None Update="PublicApi\PublicApi.approved.txt" CopyToOutputDirectory="Always" />
   </ItemGroup>
+
+  <ItemGroup>
+    <Folder Include="Models\Samples\" />
+  </ItemGroup>
 </Project>

test/Microsoft.OpenApi.Tests/Models/OpenApiDocumentTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
+// Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. 
 
 using System;
@@ -10,6 +10,7 @@
 using Microsoft.OpenApi.Extensions;
 using Microsoft.OpenApi.Interfaces;
 using Microsoft.OpenApi.Models;
+using Microsoft.OpenApi.Readers;
 using Microsoft.OpenApi.Writers;
 using VerifyXunit;
 using Xunit;
@@ -1314,5 +1315,32 @@ public void SerializeRelativeRootPathWithHostAsV2JsonWorks()
             actual.Should().Be(expected);
         }
 
+        [Fact]
+        public void TestHashCodesForSimilarOpenApiDocuments()
+        {
+            // Arrange
+            var sampleFolderPath = "Models/Samples/";            
+
+            var doc1 = ParseInputFile(Path.Combine(sampleFolderPath, "sampleDocument.yaml"));
+            var doc2 = ParseInputFile(Path.Combine(sampleFolderPath, "sampleDocument.yaml"));
+            var doc3 = ParseInputFile(Path.Combine(sampleFolderPath, "sampleDocumentWithWhiteSpaces.yaml"));
+
+            // Act && Assert
+            /*
+                Test whether reading in two similar documents yield the same hash code,
+                And reading in similar documents(one has a whitespace) yields the same hash code as the result is terse
+            */
+            Assert.True(doc1.HashCode != null && doc2.HashCode != null && doc1.HashCode.Equals(doc2.HashCode));
+            Assert.Equal(doc1.HashCode, doc3.HashCode);
+        }
+
+        private static OpenApiDocument ParseInputFile(string filePath)
+        {
+            // Read in the input yaml file
+            using FileStream stream = File.OpenRead(filePath);
+            var openApiDoc = new OpenApiStreamReader().Read(stream, out var diagnostic);
+
+            return openApiDoc;
+        }
     }
 }

test/Microsoft.OpenApi.Tests/Models/Samples/sampleDocument.yaml

@@ -0,0 +1,5 @@
+openapi : 3.0.0
+info:
+    title: Simple Document
+    version: 0.9.1
+paths: {}

test/Microsoft.OpenApi.Tests/Models/Samples/sampleDocumentWithWhiteSpaces.yaml

@@ -0,0 +1,9 @@
+openapi : 3.0.0
+
+info:
+    title: Simple Document
+
+    version: 0.9.1
+
+paths: {}
+

test/Microsoft.OpenApi.Tests/PublicApi/PublicApi.approved.txt

@@ -525,6 +525,7 @@ namespace Microsoft.OpenApi.Models
         public Microsoft.OpenApi.Models.OpenApiComponents Components { get; set; }
         public System.Collections.Generic.IDictionary<string, Microsoft.OpenApi.Interfaces.IOpenApiExtension> Extensions { get; set; }
         public Microsoft.OpenApi.Models.OpenApiExternalDocs ExternalDocs { get; set; }
+        public string HashCode { get; }
         public Microsoft.OpenApi.Models.OpenApiInfo Info { get; set; }
         public Microsoft.OpenApi.Models.OpenApiPaths Paths { get; set; }
         public System.Collections.Generic.IList<Microsoft.OpenApi.Models.OpenApiSecurityRequirement> SecurityRequirements { get; set; }
@@ -535,6 +536,7 @@ namespace Microsoft.OpenApi.Models
         public System.Collections.Generic.IEnumerable<Microsoft.OpenApi.Models.OpenApiError> ResolveReferences() { }
         public void SerializeAsV2(Microsoft.OpenApi.Writers.IOpenApiWriter writer) { }
         public void SerializeAsV3(Microsoft.OpenApi.Writers.IOpenApiWriter writer) { }
+        public static string GenerateHashValue(Microsoft.OpenApi.Models.OpenApiDocument doc) { }
     }
     public class OpenApiEncoding : Microsoft.OpenApi.Interfaces.IOpenApiElement, Microsoft.OpenApi.Interfaces.IOpenApiExtensible, Microsoft.OpenApi.Interfaces.IOpenApiSerializable
     {