Extends select guidance with Open API info. Closes #107

Author: waldekmastykarz

m365-developer-proxy-abstractions/ProxyUtils.cs

@@ -187,7 +187,7 @@ private static string RemoveExtraSlashesFromUrl(string url) {
         return new Regex(@"([^:]\/)\/+").Replace(url, "$1");
     }
 
-    private static string GetGraphVersion(string url) {
+    public static string GetGraphVersion(string url) {
         var uri = new Uri(url);
         return uri.Segments[1].Replace("/", "");
     }

m365-developer-proxy-plugins/Guidance/GraphSelectGuidancePlugin.cs

@@ -1,37 +1,146 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
+using System.Text.RegularExpressions;
 using Microsoft.Extensions.Configuration;
+using Microsoft.OpenApi.Models;
+using Microsoft.OpenApi.Readers;
 using Microsoft365.DeveloperProxy.Abstractions;
 using Titanium.Web.Proxy.Http;
 
 namespace Microsoft365.DeveloperProxy.Plugins.Guidance;
 
-public class GraphSelectGuidancePlugin : BaseProxyPlugin {
+public class GraphSelectGuidancePlugin : BaseProxyPlugin
+{
     public override string Name => nameof(GraphSelectGuidancePlugin);
+    private readonly Dictionary<string, OpenApiDocument> _openApiDocuments = new();
 
     public override void Register(IPluginEvents pluginEvents,
                             IProxyContext context,
                             ISet<UrlToWatch> urlsToWatch,
-                            IConfigurationSection? configSection = null) {
+                            IConfigurationSection? configSection = null)
+    {
+        var proxyFolder = Path.GetDirectoryName(context.Configuration.ConfigFile);
+        var stopwatch = new System.Diagnostics.Stopwatch();
+        stopwatch.Start();
+        LoadOpenAPIFiles(proxyFolder!);
+        stopwatch.Stop();
+        UpdateOpenAPIGraphFilesIfNecessary(proxyFolder!);
+
         base.Register(pluginEvents, context, urlsToWatch, configSection);
 
         pluginEvents.AfterResponse += AfterResponse;
     }
 
-    private async Task AfterResponse(object? sender, ProxyResponseArgs e) {
+    private async Task UpdateOpenAPIGraphFilesIfNecessary(string proxyFolder)
+    {
+        var modified = false;
+        var versions = new[] { "v1.0", "beta" };
+        foreach (var version in versions)
+        {
+            try
+            {
+                var file = new FileInfo(Path.Combine(proxyFolder, "GraphProxyPlugins", $"graph-{version.Replace(".", "_")}-openapi.yaml"));
+                if (file.LastWriteTime.Date == DateTime.Now.Date)
+                {
+                    // file already updated today
+                    continue;
+                }
+
+                var url = $"https://raw.githubusercontent.com/microsoftgraph/msgraph-metadata/master/openapi/{version}/openapi.yaml";
+                var client = new HttpClient();
+                var response = await client.GetStringAsync(url);
+                File.WriteAllText(file.FullName, response);
+                modified = true;
+            }
+            catch (Exception ex)
+            {
+                _logger?.LogError(ex.Message);
+            }
+        }
+
+        if (modified)
+        {
+            LoadOpenAPIFiles(proxyFolder);
+        }
+    }
+
+    private async void LoadOpenAPIFiles(string proxyFolder)
+    {
+        var versions = new[] { "v1.0", "beta" };
+        foreach (var version in versions)
+        {
+            var file = new FileInfo(Path.Combine(proxyFolder, "GraphProxyPlugins", $"graph-{version.Replace(".", "_")}-openapi.yaml"));
+            if (!file.Exists)
+            {
+                continue;
+            }
+
+            var openApiDocument = await new OpenApiStreamReader().ReadAsync(file.OpenRead());
+            _openApiDocuments[version] = openApiDocument.OpenApiDocument;
+        }
+    }
+
+    private async Task AfterResponse(object? sender, ProxyResponseArgs e)
+    {
         Request request = e.Session.HttpClient.Request;
         if (_urlsToWatch is not null && e.HasRequestUrlMatch(_urlsToWatch) && WarnNoSelect(request))
             _logger?.LogRequest(BuildUseSelectMessage(request), MessageType.Warning, new LoggingContext(e.Session));
     }
 
-    private static bool WarnNoSelect(Request request) =>
-        ProxyUtils.IsGraphRequest(request) &&
-        request.Method == "GET" &&
-        !request.RequestUri.AbsolutePath.EndsWith("/$value", StringComparison.OrdinalIgnoreCase) &&
-        !request.Url.Contains("$select", StringComparison.OrdinalIgnoreCase) &&
-        !request.Url.Contains("%24select", StringComparison.OrdinalIgnoreCase);
+    private bool WarnNoSelect(Request request)
+    {
+        if (!ProxyUtils.IsGraphRequest(request) ||
+            request.Method != "GET")
+        {
+            return false;
+        }
+
+        var graphVersion = ProxyUtils.GetGraphVersion(request.RequestUri.AbsoluteUri);
+        var tokenizedUrl = GetTokenizedUrl(request.RequestUri.AbsoluteUri);
+
+        if (EndpointSupportsSelect(graphVersion, tokenizedUrl))
+        {
+            return !request.Url.Contains("$select", StringComparison.OrdinalIgnoreCase) &&
+            !request.Url.Contains("%24select", StringComparison.OrdinalIgnoreCase);
+        }
+        else
+        {
+            return false;
+        }
+    }
+
+    private bool EndpointSupportsSelect(string graphVersion, string relativeUrl)
+    {
+        var fallback = relativeUrl.Contains("$value", StringComparison.OrdinalIgnoreCase);
+
+        if (!_openApiDocuments.ContainsKey(graphVersion))
+        {
+            return fallback;
+        }
+
+        var relativeUrlPattern = Regex.Replace(relativeUrl, @"{[^}]+}", @"{[a-zA-Z-]+}");
+        var relativeUrlRegex = new Regex($"^{relativeUrlPattern}$");
+
+        var openApiDocument = _openApiDocuments[graphVersion];
+        var pathString = openApiDocument.Paths.Keys.FirstOrDefault(k => relativeUrlRegex.IsMatch(k));
+        if (pathString is null ||
+            !openApiDocument.Paths[pathString].Operations.ContainsKey(OperationType.Get))
+        {
+            return fallback;
+        }
+
+        var operation = openApiDocument.Paths[pathString].Operations[OperationType.Get];
+        var parameters = operation.Parameters;
+        return parameters.Any(p => p.Name == "$select");
+    }
 
     private static string GetSelectParameterGuidanceUrl() => "https://aka.ms/m365/proxy/guidance/select";
     private static string[] BuildUseSelectMessage(Request r) => new[] { $"To improve performance of your application, use the $select parameter.", $"More info at {GetSelectParameterGuidanceUrl()}" };
+
+    private static string GetTokenizedUrl(string absoluteUrl)
+    {
+        var sanitizedUrl = ProxyUtils.SanitizeUrl(absoluteUrl);
+        return "/" + String.Join("", new Uri(sanitizedUrl).Segments.Skip(2).Select(s => Uri.UnescapeDataString(s)));
+    }
 }