added comments and returning SnapshotReference type from Parse()

Author: t-vvidyasaga

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationProvider.cs

@@ -884,9 +884,9 @@ await CallWithRequestTracing(async () =>
                                         _requestTracingOptions.UpdateSnapshotReferenceTracing(setting.ContentType);
                                     }
 
-                                    var snapshotReference = new SnapshotReference { SnapshotName = SnapshotReferenceParser.Parse(setting) };
+                                    var snapshotReference = SnapshotReferenceParser.Parse(setting);
 
-                                    Dictionary<string, ConfigurationSetting> resolvedSettings = await Resolve(snapshotReference, client, cancellationToken).ConfigureAwait(false);
+                                    Dictionary<string, ConfigurationSetting> resolvedSettings = await LoadSnapshotData(snapshotReference.SnapshotName, client, cancellationToken).ConfigureAwait(false);
 
                                     foreach (KeyValuePair<string, ConfigurationSetting> resolvedSetting in resolvedSettings)
                                     {
@@ -926,7 +926,7 @@ await CallWithRequestTracing(async () =>
 
                     var snapshotReference = new SnapshotReference { SnapshotName = loadOption.SnapshotName };
 
-                    Dictionary<string, ConfigurationSetting> resolvedSettings = await Resolve(snapshotReference, client, cancellationToken).ConfigureAwait(false);
+                    Dictionary<string, ConfigurationSetting> resolvedSettings = await LoadSnapshotData(snapshotReference.SnapshotName, client, cancellationToken).ConfigureAwait(false);
 
                     foreach (KeyValuePair<string, ConfigurationSetting> resolvedSetting in resolvedSettings)
                     {
@@ -938,16 +938,16 @@ await CallWithRequestTracing(async () =>
             return data;
         }
 
-        private async Task<Dictionary<string, ConfigurationSetting>> Resolve(SnapshotReference snapshotReference, ConfigurationClient client, CancellationToken cancellationToken)
+        private async Task<Dictionary<string, ConfigurationSetting>> LoadSnapshotData(string snapshotName, ConfigurationClient client, CancellationToken cancellationToken)
         {
             var resolvedSettings = new Dictionary<string, ConfigurationSetting>();
 
-            if (snapshotReference.SnapshotName == null)
+            if (snapshotName == null)
             {
                 throw new InvalidOperationException(ErrorMessages.SnapshotReferenceNull);
             }
 
-            if (snapshotReference.SnapshotName == string.Empty)
+            if (snapshotName == string.Empty)
             {
                 return resolvedSettings;
             }
@@ -956,7 +956,7 @@ private async Task<Dictionary<string, ConfigurationSetting>> Resolve(SnapshotRef
 
             try
             {
-                await CallWithRequestTracing(async () => snapshot = await client.GetSnapshotAsync(snapshotReference.SnapshotName, cancellationToken: cancellationToken).ConfigureAwait(false)).ConfigureAwait(false);
+                await CallWithRequestTracing(async () => snapshot = await client.GetSnapshotAsync(snapshotName, cancellationToken: cancellationToken).ConfigureAwait(false)).ConfigureAwait(false);
             }
             catch (RequestFailedException rfe) when (rfe.Status == (int)HttpStatusCode.NotFound)
             {
@@ -970,7 +970,7 @@ private async Task<Dictionary<string, ConfigurationSetting>> Resolve(SnapshotRef
             }
 
             IAsyncEnumerable<ConfigurationSetting> settingsEnumerable = client.GetConfigurationSettingsForSnapshotAsync(
-                snapshotReference.SnapshotName,
+                snapshotName,
                 cancellationToken);
 
             await CallWithRequestTracing(async () =>
@@ -1028,9 +1028,9 @@ private async Task<Dictionary<KeyValueIdentifier, ConfigurationSetting>> LoadKey
                             _requestTracingOptions.UpdateSnapshotReferenceTracing(watchedKv.ContentType);
                         }
 
-                        var snapshotReference = new SnapshotReference { SnapshotName = SnapshotReferenceParser.Parse(watchedKv) };
+                        var snapshotReference = SnapshotReferenceParser.Parse(watchedKv);
 
-                        Dictionary<string, ConfigurationSetting> resolvedSettings = await Resolve(snapshotReference, client, cancellationToken).ConfigureAwait(false);
+                        Dictionary<string, ConfigurationSetting> resolvedSettings = await LoadSnapshotData(snapshotReference.SnapshotName, client, cancellationToken).ConfigureAwait(false);
 
                         foreach (KeyValuePair<string, ConfigurationSetting> resolvedSetting in resolvedSettings)
                         {

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Extensions/ContentTypeExtensions.cs

@@ -83,6 +83,11 @@ public static bool IsKeyVaultReference(this ContentType contentType)
             return contentType.MediaType.Equals(KeyVaultConstants.ContentType);
         }
 
+        /*
+            Profile and media type are distinct components of the content type.
+            They aren't required to be space-separated, and their order isn't guaranteed.
+            This makes raw string matching hard.
+        */
         public static bool IsSnapshotReference(this ContentType contentType)
         {
             return contentType.MediaType.Equals(SnapshotReferenceConstants.ContentType);

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/SnapshotReferences/SnapshotReferenceParser.cs

@@ -16,9 +16,9 @@ internal static class SnapshotReferenceParser
         /// Parses a snapshot name from a snapshot reference configuration setting.
         /// </summary>
         /// <param name="setting">The configuration setting containing the snapshot reference JSON.</param>
-        /// <returns>The snapshot name if found and valid; otherwise, null.</returns>
+        /// <returns>The snapshot reference if found and valid; otherwise, null.</returns>
         /// <exception cref="FormatException">Thrown when the setting contains invalid JSON or invalid snapshot reference format.</exception>
-        public static string Parse(ConfigurationSetting setting)
+        public static SnapshotReference Parse(ConfigurationSetting setting)
         {
             if (setting == null)
             {
@@ -32,7 +32,7 @@ public static string Parse(ConfigurationSetting setting)
 
             try
             {
-                Utf8JsonReader reader = new Utf8JsonReader(System.Text.Encoding.UTF8.GetBytes(setting.Value));
+                var reader = new Utf8JsonReader(System.Text.Encoding.UTF8.GetBytes(setting.Value));
 
                 if (reader.Read() && reader.TokenType != JsonTokenType.StartObject)
                 {
@@ -50,7 +50,7 @@ public static string Parse(ConfigurationSetting setting)
                     {
                         if (reader.Read() && reader.TokenType == JsonTokenType.String)
                         {
-                            return reader.GetString();
+                            return new SnapshotReference { SnapshotName = reader.GetString() };
                         }
                         else
                         {