feat(referrers): support referrers API (#180)

Signed-off-by: Patrick Pan <[email protected]>

src/OrasProject.Oras/Exceptions/InvalidReferenceException.cs

@@ -16,7 +16,7 @@
 namespace OrasProject.Oras.Exceptions;
 
 /// <summary>
-/// InvalidReferenceException is thrown when the reference is invlid
+/// InvalidReferenceException is thrown when the reference is invalid.
 /// </summary>
 public class InvalidReferenceException : FormatException
 {

src/OrasProject.Oras/Exceptions/InvalidResponseException.cs

@@ -0,0 +1,36 @@
+// Copyright The ORAS Authors.
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
+
+namespace OrasProject.Oras.Exceptions;
+
+/// <summary>
+/// InvalidResponseException is thrown when the response is invalid.
+/// </summary>
+public class InvalidResponseException : FormatException
+{
+    public InvalidResponseException()
+    {
+    }
+
+    public InvalidResponseException(string? message)
+        : base(message)
+    {
+    }
+
+    public InvalidResponseException(string? message, Exception? inner)
+        : base(message, inner)
+    {
+    }
+}

src/OrasProject.Oras/Registry/Reference.cs

@@ -200,7 +200,7 @@ public static bool TryParse(string reference, [NotNullWhen(true)] out Reference?
             return false;
         }
     }
-
+    
     public Reference(Reference other)
     {
         if (other == null)

src/OrasProject.Oras/Registry/Remote/ManifestStore.cs

@@ -14,8 +14,6 @@
 using OrasProject.Oras.Exceptions;
 using OrasProject.Oras.Oci;
 using System;
-using System.Collections.Generic;
-using System.Collections.Immutable;
 using System.IO;
 using System.Net;
 using System.Net.Http;
@@ -274,7 +272,7 @@ private async Task UpdateReferrersIndex(Descriptor subject,
     {
         // 1. pull the original referrers index list using referrers tag schema
         var referrersTag = Referrers.BuildReferrersTag(subject);
-        var (oldDesc, oldReferrers) = await PullReferrersIndexList(referrersTag, cancellationToken).ConfigureAwait(false);
+        var (oldDesc, oldReferrers) = await Repository.PullReferrersIndexList(referrersTag, cancellationToken).ConfigureAwait(false);
 
         // 2. apply the referrer change to referrers list
         var (updatedReferrers, updateRequired) =
@@ -309,34 +307,6 @@ private async Task UpdateReferrersIndex(Descriptor subject,
         await DeleteAsync(oldDesc, cancellationToken).ConfigureAwait(false);
     }
 
-    /// <summary>
-    /// PullReferrersIndexList retrieves the referrers index list associated with the given referrers tag.
-    /// It fetches the index manifest from the repository, deserializes it into an `Index` object, 
-    /// and returns the descriptor along with the list of manifests (referrers). If the referrers index is not found, 
-    /// an empty descriptor and an empty list are returned.
-    /// </summary>
-    /// <param name="referrersTag"></param>
-    /// <param name="cancellationToken"></param>
-    /// <returns></returns>
-    internal async Task<(Descriptor?, IList<Descriptor>)> PullReferrersIndexList(String referrersTag, CancellationToken cancellationToken = default)
-    {
-        try
-        {
-            var (desc, content) = await FetchAsync(referrersTag, cancellationToken).ConfigureAwait(false);
-            var index = JsonSerializer.Deserialize<Index>(content);
-            if (index == null)
-            {
-                throw new JsonException($"null index manifests list when pulling referrers index list for referrers tag {referrersTag}");
-            }
-            return (desc, index.Manifests);
-        }
-        catch (NotFoundException)
-        {
-            return (null, ImmutableArray<Descriptor>.Empty);
-        }
-    }
-
-
     /// <summary>
     /// Pushes the manifest content, matching the expected descriptor.
     /// </summary>

src/OrasProject.Oras/Registry/Remote/Referrers.cs

@@ -12,6 +12,7 @@
 // limitations under the License.
 
 using System.Collections.Generic;
+using System.Linq;
 using OrasProject.Oras.Content;
 using OrasProject.Oras.Oci;
 
@@ -105,4 +106,40 @@ internal static (IList<Descriptor>, bool) ApplyReferrerChanges(IList<Descriptor>
 
         return (updatedReferrers, updateRequired);
     }
+
+    /// <summary>
+    /// IsReferrersFilterApplied checks if requstedFilter is in the applied filters list.
+    /// </summary>
+    /// <param name="appliedFilters"></param>
+    /// <param name="requestedFilter"></param>
+    /// <returns></returns>
+    internal static bool IsReferrersFilterApplied(string? appliedFilters, string requestedFilter) {
+        if (string.IsNullOrEmpty(appliedFilters) || string.IsNullOrEmpty(requestedFilter))
+        {
+            return false;
+        }
+
+        var filters = appliedFilters.Split(",");
+        foreach (var filter in filters)
+        {
+            if (filter == requestedFilter)
+            {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /// <summary>
+    /// FilterReferrers filters out a list of referrers based on the specified artifact type
+    /// </summary>
+    /// <param name="referrers"></param>
+    /// <param name="artifactType"></param>
+    /// <returns></returns>
+    internal static IList<Descriptor> FilterReferrers(IList<Descriptor> referrers, string? artifactType)
+    {
+        return string.IsNullOrEmpty(artifactType) ? referrers : referrers.Where(referrer => referrer.ArtifactType == artifactType).ToList();
+    }
 }
+