Implement NuGet's legacy V2 APIs

src/BaGet.Core/Extensions/DependencyInjectionExtensions.cs

@@ -75,6 +75,7 @@ private static void AddBaGetServices(this IServiceCollection services)
             services.TryAddSingleton<IPackageDownloadsSource, PackageDownloadsJsonSource>();
 
             services.TryAddSingleton<ISearchResponseBuilder, SearchResponseBuilder>();
+            services.TryAddSingleton<IV2Builder, V2Builder>();
             services.TryAddSingleton<NuGetClient>();
             services.TryAddSingleton<NullSearchIndexer>();
             services.TryAddSingleton<NullSearchService>();

src/BaGet.Core/IUrlGenerator.cs

@@ -13,6 +13,11 @@ public interface IUrlGenerator
         /// </summary>
         string GetServiceIndexUrl();
 
+        /// <summary>
+        /// Get the URL for the package source that implements the legacy NuGet V2 API.
+        /// </summary>
+        string GetServiceIndexV2Url();
+
         /// <summary>
         /// Get the URL for the root of the package content resource.
         /// See: https://docs.microsoft.com/en-us/nuget/api/package-base-address-resource
@@ -80,6 +85,13 @@ public interface IUrlGenerator
         /// <param name="id">The package's ID</param>
         string GetPackageVersionsUrl(string id);
 
+        /// <summary>
+        /// Get the URL to download a package (.nupkg).
+        /// See: https://docs.microsoft.com/en-us/nuget/api/package-base-address-resource#download-package-content-nupkg
+        /// </summary>
+        /// <param name="package">The package to download</param>
+        string GetPackageDownloadUrl(Package package);
+
         /// <summary>
         /// Get the URL to download a package (.nupkg).
         /// See: https://docs.microsoft.com/en-us/nuget/api/package-base-address-resource#download-package-content-nupkg
@@ -101,5 +113,11 @@ public interface IUrlGenerator
         /// <param name="id">The package's ID</param>
         /// <param name="version">The package's version</param>
         string GetPackageIconDownloadUrl(string id, NuGetVersion version);
+
+        /// <summary>
+        /// Get the URL for the metadata of a single package version.
+        /// </summary>
+        /// <param name="package">The package to lookup</param>
+        string GetPackageMetadataV2Url(Package package);
     }
 }

src/BaGet.Core/Metadata/RegistrationBuilder.cs

@@ -52,7 +52,7 @@ public virtual RegistrationLeafResponse BuildLeaf(Package package)
                 Listed = package.Listed,
                 Published = package.Published,
                 RegistrationLeafUrl = _url.GetRegistrationLeafUrl(id, version),
-                PackageContentUrl = _url.GetPackageDownloadUrl(id, version),
+                PackageContentUrl = _url.GetPackageDownloadUrl(package),
                 RegistrationIndexUrl = _url.GetRegistrationIndexUrl(id)
             };
         }
@@ -61,7 +61,7 @@ private BaGetRegistrationIndexPageItem ToRegistrationIndexPageItem(Package packa
             new BaGetRegistrationIndexPageItem
             {
                 RegistrationLeafUrl = _url.GetRegistrationLeafUrl(package.Id, package.Version),
-                PackageContentUrl = _url.GetPackageDownloadUrl(package.Id, package.Version),
+                PackageContentUrl = _url.GetPackageDownloadUrl(package),
                 PackageMetadata = new BaGetPackageMetadata
                 {
                     PackageId = package.Id,
@@ -78,7 +78,7 @@ private BaGetRegistrationIndexPageItem ToRegistrationIndexPageItem(Package packa
                     Listed = package.Listed,
                     MinClientVersion = package.MinClientVersion,
                     ReleaseNotes = package.ReleaseNotes,
-                    PackageContentUrl = _url.GetPackageDownloadUrl(package.Id, package.Version),
+                    PackageContentUrl = _url.GetPackageDownloadUrl(package),
                     PackageTypes = package.PackageTypes.Select(t => t.Name).ToList(),
                     ProjectUrl = package.ProjectUrlString,
                     RepositoryUrl = package.RepositoryUrlString,

src/BaGet.Core/Upstream/Clients/V2UpstreamClient.cs

@@ -23,30 +23,26 @@ namespace BaGet.Core
     /// </summary>
     public class V2UpstreamClient : IUpstreamClient, IDisposable
     {
-        private readonly SourceCacheContext _cache;
         private readonly SourceRepository _repository;
-        private readonly INuGetLogger _ngLogger;
         private readonly ILogger _logger;
 
+        private readonly SourceCacheContext _cache = new SourceCacheContext();
+        private readonly INuGetLogger _ngLogger = NullLogger.Instance;
+
         public V2UpstreamClient(
             IOptionsSnapshot<MirrorOptions> options,
             ILogger logger)
         {
-            if (options is null)
-            {
-                throw new ArgumentNullException(nameof(options));
-            }
-
-            if (options.Value?.PackageSource?.AbsolutePath == null)
-            {
-                throw new ArgumentException("No mirror package source has been set.");
-            }
+            var source = new PackageSource(options.Value.PackageSource.AbsoluteUri);
 
+            _repository = Repository.Factory.GetCoreV2(source);
             _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
 
-            _ngLogger = NullLogger.Instance;
-            _cache = new SourceCacheContext();
-            _repository = Repository.Factory.GetCoreV2(new PackageSource(options.Value.PackageSource.AbsoluteUri));
+        public V2UpstreamClient(SourceRepository repository, ILogger logger)
+        {
+            _repository = repository;
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
         }
 
         public async Task<IReadOnlyList<NuGetVersion>> ListPackageVersionsAsync(string id, CancellationToken cancellationToken)
@@ -138,9 +134,9 @@ private Package ToPackage(IPackageSearchMetadata package)
                 Description = package.Description,
                 Downloads = 0,
                 HasReadme = false,
-                Language = null,
+                Language = string.Empty,
                 Listed = package.IsListed,
-                MinClientVersion = null,
+                MinClientVersion = string.Empty,
                 Published = package.Published?.UtcDateTime ?? DateTime.MinValue,
                 RequireLicenseAcceptance = package.RequireLicenseAcceptance,
                 Summary = package.Summary,

src/BaGet.Core/V2/IV2Builder.cs

@@ -0,0 +1,13 @@
+using System.Collections.Generic;
+using System.Xml.Linq;
+
+namespace BaGet.Core
+{
+    // TODO: comments
+    public interface IV2Builder
+    {
+        XElement BuildIndex();
+        XElement BuildPackages(IReadOnlyList<Package> packages);
+        XElement BuildPackage(Package package);
+    }
+}

src/BaGet.Core/V2/V2Builder.cs

@@ -0,0 +1,231 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Xml.Linq;
+
+namespace BaGet.Core
+{
+    public class V2Builder : IV2Builder
+    {
+        private readonly IUrlGenerator _url;
+
+        public V2Builder(IUrlGenerator url)
+        {
+            _url = url;
+        }
+
+        public XElement BuildIndex()
+        {
+            var serviceIndex = _url.GetServiceIndexV2Url();
+
+            return XElement.Parse($@"
+<service xmlns=""http://www.w3.org/2007/app"" xmlns:atom=""http://www.w3.org/2005/Atom"" xml:base=""{serviceIndex}"">
+  <workspace>
+    <atom:title type=""text"">Default</atom:title>
+    <collection href=""Packages"">
+      <atom:title type=""text"">Packages</atom:title>
+    </collection>
+  </workspace>
+</service>");
+        }
+
+        public XElement BuildPackages(IReadOnlyList<Package> packages)
+        {
+            // See: https://joelverhagen.github.io/NuGetUndocs/#endpoint-find-packages-by-id
+            var serviceIndex = _url.GetServiceIndexV2Url();
+
+            // TODO: Add <?xml version="1.0" encoding="utf-8"?> to top
+            // TODO: nuget.org adds `m:null="true"` attribute to elements with no value. Is that necessary?
+            return new XElement(
+                N.feed,
+                new XAttribute(N.baze, XNamespace.Get(serviceIndex)),
+                new XAttribute(N.m, NS.m),
+                new XAttribute(N.d, NS.d),
+                new XAttribute(N.georss, NS.georss),
+                new XAttribute(N.gml, NS.gml),
+                new XElement(N.m_count, packages.Count),
+
+                packages.Select(package =>
+                {
+                    var packageV2Url = _url.GetPackageMetadataV2Url(package);
+                    var downloadUrl = _url.GetPackageDownloadUrl(package);
+
+                    return new XElement(
+                        N.entry,
+                        new XElement(N.id, packageV2Url),
+                        new XElement(N.title, package.Id),
+                        new XElement(
+                            N.content,
+                            new XAttribute("type", "application/zip"),
+                            new XAttribute("src", downloadUrl)
+                        ),
+
+                        BuildAuthor(package),
+                        BuildProperties(package)
+                    );
+                })
+            );
+        }
+
+        public XElement BuildPackage(Package package)
+        {
+            // See: https://joelverhagen.github.io/NuGetUndocs/#endpoint-get-a-single-package
+            var serviceIndex = _url.GetServiceIndexV2Url();
+            var packageV2Url = _url.GetPackageMetadataV2Url(package);
+            var downloadUrl = _url.GetPackageDownloadUrl(package);
+
+            return new XElement(
+                N.entry,
+                new XAttribute(N.baze, XNamespace.Get(serviceIndex)),
+                new XAttribute(N.m, NS.m),
+                new XAttribute(N.d, NS.d),
+                new XAttribute(N.georss, NS.georss),
+                new XAttribute(N.gml, NS.gml),
+
+                new XElement(N.id, packageV2Url),
+                new XElement(
+                    N.content,
+                    new XAttribute("type", "application/zip"),
+                    new XAttribute("src", downloadUrl)
+                ),
+                new XElement(N.summary, package.Summary),
+                new XElement(N.title, package.Title),
+
+                BuildAuthor(package),
+                BuildProperties(package)
+            );
+        }
+
+        private XElement BuildProperties(Package package)
+        {
+            // See: https://joelverhagen.github.io/NuGetUndocs/#package-entity
+            return new XElement(
+                N.m_properties,
+                new XElement(N.d_Authors, string.Join(", ", package.Authors)),
+                new XElement(N.d_Copyright, ""), // TODO
+                new XElement(N.d_Description, package.Description),
+                new XElement(
+                    N.d_DownloadCount,
+                    new XAttribute(N.m_type, "Edm.Int32"),
+                    package.Downloads),
+                new XElement(N.d_IconUrl, package.IconUrl), // TODO, URL logic
+                new XElement(N.d_Id, package.Id),
+                new XElement(N.d_IsPrerelease, package.Version.IsPrerelease),
+                new XElement(N.d_Language, package.Language),
+                new XElement(N.d_LastEdited, package.Published),
+                new XElement(N.d_LicenseUrl, package.LicenseUrl), // TODO
+                new XElement(N.d_MinClientVersion, package.MinClientVersion),
+                new XElement(N.d_NormalizedVersion, package.NormalizedVersionString),
+                new XElement(N.d_PackageHash, ""),
+                new XElement(N.d_PackageHashAlgorithm, ""),
+                new XElement(N.d_PackageSize, 0),
+                new XElement(N.d_ProjectUrl, package.ProjectUrl),
+                new XElement(N.d_Published, package.Published),
+                new XElement(N.d_ReleaseNotes, package.ReleaseNotes),
+                new XElement(N.d_RequireLicenseAcceptance, package.RequireLicenseAcceptance),
+                new XElement(N.d_Summary, package.Summary),
+                new XElement(N.d_Tags, string.Join(" ", package.Tags)),
+                new XElement(N.d_Title, package.Title),
+                new XElement(N.d_Version, package.OriginalVersionString),
+
+                BuildDependencies(package)
+            );
+        }
+
+        private XElement BuildAuthor(Package package)
+        {
+            return new XElement(
+                N.author,
+                new XElement(N.name, string.Join(", ", package.Authors))
+            );
+        }
+
+        private XElement BuildDependencies(Package package)
+        {
+            var flattenedDependencies = new List<string>();
+
+            flattenedDependencies.AddRange(
+                package
+                    .Dependencies
+                    .Where(IsFrameworkDependency)
+                    .Select(dependency => dependency.TargetFramework)
+                    .Distinct()
+                    .Select(targetFramework => $"::{targetFramework}"));
+
+            flattenedDependencies.AddRange(
+                package
+                    .Dependencies
+                    .Where(dependency => !IsFrameworkDependency(dependency))
+                    .Select(dependency => $"{dependency.Id}:{dependency.VersionRange}:{dependency.TargetFramework}"));
+
+            var result = string.Join("|", flattenedDependencies);
+
+            return new XElement(N.d_Dependencies, result);
+        }
+
+        private bool IsFrameworkDependency(PackageDependency dependency)
+        {
+            return dependency.Id == null && dependency.VersionRange == null;
+        }
+
+        private static class NS
+        {
+            public static readonly XNamespace xmlns = "http://www.w3.org/2005/Atom";
+            // TODO: Remove?
+            //public static readonly XNamespace baze = "https://www.nuget.org/api/v2/curated-feeds/microsoftdotnet";
+            public static readonly XNamespace m = "http://schemas.microsoft.com/ado/2007/08/dataservices/metadata";
+            public static readonly XNamespace d = "http://schemas.microsoft.com/ado/2007/08/dataservices";
+            public static readonly XNamespace georss = "http://www.georss.org/georss";
+            public static readonly XNamespace gml = "http://www.opengis.net/gml";
+        }
+
+        private static class N
+        {
+            public static readonly XName feed = NS.xmlns + "feed";
+            public static readonly XName entry = NS.xmlns + "entry";
+            public static readonly XName title = NS.xmlns + "title";
+            public static readonly XName author = NS.xmlns + "author";
+            public static readonly XName name = NS.xmlns + "name";
+            public static readonly XName link = NS.xmlns + "link";
+            public static readonly XName id = NS.xmlns + "id";
+            public static readonly XName content = NS.xmlns + "content";
+            public static readonly XName summary = NS.xmlns + "summary";
+
+            public static readonly XName m_count = NS.m + "count";
+            public static readonly XName m_properties = NS.m + "properties";
+            public static readonly XName m_type = NS.m + "type";
+
+            public static readonly XName d_Authors = NS.d + "Authors";
+            public static readonly XName d_Copyright = NS.d + "Copyright";
+            public static readonly XName d_Created = NS.d + "Created";
+            public static readonly XName d_Dependencies = NS.d + "Dependencies";
+            public static readonly XName d_Description = NS.d + "Description";
+            public static readonly XName d_DownloadCount = NS.d + "DownloadCount";
+            public static readonly XName d_IconUrl = NS.d + "IconUrl";
+            public static readonly XName d_Id = NS.d + "Id";
+            public static readonly XName d_IsPrerelease = NS.d + "IsPrerelease";
+            public static readonly XName d_Language = NS.d + "Language";
+            public static readonly XName d_LastEdited = NS.d + "LastEdited";
+            public static readonly XName d_LicenseUrl = NS.d + "LicenseUrl";
+            public static readonly XName d_MinClientVersion = NS.d + "MinClientVersion";
+            public static readonly XName d_NormalizedVersion = NS.d + "NormalizedVersion";
+            public static readonly XName d_PackageHash = NS.d + "PackageHash";
+            public static readonly XName d_PackageHashAlgorithm = NS.d + "PackageHashAlgorithm";
+            public static readonly XName d_PackageSize = NS.d + "PackageSize";
+            public static readonly XName d_ProjectUrl = NS.d + "ProjectUrl";
+            public static readonly XName d_Published = NS.d + "Published";
+            public static readonly XName d_ReleaseNotes = NS.d + "ReleaseNotes";
+            public static readonly XName d_ReportAbuseUrl = NS.d + "ReportAbuseUrl";
+            public static readonly XName d_RequireLicenseAcceptance = NS.d + "RequireLicenseAcceptance";
+            public static readonly XName d_Summary = NS.d + "Summary";
+            public static readonly XName d_Tags = NS.d + "Tags";
+            public static readonly XName d_Title = NS.d + "Title";
+            public static readonly XName d_Version = NS.d + "Version";
+
+            public static readonly XName baze = XNamespace.Xmlns + "base";
+            public static readonly XName m = XNamespace.Xmlns + "m";
+            public static readonly XName d = XNamespace.Xmlns + "d";
+            public static readonly XName georss = XNamespace.Xmlns + "georss";
+            public static readonly XName gml = XNamespace.Xmlns + "gml";
+        }
+    }
+}