Add initial reverse dependencies feat (without view) (#7988)

Progress on #4718

Author: dc7497-1576912

src/NuGetGallery.Core/Entities/EntitiesContext.cs

@@ -60,6 +60,7 @@ public EntitiesContext(DbConnection connection, bool readOnly)
         public DbSet<Package> Packages { get; set; }
         public DbSet<PackageDeprecation> Deprecations { get; set; }
         public DbSet<PackageRegistration> PackageRegistrations { get; set; }
+        public DbSet<PackageDependency> PackageDependencies { get; set; }
         public DbSet<Credential> Credentials { get; set; }
         public DbSet<Scope> Scopes { get; set; }
         public DbSet<UserSecurityPolicy> UserSecurityPolicies { get; set; }

src/NuGetGallery.Core/Entities/IEntitiesContext.cs

@@ -12,6 +12,7 @@ public interface IEntitiesContext : IReadOnlyEntitiesContext
         DbSet<Certificate> Certificates { get; set; }
         DbSet<PackageDeprecation> Deprecations { get; set; }
         DbSet<PackageRegistration> PackageRegistrations { get; set; }
+        DbSet<PackageDependency> PackageDependencies { get; set; }
         DbSet<Credential> Credentials { get; set; }
         DbSet<Scope> Scopes { get; set; }
         DbSet<User> Users { get; set; }

src/NuGetGallery.Services/Configuration/FeatureFlagService.cs

@@ -20,6 +20,7 @@ public class FeatureFlagService : IFeatureFlagService
         private const string EmbeddedIconFlightName = GalleryPrefix + "EmbeddedIcons";
         private const string ForceFlatContainerIconsFeatureName = GalleryPrefix + "ForceFlatContainerIcons";
         private const string GitHubUsageFlightName = GalleryPrefix + "GitHubUsage";
+        private const string PackageDependentsFlightName = GalleryPrefix + "PackageDependents";
         private const string ManageDeprecationFeatureName = GalleryPrefix + "ManageDeprecation";
         private const string ManageDeprecationForManyVersionsFeatureName = GalleryPrefix + "ManageDeprecationMany";
         private const string ManageDeprecationApiFeatureName = GalleryPrefix + "ManageDeprecationApi";
@@ -135,6 +136,11 @@ public bool IsGitHubUsageEnabled(User user)
             return _client.IsEnabled(GitHubUsageFlightName, user, defaultValue: false);
         }
 
+        public bool IsPackageDependentsEnabled(User user)
+        {
+            return _client.IsEnabled(PackageDependentsFlightName, user, defaultValue: false);
+        }
+
         public bool IsABTestingEnabled(User user)
         {
             return _client.IsEnabled(ABTestingFlightName, user, defaultValue: false);

src/NuGetGallery.Services/Configuration/IFeatureFlagService.cs

@@ -80,6 +80,14 @@ public interface IFeatureFlagService
         /// <returns>Whether or not the Flight is enabled for the user</returns>
         bool IsGitHubUsageEnabled(User user);
 
+        /// <summary>
+        /// Whether a user can see the "Package Dependents" section in a package's display page. Also, no
+        /// data is gathered from the database
+        /// </summary>
+        /// <param name="user">The user to test for the Flight</param>
+        /// <returns>Whether or not the Flight is enabled for the user</returns>
+        bool IsPackageDependentsEnabled(User user);
+
         /// <summary>
         /// Whether the OData controllers use the read-only replica.
         /// </summary>

src/NuGetGallery.Services/Models/PackageDependent.cs

@@ -0,0 +1,18 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+
+namespace NuGetGallery
+{
+    public class PackageDependent
+    {
+        public string Id { get; set; }
+        public int DownloadCount { get; set; }
+        public string Description { get; set; }
+
+        // TODO Add verify checkmark
+        // https://github.com/NuGet/NuGetGallery/issues/4718
+    }
+}
+      

src/NuGetGallery.Services/Models/PackageDependents.cs

@@ -0,0 +1,13 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+
+namespace NuGetGallery
+{
+    public class PackageDependents
+    {
+        public IReadOnlyCollection<PackageDependent> TopPackages { get; set; }
+        public int TotalPackageCount { get; set; }
+    }
+}

src/NuGetGallery.Services/NuGetGallery.Services.csproj

@@ -146,6 +146,8 @@
     <Compile Include="Helpers\MailAddressConverter.cs" />
     <Compile Include="Helpers\UploadHelper.cs" />
     <Compile Include="Models\LuceneIndexLocation.cs" />
+    <Compile Include="Models\PackageDependent.cs" />
+    <Compile Include="Models\PackageDependents.cs" />
     <Compile Include="Models\ReportPackageReason.cs" />
     <Compile Include="Models\StorageType.cs" />
     <Compile Include="PackageManagement\ActionOnNewPackageContext.cs" />

src/NuGetGallery.Services/PackageManagement/IPackageService.cs

@@ -17,6 +17,13 @@ namespace NuGetGallery
     /// </summary>
     public interface IPackageService : ICorePackageService
     {
+        /// <summary>
+        /// Returns a package dependents object that includes a collection of the top packages that 
+        /// depend on the focus package and a total count of those dependents.
+        /// </summary>
+        /// <param name="id">The package ID.</param>
+        PackageDependents GetPackageDependents(string id);
+
         /// <summary>
         /// Returns all packages with an <see cref="Package.Id"/> of <paramref name="id"/>.
         /// Includes deprecation fields based on <paramref name="deprecationFields"/>.

src/NuGetGallery.Services/PackageManagement/PackageService.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Data.Common;
 using System.Data.Entity;
 using System.IO;
 using System.Linq;
@@ -24,19 +25,22 @@ public class PackageService : CorePackageService, IPackageService
         private readonly IAuditingService _auditingService;
         private readonly ITelemetryService _telemetryService;
         private readonly ISecurityPolicyService _securityPolicyService;
+        private readonly IEntitiesContext _entitiesContext;
 
         public PackageService(
             IEntityRepository<PackageRegistration> packageRegistrationRepository,
             IEntityRepository<Package> packageRepository,
             IEntityRepository<Certificate> certificateRepository,
             IAuditingService auditingService,
             ITelemetryService telemetryService,
-            ISecurityPolicyService securityPolicyService)
+            ISecurityPolicyService securityPolicyService,
+            IEntitiesContext entitiesContext)
             : base(packageRepository, packageRegistrationRepository, certificateRepository)
         {
             _auditingService = auditingService ?? throw new ArgumentNullException(nameof(auditingService));
             _telemetryService = telemetryService ?? throw new ArgumentNullException(nameof(telemetryService));
             _securityPolicyService = securityPolicyService ?? throw new ArgumentNullException(nameof(securityPolicyService));
+            _entitiesContext = entitiesContext ?? throw new ArgumentNullException(nameof(entitiesContext));
         }
 
         /// <summary>
@@ -136,12 +140,60 @@ public override PackageRegistration FindPackageRegistrationById(string packageId
         }
 
         public virtual IReadOnlyCollection<Package> FindPackagesById(
-            string id, 
+            string id,
             PackageDeprecationFieldsToInclude deprecationFields = PackageDeprecationFieldsToInclude.None)
         {
             return GetPackagesByIdQueryable(id, deprecationFields).ToList();
         }
 
+        public PackageDependents GetPackageDependents(string id)
+        {
+            if (string.IsNullOrWhiteSpace(id))
+            {
+                throw new ArgumentNullException(nameof(id));
+            }
+            
+            PackageDependents result = new PackageDependents();
+            result.TopPackages = GetListOfDependents(id);
+            result.TotalPackageCount = GetDependentCount(id);
+            return result;
+        }
+
+        private IReadOnlyCollection<PackageDependent> GetListOfDependents(string id)
+        {
+            var packageDependentsList = new List<PackageDependent>();
+            var listPackages = (from pd in _entitiesContext.PackageDependencies
+                                join p in _entitiesContext.Packages on pd.PackageKey equals p.Key
+                                join pr in _entitiesContext.PackageRegistrations on p.PackageRegistrationKey equals pr.Key
+                                where p.IsLatestSemVer2 && pd.Id == id
+                                group 1 by new { pr.Id, pr.DownloadCount, p.Description } into ng
+                                orderby ng.Key.DownloadCount descending
+                                select new { ng.Key.Id, ng.Key.DownloadCount, ng.Key.Description }
+                                ).Take(5).ToList();
+
+            foreach(var pd in listPackages)
+            {
+                var packageDependent = new PackageDependent();
+                packageDependent.Description = pd.Description;
+                packageDependent.DownloadCount = pd.DownloadCount;
+                packageDependent.Id = pd.Id;
+                packageDependentsList.Add(packageDependent);
+            }
+
+            return packageDependentsList;
+        }
+
+        private int GetDependentCount(string id)
+        {
+            var totalCount = (from pd in _entitiesContext.PackageDependencies
+                              join p in _entitiesContext.Packages on pd.PackageKey equals p.Key
+                              where pd.Id == id && p.IsLatestSemVer2
+                              group 1 by p.PackageRegistrationKey
+                              ).Count();
+
+            return totalCount;
+        }
+
         public virtual IReadOnlyCollection<Package> FindPackagesById(
             string id,
             bool includePackageRegistration)

src/NuGetGallery/App_Data/Files/Content/flags.json

@@ -46,6 +46,12 @@
       "SiteAdmins": true,
       "Accounts": [],
       "Domains": []
+    },
+    "NuGetGallery.PackageDependents": {
+      "All": false,
+      "SiteAdmins": true,
+      "Accounts": [],
+      "Domains": []
     }
   }
 }