LockFileUtils.cs

// 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.

#nullable disable

using System;
using System.Buffers;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using NuGet.Client;
using NuGet.Common;
using NuGet.ContentModel;
using NuGet.DependencyResolver;
using NuGet.Frameworks;
using NuGet.LibraryModel;
using NuGet.Packaging;
using NuGet.Packaging.Core;
using NuGet.ProjectModel;
using NuGet.Repositories;
using NuGet.Shared;
using NuGet.Versioning;

namespace NuGet.Commands
{
    public static class LockFileUtils
    {
        public static readonly string LIBANY = nameof(LIBANY);

        public static LockFileTargetLibrary CreateLockFileTargetLibrary(
            LockFileLibrary library,
            LocalPackageInfo package,
            RestoreTargetGraph targetGraph,
            LibraryIncludeFlags dependencyType)
        {
            var (lockFileTargetLibrary, _, _, _) = CreateLockFileTargetLibrary(
                aliases: null,
                library,
                package,
                targetGraph,
                dependencyType: dependencyType,
                targetFrameworkOverride: null,
                dependencies: null,
                cache: new LockFileBuilderCache());
            return lockFileTargetLibrary;
        }

        /// <summary>
        /// Create a lock file target library for the given <paramref name="library"/>
        /// </summary>
        /// <param name="aliases">When an alias is specified, all assemblies coming from the library will need to be referenced with an alias.</param>
        /// <param name="library">The lock file library, expected to be for the equivalent package as <paramref name="library"/> and <paramref name="package"/>. </param>
        /// <param name="package">The local package info.</param>
        /// <param name="targetGraph">The target graph for which the asset selection needs to happen.</param>
        /// <param name="dependencyType">The resolved dependency type.</param>
        /// <param name="targetFrameworkOverride">The original framework if the asset selection is happening for a fallback framework.</param>
        /// <param name="dependencies">The dependencies of this package.</param>
        /// <param name="cache">The lock file build cache.</param>
        /// <returns>The LockFileTargetLibrary, whether a fallback framework criteria was used to select it, the framework selected for compile assets, and the framework selected for runtime assets.</returns>
        internal static (LockFileTargetLibrary, bool, NuGetFramework, NuGetFramework) CreateLockFileTargetLibrary(
                string aliases,
                LockFileLibrary library,
                LocalPackageInfo package,
                RestoreTargetGraph targetGraph,
                LibraryIncludeFlags dependencyType,
                NuGetFramework targetFrameworkOverride,
                List<LibraryDependency> dependencies,
                LockFileBuilderCache cache)
        {
            var runtimeIdentifier = targetGraph.RuntimeIdentifier;
            var framework = targetFrameworkOverride ?? targetGraph.Framework;

            return cache.GetLockFileTargetLibrary(targetGraph, framework, package, aliases, dependencyType, dependencies,
                () =>
                {
                    LockFileTargetLibrary lockFileLib = null;
                    NuGetFramework compileAssetFramework = null;
                    NuGetFramework runtimeAssetFramework = null;
                    // This will throw an appropriate error if the nuspec is missing
                    var nuspec = package.Nuspec;

                    List<(List<SelectionCriteria> orderedCriteria, bool fallbackUsed)> orderedCriteriaSets = cache.GetLabeledSelectionCriteria(targetGraph, framework);
                    var contentItems = cache.GetContentItems(library, package);

                    var packageTypes = nuspec.GetPackageTypes().AsList();
                    bool fallbackUsed = false;

                    for (var i = 0; i < orderedCriteriaSets.Count; i++)
                    {
                        (lockFileLib, compileAssetFramework, runtimeAssetFramework) = CreateLockFileTargetLibrary(aliases, library, package, targetGraph.Conventions, dependencyType,
                             framework, runtimeIdentifier, contentItems, nuspec, packageTypes, orderedCriteriaSets[i].orderedCriteria);
                        // Check if compatible assets were found.
                        // If no compatible assets were found and this is the last check
                        // continue on with what was given, this will fail in the normal
                        // compat verification.
                        if (CompatibilityChecker.HasCompatibleAssets(lockFileLib))
                        {
                            fallbackUsed = orderedCriteriaSets[i].fallbackUsed;
                            // Stop when compatible assets are found.
                            break;
                        }
                    }

                    // Add dependencies
                    AddDependencies(dependencies, lockFileLib, framework, nuspec);

                    // Exclude items
                    ExcludeItems(lockFileLib, dependencyType);

                    lockFileLib.Freeze();

                    return (lockFileLib, fallbackUsed, compileAssetFramework, runtimeAssetFramework);
                });
        }

        /// <summary>
        /// Create an ordered criteria list in order, based on the framework and runtime identifier provided.
        /// The boolean indicates whether the criteria is for a fallback version of the framework or not.
        /// </summary> 
        internal static List<(List<SelectionCriteria>, bool)> CreateOrderedCriteriaSets(ManagedCodeConventions codeConventions, NuGetFramework framework, string runtimeIdentifier)
        {
            // Create an ordered list of selection criteria. Each will be applied, if the result is empty
            // fallback frameworks from "imports" will be tried.
            // These are only used for framework/RID combinations where content model handles everything.
            // AssetTargetFallback and DualCompatbiility frameworks will provide multiple criteria since all assets need to be
            // evaluated before selecting the TFM to use.
            var orderedCriteriaSets = new List<(List<SelectionCriteria>, bool)>(1);

            var assetTargetFallback = framework as AssetTargetFallbackFramework;

            if (assetTargetFallback != null)
            {
                // Add the root project framework first.
                orderedCriteriaSets.Add((CreateCriteria(codeConventions, assetTargetFallback.RootFramework, runtimeIdentifier), false));
                // Add the secondary framework if dual compatibility framework.
                if (assetTargetFallback.RootFramework is DualCompatibilityFramework dualCompatibilityFramework)
                {
                    orderedCriteriaSets.Add((CreateCriteria(codeConventions, dualCompatibilityFramework.SecondaryFramework, runtimeIdentifier), false));
                }

                // Add all fallbacks in order.
                orderedCriteriaSets.AddRange(assetTargetFallback.Fallback.Select(e => (CreateCriteria(codeConventions, e, runtimeIdentifier), true)));
            }
            else
            {
                // Add the current framework.
                orderedCriteriaSets.Add((CreateCriteria(codeConventions, framework, runtimeIdentifier), false));

                if (framework is DualCompatibilityFramework dualCompatibilityFramework)
                {
                    orderedCriteriaSets.Add((CreateCriteria(codeConventions, dualCompatibilityFramework.SecondaryFramework, runtimeIdentifier), false));
                }
            }

            return orderedCriteriaSets;
        }

        private static void ApplyAliases(string aliases, LockFileItem item)
        {
            if (!string.IsNullOrEmpty(aliases))
            {
                item.Properties.Add(LockFileItem.AliasesProperty, aliases);
            }
        }

        /// <summary>
        /// Populate assets for a <see cref="LockFileLibrary"/>.
        /// </summary>
        internal static (LockFileTargetLibrary lockFileLib, NuGetFramework compileAssetFramework, NuGetFramework runtimeAssetFramework) CreateLockFileTargetLibrary(
            string aliases,
            LockFileLibrary library,
            LocalPackageInfo package,
            ManagedCodeConventions managedCodeConventions,
            LibraryIncludeFlags dependencyType,
            NuGetFramework framework,
            string runtimeIdentifier,
            ContentItemCollection contentItems,
            NuspecReader nuspec,
            IList<PackageType> packageTypes,
            List<SelectionCriteria> orderedCriteria)
        {
            LockFileTargetLibrary lockFileLib = new LockFileTargetLibrary()
            {
                Name = library.Name,
                Version = library.Version,
                Type = LibraryType.Package,
                PackageType = packageTypes
            };

            // Add framework references for desktop projects.
            AddFrameworkReferences(lockFileLib, framework, nuspec);

            // Compile
            // Set-up action to update the compile time items.
            Action<LockFileItem> applyAliases = (item) => ApplyAliases(aliases, item);

            // ref takes precedence over lib
            lockFileLib.CompileTimeAssemblies = GetLockFileItems(
                orderedCriteria,
                contentItems,
                applyAliases,
                out NuGetFramework compileFramework,
                managedCodeConventions.Patterns.CompileRefAssemblies,
                managedCodeConventions.Patterns.CompileLibAssemblies);

            // Runtime
            lockFileLib.RuntimeAssemblies = GetLockFileItems(
                orderedCriteria,
                contentItems,
                additionalAction: null,
                out NuGetFramework runtimeFramework,
                managedCodeConventions.Patterns.RuntimeAssemblies);

            // Embed
            lockFileLib.EmbedAssemblies = GetLockFileItems(
                orderedCriteria,
                contentItems,
                managedCodeConventions.Patterns.EmbedAssemblies);

            // Resources
            lockFileLib.ResourceAssemblies = GetLockFileItems(
                orderedCriteria,
                contentItems,
                managedCodeConventions.Patterns.ResourceAssemblies);

            // Native
            lockFileLib.NativeLibraries = GetLockFileItems(
                orderedCriteria,
                contentItems,
                managedCodeConventions.Patterns.NativeLibraries);

            // Add MSBuild files
            AddMSBuildAssets(library.Name, managedCodeConventions, lockFileLib, orderedCriteria, contentItems);

            // Add content files
            AddContentFiles(managedCodeConventions, lockFileLib, framework, contentItems, nuspec);

            // Runtime targets
            // These are applied only to non-RID target graphs.
            // They are not used for compatibility checks.
            AddRuntimeTargets(managedCodeConventions, dependencyType, lockFileLib, framework, runtimeIdentifier, contentItems);

            // COMPAT: Support lib/contract so older packages can be consumed
            ApplyLibContract(package, lockFileLib, framework, contentItems);

            // Apply filters from the <references> node in the nuspec
            ApplyReferenceFilter(lockFileLib, framework, nuspec);

            return (lockFileLib, compileFramework, runtimeFramework);
        }

        private static void AddMSBuildAssets(
            string libraryName,
            ManagedCodeConventions managedCodeConventions,
            LockFileTargetLibrary lockFileLib,
            List<SelectionCriteria> orderedCriteria,
            ContentItemCollection contentItems)
        {
            // Build Transitive
            var btGroup = GetLockFileItems(
                orderedCriteria,
                contentItems,
                managedCodeConventions.Patterns.MSBuildTransitiveFiles);

            var filteredBTGroup = GetBuildItemsForPackageId(btGroup, libraryName);
            lockFileLib.Build.AddRange(filteredBTGroup);

            // Build
            var buildGroup = GetLockFileItems(
                orderedCriteria,
                contentItems,
                managedCodeConventions.Patterns.MSBuildFiles);

            // filter any build asset already being added as part of build transitive
            // PERF: Avoid using LINQ in this path.
            foreach (var buildItem in GetBuildItemsForPackageId(buildGroup, libraryName))
            {
                bool found = false;
                foreach (var btItem in filteredBTGroup)
                {
                    if (Path.GetFileName(btItem.Path).Equals(Path.GetFileName(buildItem.Path), StringComparison.OrdinalIgnoreCase))
                    {
                        found = true;
                        break;
                    }
                }

                if (!found)
                {
                    lockFileLib.Build.Add(buildItem);
                }
            }

            // Build multi targeting
            var buildMultiTargetingGroup = GetLockFileItems(
                orderedCriteria,
                contentItems,
                managedCodeConventions.Patterns.MSBuildMultiTargetingFiles);

            lockFileLib.BuildMultiTargeting.AddRange(GetBuildItemsForPackageId(buildMultiTargetingGroup, libraryName));
        }

        private static void AddContentFiles(ManagedCodeConventions managedCodeConventions, LockFileTargetLibrary lockFileLib, NuGetFramework framework, ContentItemCollection contentItems, NuspecReader nuspec)
        {
            // content v2 items
            List<ContentItemGroup> contentFileGroups = new();
            contentItems.PopulateItemGroups(managedCodeConventions.Patterns.ContentFiles, contentFileGroups);

            if (contentFileGroups.Count > 0)
            {
                // Multiple groups can match the same framework, find all of them
                var contentFileGroupsForFramework = ContentFileUtils.GetContentGroupsForFramework(
                    framework,
                    contentFileGroups);

                lockFileLib.ContentFiles = ContentFileUtils.GetContentFileGroup(
                    nuspec,
                    contentFileGroupsForFramework);
            }
        }

        /// <summary>
        /// Runtime targets
        /// These are applied only to non-RID target graphs.
        /// They are not used for compatibility checks.
        /// </summary>
        private static void AddRuntimeTargets(
            ManagedCodeConventions managedCodeConventions,
            LibraryIncludeFlags dependencyType,
            LockFileTargetLibrary lockFileLib,
            NuGetFramework framework,
            string runtimeIdentifier,
            ContentItemCollection contentItems)
        {
            if (string.IsNullOrEmpty(runtimeIdentifier))
            {
                // Runtime targets contain all the runtime specific assets
                // that could be contained in the runtime specific target graphs.
                // These items are contained in a flat list and have additional properties
                // for the RID and lock file section the assembly would belong to.
                var runtimeTargetItems = new List<LockFileRuntimeTarget>();

                // Runtime
                runtimeTargetItems.AddRange(GetRuntimeTargetLockFileItems(
                    contentItems,
                    framework,
                    dependencyType,
                    LibraryIncludeFlags.Runtime,
                    managedCodeConventions.Patterns.RuntimeAssemblies,
                    "runtime"));

                // Resource
                runtimeTargetItems.AddRange(GetRuntimeTargetLockFileItems(
                    contentItems,
                    framework,
                    dependencyType,
                    LibraryIncludeFlags.Runtime,
                    managedCodeConventions.Patterns.ResourceAssemblies,
                    "resource"));

                // Native
                runtimeTargetItems.AddRange(GetRuntimeTargetLockFileItems(
                    contentItems,
                    framework,
                    dependencyType,
                    LibraryIncludeFlags.Native,
                    managedCodeConventions.Patterns.NativeLibraries,
                    "native"));

                lockFileLib.RuntimeTargets = runtimeTargetItems;
            }
        }

        /// <summary>
        /// Add framework references.
        /// </summary>
        private static void AddFrameworkReferences(LockFileTargetLibrary lockFileLib, NuGetFramework framework, NuspecReader nuspec)
        {
            // Exclude framework references for package based frameworks.
            if (!framework.IsPackageBased)
            {
                var frameworkAssemblies = nuspec.GetFrameworkAssemblyGroups().GetNearest(framework);
                if (frameworkAssemblies != null)
                {
                    foreach (var assemblyReference in frameworkAssemblies.Items)
                    {
                        lockFileLib.FrameworkAssemblies.Add(assemblyReference);
                    }
                }
            }

            // Related to: FrameworkReference item, added first in .NET Core 3.0
            var frameworkRef = nuspec.GetFrameworkRefGroups().GetNearest(framework);

            if (frameworkRef != null)
            {
                lockFileLib.FrameworkReferences.AddRange(frameworkRef.FrameworkReferences.Select(e => e.Name));
            }
        }

        /// <summary>
        /// Apply filters from the references node in the nuspec.
        /// </summary>
        private static void ApplyReferenceFilter(LockFileTargetLibrary lockFileLib, NuGetFramework framework, NuspecReader nuspec)
        {
            if (lockFileLib.CompileTimeAssemblies.Count > 0 || lockFileLib.RuntimeAssemblies.Count > 0)
            {
                var groups = nuspec.GetReferenceGroups().ToList();

                if (groups.Count > 0)
                {
                    var referenceSet = groups.GetNearest(framework);
                    if (referenceSet != null)
                    {
                        var referenceFilter = new HashSet<string>(referenceSet.Items, StringComparer.OrdinalIgnoreCase);

                        // Remove anything that starts with "lib/" and is NOT specified in the reference filter.
                        // runtimes/* is unaffected (it doesn't start with lib/)
                        lockFileLib.RuntimeAssemblies = lockFileLib.RuntimeAssemblies.Where(p => !p.Path.StartsWith("lib/", StringComparison.Ordinal) || referenceFilter.Contains(Path.GetFileName(p.Path))).ToList();
                        lockFileLib.CompileTimeAssemblies = lockFileLib.CompileTimeAssemblies.Where(p => !p.Path.StartsWith("lib/", StringComparison.Ordinal) || referenceFilter.Contains(Path.GetFileName(p.Path))).ToList();
                    }
                }
            }
        }

        /// <summary>
        /// COMPAT: Support lib/contract so older packages can be consumed
        /// </summary>
        private static void ApplyLibContract(LocalPackageInfo package, LockFileTargetLibrary lockFileLib, NuGetFramework framework, ContentItemCollection contentItems)
        {
            if (contentItems.HasContract && lockFileLib.RuntimeAssemblies.Count > 0 && !framework.IsDesktop())
            {
                var contractPath = "lib/contract/" + package.Id + ".dll";

                if (package.Files.Any(path => path == contractPath))
                {
                    lockFileLib.CompileTimeAssemblies.Clear();
                    lockFileLib.CompileTimeAssemblies.Add(new LockFileItem(contractPath));
                }
            }
        }

        private static void AddDependencies(IEnumerable<LibraryDependency> dependencies, LockFileTargetLibrary lockFileLib, NuGetFramework framework, NuspecReader nuspec)
        {
            if (dependencies == null)
            {
                // DualCompatibilityFramework & AssetFallbackFramework does not apply to dependencies.
                // Convert it to a fallback framework if needed.
                NuGetFramework currentFramework = framework;
                if (framework is AssetTargetFallbackFramework atf)
                {
                    currentFramework = atf.AsFallbackFramework();
                }
                else if (framework is DualCompatibilityFramework mcf)
                {
                    currentFramework = mcf.AsFallbackFramework();
                }

                var dependencySet = nuspec
                    .GetDependencyGroups()
                    .GetNearest(currentFramework);

                if (dependencySet != null)
                {
                    var set = dependencySet.Packages;

                    if (set != null)
                    {
                        lockFileLib.Dependencies = set.AsList();
                    }
                }
            }
            else
            {
                // Filter the dependency set down to packages and projects.
                // Framework references will not be displayed
                lockFileLib.Dependencies = dependencies
                    .Where(ld => ld.LibraryRange.TypeConstraintAllowsAnyOf(LibraryDependencyTarget.PackageProjectExternal))
                    .Select(ld => new PackageDependency(ld.Name, ld.LibraryRange.VersionRange))
                    .ToList();
            }
        }

        /// <summary>
        /// Create a library for a project.
        /// </summary>
        public static LockFileTargetLibrary CreateLockFileTargetProject(
            GraphItem<RemoteResolveResult> graphItem,
            LibraryIdentity library,
            LibraryIncludeFlags dependencyType,
            RestoreTargetGraph targetGraph,
            ProjectStyle rootProjectStyle)
        {
            var localMatch = (LocalMatch)graphItem.Data.Match;

            // Target framework information is optional and may not exist for csproj projects
            // that do not have a project.json file.
            string projectFramework = null;
            object frameworkInfoObject;
            if (localMatch.LocalLibrary.Items.TryGetValue(
                KnownLibraryProperties.TargetFrameworkInformation,
                out frameworkInfoObject))
            {
                // Retrieve the resolved framework name, if this is null it means that the
                // project is incompatible. This is marked as Unsupported.
                var targetFrameworkInformation = (TargetFrameworkInformation)frameworkInfoObject;
                projectFramework = targetFrameworkInformation.FrameworkName?.DotNetFrameworkName
                    ?? NuGetFramework.UnsupportedFramework.DotNetFrameworkName;
            }

            // Create the target entry
            var projectLib = new LockFileTargetLibrary()
            {
                Name = library.Name,
                Version = library.Version,
                Type = LibraryType.Project,
                Framework = projectFramework,

                // Find all dependencies which would be in the nuspec
                // Include dependencies with no constraints, or package/project/external
                // Exclude suppressed dependencies, the top level project is not written
                // as a target so the node depth does not matter.
                Dependencies = graphItem.Data.Dependencies
                    .Where(
                        d => (d.LibraryRange.TypeConstraintAllowsAnyOf(LibraryDependencyTarget.PackageProjectExternal))
                             && d.SuppressParent != LibraryIncludeFlags.All
                             && d.ReferenceType == LibraryDependencyReferenceType.Direct)
                    .Select(d => GetDependencyVersionRange(d))
                    .ToList()
            };

            if (rootProjectStyle == ProjectStyle.PackageReference)
            {
                if (localMatch.LocalLibrary.Items.TryGetValue(KnownLibraryProperties.MSBuildProjectPath, out object msbuildPath))
                {
                    // Find the project path, this is provided by the resolver
                    var msbuildFilePathInfo = new FileInfo((string)msbuildPath);

                    // Ensure a trailing slash for the relative path helper.
                    var projectDir = PathUtility.EnsureTrailingSlash(msbuildFilePathInfo.Directory.FullName);

                    // Create an ordered list of selection criteria. Each will be applied, if the result is empty
                    // fallback frameworks from "imports" will be tried.
                    // These are only used for framework/RID combinations where content model handles everything.
                    var orderedCriteria = CreateCriteria(targetGraph.Conventions, targetGraph.Framework, targetGraph.RuntimeIdentifier);

                    string libAnyPath = $"lib/{targetGraph.Framework.GetShortFolderName()}/any.dll";
                    var contentItems = new ContentItemCollection();

                    if (localMatch.LocalLibrary.Items.TryGetValue(KnownLibraryProperties.ProjectRestoreMetadataFiles, out object filesObject))
                    {
                        List<ProjectRestoreMetadataFile> files = (List<ProjectRestoreMetadataFile>)filesObject;
                        if (files.Count > 0)
                        {
                            var fileLookup = new Dictionary<string, ProjectRestoreMetadataFile>(StringComparer.OrdinalIgnoreCase);
                            // Process and de-dupe files
                            for (var i = 0; i < files.Count; i++)
                            {
                                var path = files[i].PackagePath;

                                // LIBANY avoid compatibility checks and will always be used.
                                if (LIBANY.Equals(path, StringComparison.Ordinal))
                                {
                                    path = libAnyPath;
                                }

                                if (!fileLookup.ContainsKey(path))
                                {
                                    fileLookup.Add(path, files[i]);
                                }
                            }

                            contentItems.Load(fileLookup.Keys);

                            // Compile
                            // ref takes precedence over lib
                            var compileGroup = GetLockFileItems(
                                orderedCriteria,
                                contentItems,
                                targetGraph.Conventions.Patterns.CompileRefAssemblies,
                                targetGraph.Conventions.Patterns.CompileLibAssemblies);

                            projectLib.CompileTimeAssemblies = ConvertToProjectPaths(fileLookup, projectDir, compileGroup);

                            // Runtime
                            var runtimeGroup = GetLockFileItems(
                                orderedCriteria,
                                contentItems,
                                targetGraph.Conventions.Patterns.RuntimeAssemblies);

                            projectLib.RuntimeAssemblies = ConvertToProjectPaths(fileLookup, projectDir, runtimeGroup);
                        }
                        else
                        {
                            // If the project did not provide a list of assets, add in default ones.
                            contentItems.Load([libAnyPath]);

                            // When there's only lib assets, compile and runtime groups are always equivalent.
                            var compileGroup = GetLockFileItems(
                                orderedCriteria,
                                contentItems,
                                targetGraph.Conventions.Patterns.CompileLibAssemblies);

                            if (compileGroup.Count > 0)
                            {
                                string relativePath = PathUtility.GetPathWithForwardSlashes(Path.Combine("bin", "placeholder", $"{localMatch.Library.Name}.dll"));
                                var lockFileItem = new LockFileItem(relativePath);
                                projectLib.CompileTimeAssemblies = new List<LockFileItem>() { lockFileItem };
                                projectLib.RuntimeAssemblies = new List<LockFileItem>() { lockFileItem };
                            }
                        }
                    }
                }
            }

            // Add frameworkAssemblies for projects
            object frameworkAssembliesObject;
            if (localMatch.LocalLibrary.Items.TryGetValue(
                KnownLibraryProperties.FrameworkAssemblies,
                out frameworkAssembliesObject))
            {
                projectLib.FrameworkAssemblies.AddRange((List<string>)frameworkAssembliesObject);
            }

            // Add frameworkReferences for projects
            object frameworkReferencesObject;
            if (localMatch.LocalLibrary.Items.TryGetValue(
                KnownLibraryProperties.FrameworkReferences,
                out frameworkReferencesObject))
            {
                projectLib.FrameworkReferences.AddRange(
                    ((IReadOnlyCollection<FrameworkDependency>)frameworkReferencesObject)
                        .Where(e => e.PrivateAssets != FrameworkDependencyFlags.All)
                        .Select(f => f.Name));
            }

            // Exclude items
            ExcludeItems(projectLib, dependencyType);

            projectLib.Freeze();

            return projectLib;
        }

        /// <summary>
        /// Convert from the expected nupkg path to the on disk path.
        /// </summary>
        private static List<LockFileItem> ConvertToProjectPaths(
            Dictionary<string, ProjectRestoreMetadataFile> fileLookup,
            string projectDir,
            IList<LockFileItem> items)
        {
            var results = new List<LockFileItem>(items.Count);
            foreach (var item in items.NoAllocEnumerate())
            {
                var diskPath = fileLookup[item.Path].AbsolutePath;
                var fixedPath = PathUtility.GetPathWithForwardSlashes(
                    PathUtility.GetRelativePath(projectDir, diskPath));

                results.Add(new LockFileItem(fixedPath));
            }
            return results;
        }

        /// <summary>
        /// Create lock file items for the best matching group, and optionally output the selected framework.
        /// </summary>
        /// <remarks>Enumerate this once after calling.</remarks>
        private static IList<LockFileItem> GetLockFileItems(
            List<SelectionCriteria> criteria,
            ContentItemCollection items,
            Action<LockFileItem> additionalAction,
            out NuGetFramework selectedFramework,
            params PatternSet[] patterns)
        {
            selectedFramework = null;
            List<LockFileItem> result = null;
            // Loop through each criteria taking the first one that matches one or more items.
            foreach (var managedCriteria in criteria)
            {
                var group = items.FindBestItemGroup(
                    managedCriteria,
                    patterns);

                if (group != null)
                {
                    if (group.Properties.TryGetValue(
                        ManagedCodeConventions.PropertyNames.TargetFrameworkMoniker, out object tfmObj))
                    {
                        selectedFramework = tfmObj as NuGetFramework;
                    }

                    result = new(group.Items.Count);
                    foreach (var item in group.Items.NoAllocEnumerate())
                    {
                        var newItem = new LockFileItem(item.Path);
                        object locale;
                        if (item.Properties.TryGetValue(ManagedCodeConventions.PropertyNames.Locale, out locale))
                        {
                            newItem.Properties[ManagedCodeConventions.PropertyNames.Locale] = (string)locale;
                        }
                        object related;
                        if (item.Properties.TryGetValue("related", out related))
                        {
                            newItem.Properties["related"] = (string)related;
                        }
                        additionalAction?.Invoke(newItem);
                        result.Add(newItem);
                    }
                    // Take only the first group that has items
                    break;
                }
            }
            return result ?? new();
        }

        /// <summary>
        /// Create lock file items for the best matching group.
        /// </summary>
        /// <remarks>Enumerate this once after calling.</remarks>
        private static IList<LockFileItem> GetLockFileItems(
            List<SelectionCriteria> criteria,
            ContentItemCollection items,
            params PatternSet[] patterns)
        {
            return GetLockFileItems(criteria, items, additionalAction: null, out _, patterns);
        }

        /// <summary>
        /// Get packageId.targets and packageId.props
        /// </summary>
        private static IEnumerable<LockFileItem> GetBuildItemsForPackageId(
            IList<LockFileItem> items,
            string packageId)
        {
            if (items.Count > 0)
            {
                var skipEmptyCheck = false;

                var ordered = items.OrderBy(c => c.Path, StringComparer.OrdinalIgnoreCase)
                                   .ToArray();

                var props = ordered.FirstOrDefault(c =>
                    $"{packageId}.props".Equals(
                        Path.GetFileName(c.Path),
                        StringComparison.OrdinalIgnoreCase));

                if (props != null)
                {
                    skipEmptyCheck = true;
                    yield return props;
                }

                var targets = ordered.FirstOrDefault(c =>
                    $"{packageId}.targets".Equals(
                        Path.GetFileName(c.Path),
                        StringComparison.OrdinalIgnoreCase));

                if (targets != null)
                {
                    skipEmptyCheck = true;
                    yield return targets;
                }

                if (!skipEmptyCheck)
                {
                    // Find _._ if it exists, this file is needed
                    // but does not match the package id above.
                    var empty = ordered.FirstOrDefault(c =>
                        c.Path.EndsWith(PackagingCoreConstants.ForwardSlashEmptyFolder, StringComparison.Ordinal));

                    if (empty != null)
                    {
                        yield return empty;
                    }
                }
            }
        }

        /// <summary>
        /// Creates an ordered list of selection criteria to use. This supports fallback frameworks.
        /// </summary>
        private static List<SelectionCriteria> CreateCriteria(
            ManagedCodeConventions conventions,
            NuGetFramework framework,
            string runtimeIdentifier)
        {
            List<SelectionCriteria> managedCriteria;

            var fallbackFramework = framework as FallbackFramework;

            // Avoid fallback criteria if this is not a fallback framework,
            // or if AssetTargetFallback is used. For AssetTargetFallback
            // the fallback frameworks will be checked later.
            if (fallbackFramework == null)
            {
                var standardCriteria = conventions.Criteria.ForFrameworkAndRuntime(
                    framework,
                    runtimeIdentifier);

                managedCriteria = new(capacity: 1)
                {
                    standardCriteria
                };
            }
            else
            {
                // Add the project framework
                var primaryFramework = NuGetFramework.Parse(fallbackFramework.DotNetFrameworkName);
                var primaryCriteria = conventions.Criteria.ForFrameworkAndRuntime(
                    primaryFramework,
                    runtimeIdentifier);

                managedCriteria = new(capacity: 1 + fallbackFramework.Fallback.Count)
                {
                    primaryCriteria
                };

                // Add each fallback framework in order
                foreach (var fallback in fallbackFramework.Fallback)
                {
                    var fallbackCriteria = conventions.Criteria.ForFrameworkAndRuntime(
                        fallback,
                        runtimeIdentifier);

                    managedCriteria.Add(fallbackCriteria);
                }
            }

            return managedCriteria;
        }

        /// <summary>
        /// Clears a lock file group and replaces the first item with _._ if
        /// the group has items. Empty groups are left alone.
        /// </summary>
        private static void ClearIfExists<T>(IList<T> group, Func<string, T> factory) where T : LockFileItem
        {
            if (GroupHasNonEmptyItems(group))
            {
                // Take the root directory
                var firstItem = group.OrderBy(item => item.Path.LastIndexOf('/'))
                    .ThenBy(item => item.Path, StringComparer.OrdinalIgnoreCase)
                    .First();

                var fileName = Path.GetFileName(firstItem.Path);

                Debug.Assert(!string.IsNullOrEmpty(fileName));
#if NETCOREAPP
                Debug.Assert(firstItem.Path.IndexOf('/', StringComparison.Ordinal) > 0);
#else
                Debug.Assert(firstItem.Path.IndexOf('/') > 0);
#endif

                var emptyDir = firstItem.Path.Substring(0, firstItem.Path.Length - fileName.Length)
                    + PackagingCoreConstants.EmptyFolder;

                group.Clear();

                // Create a new item with the _._ path
                var emptyItem = factory(emptyDir);

                // Copy over the properties from the first
                foreach (var pair in firstItem.Properties)
                {
                    emptyItem.Properties.Add(pair.Key, pair.Value);
                }

                group.Add(emptyItem);
            }
        }

        /// <summary>
        /// True if the group has items that do not end with _._
        /// </summary>
        private static bool GroupHasNonEmptyItems(IEnumerable<LockFileItem> group)
        {
            return group?.Any(item => !item.Path.EndsWith(PackagingCoreConstants.ForwardSlashEmptyFolder, StringComparison.Ordinal)) == true;
        }

        /// <summary>
        /// Group all items by the primary key, then select the nearest TxM
        /// within each group.
        /// Items that do not contain the primaryKey will be filtered out.
        /// </summary>
        private static List<ContentItemGroup> GetContentGroupsForFramework(
            NuGetFramework framework,
            List<ContentItemGroup> contentGroups,
            string primaryKey)
        {
            var groups = new List<ContentItemGroup>();

            // Group by primary key and find the nearest TxM under each.
            var primaryGroups = new Dictionary<string, List<ContentItemGroup>>(StringComparer.Ordinal);

            foreach (var group in contentGroups)
            {
                object keyObj;
                if (group.Properties.TryGetValue(primaryKey, out keyObj))
                {
                    var key = (string)keyObj;

                    List<ContentItemGroup> index;
                    if (!primaryGroups.TryGetValue(key, out index))
                    {
                        index = new List<ContentItemGroup>(1);
                        primaryGroups.Add(key, index);
                    }

                    index.Add(group);
                }
            }

            // Find the nearest TxM within each primary key group.
            foreach (var primaryGroup in primaryGroups)
            {
                var groupedItems = primaryGroup.Value;

                var nearestGroup = NuGetFrameworkUtility.GetNearest<ContentItemGroup>(groupedItems, framework,
                    group =>
                    {
                        // In the case of /native there is no TxM, here any should be used.
                        object frameworkObj;
                        if (group.Properties.TryGetValue(
                            ManagedCodeConventions.PropertyNames.TargetFrameworkMoniker,
                            out frameworkObj))
                        {
                            return (NuGetFramework)frameworkObj;
                        }

                        return NuGetFramework.AnyFramework;
                    });

                // If a compatible group exists within the secondary key add it to the results
                if (nearestGroup != null)
                {
                    groups.Add(nearestGroup);
                }
            }

            return groups;
        }

        private static List<LockFileRuntimeTarget> GetRuntimeTargetLockFileItems(
            ContentItemCollection contentItems,
            NuGetFramework framework,
            LibraryIncludeFlags dependencyType,
            LibraryIncludeFlags groupType,
            PatternSet patternSet,
            string assetType)
        {
            List<ContentItemGroup> groups = new List<ContentItemGroup>();
            contentItems.PopulateItemGroups(patternSet, groups);

            var groupsForFramework = GetContentGroupsForFramework(
                framework,
                groups,
                ManagedCodeConventions.PropertyNames.RuntimeIdentifier);

            var items = GetRuntimeTargetItems(groupsForFramework, assetType);

            if ((dependencyType & groupType) == LibraryIncludeFlags.None)
            {
                ClearIfExists(items, static path => new LockFileRuntimeTarget(path));
            }

            return items;
        }

        /// <summary>
        /// Create LockFileItems from groups of library items.
        /// </summary>
        /// <param name="groups">Library items grouped by RID.</param>
        /// <param name="assetType">Lock file section the items apply to.</param>
        private static List<LockFileRuntimeTarget> GetRuntimeTargetItems(List<ContentItemGroup> groups, string assetType)
        {
            var results = new List<LockFileRuntimeTarget>();

            // Loop through RID groups
            foreach (var group in groups)
            {
                var rid = (string)group.Properties[ManagedCodeConventions.PropertyNames.RuntimeIdentifier];

                // Create lock file entries for each assembly.
                foreach (var item in group.Items.NoAllocEnumerate())
                {
                    results.Add(new LockFileRuntimeTarget(item.Path)
                    {
                        AssetType = assetType,
                        Runtime = rid
                    });
                }
            }

            return results;
        }

        /// <summary>
        /// Replace / with the local directory separator if needed.
        /// For OSX and Linux the same string is returned.
        /// </summary>
        public static string ToDirectorySeparator(string path)
        {
            if (path == null)
            {
                throw new ArgumentNullException(nameof(path));
            }

            if (Path.DirectorySeparatorChar == '/')
            {
                return path;
            }

            return path.Replace('/', Path.DirectorySeparatorChar);
        }

        private static PackageDependency GetDependencyVersionRange(LibraryDependency dependency)
        {
            var range = dependency.LibraryRange.VersionRange ?? VersionRange.All;

            if (VersionRange.All.Equals(range)
                && (dependency.LibraryRange.TypeConstraintAllows(LibraryDependencyTarget.ExternalProject)))
            {
                // For csproj -> csproj type references where there is no range, use 1.0.0
                range = VersionRange.Parse("1.0.0");
            }

            return new PackageDependency(dependency.Name, range);
        }

        /// <summary>
        /// Replace excluded asset groups with _._ if they have > 0 items.
        /// </summary>
        public static void ExcludeItems(LockFileTargetLibrary lockFileLib, LibraryIncludeFlags dependencyType)
        {
            if ((dependencyType & LibraryIncludeFlags.Runtime) == LibraryIncludeFlags.None)
            {
                ClearIfExists(lockFileLib.RuntimeAssemblies, static path => new LockFileItem(path));
                lockFileLib.FrameworkAssemblies.Clear();
                lockFileLib.ResourceAssemblies.Clear();
            }

            if ((dependencyType & LibraryIncludeFlags.Compile) == LibraryIncludeFlags.None)
            {
                ClearIfExists(lockFileLib.CompileTimeAssemblies, static path => new LockFileItem(path));
                ClearIfExists(lockFileLib.EmbedAssemblies, static path => new LockFileItem(path));
            }

            if ((dependencyType & LibraryIncludeFlags.Native) == LibraryIncludeFlags.None)
            {
                ClearIfExists(lockFileLib.NativeLibraries, static path => new LockFileItem(path));
            }

            if ((dependencyType & LibraryIncludeFlags.ContentFiles) == LibraryIncludeFlags.None
                && GroupHasNonEmptyItems(lockFileLib.ContentFiles))
            {
                // Empty lock file items still need lock file properties for language, action, and output.
                lockFileLib.ContentFiles.Clear();
                lockFileLib.ContentFiles.Add(ContentFileUtils.CreateEmptyItem());
            }

            if ((dependencyType & LibraryIncludeFlags.BuildTransitive) == LibraryIncludeFlags.None &&
                (dependencyType & LibraryIncludeFlags.Build) == LibraryIncludeFlags.None)
            {
                // If BuildTransitive is excluded then all build assets are cleared.
                ClearIfExists(lockFileLib.Build, static path => new LockFileItem(path));
                ClearIfExists(lockFileLib.BuildMultiTargeting, static path => new LockFileItem(path));
            }
            else if ((dependencyType & LibraryIncludeFlags.Build) == LibraryIncludeFlags.None)
            {
                if (!lockFileLib.Build.Any(item => item.Path.StartsWith("buildTransitive/", StringComparison.OrdinalIgnoreCase)))
                {
                    // all build assets are from /build folder so just clear them all.
                    ClearIfExists(lockFileLib.Build, static path => new LockFileItem(path));
                    ClearIfExists(lockFileLib.BuildMultiTargeting, static path => new LockFileItem(path));
                }
                else
                {
                    // only clear /build assets, leaving /BuildTransitive behind
                    var newBuildAssets = new List<LockFileItem>();

                    for (var i = 0; i < lockFileLib.Build.Count; i++)
                    {
                        var currentBuildItem = lockFileLib.Build[i];

                        if (!currentBuildItem.Path.StartsWith("build/", StringComparison.OrdinalIgnoreCase))
                        {
                            newBuildAssets.Add(currentBuildItem);
                        }
                        else
                        {
                            // if current asset is from build then also clear it for BuildMultiTargeting if exists.
                            var multiBuildAsset = lockFileLib.BuildMultiTargeting.FirstOrDefault(
                                item => Path.GetFileName(item.Path).Equals(Path.GetFileName(currentBuildItem.Path), StringComparison.OrdinalIgnoreCase));

                            if (multiBuildAsset != null)
                            {
                                lockFileLib.BuildMultiTargeting.Remove(multiBuildAsset);
                            }
                        }
                    }

                    lockFileLib.Build = newBuildAssets;
                }
            }
        }
    }
}