// 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;
using System.Linq;
using System.Reflection;
using Microsoft.Extensions.DependencyModel;
using Xunit;

namespace Microsoft.AspNetCore.Mvc.Internal
{
    public class DefaultAssemblyPartDiscoveryProviderTests
    {
        private static readonly Assembly CurrentAssembly =
            typeof(DefaultAssemblyPartDiscoveryProviderTests).GetTypeInfo().Assembly;

        [Fact]
        public void GetCandidateLibraries_IgnoresMvcAssemblies()
        {
            // Arrange
            var expected = GetLibrary("SomeRandomAssembly", "Microsoft.AspNetCore.Mvc.Abstractions");
            var dependencyContext = new DependencyContext(
                new TargetInfo("framework", "runtime", "signature", isPortable: true),
                CompilationOptions.Default,
                new CompilationLibrary[0],
                new[]
                {
                     GetLibrary("Microsoft.AspNetCore.Mvc.Core"),
                     GetLibrary("Microsoft.AspNetCore.Mvc"),
                     GetLibrary("Microsoft.AspNetCore.Mvc.Abstractions"),
                     expected,
                },
                Enumerable.Empty<RuntimeFallbacks>());

            // Act
            var candidates = DefaultAssemblyPartDiscoveryProvider.GetCandidateLibraries(dependencyContext);

            // Assert
            Assert.Equal(new[] { expected }, candidates);
        }

        [Fact]
        public void CandidateAssemblies_ReturnsEntryAssemblyIfDependencyContextIsNull()
        {
            // Arrange & Act
            var candidates = DefaultAssemblyPartDiscoveryProvider.GetCandidateAssemblies(CurrentAssembly, dependencyContext: null);

            // Assert
            Assert.Equal(new[] { CurrentAssembly }, candidates);
        }

        [Fact]
        public void GetCandidateLibraries_ReturnsLibrariesReferencingAnyMvcAssembly()
        {
            // Arrange
            var dependencyContext = new DependencyContext(
                new TargetInfo("framework", "runtime", "signature", isPortable: true),
                CompilationOptions.Default,
                new CompilationLibrary[0],
                new[]
                {
                     GetLibrary("Foo", "Microsoft.AspNetCore.Mvc.Core"),
                     GetLibrary("Bar", "Microsoft.AspNetCore.Mvc"),
                     GetLibrary("Qux", "Not.Mvc.Assembly", "Unofficial.Microsoft.AspNetCore.Mvc"),
                     GetLibrary("Baz", "Microsoft.AspNetCore.Mvc.Abstractions"),
                },
                Enumerable.Empty<RuntimeFallbacks>());

            // Act
            var candidates = DefaultAssemblyPartDiscoveryProvider.GetCandidateLibraries(dependencyContext);

            // Assert
            Assert.Equal(new[] { "Foo", "Bar", "Baz" }, candidates.Select(a => a.Name));
        }

        [Fact]
        public void GetCandidateLibraries_SkipsMvcAssemblies()
        {
            // Arrange
            var dependencyContext = new DependencyContext(
                new TargetInfo("framework", "runtime", "signature", isPortable: true),
                CompilationOptions.Default,
                new CompilationLibrary[0],
                new[]
                {
                     GetLibrary("MvcSandbox", "Microsoft.AspNetCore.Mvc.Core", "Microsoft.AspNetCore.Mvc"),
                     GetLibrary("Microsoft.AspNetCore.Mvc.TagHelpers", "Microsoft.AspNetCore.Mvc.Razor"),
                     GetLibrary("Microsoft.AspNetCore.Mvc", "Microsoft.AspNetCore.Mvc.Abstractions", "Microsoft.AspNetCore.Mvc.Core"),
                     GetLibrary("Microsoft.AspNetCore.Mvc.Core", "Microsoft.AspNetCore.HttpAbstractions"),
                     GetLibrary("ControllersAssembly", "Microsoft.AspNetCore.Mvc"),

                },
                Enumerable.Empty<RuntimeFallbacks>());

            // Act
            var candidates = DefaultAssemblyPartDiscoveryProvider.GetCandidateLibraries(dependencyContext);

            // Assert
            Assert.Equal(new[] { "MvcSandbox", "ControllersAssembly" }, candidates.Select(a => a.Name));
        }

        // This test verifies DefaultAssemblyPartDiscoveryProvider.ReferenceAssemblies reflects the actual loadable assemblies
        // of the libraries that Microsoft.AspNetCore.Mvc dependes on.
        // If we add or remove dependencies, this test should be changed together.
        [Fact]
        public void ReferenceAssemblies_ReturnsLoadableReferenceAssemblies()
        {
            // Arrange
            var excludeAssemblies = new string[]
            {
                "Microsoft.AspNetCore.Mvc.WebApiCompatShim",
                "Microsoft.AspNetCore.Mvc.TestCommon",
                "Microsoft.AspNetCore.Mvc.Core.Test",
                "Microsoft.AspNetCore.Mvc.TestDiagnosticListener.Sources",
            };

            var additionalAssemblies = new[]
            {
                // The following assemblies are not reachable from Microsoft.AspNetCore.Mvc
                "Microsoft.AspNetCore.Mvc.TagHelpers",
                "Microsoft.AspNetCore.Mvc.Formatters.Xml",
            };

            var expected = DependencyContext.Load(CurrentAssembly)
                .RuntimeLibraries
                .Where(r => r.Name.StartsWith("Microsoft.AspNetCore.Mvc", StringComparison.Ordinal) &&
                    !excludeAssemblies.Contains(r.Name, StringComparer.OrdinalIgnoreCase))
                .Select(r => r.Name)
                .Concat(additionalAssemblies)
                .Distinct()
                .OrderBy(p => p, StringComparer.Ordinal);

            // Act
            var referenceAssemblies = DefaultAssemblyPartDiscoveryProvider
                .ReferenceAssemblies
                .OrderBy(p => p, StringComparer.Ordinal);

            // Assert
            Assert.Equal(expected, referenceAssemblies);
        }

        private static RuntimeLibrary GetLibrary(string name, params string[] dependencyNames)
        {
            var dependencies = dependencyNames?.Select(d => new Dependency(d, "42.0.0")) ?? new Dependency[0];

            return new RuntimeLibrary(
                "package",
                name,
                "23.0.0",
                "hash",
                new RuntimeAssetGroup[0],
                new RuntimeAssetGroup[0],
                new ResourceAssembly[0],
                dependencies: dependencies.ToArray(),
                serviceable: true);
        }
    }
}