// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Linq;
using Microsoft.AspNetCore.Mvc.Abstractions;
using Microsoft.AspNetCore.Mvc.ApplicationModels;
using Microsoft.AspNetCore.Mvc.Infrastructure;
using Microsoft.AspNetCore.Mvc.Razor.Compilation;
using Microsoft.AspNetCore.Mvc.Razor.Extensions;
using Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation;
using Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure;
using Microsoft.AspNetCore.Razor.Language;
using Microsoft.AspNetCore.Routing;
using Microsoft.CodeAnalysis.Razor;
using Microsoft.Extensions.DependencyInjection.Extensions;
using Microsoft.Extensions.Options;
 
namespace Microsoft.Extensions.DependencyInjection;
 
/// <summary>
/// Static class that adds razor runtime compilation extension methods.
/// </summary>
public static class RazorRuntimeCompilationMvcCoreBuilderExtensions
{
    /// <summary>
    /// Configures <see cref="IMvcCoreBuilder" /> to support runtime compilation of Razor views and Razor Pages.
    /// </summary>
    /// <param name="builder">The <see cref="IMvcCoreBuilder" />.</param>
    /// <returns>The <see cref="IMvcCoreBuilder"/>.</returns>
    public static IMvcCoreBuilder AddRazorRuntimeCompilation(this IMvcCoreBuilder builder)
    {
        ArgumentNullException.ThrowIfNull(builder);
 
        AddServices(builder.Services);
        return builder;
    }
 
    /// <summary>
    /// Configures <see cref="IMvcCoreBuilder" /> to support runtime compilation of Razor views and Razor Pages.
    /// </summary>
    /// <param name="builder">The <see cref="IMvcCoreBuilder" />.</param>
    /// <param name="setupAction">An action to configure the <see cref="MvcRazorRuntimeCompilationOptions"/>.</param>
    /// <returns>The <see cref="IMvcCoreBuilder"/>.</returns>
    public static IMvcCoreBuilder AddRazorRuntimeCompilation(this IMvcCoreBuilder builder, Action<MvcRazorRuntimeCompilationOptions> setupAction)
    {
        ArgumentNullException.ThrowIfNull(builder);
        ArgumentNullException.ThrowIfNull(setupAction);
 
        AddServices(builder.Services);
        builder.Services.Configure(setupAction);
        return builder;
    }
 
    // Internal for testing.
    internal static void AddServices(IServiceCollection services)
    {
        services.TryAddEnumerable(
            ServiceDescriptor.Transient<IConfigureOptions<MvcRazorRuntimeCompilationOptions>, MvcRazorRuntimeCompilationOptionsSetup>());
 
        var compilerProvider = services.FirstOrDefault(f =>
            f.ServiceType == typeof(IViewCompilerProvider) &&
            f.ImplementationType?.Assembly == typeof(IViewCompilerProvider).Assembly &&
            f.ImplementationType.FullName == "Microsoft.AspNetCore.Mvc.Razor.Compilation.DefaultViewCompilerProvider");
 
        if (compilerProvider != null)
        {
            // Replace the default implementation of IViewCompilerProvider
            services.Remove(compilerProvider);
        }
 
        services.TryAddSingleton<IViewCompilerProvider, RuntimeViewCompilerProvider>();
 
        var actionDescriptorProvider = services.FirstOrDefault(f =>
            f.ServiceType == typeof(IActionDescriptorProvider) &&
            f.ImplementationType == typeof(CompiledPageActionDescriptorProvider));
 
        if (actionDescriptorProvider != null)
        {
            // RuntimeCompilation registers an instance of PageActionDescriptorProvider(PageADP). CompiledPageADP and runtime compilation
            // cannot co-exist since CompiledPageADP will attempt to resolve action descriptors for lazily compiled views (such as for
            // ones from non-physical file providers). We'll instead remove CompiledPageActionDescriptors from the DI container if present.
            services.Remove(actionDescriptorProvider);
        }
 
        services.TryAddEnumerable(
            ServiceDescriptor.Singleton<IActionDescriptorProvider, PageActionDescriptorProvider>());
        services.TryAddEnumerable(ServiceDescriptor.Singleton<MatcherPolicy, PageLoaderMatcherPolicy>());
 
        services.TryAddSingleton<RuntimeCompilationFileProvider>();
        services.TryAddSingleton<RazorReferenceManager>();
        services.TryAddSingleton<CSharpCompiler>();
 
        services.TryAddSingleton<RazorProjectFileSystem, FileProviderRazorProjectFileSystem>();
        services.TryAddSingleton(s =>
        {
            var fileSystem = s.GetRequiredService<RazorProjectFileSystem>();
            var csharpCompiler = s.GetRequiredService<CSharpCompiler>();
            var projectEngine = RazorProjectEngine.Create(RazorConfiguration.Default, fileSystem, builder =>
            {
                RazorExtensions.Register(builder);
 
                // Roslyn + TagHelpers infrastructure
                var referenceManager = s.GetRequiredService<RazorReferenceManager>();
                builder.Features.Add(new LazyMetadataReferenceFeature(referenceManager));
                builder.Features.Add(new CompilationTagHelperFeature());
 
                // TagHelperDescriptorProviders (actually do tag helper discovery)
                builder.Features.Add(new DefaultTagHelperDescriptorProvider());
                builder.Features.Add(new ViewComponentTagHelperDescriptorProvider());
                builder.SetCSharpLanguageVersion(csharpCompiler.ParseOptions.LanguageVersion);
            });
 
            return projectEngine;
        });
 
        //
        // Razor Pages
        //
        services.TryAddEnumerable(
            ServiceDescriptor.Singleton<IPageRouteModelProvider, RazorProjectPageRouteModelProvider>());
 
        services.TryAddEnumerable(
            ServiceDescriptor.Singleton<IActionDescriptorChangeProvider, PageActionDescriptorChangeProvider>());
    }
}