// 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 Microsoft.AspNetCore.Routing;
using Microsoft.AspNetCore.Routing.Internal;
using Microsoft.AspNetCore.Routing.Matching;
using Microsoft.AspNetCore.Routing.Tree;
using Microsoft.Extensions.DependencyInjection.Extensions;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.ObjectPool;
using Microsoft.Extensions.Options;

namespace Microsoft.Extensions.DependencyInjection
{
    /// <summary>
    /// Contains extension methods to <see cref="IServiceCollection"/>.
    /// </summary>
    public static class RoutingServiceCollectionExtensions
    {
        /// <summary>
        /// Adds services required for routing requests.
        /// </summary>
        /// <param name="services">The <see cref="IServiceCollection"/> to add the services to.</param>
        /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
        public static IServiceCollection AddRouting(this IServiceCollection services)
        {
            if (services == null)
            {
                throw new ArgumentNullException(nameof(services));
            }

            services.TryAddTransient<IInlineConstraintResolver, DefaultInlineConstraintResolver>();
            services.TryAddSingleton<ObjectPool<UriBuildingContext>>(s =>
            {
                var provider = s.GetRequiredService<ObjectPoolProvider>();
                return provider.Create<UriBuildingContext>(new UriBuilderContextPooledObjectPolicy());
            });

            // The TreeRouteBuilder is a builder for creating routes, it should stay transient because it's
            // stateful.
            services.TryAdd(ServiceDescriptor.Transient<TreeRouteBuilder>(s =>
            {
                var loggerFactory = s.GetRequiredService<ILoggerFactory>();
                var objectPool = s.GetRequiredService<ObjectPool<UriBuildingContext>>();
                var constraintResolver = s.GetRequiredService<IInlineConstraintResolver>();
                return new TreeRouteBuilder(loggerFactory, objectPool, constraintResolver);
            }));

            services.TryAddSingleton(typeof(RoutingMarkerService));

            // Collect all data sources from DI.
            services.TryAddEnumerable(ServiceDescriptor.Transient<IConfigureOptions<EndpointOptions>, ConfigureEndpointOptions>());

            // Allow global access to the list of endpoints.
            services.TryAddSingleton<CompositeEndpointDataSource>(s =>
            {
                var options = s.GetRequiredService<IOptions<EndpointOptions>>();
                return new CompositeEndpointDataSource(options.Value.DataSources);
            });

            //
            // Endpoint Infrastructure
            //
            services.TryAddSingleton<EndpointDataSource, BuilderEndpointDataSource>();
            services.TryAddSingleton<EndpointDataSourceBuilder, DefaultEndpointDataSourceBuilder>();

            //
            // Default matcher implementation
            //
            services.TryAddSingleton<MatchProcessorFactory, DefaultMatchProcessorFactory>();
            services.TryAddSingleton<MatcherFactory, DfaMatcherFactory>();
            services.TryAddTransient<DfaMatcherBuilder>();

            // Link generation related services
            services.TryAddSingleton<IEndpointFinder<RouteValuesAddress>, RouteValuesBasedEndpointFinder>();
            services.TryAddSingleton<LinkGenerator, DefaultLinkGenerator>();

            //
            // Endpoint Selection
            //
            services.TryAddSingleton<EndpointSelector, DefaultEndpointSelector>();
            services.TryAddEnumerable(ServiceDescriptor.Singleton<MatcherPolicy, HttpMethodMatcherPolicy>());

            return services;
        }

        /// <summary>
        /// Adds services required for routing requests.
        /// </summary>
        /// <param name="services">The <see cref="IServiceCollection"/> to add the services to.</param>
        /// <param name="configureOptions">The routing options to configure the middleware with.</param>
        /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
        public static IServiceCollection AddRouting(
            this IServiceCollection services,
            Action<RouteOptions> configureOptions)
        {
            if (services == null)
            {
                throw new ArgumentNullException(nameof(services));
            }

            if (configureOptions == null)
            {
                throw new ArgumentNullException(nameof(configureOptions));
            }

            services.Configure(configureOptions);
            services.AddRouting();

            return services;
        }
    }
}