Dependify/src/Dependify/IServiceCollectionExtensions.cs

// Copyright 2017 Dávid Kaya. All rights reserved.
// Use of this source code is governed by the MIT license,
// as found in the LICENSE file.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using Dependify.Attributes;
using Dependify.Utilities;
using Microsoft.Extensions.DependencyInjection;

namespace Dependify {
    // ReSharper disable once InconsistentNaming
    public static class IServiceCollectionExtensions {
        /// <summary>
        /// Adds all classes and factory methods with <see cref="RegisterScoped"/>, 
        /// <see cref="RegisterSingleton"/> or <see cref="RegisterTransient"/> attribute for classes
        /// and <see cref="RegisterScopedFactory"/>, <see cref="RegisterSingletonFactory"/> or <see cref="RegisterTransientFactory"/> for 
        /// factory methods to <see cref="IServiceCollection"/>.
        /// </summary>
        /// <param name="services">Service collection.</param>
        /// <returns>Service collection.</returns>
        public static IServiceCollection AutoRegister(this IServiceCollection services) {
            var assemblies = AppDomain.CurrentDomain.GetAssemblies();
            return services.AutoRegister(assemblies);
        }

        /// <summary>
        /// Adds all classes and factory methods from specified <paramref name="assemblies"/> with <see cref="RegisterScoped"/>, 
        /// <see cref="RegisterSingleton"/> or <see cref="RegisterTransient"/> attribute for classes
        /// and <see cref="RegisterScopedFactory"/>, <see cref="RegisterSingletonFactory"/> or <see cref="RegisterTransientFactory"/> for 
        /// factory methods to <see cref="IServiceCollection"/>.
        /// </summary>
        /// <param name="services">Service collection.</param>
        /// <param name="assemblies">Assemblies to scan</param>
        /// <returns>Service collection.</returns>
        public static IServiceCollection AutoRegister(this IServiceCollection services, params Assembly[] assemblies) {
            services.AddFactories(DependifyUtils.GetFactoryMethods(assemblies));
            services.AddClasses(DependifyUtils.GetClassTypes(assemblies));
            return services;
        }

        /// <summary>
        /// Adds all classes and factory methods, from namespaces that start with <paramref name="namespace"/>, with <see cref="RegisterScoped"/>, 
        /// <see cref="RegisterSingleton"/> or <see cref="RegisterTransient"/> attribute for classes
        /// and <see cref="RegisterScopedFactory"/>, <see cref="RegisterSingletonFactory"/> or <see cref="RegisterTransientFactory"/> for 
        /// factory methods to <see cref="IServiceCollection"/>.
        /// </summary>
        /// <param name="services">Service collection.</param>
        /// <param name="namespace">Scanned namespace.</param>
        /// <returns></returns>
        public static IServiceCollection AutoRegister(this IServiceCollection services, string @namespace) {
            var assemblies = AppDomain.CurrentDomain.GetAssemblies();
            services.AddFactories(DependifyUtils.GetFactoryMethodsFromNamespace(assemblies, @namespace));
            services.AddClasses(DependifyUtils.GetClassTypesFromNamespace(assemblies, @namespace));
            return services;
        }

        /// <summary>
        /// Adds all classes and factory methods resolved from <paramref name="assemblyResolver"/> with <see cref="RegisterScoped"/>, 
        /// <see cref="RegisterSingleton"/> or <see cref="RegisterTransient"/> attribute for classes
        /// and <see cref="RegisterScopedFactory"/>, <see cref="RegisterSingletonFactory"/> or <see cref="RegisterTransientFactory"/> for 
        /// factory methods to <see cref="IServiceCollection"/>. 
        /// </summary>
        /// <param name="services">Service collection.</param>
        /// <param name="assemblyResolver">Assembly resolver.</param>
        /// <returns></returns>
        public static IServiceCollection AutoRegister(this IServiceCollection services, IAssemblyResolver assemblyResolver) {
            return services.AutoRegister(assemblyResolver.Resolve().ToArray());
        }

        internal static IServiceCollection AddFactories(this IServiceCollection services, IEnumerable<MethodInfo> methodInfos) {
            foreach (var methodInfo in methodInfos) {
                var factoryAttribute = methodInfo.GetCustomAttributes<RegisterFactory>(true).First();
                var factoryAttributeType = factoryAttribute.GetType();
                var factoryReturnType = factoryAttribute.ReturnType;

                if (factoryAttributeType == typeof(RegisterTransientFactory))
                    services.AddTransient(factoryReturnType, DependifyUtils.GetFactoryMethod(methodInfo));
                if (factoryAttributeType == typeof(RegisterScopedFactory))
                    services.AddScoped(factoryReturnType, DependifyUtils.GetFactoryMethod(methodInfo));
                if (factoryAttributeType == typeof(RegisterSingletonFactory))
                    services.AddSingleton(factoryReturnType, DependifyUtils.GetFactoryMethod(methodInfo));
            }
            return services;
        }

        internal static void AddClasses(this IServiceCollection services, IEnumerable<Type> classTypes) {
            foreach (var classType in classTypes) {
                var classAttributes = classType.GetCustomAttributes<Register>(true);
                foreach (var classAttribute in classAttributes) {
                    var registrationType = classAttribute.GetType();
                    var interfaceTypes = classAttribute.InterfaceTypes == null || !classAttribute.InterfaceTypes.Any() ? classType.GetInterfaces() : classAttribute.InterfaceTypes;

                    foreach (var interfaceType in interfaceTypes) {
                        if (registrationType == typeof(RegisterTransient))
                            services.AddTransient(interfaceType, classType);
                        if (registrationType == typeof(RegisterScoped))
                            services.AddScoped(interfaceType, classType);
                        if (registrationType == typeof(RegisterSingleton))
                            services.AddSingleton(interfaceType, classType);
                    }
                }
            }
        }
    }
}