// 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.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc.Abstractions;
using Microsoft.AspNetCore.Mvc.Controllers;
using Microsoft.AspNetCore.Mvc.Infrastructure;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Internal;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using Moq;
using Xunit;

namespace Microsoft.AspNetCore.Mvc.Filters
{
    public class MiddlewareFilterTest
    {
        private readonly TestController _controller = new TestController();

        [Fact]
        public async Task MiddlewareFilter_SetsMiddlewareFilterFeature_OnExecution()
        {
            // Arrange
            Task requestDelegate(HttpContext context) => Task.FromResult(true);
            var middlewareFilter = new MiddlewareFilter(requestDelegate);
            var httpContext = new DefaultHttpContext();
            var resourceExecutingContext = GetResourceExecutingContext(httpContext);
            var resourceExecutionDelegate = GetResourceExecutionDelegate(httpContext);

            // Act
            await middlewareFilter.OnResourceExecutionAsync(resourceExecutingContext, resourceExecutionDelegate);

            // Assert
            var feature = resourceExecutingContext.HttpContext.Features.Get<IMiddlewareFilterFeature>();
            Assert.NotNull(feature);
            Assert.Same(resourceExecutingContext, feature.ResourceExecutingContext);
            Assert.Same(resourceExecutionDelegate, feature.ResourceExecutionDelegate);
        }

        [Fact]
        public async Task OnMiddlewareShortCircuit_DoesNotExecute_RestOfFilterPipeline()
        {
            // Arrange
            var expectedHeader = "h1";
            Pipeline1.ConfigurePipeline = (appBuilder) =>
            {
                appBuilder.Use((httpContext, next) =>
                {
                    httpContext.Response.Headers.Add(expectedHeader, "");
                    return Task.FromResult(true); // short circuit the request
                });
            };
            var resourceFilter1 = new TestResourceFilter(TestResourceFilterAction.Passthrough);
            var middlewareResourceFilter = new MiddlewareFilter(GetMiddlewarePipeline(typeof(Pipeline1)));
            var exceptionThrowingResourceFilter = new TestResourceFilter(TestResourceFilterAction.ThrowException);

            var invoker = CreateInvoker(
                new IFilterMetadata[]
                {
                    resourceFilter1,
                    middlewareResourceFilter,
                    exceptionThrowingResourceFilter,
                },
                actionThrows: true); // The action won't run

            // Act
            await invoker.InvokeAsync();

            // Assert
            var resourceExecutedContext = resourceFilter1.ResourceExecutedContext;
            Assert.True(resourceExecutedContext.HttpContext.Response.Headers.ContainsKey(expectedHeader));
            Assert.True(resourceExecutedContext.Canceled);
            Assert.False(invoker.ControllerFactory.CreateCalled);
        }

        // Example: Middleware filters are applied at Global, Controller & Action level
        [Fact]
        public async Task Multiple_MiddlewareFilters_ConcatsTheMiddlewarePipelines()
        {
            // Arrange
            var expectedHeader = "h1";
            var expectedHeaderValue = "pipeline1-pipeline2";
            Pipeline1.ConfigurePipeline = (appBuilder) =>
            {
                appBuilder.Use((httpContext, next) =>
                {
                    httpContext.Response.Headers["h1"] = "pipeline1";
                    return next();
                });
            };
            Pipeline2.ConfigurePipeline = (appBuilder) =>
            {
                appBuilder.Use((httpContext, next) =>
                {
                    httpContext.Response.Headers["h1"] = httpContext.Response.Headers["h1"] + "-pipeline2";
                    return Task.FromResult(true); // short circuits the request
                });
            };
            var resourceFilter1 = new TestResourceFilter(TestResourceFilterAction.Passthrough);
            var middlewareResourceFilter1 = new MiddlewareFilter(GetMiddlewarePipeline(typeof(Pipeline1)));
            var middlewareResourceFilter2 = new MiddlewareFilter(GetMiddlewarePipeline(typeof(Pipeline2)));
            var exceptionThrowingResourceFilter = new TestResourceFilter(TestResourceFilterAction.ThrowException);

            var invoker = CreateInvoker(
                new IFilterMetadata[]
                {
                    resourceFilter1,                    // This filter will pass through
                    middlewareResourceFilter1,          // This filter will pass through
                    middlewareResourceFilter2,          // This filter will short circuit
                    exceptionThrowingResourceFilter,    // This shouldn't run
                },
                actionThrows: true); // The action won't run

            // Act
            await invoker.InvokeAsync();

            // Assert
            var resourceExecutedContext = resourceFilter1.ResourceExecutedContext;
            var response = resourceExecutedContext.HttpContext.Response;
            Assert.True(response.Headers.ContainsKey(expectedHeader));
            Assert.Equal(expectedHeaderValue, response.Headers[expectedHeader]);
            Assert.True(resourceExecutedContext.Canceled);
            Assert.False(invoker.ControllerFactory.CreateCalled);
        }

        [Fact]
        public async Task UnhandledException_InMiddleware_PropagatesBackToInvoker()
        {
            // Arrange
            var expectedMessage = "Error!!!";
            Pipeline1.ConfigurePipeline = (appBuilder) =>
            {
                appBuilder.Use((httpContext, next) =>
                {
                    throw new InvalidOperationException(expectedMessage);
                });
            };
            var resourceFilter1 = new TestResourceFilter(TestResourceFilterAction.Passthrough);
            var middlewareResourceFilter = new MiddlewareFilter(GetMiddlewarePipeline(typeof(Pipeline1)));
            var exceptionThrowingResourceFilter = new TestResourceFilter(TestResourceFilterAction.ThrowException);

            var invoker = CreateInvoker(
                new IFilterMetadata[]
                {
                    resourceFilter1,
                    middlewareResourceFilter,
                    exceptionThrowingResourceFilter, // This shouldn't run
                },
                actionThrows: true); // The action won't run

            // Act
            var exception = await Assert.ThrowsAsync<InvalidOperationException>(async () => await invoker.InvokeAsync());

            // Assert
            Assert.Equal(expectedMessage, exception.Message);
        }

        [Fact]
        public async Task ExceptionThrownInMiddleware_CanBeHandled_ByEarlierMiddleware()
        {
            // Arrange
            var expectedMessage = "Error!!!";
            Pipeline1.ConfigurePipeline = (appBuilder) =>
            {
                appBuilder.Use(async (httpContext, next) =>
                {
                    try
                    {
                        await next();
                    }
                    catch
                    {
                        httpContext.Response.StatusCode = 500;
                        httpContext.Response.Headers.Add("Error", "Error!!!!");
                    }
                });
            };
            Pipeline2.ConfigurePipeline = (appBuilder) =>
            {
                appBuilder.Use((httpContext, next) =>
                {
                    throw new InvalidOperationException(expectedMessage);
                });
            };
            var resourceFilter1 = new TestResourceFilter(TestResourceFilterAction.Passthrough);
            var middlewareResourceFilter1 = new MiddlewareFilter(GetMiddlewarePipeline(typeof(Pipeline1)));
            var middlewareResourceFilter2 = new MiddlewareFilter(GetMiddlewarePipeline(typeof(Pipeline2)));
            var exceptionThrowingResourceFilter = new TestResourceFilter(TestResourceFilterAction.ThrowException);

            var invoker = CreateInvoker(
                new IFilterMetadata[]
                {
                    resourceFilter1,
                    middlewareResourceFilter1,
                    middlewareResourceFilter2,
                    exceptionThrowingResourceFilter, // This shouldn't run
                },
                actionThrows: true); // The action won't run

            // Act
            var exception = await Assert.ThrowsAsync<InvalidOperationException>(async () => await invoker.InvokeAsync());

            // Assert
            var resourceExecutedContext = resourceFilter1.ResourceExecutedContext;
            var response = resourceExecutedContext.HttpContext.Response;
            Assert.Equal(500, response.StatusCode);
            Assert.True(response.Headers.ContainsKey("Error"));
            Assert.False(invoker.ControllerFactory.CreateCalled);
        }

        private ResourceExecutingContext GetResourceExecutingContext(HttpContext httpContext)
        {
            return new ResourceExecutingContext(
                new ActionContext(httpContext, new RouteData(), new ActionDescriptor(), new ModelStateDictionary()),
                new List<IFilterMetadata>(),
                new List<IValueProviderFactory>());
        }

        private ResourceExecutionDelegate GetResourceExecutionDelegate(HttpContext httpContext)
        {
            return new ResourceExecutionDelegate(
                () => Task.FromResult(new ResourceExecutedContext(new ActionContext(), new List<IFilterMetadata>())));
        }

        private TestControllerActionInvoker CreateInvoker(
            IFilterMetadata[] filters,
            bool actionThrows = false)
        {
            var actionDescriptor = new ControllerActionDescriptor()
            {
                FilterDescriptors = new List<FilterDescriptor>(),
                Parameters = new List<ParameterDescriptor>(),
            };

            if (actionThrows)
            {
                actionDescriptor.MethodInfo = typeof(ControllerActionInvokerTest.TestController).GetMethod(
                    nameof(ControllerActionInvokerTest.TestController.ThrowingActionMethod));
            }
            else
            {
                actionDescriptor.MethodInfo = typeof(ControllerActionInvokerTest.TestController).GetMethod(
                    nameof(ControllerActionInvokerTest.TestController.ActionMethod));
            }
            actionDescriptor.ControllerTypeInfo = typeof(ControllerActionInvokerTest.TestController).GetTypeInfo();

            return CreateInvoker(filters, actionDescriptor, _controller);
        }

        private TestControllerActionInvoker CreateInvoker(
            IFilterMetadata[] filters,
            ControllerActionDescriptor actionDescriptor,
            object controller)
        {
            var httpContext = GetHttpContext();
            httpContext.Response.Body = new MemoryStream();

            var options = new MvcOptions();
            var optionsAccessor = new Mock<IOptions<MvcOptions>>();
            optionsAccessor
                .SetupGet(o => o.Value)
                .Returns(options);

            var actionContext = new ActionContext(httpContext, new RouteData(), actionDescriptor);

            var diagnosticListener = new DiagnosticListener("Microsoft.AspNetCore");
            diagnosticListener.SubscribeWithAdapter(new TestDiagnosticListener());

            var invoker = new TestControllerActionInvoker(
                filters,
                new MockControllerFactory(controller ?? this),
                new NullLoggerFactory().CreateLogger<ControllerActionInvoker>(),
                diagnosticListener,
                new ActionResultTypeMapper(),
                actionContext,
                new List<IValueProviderFactory>(),
                maxAllowedErrorsInModelState: 200);
            return invoker;
        }

        private class Pipeline1
        {
            public static Action<IApplicationBuilder> ConfigurePipeline { get; set; }

            public void Configure(IApplicationBuilder appBuilder)
            {
                ConfigurePipeline(appBuilder);
            }
        }

        private class Pipeline2
        {
            public static Action<IApplicationBuilder> ConfigurePipeline { get; set; }

            public void Configure(IApplicationBuilder appBuilder)
            {
                ConfigurePipeline(appBuilder);
            }
        }

        private static HttpContext GetHttpContext()
        {
            var services = CreateServices();

            var httpContext = new DefaultHttpContext
            {
                RequestServices = services.BuildServiceProvider()
            };

            return httpContext;
        }

        private RequestDelegate GetMiddlewarePipeline(Type middlewarePipelineProviderType)
        {
            var applicationServices = new ServiceCollection();
            var applicationBuilder = new ApplicationBuilder(applicationServices.BuildServiceProvider());
            var middlewareFilterBuilderService = new MiddlewareFilterBuilder(
                new MiddlewareFilterConfigurationProvider())
            {
                ApplicationBuilder = applicationBuilder
            };

            return middlewareFilterBuilderService.GetPipeline(middlewarePipelineProviderType);
        }

        private static IServiceCollection CreateServices()
        {
            var services = new ServiceCollection();

            services.AddSingleton<ILoggerFactory>(NullLoggerFactory.Instance);
            return services;
        }

        private class MockControllerFactory
        {
            private object _controller;

            public MockControllerFactory(object controller)
            {
                _controller = controller;
            }

            public bool CreateCalled { get; private set; }

            public bool ReleaseCalled { get; private set; }

            public ControllerContext ControllerContext { get; private set; }

            public object CreateController(ControllerContext context)
            {
                ControllerContext = context;
                CreateCalled = true;
                return _controller;
            }

            public void ReleaseController(ControllerContext context, object controller)
            {
                Assert.NotNull(controller);
                Assert.Same(_controller, controller);
                ReleaseCalled = true;
            }

            public void Verify()
            {
                if (CreateCalled && !ReleaseCalled)
                {
                    Assert.False(true, "ReleaseController should have been called.");
                }
            }
        }

        private class TestControllerActionInvoker : ControllerActionInvoker
        {
            public TestControllerActionInvoker(
                IFilterMetadata[] filters,
                MockControllerFactory controllerFactory,
                ILogger logger,
                DiagnosticListener diagnosticListener,
                IActionResultTypeMapper mapper,
                ActionContext actionContext,
                IReadOnlyList<IValueProviderFactory> valueProviderFactories,
                int maxAllowedErrorsInModelState)
                : base(
                      logger,
                      diagnosticListener,
                      ActionContextAccessor.Null,
                      mapper,
                      CreateControllerContext(actionContext, valueProviderFactories, maxAllowedErrorsInModelState),
                      CreateCacheEntry((ControllerActionDescriptor)actionContext.ActionDescriptor, controllerFactory),
                      filters)
            {
                ControllerFactory = controllerFactory;
            }

            public MockControllerFactory ControllerFactory { get; }

            public async override Task InvokeAsync()
            {
                await base.InvokeAsync();

                // Make sure that the controller was disposed in every test that creates ones.
                ControllerFactory.Verify();
            }

            private static ObjectMethodExecutor CreateExecutor(ControllerActionDescriptor actionDescriptor)
            {
                return ObjectMethodExecutor.Create(actionDescriptor.MethodInfo, actionDescriptor.ControllerTypeInfo);
            }

            private static ControllerContext CreateControllerContext(
                ActionContext actionContext,
                IReadOnlyList<IValueProviderFactory> valueProviderFactories,
                int maxAllowedErrorsInModelState)
            {
                var controllerContext = new ControllerContext(actionContext)
                {
                    ValueProviderFactories = valueProviderFactories.ToList()
                };
                controllerContext.ModelState.MaxAllowedErrors = maxAllowedErrorsInModelState;

                return controllerContext;
            }

            private static ControllerActionInvokerCacheEntry CreateCacheEntry(
                ControllerActionDescriptor actionDescriptor,
                MockControllerFactory controllerFactory)
            {
                var objectMethodExecutor = CreateExecutor(actionDescriptor);
                return new ControllerActionInvokerCacheEntry(
                    new FilterItem[0],
                    controllerFactory.CreateController,
                    controllerFactory.ReleaseController,
                    null,
                    objectMethodExecutor,
                    ActionMethodExecutor.GetExecutor(objectMethodExecutor));
            }
        }

        private sealed class TestController
        {
        }

        private enum TestResourceFilterAction
        {
            ShortCircuit,
            ThrowException,
            Passthrough
        }

        private class TestResourceFilter : IAsyncResourceFilter
        {
            private readonly TestResourceFilterAction _action;
            public TestResourceFilter(TestResourceFilterAction action)
            {
                _action = action;
            }

            public ResourceExecutedContext ResourceExecutedContext { get; private set; }

            public async Task OnResourceExecutionAsync(ResourceExecutingContext context, ResourceExecutionDelegate next)
            {
                if (_action == TestResourceFilterAction.ThrowException)
                {
                    throw new NotImplementedException("This filter should not have been run!");

                }
                else if (_action == TestResourceFilterAction.Passthrough)
                {
                    ResourceExecutedContext = await next();
                }
                else
                {
                    context.Result = new TestActionResult();
                }
            }
        }

        public class TestActionResult : IActionResult
        {
            public Task ExecuteResultAsync(ActionContext context)
            {
                context.HttpContext.Response.StatusCode = 200;
                return context.HttpContext.Response.WriteAsync("Shortcircuited");
            }
        }
    }
}
