// Copyright (c) Microsoft Open Technologies, Inc. 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.IO;
using System.Reflection;
using System.Threading.Tasks;
using InlineConstraints;
using Microsoft.AspNet.Builder;
using Microsoft.AspNet.Routing;
using Microsoft.AspNet.TestHost;
using Microsoft.Framework.DependencyInjection;
using Microsoft.Framework.DependencyInjection.Fallback;
using Microsoft.Framework.Runtime;
using Microsoft.Framework.Runtime.Infrastructure;
using Xunit;

namespace Microsoft.AspNet.Mvc.FunctionalTests
{
    public static class TestHelper
    {
        public static IServiceProvider CreateServices(string applicationWebSiteName)
        {
            var originalProvider = CallContextServiceLocator.Locator.ServiceProvider;
            var appEnvironment = originalProvider.GetService<IApplicationEnvironment>();

            // When an application executes in a regular context, the application base path points to the root
            // directory where the application is located, for example MvcSample.Web. However, when executing
            // an aplication as part of a test, the ApplicationBasePath of the IApplicationEnvironment points
            // to the root folder of the test project.
            // To compensate for this, we need to calculate the original path and override the application
            // environment value so that components like the view engine work properly in the context of the
            // test.
            var appBasePath = CalculateApplicationBasePath(appEnvironment, applicationWebSiteName);
            var provider = new ServiceCollection()
                            .AddInstance(typeof(IApplicationEnvironment),
                                         new TestApplicationEnvironment(appEnvironment, appBasePath))
                            .BuildServiceProvider(originalProvider);

            return provider;
        }

        // Calculate the path relative to the application base path.
        public static string CalculateApplicationBasePath(IApplicationEnvironment appEnvironment,
                                                          string applicationWebSiteName)
        {
            // Mvc/test/Microsoft.AspNet.Mvc.FunctionalTests
            var appBase = appEnvironment.ApplicationBasePath;

            // Mvc/test
            var test = Path.GetDirectoryName(appBase);

            // Mvc/test/WebSites/applicationWebSiteName
            return Path.GetFullPath(Path.Combine(appBase, "..", "WebSites", applicationWebSiteName));
        }
    }
}