// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.Globalization;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Runtime.CompilerServices;
using System.Threading.Tasks;
using System.Xml.Linq;
using Microsoft.AspNetCore.Server.IntegrationTesting;
using Microsoft.AspNetCore.Server.IntegrationTesting.IIS;
using Microsoft.AspNetCore.Testing;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Testing;
using Microsoft.Net.Http.Headers;
using Xunit;
using Xunit.Abstractions;
using Xunit.Sdk;

namespace ServerComparison.FunctionalTests
{
    public class ResponseCompressionTests : LoggedTest
    {
        // NGinx's default min size is 20 bytes
        private static readonly string HelloWorldBody = "Hello World;" + new string('a', 20);

        public ResponseCompressionTests(ITestOutputHelper output) : base(output)
        {
        }

        public static TestMatrix NoCompressionTestVariants
            => TestMatrix.ForServers(ServerType.IISExpress, ServerType.Kestrel, ServerType.Nginx,  ServerType.HttpSys)
                .WithTfms(Tfm.Default)
                .WithAllHostingModels();

        [ConditionalTheory]
        [MemberData(nameof(NoCompressionTestVariants))]
        public Task ResponseCompression_NoCompression(TestVariant variant)
        {
            return ResponseCompression(variant, CheckNoCompressionAsync, hostCompression: false);
        }

        public static TestMatrix HostCompressionTestVariants
            => TestMatrix.ForServers(ServerType.IISExpress, ServerType.Nginx)
                .WithTfms(Tfm.Default)
                .WithAllHostingModels();

        [ConditionalTheory]
        [MemberData(nameof(HostCompressionTestVariants))]
        public Task ResponseCompression_HostCompression(TestVariant variant)
        {
            return ResponseCompression(variant, CheckHostCompressionAsync, hostCompression: true);
        }

        public static TestMatrix AppCompressionTestVariants
            => TestMatrix.ForServers(ServerType.IISExpress, ServerType.Kestrel, ServerType.HttpSys) // No pass-through compression for nginx
                .WithTfms(Tfm.Default)
                .WithAllHostingModels();

        [ConditionalTheory]
        [MemberData(nameof(AppCompressionTestVariants))]
        public Task ResponseCompression_AppCompression(TestVariant variant)
        {
            return ResponseCompression(variant, CheckAppCompressionAsync, hostCompression: false);
        }

        public static TestMatrix HostAndAppCompressionTestVariants
            => TestMatrix.ForServers(ServerType.IISExpress, ServerType.Kestrel, ServerType.Nginx, ServerType.HttpSys)
                .WithTfms(Tfm.Default)
                .WithAllHostingModels();

        [ConditionalTheory]
        [MemberData(nameof(HostAndAppCompressionTestVariants))]
        public Task ResponseCompression_AppAndHostCompression(TestVariant variant)
        {
            return ResponseCompression(variant, CheckAppCompressionAsync, hostCompression: true);
        }

        private async Task ResponseCompression(TestVariant variant,
            Func<HttpClient, ILogger, Task> scenario,
            bool hostCompression,
            [CallerMemberName] string testName = null)
        {
            testName = $"{testName}_{variant.Server}_{variant.Tfm}_{variant.Architecture}_{variant.ApplicationType}";
            using (StartLog(out var loggerFactory,
                variant.Server == ServerType.Nginx ? LogLevel.Trace : LogLevel.Debug, // https://github.com/aspnet/ServerTests/issues/144
                testName))
            {
                var logger = loggerFactory.CreateLogger("ResponseCompression");

                var deploymentParameters = new DeploymentParameters(variant)
                {
                    ApplicationPath = Helpers.GetApplicationPath(),
                    EnvironmentName = "ResponseCompression",
                };

                if (variant.Server == ServerType.Nginx)
                {
                    deploymentParameters.ServerConfigTemplateContent = hostCompression
                        ? Helpers.GetNginxConfigContent("nginx.conf")
                        : Helpers.GetNginxConfigContent("NoCompression.conf");
                }
                else if (variant.Server == ServerType.IISExpress && !hostCompression)
                {
                    var iisDeploymentParameters = new IISDeploymentParameters(deploymentParameters);
                    iisDeploymentParameters.ServerConfigActionList.Add(
                        (element, _) => {
                            var compressionElement = element
                                .RequiredElement("system.webServer")
                                .RequiredElement("httpCompression");

                            compressionElement
                                .RequiredElement("dynamicTypes")
                                .Elements()
                                .SkipLast(1)
                                .Remove();

                            compressionElement
                                .RequiredElement("staticTypes")
                                .Elements()
                                .SkipLast(1)
                                .Remove();
                            // last element in both dynamicTypes and staticTypes disables compression
                            // <add mimeType="*/*" enabled="false" />
                        });
                    deploymentParameters = iisDeploymentParameters;
                }

                using (var deployer = IISApplicationDeployerFactory.Create(deploymentParameters, loggerFactory))
                {
                    var deploymentResult = await deployer.DeployAsync();
                    var httpClientHandler = new HttpClientHandler() { AutomaticDecompression = DecompressionMethods.None };
                    Assert.True(httpClientHandler.SupportsAutomaticDecompression);
                    var httpClient = deploymentResult.CreateHttpClient(httpClientHandler);

                    // Request to base address and check if various parts of the body are rendered & measure the cold startup time.
                    var response = await RetryHelper.RetryRequest(() =>
                    {
                        return httpClient.GetAsync(string.Empty);
                    }, logger, deploymentResult.HostShutdownToken);

                    var responseText = await response.Content.ReadAsStringAsync();
                    try
                    {
                        Assert.Equal("Running", responseText);
                    }
                    catch (XunitException)
                    {
                        logger.LogWarning(response.ToString());
                        logger.LogWarning(responseText);
                        throw;
                    }

                    await scenario(httpClient, logger);
                }
            }
        }

        private static async Task CheckNoCompressionAsync(HttpClient client, ILogger logger)
        {
            logger.LogInformation("Testing /NoAppCompression");
            var request = new HttpRequestMessage(HttpMethod.Get, "NoAppCompression");
            request.Headers.AcceptEncoding.ParseAdd("gzip,deflate");
            var response = await client.SendAsync(request);
            var responseText = await response.Content.ReadAsStringAsync();
            try
            {
                Assert.Equal(HelloWorldBody, responseText);
                Assert.Equal(HelloWorldBody.Length.ToString(CultureInfo.InvariantCulture), GetContentLength(response));
                Assert.Equal(0, response.Content.Headers.ContentEncoding.Count);
            }
            catch (XunitException)
            {
                logger.LogWarning(response.ToString());
                logger.LogWarning(responseText);
                throw;
            }
        }

        private static Task CheckHostCompressionAsync(HttpClient client, ILogger logger)
        {
            return CheckCompressionAsync(client, "NoAppCompression", logger);
        }

        private static Task CheckAppCompressionAsync(HttpClient client, ILogger logger)
        {
            return CheckCompressionAsync(client, "AppCompression", logger);
        }

        private static async Task CheckCompressionAsync(HttpClient client, string url, ILogger logger)
        {
            // Manage the compression manually because HttpClient removes the Content-Encoding header when decompressing.
            logger.LogInformation($"Testing /{url}");
            var request = new HttpRequestMessage(HttpMethod.Get, url);
            request.Headers.AcceptEncoding.ParseAdd("gzip,deflate");
            var response = await client.SendAsync(request);
            var responseText = await response.Content.ReadAsStringAsync();
            try
            {
                responseText = await ReadCompressedAsStringAsync(response.Content);
                Assert.Equal(HelloWorldBody, responseText);
                Assert.Equal(1, response.Content.Headers.ContentEncoding.Count);
                Assert.Equal("gzip", response.Content.Headers.ContentEncoding.First());
            }
            catch (XunitException)
            {
                logger.LogWarning(response.ToString());
                logger.LogWarning(responseText);
                throw;
            }
        }

        private static string GetContentLength(HttpResponseMessage response)
        {
            // Don't use response.Content.Headers.ContentLength, it will dynamically calculate the value if it can.
            return response.Content.Headers.TryGetValues(HeaderNames.ContentLength, out var values) ? values.FirstOrDefault() : null;
        }

        private static async Task<string> ReadCompressedAsStringAsync(HttpContent content)
        {
            using (var stream = await content.ReadAsStreamAsync())
            using (var compressStream = new GZipStream(stream, CompressionMode.Decompress))
            using (var reader = new StreamReader(compressStream))
            {
                return await reader.ReadToEndAsync();
            }
        }
    }
}
