// 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.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Sockets;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Hosting.Server.Features;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Extensions;
using Microsoft.AspNetCore.Server.Kestrel.Internal.Networking;
using Microsoft.AspNetCore.Testing.xunit;
using Xunit;

namespace Microsoft.AspNetCore.Server.Kestrel.FunctionalTests
{
    public class AddressRegistrationTests
    {

        [Theory, MemberData(nameof(AddressRegistrationDataIPv4))]
        public async Task RegisterAddresses_IPv4_Success(string addressInput, Func<IServerAddressesFeature, string[]> testUrls)
        {
            await RegisterAddresses_Success(addressInput, testUrls);
        }

        [ConditionalTheory, MemberData(nameof(AddressRegistrationDataIPv4Port80))]
        [Port80SupportedCondition]
        public async Task RegisterAddresses_IPv4Port80_Success(string addressInput, Func<IServerAddressesFeature, string[]> testUrls)
        {
            await RegisterAddresses_Success(addressInput, testUrls);
        }

        [ConditionalTheory, MemberData(nameof(AddressRegistrationDataIPv6))]
        [IPv6SupportedCondition]
        public async Task RegisterAddresses_IPv6_Success(string addressInput, Func<IServerAddressesFeature, string[]> testUrls)
        {
            await RegisterAddresses_Success(addressInput, testUrls);
        }

        [ConditionalTheory, MemberData(nameof(AddressRegistrationDataIPv6Port80))]
        [IPv6SupportedCondition]
        [Port80SupportedCondition]
        public async Task RegisterAddresses_IPv6Port80_Success(string addressInput, Func<IServerAddressesFeature, string[]> testUrls)
        {
            await RegisterAddresses_Success(addressInput, testUrls);
        }

        [ConditionalTheory, MemberData(nameof(AddressRegistrationDataIPv6ScopeId))]
        [IPv6SupportedCondition]
        [OSSkipCondition(OperatingSystems.Linux, SkipReason = "HttpClient does not support IPv6 with scope ID on Linux (https://github.com/dotnet/corefx/issues/8235).")]
        [OSSkipCondition(OperatingSystems.MacOSX, SkipReason = "HttpClient does not support IPv6 with scope ID on Mac (https://github.com/dotnet/corefx/issues/8235).")]
        public async Task RegisterAddresses_IPv6ScopeId_Success(string addressInput, Func<IServerAddressesFeature, string[]> testUrls)
        {
            await RegisterAddresses_Success(addressInput, testUrls);
        }

        private async Task RegisterAddresses_Success(string addressInput, Func<IServerAddressesFeature, string[]> testUrls)
        {
            var hostBuilder = new WebHostBuilder()
                .UseKestrel()
                .UseUrls(addressInput)
                .Configure(ConfigureEchoAddress);

            using (var host = hostBuilder.Build())
            {
                host.Start();

                using (var client = new HttpClient())
                {
                    foreach (var testUrl in testUrls(host.ServerFeatures.Get<IServerAddressesFeature>()))
                    {
                        var response = await client.GetAsync(testUrl);
                        
                        // Compare the response with the RequestMessage.RequestUri, rather than testUrl directly.
                        // Required to handle IPv6 addresses with zone index, like "fe80::3%1"
                        Assert.Equal(
                            response.RequestMessage.RequestUri.ToString(),
                            await response.Content.ReadAsStringAsync());
                    }
                }
            }
        }

        [Fact]
        public void ThrowsWhenBindingLocalhostToIPv4AddressInUse()
        {
            ThrowsWhenBindingLocalhostToAddressInUse(AddressFamily.InterNetwork, IPAddress.Loopback);
        }

        [ConditionalFact]
        [IPv6SupportedCondition]
        public void ThrowsWhenBindingLocalhostToIPv6AddressInUse()
        {
            ThrowsWhenBindingLocalhostToAddressInUse(AddressFamily.InterNetworkV6, IPAddress.IPv6Loopback);
        }

        [Fact]
        public void ThrowsWhenBindingLocalhostToDynamicPort()
        {
            var hostBuilder = new WebHostBuilder()
                    .UseKestrel()
                    .UseUrls("http://localhost:0")
                    .Configure(ConfigureEchoAddress);

            using (var host = hostBuilder.Build())
            {
                Assert.Throws<InvalidOperationException>(() => host.Start());
            }
        }

        private void ThrowsWhenBindingLocalhostToAddressInUse(AddressFamily addressFamily, IPAddress address)
        {
            using (var socket = new Socket(addressFamily, SocketType.Stream, ProtocolType.Tcp))
            {
                var port = GetNextPort();
                socket.Bind(new IPEndPoint(address, port));

                var hostBuilder = new WebHostBuilder()
                    .UseKestrel()
                    .UseUrls($"http://localhost:{port}")
                    .Configure(ConfigureEchoAddress);

                using (var host = hostBuilder.Build())
                {
                    var exception = Assert.Throws<AggregateException>(() => host.Start());
                    Assert.Contains(exception.InnerExceptions, ex => ex is UvException);
                }
            }
        }

        public static TheoryData<string, Func<IServerAddressesFeature, string[]>> AddressRegistrationDataIPv4
        {
            get
            {
                var dataset = new TheoryData<string, Func<IServerAddressesFeature, string[]>>();

                // Default host and port
                dataset.Add(null, _ => new[] { "http://127.0.0.1:5000/" });
                dataset.Add(string.Empty, _ => new[] { "http://127.0.0.1:5000/" });

                // Static ports
                var port1 = GetNextPort();
                var port2 = GetNextPort();

                // Loopback
                dataset.Add($"http://127.0.0.1:{port1}", _ => new[] { $"http://127.0.0.1:{port1}/" });

                // Localhost
                dataset.Add($"http://localhost:{port1}", _ => new[] { $"http://localhost:{port1}/", $"http://127.0.0.1:{port1}/" });

                // Any
                dataset.Add($"http://*:{port1}/", _ => new[] { $"http://127.0.0.1:{port1}/" });
                dataset.Add($"http://+:{port1}/", _ => new[] { $"http://127.0.0.1:{port1}/" });

                // Multiple addresses
                dataset.Add($"http://127.0.0.1:{port1};http://127.0.0.1:{port2}", _ => new[] { $"http://127.0.0.1:{port1}/", $"http://127.0.0.1:{port2}/" });

                // Path after port
                dataset.Add($"http://127.0.0.1:{port1}/base/path", _ => new[] { $"http://127.0.0.1:{port1}/base/path" });

                // Dynamic port and non-loopback addresses
                dataset.Add("http://127.0.0.1:0/", GetTestUrls);
                dataset.Add($"http://{Dns.GetHostName()}:0/", GetTestUrls);

                var ipv4Addresses = Dns.GetHostAddressesAsync(Dns.GetHostName()).Result
                    .Where(ip => ip.AddressFamily == AddressFamily.InterNetwork);
                foreach (var ip in ipv4Addresses)
                {
                    dataset.Add($"http://{ip}:0/", GetTestUrls);
                }

                return dataset;
            }
        }

        public static TheoryData<string, Func<IServerAddressesFeature, string[]>> AddressRegistrationDataIPv4Port80
        {
            get
            {
                var dataset = new TheoryData<string, Func<IServerAddressesFeature, string[]>>();

                // Default port for HTTP (80)
                dataset.Add("http://127.0.0.1", _ => new[] { "http://127.0.0.1/" });
                dataset.Add("http://localhost", _ => new[] { "http://127.0.0.1/" });
                dataset.Add("http://*", _ => new[] { "http://127.0.0.1/" });

                return dataset;
            }
        }

        public static TheoryData<string, Func<IServerAddressesFeature, string[]>> AddressRegistrationDataIPv6
        {
            get
            {
                var dataset = new TheoryData<string, Func<IServerAddressesFeature, string[]>>();

                // Default host and port
                dataset.Add(null, _ => new[] { "http://127.0.0.1:5000/", "http://[::1]:5000/" });
                dataset.Add(string.Empty, _ => new[] { "http://127.0.0.1:5000/", "http://[::1]:5000/" });

                // Static ports
                var port1 = GetNextPort();
                var port2 = GetNextPort();

                // Loopback
                dataset.Add($"http://[::1]:{port1}/", _ => new[] { $"http://[::1]:{port1}/" });

                // Localhost
                dataset.Add($"http://localhost:{port1}", _ => new[] { $"http://localhost:{port1}/", $"http://127.0.0.1:{port1}/", $"http://[::1]:{port1}/" });

                // Any
                dataset.Add($"http://*:{port1}/", _ => new[] { $"http://127.0.0.1:{port1}/", $"http://[::1]:{port1}/" });
                dataset.Add($"http://+:{port1}/", _ => new[] { $"http://127.0.0.1:{port1}/", $"http://[::1]:{port1}/" });

                // Multiple addresses
                dataset.Add($"http://127.0.0.1:{port1}/;http://[::1]:{port1}/", _ => new[] { $"http://127.0.0.1:{port1}/", $"http://[::1]:{port1}/" });
                dataset.Add($"http://[::1]:{port1};http://[::1]:{port2}", _ => new[] { $"http://[::1]:{port1}/", $"http://[::1]:{port2}/" });

                // Path after port
                dataset.Add($"http://[::1]:{port1}/base/path", _ => new[] { $"http://[::1]:{port1}/base/path" });

                // Dynamic port and non-loopback addresses
                var ipv6Addresses = Dns.GetHostAddressesAsync(Dns.GetHostName()).Result
                    .Where(ip => ip.AddressFamily == AddressFamily.InterNetworkV6)
                    .Where(ip => ip.ScopeId == 0);
                foreach (var ip in ipv6Addresses)
                {
                    dataset.Add($"http://[{ip}]:0/", GetTestUrls);
                }

                return dataset;
            }
        }

        public static TheoryData<string, Func<IServerAddressesFeature, string[]>> AddressRegistrationDataIPv6Port80
        {
            get
            {
                var dataset = new TheoryData<string, Func<IServerAddressesFeature, string[]>>();

                // Default port for HTTP (80)
                dataset.Add("http://[::1]", _ => new[] { "http://[::1]/" });
                dataset.Add("http://localhost", _ => new[] { "http://127.0.0.1/", "http://[::1]/" });
                dataset.Add("http://*", _ => new[] { "http://[::1]/" });

                return dataset;
            }
        }

        public static TheoryData<string, Func<IServerAddressesFeature, string[]>> AddressRegistrationDataIPv6ScopeId
        {
            get
            {
                var dataset = new TheoryData<string, Func<IServerAddressesFeature, string[]>>();

                // Dynamic port
                var ipv6Addresses = Dns.GetHostAddressesAsync(Dns.GetHostName()).Result
                    .Where(ip => ip.AddressFamily == AddressFamily.InterNetworkV6)
                    .Where(ip => ip.ScopeId != 0);
                foreach (var ip in ipv6Addresses)
                {
                    dataset.Add($"http://[{ip}]:0/", GetTestUrls);
                }

                return dataset;
            }
        }

        private static string[] GetTestUrls(IServerAddressesFeature addressesFeature)
        {
            return addressesFeature.Addresses
                .Select(a => a.Replace("://+", "://localhost"))
                .Select(a => a.EndsWith("/") ? a : a + "/")
                .ToArray();
        }

        private void ConfigureEchoAddress(IApplicationBuilder app)
        {
            app.Run(context =>
            {
                return context.Response.WriteAsync(context.Request.GetDisplayUrl());
            });
        }

        private static int _nextPort = 8001;
        private static object _portLock = new object();
        private static int GetNextPort()
        {
            lock (_portLock)
            {
                using (var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
                {
                    while (true)
                    {
                        try
                        {
                            var port = _nextPort++;
                            socket.Bind(new IPEndPoint(IPAddress.Loopback, port));
                            return port;
                        }
                        catch (SocketException)
                        {
                            // Retry unless exhausted
                            if (_nextPort == 65536)
                            {
                                throw;
                            }
                        }
                    }
                }
            }
        }

        [AttributeUsage(AttributeTargets.Method, AllowMultiple = false)]
        private class Port80SupportedConditionAttribute : Attribute, ITestCondition
        {
            private static readonly Lazy<bool> _port80Supported = new Lazy<bool>(CanBindToPort80);

            public bool IsMet
            {
                get
                {
                    return _port80Supported.Value;
                }
            }

            public string SkipReason
            {
                get
                {
                    return "Cannot bind to port 80 on the host.";
                }
            }

            private static bool CanBindToPort80()
            {
                try
                {
                    using (var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
                    {
                        socket.Bind(new IPEndPoint(IPAddress.Loopback, 80));
                        return true;
                    }
                }
                catch (SocketException)
                {
                    return false;
                }
            }
        }
    }
}