using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using MQTTnet.Core.Adapter;
using MQTTnet.Core.Client;
using MQTTnet.Core.Protocol;
using MQTTnet.Core.Server;
using Microsoft.Extensions.DependencyInjection;
using MQTTnet.Core.Packets;

namespace MQTTnet.Core.Tests
{
    [TestClass]
    public class MqttServerTests
    {
        [TestMethod]
        public void MqttServer_PublishSimple_AtMostOnce()
        {
            TestPublishAsync(
                "A/B/C",
                MqttQualityOfServiceLevel.AtMostOnce,
                "A/B/C",
                MqttQualityOfServiceLevel.AtMostOnce,
                1).Wait();
        }

        [TestMethod]
        public void MqttServer_PublishSimple_AtLeastOnce()
        {
            TestPublishAsync(
                "A/B/C",
                MqttQualityOfServiceLevel.AtLeastOnce,
                "A/B/C",
                MqttQualityOfServiceLevel.AtLeastOnce,
                1).Wait();
        }

        [TestMethod]
        public void MqttServer_PublishSimple_ExactlyOnce()
        {
            TestPublishAsync(
                "A/B/C",
                MqttQualityOfServiceLevel.ExactlyOnce,
                "A/B/C",
                MqttQualityOfServiceLevel.ExactlyOnce,
                1).Wait();
        }

        [TestMethod]
        public async Task MqttServer_WillMessage()
        {
            var serverAdapter = new TestMqttServerAdapter();
            var services = new ServiceCollection()
                .AddLogging()
                .AddMqttServer()
                .AddSingleton<IMqttServerAdapter>(serverAdapter)
                .BuildServiceProvider();

            var s = new MqttFactory(services).CreateMqttServer();
            var receivedMessagesCount = 0;
            try
            {
                await s.StartAsync();

                var willMessage = new MqttApplicationMessageBuilder().WithTopic("My/last/will").WithAtMostOnceQoS().Build();
                var c1 = await serverAdapter.ConnectTestClient(s, "c1");
                var c2 = await serverAdapter.ConnectTestClient(s, "c2", willMessage);

                c1.ApplicationMessageReceived += (_, __) => receivedMessagesCount++;
                await c1.SubscribeAsync(new TopicFilter("#", MqttQualityOfServiceLevel.AtMostOnce));

                await c2.DisconnectAsync();

                await Task.Delay(1000);
            }
            finally
            {
                await s.StopAsync();
            }
            Assert.AreEqual(1, receivedMessagesCount);
        }

        [TestMethod]
        public async Task MqttServer_Unsubscribe()
        {
            var serverAdapter = new TestMqttServerAdapter();
            var services = new ServiceCollection()
                .AddLogging()
                .AddMqttServer()
                .AddSingleton<IMqttServerAdapter>(serverAdapter)
                .BuildServiceProvider();

            var s = new MqttFactory(services).CreateMqttServer();

            var receivedMessagesCount = 0;

            try
            {
                await s.StartAsync();

                var c1 = await serverAdapter.ConnectTestClient(s, "c1");
                var c2 = await serverAdapter.ConnectTestClient(s, "c2");
                c1.ApplicationMessageReceived += (_, __) => receivedMessagesCount++;

                var message = new MqttApplicationMessageBuilder().WithTopic("a").WithAtLeastOnceQoS().Build();

                await c2.PublishAsync(message);
                Assert.AreEqual(0, receivedMessagesCount);

                await c1.SubscribeAsync(new TopicFilter("a", MqttQualityOfServiceLevel.AtLeastOnce));
                await c2.PublishAsync(message);

                await Task.Delay(500);
                Assert.AreEqual(1, receivedMessagesCount);

                await c1.UnsubscribeAsync("a");
                await c2.PublishAsync(message);

                await Task.Delay(500);
                Assert.AreEqual(1, receivedMessagesCount);
            }
            finally
            {
                await s.StopAsync();
            }
            await Task.Delay(500);

            Assert.AreEqual(1, receivedMessagesCount);
        }

        [TestMethod]
        public async Task MqttServer_Publish()
        {
            var serverAdapter = new TestMqttServerAdapter();
            var services = new ServiceCollection()
                .AddLogging()
                .AddMqttServer()
                .AddSingleton<IMqttServerAdapter>(serverAdapter)
                .BuildServiceProvider();

            var s = new MqttFactory(services).CreateMqttServer();
            var receivedMessagesCount = 0;

            try
            {
                await s.StartAsync();

                var c1 = await serverAdapter.ConnectTestClient(s, "c1");

                c1.ApplicationMessageReceived += (_, __) => receivedMessagesCount++;

                var message = new MqttApplicationMessageBuilder().WithTopic("a").WithAtLeastOnceQoS().Build();
                await c1.SubscribeAsync(new TopicFilter("a", MqttQualityOfServiceLevel.AtLeastOnce));

                s.PublishAsync(message).Wait();
                await Task.Delay(500);
            }
            finally
            {
                await s.StopAsync();
            }
            
            Assert.AreEqual(1, receivedMessagesCount);
        }

        [TestMethod]
        public async Task MqttServer_NoRetainedMessage()
        {
            var serverAdapter = new TestMqttServerAdapter();
            var services = new ServiceCollection()
                .AddLogging()
                .AddMqttServer()
                .AddSingleton<IMqttServerAdapter>(serverAdapter)
                .BuildServiceProvider();

            var s = new MqttFactory(services).CreateMqttServer();
            var receivedMessagesCount = 0;

            try
            {
                await s.StartAsync();

                var c1 = await serverAdapter.ConnectTestClient(s, "c1");
                await c1.PublishAsync(new MqttApplicationMessageBuilder().WithTopic("retained").WithPayload(new byte[3]).Build());
                await c1.DisconnectAsync();

                var c2 = await serverAdapter.ConnectTestClient(s, "c2");
                c2.ApplicationMessageReceived += (_, __) => receivedMessagesCount++;
                await c2.SubscribeAsync(new TopicFilter("retained", MqttQualityOfServiceLevel.AtMostOnce));

                await Task.Delay(500);
            }
            finally
            {
                await s.StopAsync();
            }

            Assert.AreEqual(0, receivedMessagesCount);
        }

        [TestMethod]
        public async Task MqttServer_RetainedMessage()
        {
            var serverAdapter = new TestMqttServerAdapter();
            var services = new ServiceCollection()
                .AddLogging()
                .AddMqttServer()
                .AddSingleton<IMqttServerAdapter>(serverAdapter)
                .BuildServiceProvider();

            var s = new MqttFactory(services).CreateMqttServer();
            var retainMessagemanager = services.GetRequiredService<IMqttClientRetainedMessageManager>();

            var receivedMessagesCount = 0;
            try
            {
                await s.StartAsync();

                var c1 = await serverAdapter.ConnectTestClient(s, "c1");
                await c1.PublishAsync(new MqttApplicationMessageBuilder().WithTopic("retained").WithPayload(new byte[3]).WithRetainFlag().Build());
                await c1.DisconnectAsync();

                var subscribe = new MqttSubscribePacket()
                {
                    TopicFilters = new List<TopicFilter>()
                    {
                        new TopicFilter("retained", MqttQualityOfServiceLevel.AtMostOnce)
                    }
                };

                //make shure the retainedMessageManagerreceived the package
                while (!retainMessagemanager.GetMessages(subscribe).Any())
                {
                    await Task.Delay(TimeSpan.FromMilliseconds(10));
                }

                var c2 = await serverAdapter.ConnectTestClient(s, "c2");
                c2.ApplicationMessageReceived += (_, __) => receivedMessagesCount++;
                await c2.SubscribeAsync(new TopicFilter("retained", MqttQualityOfServiceLevel.AtMostOnce));

                await Task.Delay(500);
            }
            finally
            {
                await s.StopAsync();
            }
            
            Assert.AreEqual(1, receivedMessagesCount);
        }

        [TestMethod]
        public async Task MqttServer_ClearRetainedMessage()
        {
            var serverAdapter = new TestMqttServerAdapter();
            var services = new ServiceCollection()
                .AddLogging()
                .AddMqttServer()
                .AddSingleton<IMqttServerAdapter>(serverAdapter)
                .BuildServiceProvider();

            var s = new MqttFactory(services).CreateMqttServer();
            var receivedMessagesCount = 0;
            try
            {
                await s.StartAsync();

                var c1 = await serverAdapter.ConnectTestClient(s, "c1");
                await c1.PublishAsync(new MqttApplicationMessageBuilder().WithTopic("retained").WithPayload(new byte[3]).WithRetainFlag().Build());
                await c1.PublishAsync(new MqttApplicationMessageBuilder().WithTopic("retained").WithPayload(new byte[0]).WithRetainFlag().Build());
                await c1.DisconnectAsync();

                var c2 = await serverAdapter.ConnectTestClient(s, "c2");
                c2.ApplicationMessageReceived += (_, __) => receivedMessagesCount++;
                await c2.SubscribeAsync(new TopicFilter("retained", MqttQualityOfServiceLevel.AtMostOnce));

                await Task.Delay(500);
            }
            finally
            {
                await s.StopAsync();
            }


            Assert.AreEqual(0, receivedMessagesCount);
        }

        [TestMethod]
        public async Task MqttServer_PersistRetainedMessage()
        {
            var storage = new TestStorage();
            var serverAdapter = new TestMqttServerAdapter();

            var services = new ServiceCollection()
                .AddLogging()
                .AddMqttServer()
                .AddSingleton<IMqttServerAdapter>(serverAdapter)
                .BuildServiceProvider();

            var s = new MqttFactory(services).CreateMqttServer(options => options.Storage = storage);

            try
            {
                await s.StartAsync();

                var c1 = await serverAdapter.ConnectTestClient(s, "c1");
                await c1.PublishAsync(new MqttApplicationMessageBuilder().WithTopic("retained").WithPayload(new byte[3]).WithRetainFlag().Build());
                await c1.DisconnectAsync();
            }
            finally
            {
                await s.StopAsync();
            }

            s = new MqttFactory(services).CreateMqttServer(options => options.Storage = storage);

            var receivedMessagesCount = 0;
            try
            {
                await s.StartAsync();

                var c2 = await serverAdapter.ConnectTestClient(s, "c2");
                c2.ApplicationMessageReceived += (_, __) => receivedMessagesCount++;
                await c2.SubscribeAsync(new TopicFilter("retained", MqttQualityOfServiceLevel.AtMostOnce));

                await Task.Delay(500);
            }
            finally
            {
                await s.StopAsync();
            }

            Assert.AreEqual(1, receivedMessagesCount);
        }

        [TestMethod]
        public async Task MqttServer_InterceptMessage()
        {
            void Interceptor(MqttApplicationMessageInterceptorContext context)
            {
                context.ApplicationMessage.Payload = Encoding.ASCII.GetBytes("extended");
            }

            var serverAdapter = new TestMqttServerAdapter();
            var services = new ServiceCollection()
                .AddLogging()
                .AddMqttServer()
                .AddSingleton<IMqttServerAdapter>(serverAdapter)
                .BuildServiceProvider();

            var s = new MqttFactory(services).CreateMqttServer(options => options.ApplicationMessageInterceptor = Interceptor);
            try
            {
                await s.StartAsync();

                var c1 = await serverAdapter.ConnectTestClient(s, "c1");
                var c2 = await serverAdapter.ConnectTestClient(s, "c2");
                await c2.SubscribeAsync(new TopicFilterBuilder().WithTopic("test").Build());

                var isIntercepted = false;
                c2.ApplicationMessageReceived += (sender, args) =>
                {
                    isIntercepted = string.Compare("extended", Encoding.UTF8.GetString(args.ApplicationMessage.Payload), StringComparison.Ordinal) == 0;
                };

                var m = new MqttApplicationMessageBuilder().WithTopic("test").Build();
                await c1.PublishAsync(m);
                await c1.DisconnectAsync();

                await Task.Delay(500);

                Assert.IsTrue(isIntercepted);
            }
            finally
            {
                await s.StopAsync();
            }
        }

        private class TestStorage : IMqttServerStorage
        {
            private IList<MqttApplicationMessage> _messages = new List<MqttApplicationMessage>();

            public Task SaveRetainedMessagesAsync(IList<MqttApplicationMessage> messages)
            {
                _messages = messages;
                return Task.CompletedTask;
            }

            public Task<IList<MqttApplicationMessage>> LoadRetainedMessagesAsync()
            {
                return Task.FromResult(_messages);
            }
        }

        private static async Task TestPublishAsync(
            string topic,
            MqttQualityOfServiceLevel qualityOfServiceLevel,
            string topicFilter,
            MqttQualityOfServiceLevel filterQualityOfServiceLevel,
            int expectedReceivedMessagesCount)
        {
            var serverAdapter = new TestMqttServerAdapter();
            var services = new ServiceCollection()
                .AddMqttServer()
                .AddLogging()
                .AddSingleton<IMqttServerAdapter>(serverAdapter)
                .BuildServiceProvider();

            var s = services.GetRequiredService<IMqttServer>();
            var receivedMessagesCount = 0;
            try
            {
                await s.StartAsync();

                var c1 = await serverAdapter.ConnectTestClient(s, "c1");
                var c2 = await serverAdapter.ConnectTestClient(s, "c2");

                c1.ApplicationMessageReceived += (_, __) => receivedMessagesCount++;

                await c1.SubscribeAsync(new TopicFilterBuilder().WithTopic(topicFilter).WithQualityOfServiceLevel(filterQualityOfServiceLevel).Build());
                await c2.PublishAsync(new MqttApplicationMessageBuilder().WithTopic(topic).WithPayload(new byte[0]).WithQualityOfServiceLevel(qualityOfServiceLevel).Build());

                await Task.Delay(500);
                await c1.UnsubscribeAsync(topicFilter);

                await Task.Delay(500);
            }
            finally
            {
                await s.StopAsync();
            }
            
            Assert.AreEqual(expectedReceivedMessagesCount, receivedMessagesCount);
        }
    }
}