// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using MQTTnet.Exceptions;
using MQTTnet.LowLevelClient;
using MQTTnet.Packets;
using MQTTnet.Protocol;
using MQTTnet.Server;

namespace MQTTnet.Tests.Clients.LowLevelMqttClient;

// ReSharper disable InconsistentNaming
[TestClass]
public sealed class LowLevelMqttClient_Tests : BaseTestClass
{
    [TestMethod]
    public async Task Authenticate()
    {
        using var testEnvironment = CreateTestEnvironment();
        await testEnvironment.StartServer();

        var factory = new MqttClientFactory();
        var lowLevelClient = factory.CreateLowLevelMqttClient();

        await lowLevelClient.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort).Build(), CancellationToken.None);

        var receivedPacket = await Authenticate(lowLevelClient);

        await lowLevelClient.DisconnectAsync(CancellationToken.None);

        Assert.IsNotNull(receivedPacket);
        Assert.AreEqual(MqttConnectReturnCode.ConnectionAccepted, receivedPacket.ReturnCode);
    }

    [TestMethod]
    public async Task Connect_And_Disconnect()
    {
        using var testEnvironment = CreateTestEnvironment();
        await testEnvironment.StartServer();

        var lowLevelClient = testEnvironment.ClientFactory.CreateLowLevelMqttClient();

        await lowLevelClient.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort).Build(), CancellationToken.None);

        await lowLevelClient.DisconnectAsync(CancellationToken.None);
    }

    [TestMethod]
    public Task Connect_To_Not_Existing_Broker()
    {
        return Assert.ThrowsExactlyAsync<MqttCommunicationException>(async () =>
        {
            var client = new MqttClientFactory().CreateLowLevelMqttClient();
            var options = new MqttClientOptionsBuilder().WithTcpServer("localhost").Build();

            await client.ConnectAsync(options, CancellationToken.None);
        });
    }

    [TestMethod]
    public Task Connect_To_Wrong_Host()
    {
        return Assert.ThrowsExactlyAsync<MqttCommunicationException>(async () =>
        {
            var client = new MqttClientFactory().CreateLowLevelMqttClient();
            var options = new MqttClientOptionsBuilder().WithTcpServer("123.456.789.10").Build();

            await client.ConnectAsync(options, CancellationToken.None);
        });
    }

    [TestMethod]
    public async Task Loose_Connection()
    {
        using var testEnvironment = CreateTestEnvironment();
        testEnvironment.IgnoreServerLogErrors = true;

        testEnvironment.ServerPort = 8364;
        var server = await testEnvironment.StartServer();

        var client = await testEnvironment.ConnectLowLevelClient(o => o.WithTimeout(TimeSpan.Zero));

        await Authenticate(client);

        await server.StopAsync();

        await Task.Delay(2000);

        try
        {
            await client.SendAsync(MqttPingReqPacket.Instance, CancellationToken.None);
            await Task.Delay(2000);
            await client.SendAsync(MqttPingReqPacket.Instance, CancellationToken.None);
        }
        catch (MqttCommunicationException exception)
        {
            Assert.IsTrue(exception.InnerException is SocketException);
            return;
        }
        catch
        {
            Assert.Fail("Wrong exception type thrown.");
        }

        Assert.Fail("This MUST fail");
    }

    [TestMethod]
    public async Task Maintain_IsConnected_Property()
    {
        using var testEnvironment = CreateTestEnvironment();
        testEnvironment.IgnoreServerLogErrors = true;

        var server = await testEnvironment.StartServer();

        using var lowLevelClient = testEnvironment.CreateLowLevelClient();
        Assert.IsFalse(lowLevelClient.IsConnected);

        var clientOptions = new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort).WithTimeout(TimeSpan.FromSeconds(1)).Build();

        await lowLevelClient.ConnectAsync(clientOptions, CancellationToken.None);

        Assert.IsTrue(lowLevelClient.IsConnected);

        await server.StopAsync();
        server.Dispose();

        await LongTestDelay();

        Assert.IsTrue(lowLevelClient.IsConnected);

        try
        {
            using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(5));
            await lowLevelClient.SendAsync(MqttPingReqPacket.Instance, CancellationToken.None);
            await LongTestDelay();

            await lowLevelClient.ReceiveAsync(timeout.Token);
        }
        catch
        {
            // The connection is now closed!
        }

        Assert.IsFalse(lowLevelClient.IsConnected);
    }

    [TestMethod]
    public async Task Subscribe()
    {
        using var testEnvironment = CreateTestEnvironment();
        await testEnvironment.StartServer();

        var factory = new MqttClientFactory();
        var lowLevelClient = factory.CreateLowLevelMqttClient();

        await lowLevelClient.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort).Build(), CancellationToken.None);

        await Authenticate(lowLevelClient);

        var receivedPacket = await Subscribe(lowLevelClient, "a");

        await lowLevelClient.DisconnectAsync(CancellationToken.None);

        Assert.IsNotNull(receivedPacket);
        Assert.AreEqual(MqttSubscribeReasonCode.GrantedQoS0, receivedPacket.ReasonCodes[0]);
    }

    async Task<MqttConnAckPacket> Authenticate(ILowLevelMqttClient client)
    {
        await client.SendAsync(
                new MqttConnectPacket
                {
                    CleanSession = true,
                    ClientId = TestContext.TestName,
                    Username = "user",
                    Password = Encoding.UTF8.GetBytes("pass")
                },
                CancellationToken.None);

        return await client.ReceiveAsync(CancellationToken.None) as MqttConnAckPacket;
    }

    async Task<MqttSubAckPacket> Subscribe(ILowLevelMqttClient client, string topic)
    {
        await client.SendAsync(
                new MqttSubscribePacket
                {
                    PacketIdentifier = 1,
                    TopicFilters =
                    {
                        new MqttTopicFilter
                        {
                            Topic = topic
                        }
                    }
                },
                CancellationToken.None);

        return await client.ReceiveAsync(CancellationToken.None) as MqttSubAckPacket;
    }
}