using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using MQTTnet.Adapter;
using MQTTnet.Exceptions;
using MQTTnet.Formatter;
using MQTTnet.Formatter.V3;
using MQTTnet.Formatter.V5;
using MQTTnet.Internal;
using MQTTnet.Packets;
using MQTTnet.Protocol;

namespace MQTTnet.Tests
{
    [TestClass]
    public class MqttPacketSerializer_Tests
    {
        [TestMethod]
        public void DetectVersionFromMqttConnectPacket()
        {
            var p = new MqttConnectPacket
            {
                ClientId = "XYZ",
                Password = Encoding.UTF8.GetBytes("PASS"),
                Username = "USER",
                KeepAlivePeriod = 123,
                CleanSession = true
            };
            var adapter = new MqttPacketFormatterAdapter(WriterFactory());
                        
            Assert.AreEqual(MqttProtocolVersion.V310, DeserializeAndDetectVersion(adapter, Serialize(p, MqttProtocolVersion.V310)));
            Assert.AreEqual(MqttProtocolVersion.V311, DeserializeAndDetectVersion(adapter, Serialize(p, MqttProtocolVersion.V311)));
            Assert.AreEqual(MqttProtocolVersion.V500, DeserializeAndDetectVersion(adapter, Serialize(p, MqttProtocolVersion.V500)));
            
            var ex = Assert.ThrowsException<MqttProtocolViolationException>(() => DeserializeAndDetectVersion(adapter, WriterFactory().AddMqttHeader(MqttControlPacketType.Connect, new byte[0])));
            Assert.AreEqual("CONNECT packet must have at least 7 bytes.", ex.Message);
            ex = Assert.ThrowsException<MqttProtocolViolationException>(() => DeserializeAndDetectVersion(adapter, WriterFactory().AddMqttHeader(MqttControlPacketType.Connect, new byte[7])));
            Assert.AreEqual("Protocol '' not supported.", ex.Message);
            ex = Assert.ThrowsException<MqttProtocolViolationException>(() => DeserializeAndDetectVersion(adapter, WriterFactory().AddMqttHeader(MqttControlPacketType.Connect, new byte[] { 255, 255, 0,0,0,0,0 })));
            Assert.AreEqual("Expected at least 65537 bytes but there are only 7 bytes", ex.Message);
        }

        [TestMethod]
        public void SerializeV310_MqttConnectPacket()
        {
            var p = new MqttConnectPacket
            {
                ClientId = "XYZ",
                Password = Encoding.UTF8.GetBytes("PASS"),
                Username = "USER",
                KeepAlivePeriod = 123,
                CleanSession = true
            };

            SerializeAndCompare(p, "EB0ABk1RSXNkcAPCAHsAA1hZWgAEVVNFUgAEUEFTUw==", MqttProtocolVersion.V310);
        }

        [TestMethod]
        public void SerializeV311_MqttConnectPacket()
        {
            var p = new MqttConnectPacket
            {
                ClientId = "XYZ",
                Password = Encoding.UTF8.GetBytes("PASS"),
                Username = "USER",
                KeepAlivePeriod = 123,
                CleanSession = true
            };

            SerializeAndCompare(p, "EBsABE1RVFQEwgB7AANYWVoABFVTRVIABFBBU1M=");
        }

        [TestMethod]
        public void SerializeV311_MqttConnectPacketWithWillMessage()
        {
            var p = new MqttConnectPacket
            {
                ClientId = "XYZ",
                Password = Encoding.UTF8.GetBytes("PASS"),
                Username = "USER",
                KeepAlivePeriod = 123,
                CleanSession = true,
                WillMessage = new MqttApplicationMessage
                {
                    Topic = "My/last/will",
                    Payload = Encoding.UTF8.GetBytes("Good byte."),
                    QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce,
                    Retain = true
                }
            };

            SerializeAndCompare(p, "EDUABE1RVFQE7gB7AANYWVoADE15L2xhc3Qvd2lsbAAKR29vZCBieXRlLgAEVVNFUgAEUEFTUw==");
        }

        [TestMethod]
        public void DeserializeV311_MqttConnectPacket()
        {
            var p = new MqttConnectPacket
            {
                ClientId = "XYZ",
                Password = Encoding.UTF8.GetBytes("PASS"),
                Username = "USER",
                KeepAlivePeriod = 123,
                CleanSession = true
            };

            DeserializeAndCompare(p, "EBsABE1RVFQEwgB7AANYWVoABFVTRVIABFBBU1M=");
        }

        [TestMethod]
        public void DeserializeV311_MqttConnectPacketWithWillMessage()
        {
            var p = new MqttConnectPacket
            {
                ClientId = "XYZ",
                Password = Encoding.UTF8.GetBytes("PASS"),
                Username = "USER",
                KeepAlivePeriod = 123,
                CleanSession = true,
                WillMessage = new MqttApplicationMessage
                {
                    Topic = "My/last/will",
                    Payload = Encoding.UTF8.GetBytes("Good byte."),
                    QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce,
                    Retain = true
                }
            };

            DeserializeAndCompare(p, "EDUABE1RVFQE7gB7AANYWVoADE15L2xhc3Qvd2lsbAAKR29vZCBieXRlLgAEVVNFUgAEUEFTUw==");
        }

        [TestMethod]
        public void SerializeV311_MqttConnAckPacket()
        {
            var p = new MqttConnAckPacket
            {
                IsSessionPresent = true,
                ReturnCode = MqttConnectReturnCode.ConnectionRefusedNotAuthorized
            };

            SerializeAndCompare(p, "IAIBBQ==");
        }

        [TestMethod]
        public void SerializeV310_MqttConnAckPacket()
        {
            var p = new MqttConnAckPacket
            {
                ReturnCode = MqttConnectReturnCode.ConnectionRefusedNotAuthorized
            };

            SerializeAndCompare(p, "IAIABQ==", MqttProtocolVersion.V310);
        }

        [TestMethod]
        public void DeserializeV311_MqttConnAckPacket()
        {
            var p = new MqttConnAckPacket
            {
                IsSessionPresent = true,
                ReturnCode = MqttConnectReturnCode.ConnectionRefusedNotAuthorized
            };

            DeserializeAndCompare(p, "IAIBBQ==");
        }

        [TestMethod]
        public void DeserializeV310_MqttConnAckPacket()
        {
            var p = new MqttConnAckPacket
            {
                ReturnCode = MqttConnectReturnCode.ConnectionRefusedNotAuthorized
            };

            DeserializeAndCompare(p, "IAIABQ==", MqttProtocolVersion.V310);
        }

        [TestMethod]
        public void Serialize_LargePacket()
        {
            var serializer = new MqttV311PacketFormatter(WriterFactory());

            const int payloadLength = 80000;

            var payload = new byte[payloadLength];

            var value = 0;
            for (var i = 0; i < payloadLength; i++)
            {
                if (value > 255)
                {
                    value = 0;
                }

                payload[i] = (byte)value;
            }

            var publishPacket = new MqttPublishPacket
            {
                Topic = "abcdefghijklmnopqrstuvwxyz0123456789",
                Payload = payload
            };

            var buffer = serializer.Encode(publishPacket);
            var testChannel = new TestMqttChannel(new MemoryStream(buffer.Array, buffer.Offset, buffer.Count));

            var header = new MqttPacketReader(testChannel).ReadFixedHeaderAsync(
                new byte[2],
                CancellationToken.None).GetAwaiter().GetResult().FixedHeader;

            var eof = buffer.Offset + buffer.Count;

            var receivedPacket = new ReceivedMqttPacket(
                header.Flags,
                new MqttPacketBodyReader(buffer.Array, eof - header.RemainingLength, buffer.Count + buffer.Offset),
                0);

            var packet = (MqttPublishPacket)serializer.Decode(receivedPacket);

            Assert.AreEqual(publishPacket.Topic, packet.Topic);
            Assert.IsTrue(publishPacket.Payload.SequenceEqual(packet.Payload));
        }

        [TestMethod]
        public void SerializeV311_MqttDisconnectPacket()
        {
            SerializeAndCompare(new MqttDisconnectPacket(), "4AA=");
        }

        [TestMethod]
        public void SerializeV311_MqttPingReqPacket()
        {
            SerializeAndCompare(new MqttPingReqPacket(), "wAA=");
        }

        [TestMethod]
        public void SerializeV311_MqttPingRespPacket()
        {
            SerializeAndCompare(new MqttPingRespPacket(), "0AA=");
        }

        [TestMethod]
        public void SerializeV311_MqttPublishPacket()
        {
            var p = new MqttPublishPacket
            {
                PacketIdentifier = 123,
                Dup = true,
                Retain = true,
                Payload = Encoding.ASCII.GetBytes("HELLO"),
                QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce,
                Topic = "A/B/C"
            };

            SerializeAndCompare(p, "Ow4ABUEvQi9DAHtIRUxMTw==");
        }

        [TestMethod]
        public void SerializeV500_MqttPublishPacket()
        {
            var prop = new MqttPublishPacketProperties {UserProperties = new List<MqttUserProperty>()};

            prop.ResponseTopic = "/Response";

            prop.UserProperties.Add(new MqttUserProperty("Foo", "Bar"));

            var p = new MqttPublishPacket
            {
                PacketIdentifier = 123,
                Dup = true,
                Retain = true,
                Payload = Encoding.ASCII.GetBytes("HELLO"),
                QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce,
                Topic = "A/B/C",
                Properties = prop
            };

            var deserialized = Roundtrip(p, MqttProtocolVersion.V500);

            Assert.AreEqual(prop.ResponseTopic, deserialized.Properties.ResponseTopic);
            Assert.IsTrue(deserialized.Properties.UserProperties.Any(x => x.Name == "Foo"));
        }


        [TestMethod]
        public void SerializeV500_MqttPublishPacket_CorrelationData()
        {
            var data = "123456789";
            var req = new MqttApplicationMessageBuilder()
                      .WithTopic("Foo")
                      .WithResponseTopic($"_")
                      .WithCorrelationData(Guid.NewGuid().ToByteArray())
                      .WithPayload(data)
                      .WithQualityOfServiceLevel(MqttQualityOfServiceLevel.AtMostOnce)
                      .Build();

            var p = new MqttV500DataConverter().CreatePublishPacket(req);

            var deserialized = Roundtrip(p, MqttProtocolVersion.V500);

            Assert.IsTrue(p.Payload.SequenceEqual(deserialized.Payload));
        }

        [TestMethod]
        public void DeserializeV311_MqttPublishPacket()
        {
            var p = new MqttPublishPacket
            {
                PacketIdentifier = 123,
                Dup = true,
                Retain = true,
                Payload = Encoding.ASCII.GetBytes("HELLO"),
                QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce,
                Topic = "A/B/C"
            };

            DeserializeAndCompare(p, "Ow4ABUEvQi9DAHtIRUxMTw==");
        }

        [TestMethod]
        public void DeserializeV311_MqttPublishPacket_Qos1()
        {
            var p = new MqttPublishPacket
            {
                QualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce,
            };

            var p2 = Roundtrip(p);

            Assert.AreEqual(p.QualityOfServiceLevel, p2.QualityOfServiceLevel);
            Assert.AreEqual(p.Dup, p2.Dup);
        }

        [TestMethod]
        public void DeserializeV311_MqttPublishPacket_Qos2()
        {
            var p = new MqttPublishPacket
            {
                QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce,
                PacketIdentifier = 1
            };

            var p2 = Roundtrip(p);

            Assert.AreEqual(p.QualityOfServiceLevel, p2.QualityOfServiceLevel);
            Assert.AreEqual(p.Dup, p2.Dup);
        }

        [TestMethod]
        public void DeserializeV311_MqttPublishPacket_Qos3()
        {
            var p = new MqttPublishPacket
            {
                QualityOfServiceLevel = MqttQualityOfServiceLevel.ExactlyOnce,
                PacketIdentifier = 1
            };

            var p2 = Roundtrip(p);

            Assert.AreEqual(p.QualityOfServiceLevel, p2.QualityOfServiceLevel);
            Assert.AreEqual(p.Dup, p2.Dup);
        }


        [TestMethod]
        public void DeserializeV311_MqttPublishPacket_DupFalse()
        {
            var p = new MqttPublishPacket
            {
                Dup = false,
            };

            var p2 = Roundtrip(p);

            Assert.AreEqual(p.Dup, p2.Dup);
        }

        [TestMethod]
        public void SerializeV311_MqttPubAckPacket()
        {
            var p = new MqttPubAckPacket
            {
                PacketIdentifier = 123
            };

            SerializeAndCompare(p, "QAIAew==");
        }

        [TestMethod]
        public void DeserializeV311_MqttPubAckPacket()
        {
            var p = new MqttPubAckPacket
            {
                PacketIdentifier = 123
            };

            DeserializeAndCompare(p, "QAIAew==");
        }

        [TestMethod]
        public void SerializeV311_MqttPubRecPacket()
        {
            var p = new MqttPubRecPacket
            {
                PacketIdentifier = 123
            };

            SerializeAndCompare(p, "UAIAew==");
        }

        [TestMethod]
        public void DeserializeV311_MqttPubRecPacket()
        {
            var p = new MqttPubRecPacket
            {
                PacketIdentifier = 123
            };

            DeserializeAndCompare(p, "UAIAew==");
        }

        [TestMethod]
        public void SerializeV311_MqttPubRelPacket()
        {
            var p = new MqttPubRelPacket
            {
                PacketIdentifier = 123
            };

            SerializeAndCompare(p, "YgIAew==");
        }

        [TestMethod]
        public void DeserializeV311_MqttPubRelPacket()
        {
            var p = new MqttPubRelPacket
            {
                PacketIdentifier = 123
            };

            DeserializeAndCompare(p, "YgIAew==");
        }

        [TestMethod]
        public void SerializeV311_MqttPubCompPacket()
        {
            var p = new MqttPubCompPacket
            {
                PacketIdentifier = 123
            };

            SerializeAndCompare(p, "cAIAew==");
        }

        [TestMethod]
        public void DeserializeV311_MqttPubCompPacket()
        {
            var p = new MqttPubCompPacket
            {
                PacketIdentifier = 123
            };

            DeserializeAndCompare(p, "cAIAew==");
        }

        [TestMethod]
        public void SerializeV311_MqttSubscribePacket()
        {
            var p = new MqttSubscribePacket
            {
                PacketIdentifier = 123
            };

            p.TopicFilters.Add(new MqttTopicFilter { Topic = "A/B/C", QualityOfServiceLevel = MqttQualityOfServiceLevel.ExactlyOnce });
            p.TopicFilters.Add(new MqttTopicFilter { Topic = "1/2/3", QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce });
            p.TopicFilters.Add(new MqttTopicFilter { Topic = "x/y/z", QualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce });

            SerializeAndCompare(p, "ghoAewAFQS9CL0MCAAUxLzIvMwEABXgveS96AA==");
        }

        [TestMethod]
        public void DeserializeV311_MqttSubscribePacket()
        {
            var p = new MqttSubscribePacket
            {
                PacketIdentifier = 123
            };

            p.TopicFilters.Add(new MqttTopicFilter { Topic = "A/B/C", QualityOfServiceLevel = MqttQualityOfServiceLevel.ExactlyOnce });
            p.TopicFilters.Add(new MqttTopicFilter { Topic = "1/2/3", QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce });
            p.TopicFilters.Add(new MqttTopicFilter { Topic = "x/y/z", QualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce });

            DeserializeAndCompare(p, "ghoAewAFQS9CL0MCAAUxLzIvMwEABXgveS96AA==");
        }

        [TestMethod]
        public void SerializeV311_MqttSubAckPacket()
        {
            var p = new MqttSubAckPacket
            {
                PacketIdentifier = 123
            };

            p.ReturnCodes.Add(MqttSubscribeReturnCode.SuccessMaximumQoS0);
            p.ReturnCodes.Add(MqttSubscribeReturnCode.SuccessMaximumQoS1);
            p.ReturnCodes.Add(MqttSubscribeReturnCode.SuccessMaximumQoS2);
            p.ReturnCodes.Add(MqttSubscribeReturnCode.Failure);

            SerializeAndCompare(p, "kAYAewABAoA=");
        }

        [TestMethod]
        public void DeserializeV311_MqttSubAckPacket()
        {
            var p = new MqttSubAckPacket
            {
                PacketIdentifier = 123
            };

            p.ReturnCodes.Add(MqttSubscribeReturnCode.SuccessMaximumQoS0);
            p.ReturnCodes.Add(MqttSubscribeReturnCode.SuccessMaximumQoS1);
            p.ReturnCodes.Add(MqttSubscribeReturnCode.SuccessMaximumQoS2);
            p.ReturnCodes.Add(MqttSubscribeReturnCode.Failure);

            DeserializeAndCompare(p, "kAYAewABAoA=");
        }

        [TestMethod]
        public void SerializeV311_MqttUnsubscribePacket()
        {
            var p = new MqttUnsubscribePacket
            {
                PacketIdentifier = 123
            };

            p.TopicFilters.Add("A/B/C");
            p.TopicFilters.Add("1/2/3");
            p.TopicFilters.Add("x/y/z");

            SerializeAndCompare(p, "ohcAewAFQS9CL0MABTEvMi8zAAV4L3kveg==");
        }

        [TestMethod]
        public void DeserializeV311_MqttUnsubscribePacket()
        {
            var p = new MqttUnsubscribePacket
            {
                PacketIdentifier = 123
            };

            p.TopicFilters.Add("A/B/C");
            p.TopicFilters.Add("1/2/3");
            p.TopicFilters.Add("x/y/z");

            DeserializeAndCompare(p, "ohcAewAFQS9CL0MABTEvMi8zAAV4L3kveg==");
        }

        [TestMethod]
        public void SerializeV311_MqttUnsubAckPacket()
        {
            var p = new MqttUnsubAckPacket
            {
                PacketIdentifier = 123
            };

            SerializeAndCompare(p, "sAIAew==");
        }

        [TestMethod]
        public void DeserializeV311_MqttUnsubAckPacket()
        {
            var p = new MqttUnsubAckPacket
            {
                PacketIdentifier = 123
            };

            DeserializeAndCompare(p, "sAIAew==");
        }

        private void SerializeAndCompare(MqttBasePacket packet, string expectedBase64Value, MqttProtocolVersion protocolVersion = MqttProtocolVersion.V311)
        {
            Assert.AreEqual(expectedBase64Value, Convert.ToBase64String(Serialize(packet, protocolVersion)));
        }

        private byte[] Serialize(MqttBasePacket packet, MqttProtocolVersion protocolVersion = MqttProtocolVersion.V311)
        {
            var serializer = MqttPacketFormatterAdapter.GetMqttPacketFormatter(protocolVersion, WriterFactory());
            return Join(serializer.Encode(packet));
        }

        protected virtual IMqttPacketWriter WriterFactory()
        {
            return new MqttPacketWriter();
        }

        protected virtual IMqttPacketBodyReader ReaderFactory(byte[] data)
        {
            return new MqttPacketBodyReader(data, 0, data.Length);
        }

        private void DeserializeAndCompare(MqttBasePacket packet, string expectedBase64Value, MqttProtocolVersion protocolVersion = MqttProtocolVersion.V311)
        {
            var writer = WriterFactory();

            var serializer = MqttPacketFormatterAdapter.GetMqttPacketFormatter(protocolVersion, writer);

            var buffer1 = serializer.Encode(packet);

            using (var headerStream = new MemoryStream(Join(buffer1)))
            {
                var channel = new TestMqttChannel(headerStream);
                var fixedHeader = new byte[2];
                var header = new MqttPacketReader(channel).ReadFixedHeaderAsync(fixedHeader, CancellationToken.None).GetAwaiter().GetResult().FixedHeader;

                using (var bodyStream = new MemoryStream(Join(buffer1), (int)headerStream.Position, header.RemainingLength))
                {
                    var reader = ReaderFactory(bodyStream.ToArray());
                    var deserializedPacket = serializer.Decode(new ReceivedMqttPacket(header.Flags, reader, 0));
                    var buffer2 = serializer.Encode(deserializedPacket);

                    Assert.AreEqual(expectedBase64Value, Convert.ToBase64String(Join(buffer2)));
                }
            }
        }

        private T Roundtrip<T>(T packet, MqttProtocolVersion protocolVersion = MqttProtocolVersion.V311)
            where T : MqttBasePacket
        {
            var writer = WriterFactory();

            var serializer = MqttPacketFormatterAdapter.GetMqttPacketFormatter(protocolVersion, writer);
            
            var buffer1 = serializer.Encode(packet);

            using (var headerStream = new MemoryStream(Join(buffer1)))
            {
                var channel = new TestMqttChannel(headerStream);
                var fixedHeader = new byte[2];

                var header = new MqttPacketReader(channel).ReadFixedHeaderAsync(fixedHeader, CancellationToken.None).GetAwaiter().GetResult().FixedHeader;

                using (var bodyStream = new MemoryStream(Join(buffer1), (int)headerStream.Position, (int)header.RemainingLength))
                {
                    var reader = ReaderFactory(bodyStream.ToArray());
                    return (T)serializer.Decode(new ReceivedMqttPacket(header.Flags, reader, 0));
                }
            }
        }

        private MqttProtocolVersion DeserializeAndDetectVersion(MqttPacketFormatterAdapter adapter, byte[] buffer)
        {
            using (var headerStream = new MemoryStream(buffer))
            {
                var channel = new TestMqttChannel(headerStream);
                var fixedHeader = new byte[2];

                var header = new MqttPacketReader(channel).ReadFixedHeaderAsync(fixedHeader, CancellationToken.None).GetAwaiter().GetResult().FixedHeader;

                using (var bodyStream = new MemoryStream(buffer, (int)headerStream.Position, (int)header.RemainingLength))
                {
                    var reader = ReaderFactory(bodyStream.ToArray());
                    var packet = new ReceivedMqttPacket(header.Flags, reader, 0);
                    adapter.DetectProtocolVersion(packet);
                    return adapter.ProtocolVersion;
                }
            }
        }

        private static byte[] Join(params ArraySegment<byte>[] chunks)
        {
            var buffer = new MemoryStream();
            foreach (var chunk in chunks)
            {
                buffer.Write(chunk.Array, chunk.Offset, chunk.Count);
            }

            return buffer.ToArray();
        }
    }
}