defining packet types

src/TurboMqtt.Core/PacketTypes/MqttPacket.cs

@@ -0,0 +1,34 @@
+namespace TurboMqtt.Core.PacketTypes;
+
+/// <summary>
+/// Base for all MQTT packets.
+/// </summary>
+public abstract class MqttPacket
+{
+    public abstract MqttPacketType PacketType { get; }
+
+    public virtual bool Duplicate => false;
+
+    public virtual QualityOfService QualityOfService => QualityOfService.AtMostOnce;
+
+    public virtual bool RetainRequested => false;
+
+    public override string ToString()
+    {
+        return $"{GetType().Name}[Type={PacketType}, QualityOfService={QualityOfService}, Duplicate={Duplicate}, Retain={RetainRequested}]";
+    }
+}
+
+/// <summary>
+/// Base for MQTT packets that require a packet identifier.
+/// </summary>
+public abstract class MqttPacketWithId : MqttPacket
+{
+    /// <summary>
+    /// The unique identifier assigned to the packet.
+    /// </summary>
+    /// <remarks>
+    /// Not all packets require an identifier.
+    /// </remarks>
+    public int PacketId { get; set; }
+}

src/TurboMqtt.Core/PacketTypes/PingReqPacket.cs

@@ -0,0 +1,20 @@
+namespace TurboMqtt.Core.PacketTypes;
+
+/// <summary>
+/// Packet sent to the client by the server in response to a <see cref="PingReqPacket"/>.
+/// </summary>
+/// <remarks>
+/// Used to keep the connection alive.
+/// </remarks>
+public sealed class PingReqPacket : MqttPacket
+{
+    public static readonly PingReqPacket Instance = new PingReqPacket();
+
+    private PingReqPacket(){}
+    public override MqttPacketType PacketType => MqttPacketType.PingReq;
+
+    public override string ToString()
+    {
+        return "PingReq";
+    }
+}

src/TurboMqtt.Core/PacketTypes/PingRespPacket.cs

@@ -0,0 +1,17 @@
+namespace TurboMqtt.Core.PacketTypes;
+
+/// <summary>
+/// Packet sent to the client by the server in response to a <see cref="PingReqPacket"/>.
+/// </summary>
+public sealed class PingRespPacket : MqttPacket
+{
+    public static readonly PingRespPacket Instance = new PingRespPacket();
+
+    private PingRespPacket(){}
+    public override MqttPacketType PacketType => MqttPacketType.PingResp;
+
+    public override string ToString()
+    {
+        return "PingResp";
+    }
+}

src/TurboMqtt.Core/PacketTypes/PublishPacket.cs

@@ -0,0 +1,67 @@
+namespace TurboMqtt.Core.PacketTypes;
+
+/// <summary>
+/// Used to send data to the server or client.
+/// </summary>
+/// <param name="PacketId">The unique id of this packet - may not be needed with <see cref="QualityOfService.AtMostOnce"/>.</param>
+/// <param name="Qos">The delivery guarantee for this packet.</param>
+/// <param name="Duplicate">Is this packet a duplicate?</param>
+/// <param name="RetainRequested">Indicates whether or not this value has been retained by the MQTT broker.</param>
+public sealed class PublishPacket(int PacketId, QualityOfService Qos, bool Duplicate, bool RetainRequested) : MqttPacketWithId
+{
+    public override MqttPacketType PacketType => MqttPacketType.Publish;
+
+    public override bool Duplicate { get; } = Duplicate;
+
+    public override QualityOfService QualityOfService { get; } = Qos;
+
+    public override bool RetainRequested { get; } = RetainRequested;
+
+    /// <summary>
+    /// Optional for <see cref="QualityOfService.AtMostOnce"/>
+    /// </summary>
+    public string? TopicName { get; set; }
+
+    public int PacketIdentifier { get; set; } // Only needed for QoS 1 and 2
+
+    // Payload
+    public ReadOnlyMemory<byte> Payload { get; set; } = ReadOnlyMemory<byte>.Empty;
+
+    // MQTT 3.1.1 and 5.0 - Optional Properties
+
+    /// <summary>
+    /// The Content Type property, available in MQTT 5.0.
+    /// This property is optional and indicates the MIME type of the application message.
+    /// </summary>
+    public string? ContentType { get; set; } // MQTT 5.0 only
+
+    /// <summary>
+    /// Response Topic property, available in MQTT 5.0.
+    /// It specifies the topic name for a response message.
+    /// </summary>
+    public string? ResponseTopic { get; set; } // MQTT 5.0 only
+
+    /// <summary>
+    /// Correlation Data property, available in MQTT 5.0.
+    /// This property is used by the sender of the request message to identify which request the response message is for when it receives a response.
+    /// </summary>
+    public byte[]? CorrelationData { get; set; } // MQTT 5.0 only
+
+    /// <summary>
+    /// User Property, available in MQTT 5.0.
+    /// This is a key-value pair that can be sent multiple times to convey additional information that is not covered by other means.
+    /// </summary>
+    public IDictionary<string, string>? UserProperties { get; set; } // MQTT 5.0 only
+
+    /// <summary>
+    /// Subscription Identifiers, available in MQTT 5.0.
+    /// This property allows associating the publication with multiple subscriptions.
+    /// Each identifier corresponds to a different subscription that matches the published message.
+    /// </summary>
+    public List<uint>? SubscriptionIdentifiers { get; set; } // MQTT 5.0 only
+
+    public override string ToString()
+    {
+        return $"Publish: [Topic={TopicName}] [PayloadLength={Payload.Length}] [QoSLevel={QualityOfService}] [Dup={Duplicate}] [Retain={RetainRequested}] [PacketIdentifier={PacketIdentifier}]";
+    }
+}

src/TurboMqtt.Core/QualityOfService.cs

@@ -1,5 +1,8 @@
 namespace TurboMqtt.Core;
 
+/// <summary>
+/// QoS value - corresponds to the MQTT specification.
+/// </summary>
 public enum QualityOfService
 {
     AtMostOnce = 0,