Basic support for 1.19.2

MinecraftClient/Protocol/Message/LastSeenMessageList.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace MinecraftClient.Protocol.Message
+{
+    /// <summary>
+    /// A list of messages a client has seen.
+    /// </summary>
+    public class LastSeenMessageList
+    {
+        public static readonly LastSeenMessageList EMPTY = new(new Entry[0]);
+        public static readonly int MAX_ENTRIES = 5;
+
+        public Entry[] entries;
+
+        public LastSeenMessageList(Entry[] list)
+        {
+            entries = list;
+        }
+
+        public void WriteForSign(List<byte> data)
+        {
+            foreach (Entry entry in entries)
+            {
+                data.Add(70);
+                data.AddRange(entry.profileId.ToBigEndianBytes());
+                data.AddRange(entry.lastSignature);
+            }
+        }
+
+        /// <summary>
+        ///  A pair of a player's UUID and the signature of the last message they saw, used as an entry of LastSeenMessageList.
+        /// </summary>
+        public class Entry
+        {
+            public Guid profileId;
+            public byte[] lastSignature;
+
+            public Entry(Guid profileId, byte[] lastSignature)
+            {
+                this.profileId = profileId;
+                this.lastSignature = lastSignature;
+            }
+        }
+
+        /// <summary>
+        /// A record of messages acknowledged by a client.
+        /// This holds the messages the client has recently seen, as well as the last message they received, if any.
+        /// </summary>
+        public class Acknowledgment
+        {
+            public LastSeenMessageList lastSeen;
+            public Entry? lastReceived;
+
+            public Acknowledgment(LastSeenMessageList lastSeenMessageList, Entry? lastReceivedMessage)
+            {
+                lastSeen = lastSeenMessageList;
+                lastReceived = lastReceivedMessage;
+            }
+        }
+    }
+
+    /// <summary>
+    /// Collects the message that are last seen by a client.
+    /// The message, along with the "last received" message, forms an "acknowledgment" of received messages.
+    /// They are sent to the server when the client has enough messages received or when they send a message.
+    /// The maximum amount of message entries are specified in the constructor.The vanilla clients collect 5 entries.
+    /// Calling add adds the message to the beginning of the entries list, and evicts the oldest message.
+    /// If there are entries with the same sender profile ID, the older entry will be replaced with null instead of filling the hole.
+    /// </summary>
+    public class LastSeenMessagesCollector
+    {
+        private readonly LastSeenMessageList.Entry[] entries;
+        private int size = 0;
+        private LastSeenMessageList lastSeenMessages;
+
+        public LastSeenMessagesCollector(int size)
+        {
+            lastSeenMessages = LastSeenMessageList.EMPTY;
+            entries = new LastSeenMessageList.Entry[size];
+        }
+
+        public void Add(LastSeenMessageList.Entry entry)
+        {
+            LastSeenMessageList.Entry? lastEntry = entry;
+
+            for (int i = 0; i < size; ++i)
+            {
+                LastSeenMessageList.Entry curEntry = entries[i];
+                entries[i] = lastEntry;
+                lastEntry = curEntry;
+                if (curEntry.profileId == entry.profileId)
+                {
+                    lastEntry = null;
+                    break;
+                }
+            }
+
+            if (lastEntry != null && size < entries.Length)
+                entries[size++] = lastEntry;
+
+            LastSeenMessageList.Entry[] msgList = new LastSeenMessageList.Entry[size];
+            for (int i = 0; i < size; ++i) 
+                msgList[i] = entries[i];
+            lastSeenMessages = new LastSeenMessageList(msgList);
+        }
+
+        public LastSeenMessageList GetLastSeenMessages()
+        {
+            return lastSeenMessages;
+        }
+
+    }
+}