fix(core): Converts vendor buy packets (#339)

Projects/Server.Tests/Tests/Network/Packets/Outgoing/VendorBuyPackets.cs

@@ -0,0 +1,80 @@
+using System.Collections.Generic;
+using Server.Items;
+
+namespace Server.Network
+{
+    public sealed class VendorBuyContent : Packet
+    {
+        public VendorBuyContent(List<BuyItemState> list, bool containerGridLines) : base(0x3C)
+        {
+            EnsureCapacity(list.Count * 19 + 5);
+
+            Stream.Write((short)list.Count);
+
+            for (var i = list.Count - 1; i >= 0; --i)
+            {
+                var bis = list[i];
+
+                Stream.Write(bis.MySerial);
+                Stream.Write((ushort)bis.ItemID);
+                Stream.Write((byte)0); // itemID offset
+                Stream.Write((ushort)bis.Amount);
+                Stream.Write((short)(i + 1)); // x
+                Stream.Write((short)1);       // y
+                if (containerGridLines)
+                {
+                    Stream.Write((byte)0); // Grid Location?
+                }
+                Stream.Write(bis.ContainerSerial);
+                Stream.Write((ushort)bis.Hue);
+            }
+        }
+    }
+
+    public sealed class DisplayBuyList : Packet
+    {
+        public DisplayBuyList(Serial vendor, bool highSeas) : base(0x24, highSeas ? 9 : 7)
+        {
+            Stream.Write(vendor);
+            Stream.Write((short)0x30); // buy window id?
+            if (highSeas)
+            {
+                Stream.Write((short)0x00);
+            }
+        }
+    }
+
+    public sealed class VendorBuyList : Packet
+    {
+        public VendorBuyList(Mobile vendor, List<BuyItemState> list) : base(0x74)
+        {
+            EnsureCapacity(256);
+
+            Stream.Write(!(vendor.FindItemOnLayer(Layer.ShopBuy) is Container buyPack) ? Serial.MinusOne : buyPack.Serial);
+
+            Stream.Write((byte)list.Count);
+
+            for (var i = 0; i < list.Count; ++i)
+            {
+                var bis = list[i];
+
+                Stream.Write(bis.Price);
+
+                var desc = bis.Description ?? "";
+
+                Stream.Write((byte)desc.Length);
+                Stream.WriteAsciiFixed(desc, desc.Length);
+            }
+        }
+    }
+
+    public sealed class EndVendorBuy : Packet
+    {
+        public EndVendorBuy(Serial vendor) : base(0x3B, 8)
+        {
+            Stream.Write((ushort)8); // length
+            Stream.Write(vendor);
+            Stream.Write((byte)0);
+        }
+    }
+}