more work on sending map

apps/amethyst/lib/apps/connection_handler.ex

@@ -120,13 +120,27 @@ defmodule Amethyst.ConnectionHandler do
   end
 
   defp process_chunk(chunk, state) do
+    import Amethyst.NBT.Write
+    alias Amethyst.Minecraft.Write
+
     chunk_array = Amethyst.API.Game.chunk(Map.get(state, :game), chunk)
 
     # TODO: Actually do heightmaps
-    import Amethyst.NBT.Write
     heightmaps = compound(%{})
 
     data = Enum.chunk_every(chunk_array, 16, 16, 0) # 0 -> air
+        |> Enum.reduce(fn chunk_section, acc ->
+          blocks = chunk_section |> List.flatten()
+          block_count = blocks
+            |> Enum.map(&(if &1 == 0, do: 0, else: 1))
+            |> Enum.sum()
+
+          # TODO: Proper paletting
+          acc <> Write.short(block_count) <> Write.ubyte(15)
+        end)
+
+    # TODO: Use paletting
+
   end
 
   defp handle_packet(id, data, connstate, version, state) do