Add big and awful code

lib/data.ex

@@ -63,6 +63,10 @@ defmodule Amethyst.Minecraft.Write do
   def string(value) do
     <<varint(byte_size(value))::binary, value::binary>>
   end
+
+  def position({x, y, z}) do
+    <<x::signed-big-26, z::signed-big-26, y::signed-big-12>>
+  end
 end
 
 defmodule Amethyst.Minecraft.Read do

lib/servers/play.ex

@@ -38,7 +38,23 @@ defmodule Amethyst.Server.Play do
 
   ## SERIALIZATION
   @impl true
-
+  # Login https://wiki.vg/Protocol#Login_(play)
+  def serialize({:login, eid, hardcore, dimensions,
+    max_players, view_distance, simulation_distance,
+    reduce_debug, enable_respawn_screen, limited_crafting,
+    dim_type, dim_name, hashed_seed, gamemode, prev_gm,
+    is_debug, is_flat, death_loc, portal_cooldown, enforce_chat}) do
+      # TODO: this singlehandedly made me regret not making the write API better, please rework :(
+      <<eid::big-signed-32>> <> if(hardcore, do: <<1::big-8>>, else: <<0::big-8>>) <>
+      Write.varint(length(dimensions)) <> Enum.reduce(dimensions, "", fn dim, acc -> acc <> Write.string(dim) end) <>
+      Write.varint(max_players) <> Write.varint(view_distance) <> Write.varint(simulation_distance) <> if(reduce_debug, do: <<1::big-8>>, else: <<0::big-8>>) <>
+      if(enable_respawn_screen, do: <<1::big-8>>, else: <<0::big-8>>)
+      if(limited_crafting, do: <<1::big-8>>, else: <<0::big-8>>) <> Write.varint(dim_type) <> Write.string(dim_name) <>
+      hashed_seed <> <<gamemode_id(gamemode)::unsigned-big-8>> <> <<gamemode_id(prev_gm)::signed-big-8>> <>
+      if(is_debug, do: <<1::big-8>>, else: <<0::big-8>>) <> if(is_flat, do: <<1::big-8>>, else: <<0::big-8>>) <>
+      if(death_loc == nil, do: <<0::big-8>>, else: <<1::big-8>> <> Write.string(elem(death_loc, 0)) <> Write.position(elem(death_loc, 1))) <>
+      Write.varint(portal_cooldown) <> if(enforce_chat, do: <<1::big-8>>, else: <<0::big-8>>)
+    end
   def serialize(packet) do
     raise ArgumentError, "Tried serializing unknown packet #{inspect(packet)}"
   end
@@ -49,4 +65,14 @@ defmodule Amethyst.Server.Play do
     Logger.error("Unhandled but known packet #{elem(tuple, 0)}")
     {:unhandled, state}
   end
+
+  defp gamemode_id(gm) do
+    case gm do
+      nil -> -1
+      :survival -> 0
+      :creative -> 1
+      :adventure -> 2
+      :spectator -> 3
+    end
+  end
 end