From 9c53e89876191cf3228484dd60766760923ba901 Mon Sep 17 00:00:00 2001
From: lthms <contact@thomasletan.fr>
Date: Tue, 2 Jan 2018 07:47:27 +0000
Subject: puppeteer, system: Introduce cast_return and call_return

---
 lib/lkn/core/puppeteer.ex | 53 ++++++++++++++++---------
 lib/lkn/core/specs.ex     | 12 ++++++
 lib/lkn/core/system.ex    | 99 +++++++++++++++++++++++++++--------------------
 test/core_test.exs        | 21 +++++-----
 4 files changed, 115 insertions(+), 70 deletions(-)

diff --git a/lib/lkn/core/puppeteer.ex b/lib/lkn/core/puppeteer.ex
index 996c78b..ab373ea 100644
--- a/lib/lkn/core/puppeteer.ex
+++ b/lib/lkn/core/puppeteer.ex
@@ -53,6 +53,7 @@ defmodule Lkn.Core.Puppeteer do
         )
 
         defmacro __using__(args) do
+
           plugin_clients = case args do
                              [do: use_block] ->
                                Specs.gen_server_plugin_entry_point(
@@ -76,7 +77,9 @@ defmodule Lkn.Core.Puppeteer do
             alias Lkn.Core.Instance
             alias Lkn.Core, as: L
 
-            defmodule State do
+            unquote(Specs.gen_server_returns())
+
+            defmodule PrivateState do
               @moduledoc false
 
               defstruct [
@@ -86,7 +89,7 @@ defmodule Lkn.Core.Puppeteer do
                 :state,
               ]
 
-              @type t :: %State{
+              @type t :: %PrivateState{
                 puppeteer_key: Puppeteer.k,
                 instance_key:  Lkn.Prelude.Option.t(Instance.k),
                 map_key:       Lkn.Prelude.Option.t(L.Map.k),
@@ -95,80 +98,92 @@ defmodule Lkn.Core.Puppeteer do
 
               @spec new(Puppeteer.t, Lkn.Core.Puppeteer.state) :: t
               def new(pk, s) do
-                %State{
+                %PrivateState{
                   puppeteer_key: pk,
                   instance_key:  Lkn.Prelude.Option.nothing(),
                   map_key:       Lkn.Prelude.Option.nothing(),
                   state:         s,
                 }
               end
+
+              def update(state, opts) do
+                st = Keyword.get(opts, :state, state.state)
+                instance = Keyword.get(opts, :instance, state.instance_key)
+                mapk = Keyword.get(opts, :map, state.map_key)
+
+                %PrivateState{state|
+                       state: st,
+                       map_key: mapk,
+                       instance_key: instance
+                }
+              end
             end
 
             def init({puppeteer_key, args}) do
               {:ok, s} = init_state(args)
-              {:ok, State.new(puppeteer_key, s)}
+              {:ok, PrivateState.new(puppeteer_key, s)}
             end
 
             def handle_cast({:puppet_enter, instance_key, puppet_key, digest}, state) do
               if state.instance_key == Lkn.Prelude.Option.some(instance_key) do
-                s2 = puppet_enter(state.state, state.instance_key, puppet_key, digest)
+                opts = puppet_enter(state.state, state.instance_key, puppet_key, digest)
 
-                {:noreply, %State{state|state: s2}}
+                {:noreply, PrivateState.update(state, opts)}
               else
                 {:noreply, state}
               end
             end
             def handle_cast({:puppet_leave, instance_key, puppet_key}, state) do
               if state.instance_key == Lkn.Prelude.Option.some(instance_key) do
-                s2 = puppet_leave(state.state, state.instance_key, puppet_key)
+                opts = puppet_leave(state.state, state.instance_key, puppet_key)
 
-                {:noreply, %State{state|state: s2}}
+                {:noreply, PrivateState.update(state, opts)}
               else
                 {:noreply, state}
               end
             end
             def handle_cast({:instance_digest, instance_key, map_key, map, puppets}, state) do
               if state.instance_key == Lkn.Prelude.Option.some(instance_key) do
-                s2 = instance_digest(state.state, instance_key, map_key, map, puppets)
-                {:noreply, %State{state|state: s2}}
+                opts = instance_digest(state.state, instance_key, map_key, map, puppets)
+                {:noreply, PrivateState.update(state, opts)}
               else
                 {:noreply, state}
               end
             end
             def handle_cast({:leave_instance, instance_key}, state) do
               if state.instance_key == Lkn.Prelude.Option.some(instance_key) do
-                s2 = leave_instance(state.state, instance_key)
+                opts = leave_instance(state.state, instance_key)
 
                 Instance.unregister_puppeteer(instance_key, state.puppeteer_key)
 
-                {:noreply, %State{state|instance_key: Lkn.Prelude.Option.nothing(), state: s2}}
+                {:noreply, PrivateState.update(state, opts)}
               else
                 {:noreply, state}
               end
             end
             def handle_cast({:spec, {name, args}}, state) do
-              s = :erlang.apply(__MODULE__, name, [state.puppeteer_key|args]++[state.instance_key, state.state])
+              opts = :erlang.apply(__MODULE__, name, [state.puppeteer_key|args]++[state.instance_key, state.state])
 
-              {:noreply, %State{state|state: s}}
+              {:noreply, PrivateState.update(state, opts)}
             end
             def handle_cast({:plugin, {name, args}}, state) do
               name = String.to_atom(String.replace_suffix(Atom.to_string(name), "", "_plugin"))
-              s = :erlang.apply(__MODULE__, name, [state.puppeteer_key|args]++[state.instance_key, state.state])
+              opts = :erlang.apply(__MODULE__, name, [state.puppeteer_key|args]++[state.instance_key, state.state])
 
-              {:noreply, %State{state|state: s}}
+              {:noreply, PrivateState.update(state, opts)}
             end
 
             def handle_call({:find_instance, map_key}, _from, state) do
               instance_key = Lkn.Core.Pool.register_puppeteer(map_key, state.puppeteer_key, __MODULE__)
 
-              state = %State{state|instance_key: Lkn.Prelude.Option.some(instance_key)}
+              state = %PrivateState{state|instance_key: Lkn.Prelude.Option.some(instance_key)}
 
               {:reply, instance_key, state}
             end
             def handle_call({:spec, {name, args}}, _call, state) do
-              {res, s} = :erlang.apply(__MODULE__, name, [state.puppeteer_key|args] ++ [state.state])
+              {res, opts} = :erlang.apply(__MODULE__, name, [state.puppeteer_key|args] ++ [state.state])
 
-              {:reply, res, %State{state|state: s}}
+              {:reply, res, PrivateState.update(state, opts)}
             end
 
             unquote(plugin_clients)
diff --git a/lib/lkn/core/specs.ex b/lib/lkn/core/specs.ex
index 986b29a..fc3be37 100644
--- a/lib/lkn/core/specs.ex
+++ b/lib/lkn/core/specs.ex
@@ -54,6 +54,18 @@ defmodule Lkn.Core.Specs do
     end
   end
 
+  def gen_server_returns() do
+    quote do
+      defp cast_return(opts \\ []) do
+        opts
+      end
+
+      defp call_return(res, opts \\ []) do
+        {res, opts}
+      end
+    end
+  end
+
   def gen_server_from_specs(block, key_type, key_to_name, state_type, keywords \\ []) do
     block = case block do
               {:__block__, _, x} -> x
diff --git a/lib/lkn/core/system.ex b/lib/lkn/core/system.ex
index aa8577a..c57dd54 100644
--- a/lib/lkn/core/system.ex
+++ b/lib/lkn/core/system.ex
@@ -126,27 +126,38 @@ defmodule Lkn.Core.System do
   @typedoc "A set of “compatible” puppets."
   @type puppets :: MapSet.t(Puppet.t)
 
-  defmodule State do
+  defmodule PrivateState do
     @moduledoc false
 
     defstruct [
       :map_key,
       :instance_key,
       :puppets,
+      :state,
     ]
 
-    @type t :: %State{
+    @type t :: %PrivateState{
       map_key: Map.k,
       instance_key: Instance.k,
       puppets: System.puppets,
+      state: term,
     }
 
-    @spec new(Instance.k, Map.k) :: t
-    def new(instance_key, map_key) do
-      %State{
+    @spec new(Instance.k, Map.k, term) :: t
+    def new(instance_key, map_key, public) do
+      %PrivateState{
         puppets: MapSet.new(),
         instance_key: instance_key,
         map_key: map_key,
+        state: public,
+      }
+    end
+
+    def update(state, opts) do
+      st = Keyword.get(opts, :state, state.state)
+
+      %PrivateState{state|
+                    state: st
       }
     end
 
@@ -154,14 +165,14 @@ defmodule Lkn.Core.System do
     def put(state, puppet_key) do
       puppets = MapSet.put(state.puppets, puppet_key)
 
-      %State{state|
+      %PrivateState{state|
              puppets: puppets
       }
     end
 
     @spec delete(t, Puppet.k) :: t
     def delete(state, puppet_key) do
-      %State{state|
+      %PrivateState{state|
              puppets: MapSet.delete(state.puppets, puppet_key)
       }
     end
@@ -199,7 +210,7 @@ defmodule Lkn.Core.System do
     instance_key :: Instance.k,
     map_key :: Map.k,
     puppets :: System.puppets,
-    puppet_key :: Puppet.k) :: state
+    puppet_key :: Puppet.k) :: term
 
   @doc """
   A hook function which is called when a “compatible” puppet leaves the Instance.
@@ -209,7 +220,7 @@ defmodule Lkn.Core.System do
     instance_key :: Instance.k,
     map_key :: Map.k,
     puppets :: System.puppets,
-    puppet_key :: Puppet.k) :: state
+    puppet_key :: Puppet.k) :: term
 
   @doc """
   A macro to ease the definition of a new System which provides the
@@ -231,6 +242,8 @@ defmodule Lkn.Core.System do
 
         @behaviour Lkn.Core.System
 
+        unquote(Specs.gen_server_returns())
+
         unquote(Specs.gen_server_from_specs(
               block,
               key_type,
@@ -259,53 +272,54 @@ defmodule Lkn.Core.System do
           {:ok, st}
         end
 
-        defp priv_handle_cast({:notify, notification}, priv: priv, pub: pub) do
-          State.notify(priv, notification)
-          [priv: priv, pub: pub]
+        defp priv_handle_cast({:notify, notification}, state) do
+          PrivateState.notify(state, notification)
+
+          {:noreply, state}
         end
 
-        defp priv_handle_call({:register_puppet, entity_key}, _from, priv: priv, pub: pub) do
-          {res, priv, pub} = if Lkn.Core.Entity.has_component?(entity_key, __MODULE__) do
-            {true, State.put(priv, entity_key), puppet_enter(pub, priv.instance_key, priv.map_key, priv.puppets, entity_key)}
+        defp priv_handle_call({:register_puppet, entity_key}, _from, state) do
+          if Lkn.Core.Entity.has_component?(entity_key, __MODULE__) do
+            state = PrivateState.put(state, entity_key)
+            opts =  puppet_enter(state.state, state.instance_key, state.map_key, state.puppets, entity_key)
+
+            {:reply, true, PrivateState.update(state, opts)}
           else
-            {false, priv, pub}
+            {:reply, false, state}
           end
-
-          {:reply, res, [priv: priv, pub: pub]}
         end
-        defp priv_handle_call({:unregister_puppet, entity_key}, _from, priv: priv, pub: pub) do
-          {res, priv, pub} =
+        defp priv_handle_call({:unregister_puppet, entity_key}, _from, state) do
           if Lkn.Core.Entity.has_component?(entity_key, __MODULE__) do
-            priv = State.delete(priv, entity_key)
-            {true, priv, puppet_leave(pub, priv.instance_key, priv.map_key, priv.puppets, entity_key)}
+            opts = puppet_leave(state.state, state.instance_key, state.map_key, state.puppets, entity_key)
+            state = PrivateState.delete(state, entity_key)
+
+            {:reply, true, PrivateState.update(state, opts)}
           else
-            {false, priv, pub}
+            {:reply, false, state}
           end
-
-          {:reply, res, [priv: priv, pub: pub]}
         end
-        defp priv_handle_call(:population_size, _from, priv: priv, pub: pub) do
-          {:reply, State.population(priv), [priv: priv, pub: pub]}
+        defp priv_handle_call(:population_size, _from, state) do
+          {:reply, PrivateState.population(state), state}
         end
 
         def handle_cast({:priv, cmd}, state) do
-          {:noreply, priv_handle_cast(cmd, state)}
+          priv_handle_cast(cmd, state)
         end
-        def handle_cast({:spec, {name, args}}, priv: priv, pub: pub) do
+        def handle_cast({:spec, {name, args}}, state) do
           name = String.to_atom(String.replace_suffix(Atom.to_string(name), "", "_impl"))
-          s = :erlang.apply(__MODULE__, name, [priv.instance_key|args] ++ [priv.map_key, priv.puppets, pub])
+          opts = :erlang.apply(__MODULE__, name, [state.instance_key|args] ++ [state.map_key, state.puppets, state.state])
 
-          {:noreply, [priv: priv, pub: s]}
+          {:noreply, PrivateState.update(state, opts)}
         end
 
-        def handle_call({:spec, {name, args}}, _call, priv: priv, pub: pub) do
+        def handle_call({:spec, {name, args}}, _call, state) do
           name = String.to_atom(String.replace_suffix(Atom.to_string(name), "", "_impl"))
-          {res, s} = :erlang.apply(__MODULE__, name, [priv.instance_key|args] ++ [priv.map_key, priv.puppets, pub])
+          {res, opts} = :erlang.apply(__MODULE__, name, [state.instance_key|args] ++ [state.map_key, state.puppets, state.state])
 
-          {:reply, res, [priv: priv, pub: s]}
+          {:reply, res, PrivateState.update(state, opts)}
         end
-        def handle_call({:priv, cmd}, from, priv: priv, pub: pub) do
-          priv_handle_call(cmd, from, priv: priv, pub: pub)
+        def handle_call({:priv, cmd}, from, state) do
+          priv_handle_call(cmd, from, state)
         end
 
         @spec notify(any) :: :ok
@@ -319,12 +333,13 @@ defmodule Lkn.Core.System do
   @doc false
   @spec start_link(m, Instance.k, Map.k) :: GenServer.on_start
   def start_link(module, instance_key, map_key) do
-    GenServer.start_link(module,
-      [
-        priv: State.new(instance_key, map_key),
-        pub: module.init_state(instance_key, map_key),
-      ],
-      name: Name.system(instance_key, module))
+    pub = module.init_state(instance_key, map_key)
+
+    GenServer.start_link(
+      module,
+      PrivateState.new(instance_key, map_key, pub),
+      name: Name.system(instance_key, module)
+    )
   end
 
   @doc false
diff --git a/test/core_test.exs b/test/core_test.exs
index 71aeed8..6d7accf 100644
--- a/test/core_test.exs
+++ b/test/core_test.exs
@@ -417,19 +417,21 @@ defsystem Test.System do
 
   def puppet_enter(:ok, _instance_key, _map_key, _entities, key) do
     notify(&(Test.Puppeteer.Specs.emit(&1, {:enter, key})))
-    :ok
+
+    cast_return()
   end
 
   def puppet_leave(:ok, _instance_key, _map_key, _entities, key) do
     notify(&(Test.Puppeteer.Specs.emit(&1, {:leave, key})))
-    :ok
+
+    cast_return()
   end
 
   cast level_up(puppet_key :: Puppet.k) do
     notif = Test.System.Puppet.level_up(puppet_key)
     notify(&(Test.Puppeteer.Specs.emit(&1, {:level_up, notif})))
 
-    state
+    cast_return()
   end
 end
 
@@ -542,7 +544,8 @@ defmodule Test.Puppeteer do
       for i <- 0..(n-1) do
         send state, {:wizz, i, key}
       end
-      state
+
+      cast_return()
     end
   end
 
@@ -555,15 +558,15 @@ defmodule Test.Puppeteer do
   end
 
   def instance_digest(state, _instance_key, map_key, _map, _puppets) do
-    state
+    cast_return()
   end
 
   def puppet_enter(state, _instance_key, _puppet_key, _digest) do
-    state
+    cast_return()
   end
 
   def puppet_leave(state, _instance_key, _puppet_key) do
-    state
+    cast_return()
   end
 
   def destroy(puppeteer_key, state, _instance_key, _reason) do
@@ -572,12 +575,12 @@ defmodule Test.Puppeteer do
 
   def leave_instance(target, _instance_key) do
     send(target, :kick)
-    target
+    cast_return()
   end
 
   def emit(_puppeteer_key, msg, instance_key, target) do
     send target, msg
-    target
+    cast_return()
   end
 end
 
-- 
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