From 564d095f2a2887c9af71f5762cc0f8e084c7f3dd Mon Sep 17 00:00:00 2001
From: Zach Daniel <zachary.s.daniel@gmail.com>
Date: Sat, 27 Jun 2020 14:24:54 -0400
Subject: [PATCH] feat: section option configuration

---
 lib/ash/data_layer/ets/ets.ex |  2 +-
 lib/ash/dsl/extension.ex      | 48 ++++++++++++++++++++++++++++++++---
 lib/ash/dsl/section.ex        | 11 +++++++-
 3 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/lib/ash/data_layer/ets/ets.ex b/lib/ash/data_layer/ets/ets.ex
index 35e453c67..27a57231d 100644
--- a/lib/ash/data_layer/ets/ets.ex
+++ b/lib/ash/data_layer/ets/ets.ex
@@ -28,7 +28,7 @@ defmodule Ash.DataLayer.Ets do
 
   @spec private?(Ash.resource()) :: boolean
   def private?(resource) do
-    Extension.get_opt(resource, [:ets], :private?) || false
+    Extension.get_opt(resource, [:ets], :private?, false, true)
   end
 
   defmodule Query do
diff --git a/lib/ash/dsl/extension.ex b/lib/ash/dsl/extension.ex
index 131144bd4..9f55c3531 100644
--- a/lib/ash/dsl/extension.ex
+++ b/lib/ash/dsl/extension.ex
@@ -106,9 +106,51 @@ defmodule Ash.Dsl.Extension do
     :persistent_term.get({resource, :ash, path}, %{entities: []}).entities
   end
 
-  @doc "Get an option value for a section at a given path"
-  def get_opt(resource, path, value) do
-    :persistent_term.get({resource, :ash, path}, %{opts: []}).opts[value]
+  @doc """
+  Get an option value for a section at a given path.
+
+  Checks to see if it has been overridden via configuration.
+  """
+  def get_opt(resource, path, value, default, configurable? \\ false) do
+    if configurable? do
+      case get_opt_config(resource, path, value) do
+        {:ok, value} ->
+          value
+
+        _ ->
+          Keyword.get(
+            :persistent_term.get({resource, :ash, path}, %{opts: []}).opts,
+            value,
+            default
+          )
+      end
+    else
+      Keyword.get(
+        :persistent_term.get({resource, :ash, path}, %{opts: []}).opts,
+        value,
+        default
+      )
+    end
+  end
+
+  def get_opt_config(resource, path, value) do
+    with {:ok, config} <- Application.fetch_env(:ash, resource),
+         {:ok, value} <-
+           path
+           |> List.wrap()
+           |> Kernel.++([value])
+           |> Enum.reduce_while({:ok, config}, fn key, {:ok, config} ->
+             if Keyword.keyword?(config) do
+               case Keyword.fetch(config, key) do
+                 {:ok, value} -> {:cont, {:ok, value}}
+                 :error -> {:halt, :error}
+               end
+             else
+               {:halt, :error}
+             end
+           end) do
+      {:ok, value}
+    end
   end
 
   @doc false
diff --git a/lib/ash/dsl/section.ex b/lib/ash/dsl/section.ex
index a72da45bf..1b7aa482b 100644
--- a/lib/ash/dsl/section.ex
+++ b/lib/ash/dsl/section.ex
@@ -20,13 +20,22 @@ defmodule Ash.Dsl.Section do
 
   For a full example, see `Ash.Dsl.Extension`.
   """
-  defstruct [:name, imports: [], schema: [], describe: "", entities: [], sections: []]
+  defstruct [
+    :name,
+    imports: [],
+    schema: [],
+    configurable: [],
+    describe: "",
+    entities: [],
+    sections: []
+  ]
 
   @type t :: %__MODULE__{
           name: atom,
           describe: String.t(),
           entities: [Ash.Dsl.Entity.t()],
           sections: [%__MODULE__{}],
+          configurable: [atom],
           schema: NimbleOptions.schema()
         }