From 696b3dbfcb55b45753fbaa99e83eb4d9f8a3de07 Mon Sep 17 00:00:00 2001
From: Michael Ruoss <michael@michaelruoss.ch>
Date: Sat, 1 Apr 2023 10:14:10 +0200
Subject: [PATCH] next approach

---
 .../admission_control/admission_review.ex     | 12 ++-
 lib/bonny/admission_control/plug.ex           | 82 +++++++++++++++++++
 lib/bonny/admission_control/webhook_router.ex | 77 -----------------
 3 files changed, 90 insertions(+), 81 deletions(-)
 create mode 100644 lib/bonny/admission_control/plug.ex
 delete mode 100644 lib/bonny/admission_control/webhook_router.ex

diff --git a/lib/bonny/admission_control/admission_review.ex b/lib/bonny/admission_control/admission_review.ex
index a0fdd2d..2def083 100644
--- a/lib/bonny/admission_control/admission_review.ex
+++ b/lib/bonny/admission_control/admission_review.ex
@@ -5,15 +5,19 @@ defmodule Bonny.AdmissionControl.AdmissionReview do
 
   require Logger
 
+  @derive Pluggable.Token
+
+  @type webhook_type :: :mutating | :validating
   @type t :: %__MODULE__{
           request: map(),
           response: map(),
-          webhook_type: :mutating | :validating
+          webhook_type: webhook_type(),
+          halted: boolean(),
+          assigns: map()
         }
 
-  @fields [:request, :response, :webhook_type]
-  @enforce_keys @fields
-  defstruct @fields
+  @enforce_keys [:request, :response, :webhook_type]
+  defstruct [:request, :response, :webhook_type, halted: false, assigns: %{}]
 
   def new(%{"kind" => "AdmissionReview", "request" => request}, webhook_type) do
     struct!(__MODULE__,
diff --git a/lib/bonny/admission_control/plug.ex b/lib/bonny/admission_control/plug.ex
new file mode 100644
index 0000000..17c6e5f
--- /dev/null
+++ b/lib/bonny/admission_control/plug.ex
@@ -0,0 +1,82 @@
+defmodule Bonny.AdmissionControl.Plug do
+  use Plug.Builder
+
+  alias Bonny.AdmissionControl.AdmissionReview
+
+  require Logger
+
+  @api_version "admission.k8s.io/v1"
+  @kind "AdmissionReview"
+
+  plug(Plug.Parsers,
+    parsers: [:urlencoded, :json],
+    json_decoder: Jason
+  )
+
+  @impl true
+  def init(opts) do
+    if opts[:webhook_type] not in [:mutating, :validating] do
+      raise(CompileError,
+        file: __ENV__.file,
+        line: __ENV__.line,
+        description:
+          "#{__MODULE__} requires you to define the :webhook_type option as :mutating or :validating when plugged."
+      )
+    end
+
+    webhook_handler =
+      case opts[:webhook_handler] do
+        {module, init_opts} ->
+          {module, module.init(init_opts)}
+
+        nil ->
+          raise(CompileError,
+            file: __ENV__.file,
+            line: __ENV__.line,
+            description: "#{__MODULE__} requires you to set the :webhook_handler option."
+          )
+
+        module ->
+          {module, []}
+      end
+
+    %{
+      webhook_type: opts[:webhook_type],
+      webhook_handler: webhook_handler
+    }
+  end
+
+  @doc false
+  @impl true
+  def call(conn, webhook_config) do
+    %{
+      webhook_type: webhook_type,
+      webhook_handler: {webhook_handler, opts}
+    } = webhook_config
+
+    conn
+    |> super([])
+    |> Map.get(:body_params)
+    |> AdmissionReview.new(webhook_type)
+    |> tap(fn review ->
+      Logger.debug("Processing Admission Review Request", library: :bonny, review: review)
+    end)
+    |> AdmissionReview.allow()
+    |> webhook_handler.call(opts)
+    |> encode_response()
+    |> send_response(conn)
+  end
+
+  defp send_response(response_body, conn) do
+    conn
+    |> put_resp_content_type("application/json")
+    |> send_resp(200, response_body)
+  end
+
+  @spec encode_response(AdmissionReview.t()) :: binary()
+  defp encode_response(admission_review) do
+    %{"apiVersion" => @api_version, "kind" => @kind}
+    |> Map.put("response", admission_review.response)
+    |> Jason.encode!()
+  end
+end
diff --git a/lib/bonny/admission_control/webhook_router.ex b/lib/bonny/admission_control/webhook_router.ex
deleted file mode 100644
index 6c665c5..0000000
--- a/lib/bonny/admission_control/webhook_router.ex
+++ /dev/null
@@ -1,77 +0,0 @@
-defmodule Bonny.AdmissionControl.WebhookRouter do
-  import Plug.Conn
-
-  alias Bonny.AdmissionControl.AdmissionReview
-
-  require Logger
-
-  @api_version "admission.k8s.io/v1"
-  @kind "AdmissionReview"
-
-  @callback process(AdmissionReview.t()) :: AdmissionReview.t()
-
-  defmacro __using__(_opts) do
-    quote do
-      use Plug.Builder
-
-      alias Bonny.AdmissionControl.WebhookRouter
-
-      @behaviour WebhookRouter
-
-      plug(Plug.Parsers,
-        parsers: [:urlencoded, :json],
-        json_decoder: Jason
-      )
-
-      def init(opts) do
-        WebhookRouter.plug_init(opts, __MODULE__)
-      end
-
-      def call(%Plug.Conn{} = conn, webhook_type) do
-        conn
-        |> super([])
-        |> WebhookRouter.process_request(__MODULE__, webhook_type)
-      end
-    end
-  end
-
-  @doc false
-  def plug_init(opts, module) do
-    if opts[:webhook_type] not in [:mutating, :validating] do
-      raise(CompileError,
-        file: __ENV__.file,
-        line: __ENV__.line,
-        description:
-          "#{module} requires you to define the :webhook_type as :mutating or :validating when plugged."
-      )
-    end
-
-    opts[:webhook_type]
-  end
-
-  @doc false
-  def process_request(conn, router, webhook_type) do
-    conn.body_params
-    |> AdmissionReview.new(webhook_type)
-    |> tap(fn review ->
-      Logger.debug("Processing Admission Review Request", library: :bonny, review: review)
-    end)
-    |> AdmissionReview.allow()
-    |> router.process()
-    |> encode_response()
-    |> send_response(conn)
-  end
-
-  defp send_response(response_body, conn) do
-    conn
-    |> put_resp_content_type("application/json")
-    |> send_resp(200, response_body)
-  end
-
-  @spec encode_response(AdmissionReview.t()) :: binary()
-  defp encode_response(admission_review) do
-    %{"apiVersion" => @api_version, "kind" => @kind}
-    |> Map.put("response", admission_review.response)
-    |> Jason.encode!()
-  end
-end