Add captcha to support requests

lib/recycledcloud/captcha.ex

@@ -0,0 +1,32 @@
+defmodule RecycledCloud.Captcha do
+  # We can't use a graphical-only captcha library such as
+  # https://hex.pm/packages/captcha since it would break accessibility for
+  # blind people. Let's make it simple maths instead!
+
+  def validate(changeset, expected_result) do
+    captcha_result = Ecto.Changeset.get_field(changeset, :captcha)
+    if captcha_result == expected_result do
+      changeset
+    else
+      Ecto.Changeset.add_error(changeset, :captcha, "does not match")
+    end
+  end
+
+  def generate do
+    terms = 1..6
+    operands = ["+", "-", "*"]
+
+    left = terms |> Enum.random
+    right = terms |> Enum.random
+    operation = operands |> Enum.random
+
+    text = "#{left} #{operation} #{right}"
+    value = case operation do
+      "+" -> left + right
+      "-" -> left - right
+      "*" -> left * right
+    end
+
+    {text, value}
+  end
+end

lib/recycledcloud/support_request.ex

@@ -5,19 +5,24 @@ defmodule RecycledCloud.SupportRequest do
 
   alias RecycledCloud.SupportRequest
   alias RecycledCloud.Mailer
+  alias RecycledCloud.Captcha
 
   embedded_schema do
     field :name, :string
     field :email, :string
     field :message, :string
+    field :captcha, :integer
 
     timestamps()
   end
 
   def changeset(key, attrs) do
+    expected_captcha_result = attrs |> Map.get("expected_captcha")
+
     key
-    |> cast(attrs, [:name, :email, :message])
-    |> validate_required([:name, :email, :message])
+    |> cast(attrs, [:name, :email, :message, :captcha])
+    |> validate_required([:name, :email, :message, :captcha])
+    |> Captcha.validate(expected_captcha_result)
   end
 
   def send(%SupportRequest{} = request) do

lib/recycledcloud_web/controllers/support_controller.ex

@@ -2,18 +2,26 @@ defmodule RecycledCloudWeb.SupportController do
   use RecycledCloudWeb, :controller
 
   alias RecycledCloud.SupportRequest
+  alias RecycledCloud.Captcha
 
   def new(conn, _params) do
+    {captcha_text, captcha_result} = Captcha.generate()
+
     conn
     |> assign(:request_changeset, SupportRequest.changeset(%SupportRequest{}, %{}))
+    |> assign(:captcha, captcha_text)
+    |> put_session(:captcha, captcha_result)
     |> render("new.html")
   end
 
-  def create(conn, %{"support_request" => request} = params) do
-    action = SupportRequest.changeset(%SupportRequest{}, request)
+  def create(conn, %{"support_request" => raw} = params) do
+    attrs = raw |> Map.put("expected_captcha", get_session(conn, :captcha))
+    action = SupportRequest.changeset(%SupportRequest{}, attrs)
              |> Ecto.Changeset.apply_action(:update)
+
     case action do
       {:ok, request} ->
+        # FIXME: check for error?
         SupportRequest.send(request)
 
         conn
@@ -21,8 +29,12 @@ defmodule RecycledCloudWeb.SupportController do
         |> redirect(to: Routes.page_path(conn, :index))
 
       {:error, changeset} ->
+        {captcha_text, captcha_result} = Captcha.generate()
+
         conn
         |> assign(:request_changeset, changeset)
+        |> assign(:captcha, captcha_text)
+        |> put_session(:captcha, captcha_result)
         |> render("new.html")
     end
   end

lib/recycledcloud_web/templates/support/new.html.eex

@@ -20,6 +20,22 @@
   <%= textarea f, :message, placeholder: "Your message" %>
   <%= error_tag f, :message %>
 
+  <br />
+
+  <p>
+  Can you answer the following expression to confirm that you are not basic
+  robot?
+
+  <br />
+
+  <b><%= @captcha %> = </b>
+
+  <%= text_input f, :captcha, placeholder: "Captcha" %>
+  <%= error_tag f, :captcha %>
+
+  </p>
+
+
   <div>
     <%= submit "Send" %>
   </div>