From ea35bc4c5afd09ff7215203318150808883244a7 Mon Sep 17 00:00:00 2001
From: Eduardo Gurgel <edgurgel@gmail.com>
Date: Wed, 22 Jan 2014 13:45:39 -0300
Subject: [PATCH] Add '/base64/:value'

---
 lib/httparrot.ex                |  3 ++-
 lib/httparrot/base64_handler.ex | 38 +++++++++++++++++++++++++++++++++
 test/base64_handler_test.exs    | 21 ++++++++++++++++++
 3 files changed, 61 insertions(+), 1 deletion(-)
 create mode 100644 lib/httparrot/base64_handler.ex
 create mode 100644 test/base64_handler_test.exs

diff --git a/lib/httparrot.ex b/lib/httparrot.ex
index 32ff04a..f93a9b6 100644
--- a/lib/httparrot.ex
+++ b/lib/httparrot.ex
@@ -22,7 +22,8 @@ defmodule HTTParrot do
              {'/stream/:n', HTTParrot.StreamHandler, []},
              {'/delay/:n', HTTParrot.DelayedHandler, []},
              {'/html', :cowboy_static, {:priv_file, :httparrot, "html.html"}},
-             {'/deny', HTTParrot.DenyHandler, []} ] }
+             {'/deny', HTTParrot.DenyHandler, []},
+             {'/base64/:value', HTTParrot.Base64Handler, []} ] }
     ])
     {:ok, http_port} = :application.get_env(:httparrot, :http_port)
     {:ok, https_port} = :application.get_env(:httparrot, :https_port)
diff --git a/lib/httparrot/base64_handler.ex b/lib/httparrot/base64_handler.ex
new file mode 100644
index 0000000..2ed85a3
--- /dev/null
+++ b/lib/httparrot/base64_handler.ex
@@ -0,0 +1,38 @@
+defmodule HTTParrot.Base64Handler do
+  @moduledoc """
+  Returns urlsafe base64 decoded data.
+  """
+
+  def init(_transport, _req, _opts) do
+    {:upgrade, :protocol, :cowboy_rest}
+  end
+
+  def allowed_methods(req, state) do
+    {["GET", "HEAD", "OPTIONS"], req, state}
+  end
+
+  def content_types_provided(req, state) do
+    {[{{"application", "octet-stream", []}, :get_binary}], req, state}
+  end
+
+  def get_binary(req, state) do
+    {value, req} = :cowboy_req.binding(:value, req)
+    value = decode(value)
+    {value, req, state}
+  end
+
+  defp decode(bin) when is_binary(bin) do
+    bin = case rem(byte_size(bin), 4) do
+      2 -> << bin :: binary, "==" >>
+      3 -> << bin :: binary, "=" >>
+      _ -> bin
+    end
+    bc <<x>> inbits :base64.decode(bin), x != ?=, do: <<urldecode_digit(x)>>
+  end
+
+  defp urldecode_digit(?_), do: ?/
+  defp urldecode_digit(?-), do: ?+
+  defp urldecode_digit(d), do: d
+
+  def terminate(_, _, _), do: :ok
+end
diff --git a/test/base64_handler_test.exs b/test/base64_handler_test.exs
new file mode 100644
index 0000000..d15f06f
--- /dev/null
+++ b/test/base64_handler_test.exs
@@ -0,0 +1,21 @@
+defmodule HTTParrot.Base64HandlerTest do
+  use ExUnit.Case
+  import :meck
+  import HTTParrot.Base64Handler
+
+  setup do
+    new :cowboy_req
+  end
+
+  teardown do
+    unload :cowboy_req
+  end
+
+  test "returns decoded base64 urlsafe" do
+    expect(:cowboy_req, :binding, [{[:value, :req1], {"LytiYXNlNjQrLw", :req2}}])
+
+    assert get_binary(:req1, :state) == { "/+base64+/", :req2, :state}
+
+    assert validate :cowboy_req
+  end
+end