Add inline images in mandrill adapter (#608)

This commit adds support to send to mandrill images inline.

.tool-versions

@@ -1,2 +1,2 @@
-erlang 21.2
-elixir 1.8.1
+erlang 22.3.4
+elixir 1.8

lib/bamboo/adapters/mandrill_adapter.ex

@@ -103,12 +103,23 @@ defmodule Bamboo.MandrillAdapter do
       subject: email.subject,
       text: email.text_body,
       html: email.html_body,
-      headers: email.headers,
-      attachments: attachments(email)
+      headers: email.headers
     }
+    |> add_attachments(email)
     |> add_message_params(email)
   end
 
+  defp add_attachments(mandrill_message, %{attachments: attachments}) do
+    {images, files} =
+      attachments
+      |> Enum.reverse()
+      |> Enum.split_with(&is_inline_image?/1)
+
+    mandrill_message
+    |> Map.put(:attachments, format_attachments(files))
+    |> Map.put(:images, format_attachments(images))
+  end
+
   defp add_message_params(mandrill_message, %{private: %{message_params: message_params}}) do
     Enum.reduce(message_params, mandrill_message, fn {key, value}, mandrill_message ->
       Map.put(mandrill_message, key, value)
@@ -117,18 +128,23 @@ defmodule Bamboo.MandrillAdapter do
 
   defp add_message_params(mandrill_message, _), do: mandrill_message
 
-  defp attachments(%{attachments: attachments}) do
-    attachments
-    |> Enum.reverse()
-    |> Enum.map(fn attachment ->
+  defp format_attachments(attachments) do
+    Enum.map(attachments, fn attachment ->
+      name = if is_inline_image?(attachment), do: attachment.content_id, else: attachment.filename
+
       %{
-        name: attachment.filename,
+        name: name,
         type: attachment.content_type,
         content: Base.encode64(attachment.data)
       }
     end)
   end
 
+  defp is_inline_image?(%_{content_type: "image/" <> _, content_id: cid}) when not is_nil(cid),
+    do: true
+
+  defp is_inline_image?(_), do: false
+
   defp recipients(email) do
     []
     |> add_recipients(email.to, type: "to")

test/lib/bamboo/adapters/mandrill_adapter_test.exs

@@ -1,5 +1,6 @@
 defmodule Bamboo.MandrillAdapterTest do
   use ExUnit.Case
+  alias Bamboo.Attachment
   alias Bamboo.Email
   alias Bamboo.MandrillHelper
   alias Bamboo.MandrillAdapter
@@ -103,6 +104,8 @@ defmodule Bamboo.MandrillAdapterTest do
   end
 
   test "deliver/2 sends from, html and text body, subject, headers and attachment" do
+    file_path = Path.join(__DIR__, "../../../support/attachment.txt")
+
     email =
       new_email(
         from: {"From", "[email protected]"},
@@ -111,7 +114,20 @@ defmodule Bamboo.MandrillAdapterTest do
         html_body: "HTML BODY"
       )
       |> Email.put_header("Reply-To", "[email protected]")
-      |> Email.put_attachment(Path.join(__DIR__, "../../../support/attachment.txt"))
+      |> Email.put_attachment(file_path)
+      |> Email.put_attachment(
+        Attachment.new(file_path, content_id: "my_fake_image", filename: "fake_image.jpg")
+      )
+      |> Email.put_attachment(%Attachment{
+        content_type: "image/png",
+        content_id: "my_image",
+        filename: "my_image.png",
+        data:
+          <<137, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82, 0, 0, 0, 1, 0, 0, 0, 1,
+            8, 6, 0, 0, 0, 31, 21, 196, 137, 0, 0, 0, 13, 73, 68, 65, 84, 120, 218, 99, 252, 207,
+            192, 80, 15, 0, 4, 133, 1, 128, 132, 169, 140, 33, 0, 0, 0, 0, 73, 69, 78, 68, 174,
+            66, 96, 130>>
+      })
 
     email |> MandrillAdapter.deliver(@config)
 
@@ -131,6 +147,20 @@ defmodule Bamboo.MandrillAdapterTest do
                "type" => "text/plain",
                "name" => "attachment.txt",
                "content" => "VGVzdCBBdHRhY2htZW50Cg=="
+             },
+             %{
+               "type" => "text/plain",
+               "name" => "fake_image.jpg",
+               "content" => "VGVzdCBBdHRhY2htZW50Cg=="
+             }
+           ]
+
+    assert message["images"] == [
+             %{
+               "type" => "image/png",
+               "name" => "my_image",
+               "content" =>
+                 "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8BQDwAEhQGAhKmMIQAAAABJRU5ErkJggg=="
              }
            ]
   end