Parse Last.fm session

lib/last_fm/session.ex

@@ -0,0 +1,62 @@
+defmodule LastFm.Session do
+  require Record
+
+  defstruct [:name, :key, :pro]
+
+  Record.defrecord(
+    :xmlAttribute,
+    Record.extract(:xmlAttribute, from_lib: "xmerl/include/xmerl.hrl")
+  )
+
+  Record.defrecord(:xmlText, Record.extract(:xmlText, from_lib: "xmerl/include/xmerl.hrl"))
+
+  def parse(xml_string) do
+    doc = scan(xml_string)
+
+    name =
+      doc
+      |> first("//lfm/session/name")
+      |> text()
+
+    key =
+      doc
+      |> first("//lfm/session/key")
+      |> text()
+
+    subscriber =
+      doc
+      |> first("//lfm/session/subscriber")
+      |> text()
+
+    %__MODULE__{
+      name: name,
+      key: key,
+      pro: subscriber == "1"
+    }
+  end
+
+  defp scan(xml_string) do
+    {doc, []} =
+      xml_string
+      |> :binary.bin_to_list()
+      |> :xmerl_scan.string(quiet: true)
+
+    doc
+  end
+
+  defp first(node, path), do: node |> xpath(path) |> take_one
+
+  defp take_one([head | _]), do: head
+  defp take_one(_), do: nil
+
+  defp xpath(nil, _), do: []
+
+  defp xpath(node, path) do
+    :xmerl_xpath.string(to_charlist(path), node)
+  end
+
+  def text(node), do: node |> xpath(~c"./text()") |> extract_text
+
+  defp extract_text([xmlText(value: value)]), do: List.to_string(value)
+  defp extract_text(_x), do: nil
+end

mix.exs

@@ -20,7 +20,7 @@ defmodule MusicLibrary.MixProject do
   def application do
     [
       mod: {MusicLibrary.Application, []},
-      extra_applications: [:logger, :runtime_tools]
+      extra_applications: [:logger, :runtime_tools, :xmerl]
     ]
   end
 

test/last_fm/session_test.exs

@@ -0,0 +1,24 @@
+defmodule LastFm.SessionTest do
+  use ExUnit.Case, async: true
+
+  alias LastFm.Session
+
+  @xml """
+  <?xml version="1.0" encoding="UTF-8"?>
+  <lfm status="ok">
+    <session>
+      <name>cloud8421</name>
+      <key>super-secret</key>
+      <subscriber>1</subscriber>
+    </session>
+  </lfm>
+  """
+
+  test "parse/1" do
+    assert %Session{
+             name: "cloud8421",
+             key: "super-secret",
+             pro: true
+           } == Session.parse(@xml)
+  end
+end