Add RSS-in-JSON parser

lib/feed_parser.ex

@@ -1,9 +1,14 @@
 defmodule FeedParser do
-  @default_parsers [FeedParser.RSS2.Parser, FeedParser.Atom.Parser, FeedParser.JSONFeed.Parser]
+  @default_parsers [
+    FeedParser.RSS2.Parser,
+    FeedParser.Atom.Parser,
+    FeedParser.JSONFeed.Parser,
+    FeedParser.RSSInJSON.Parser
+  ]
 
-  @spec parse_feed(data :: String.t(), content_type :: String.t(), parsers :: [module()]) ::
+  @spec parse(data :: String.t(), content_type :: String.t(), parsers :: [module()]) ::
           {:ok, feed :: FeedParser.Feed.t()} | {:error, reason :: String.t()}
-  def parse_feed(data, content_type, parsers \\ @default_parsers) when is_binary(data) do
+  def parse(data, content_type, parsers \\ @default_parsers) when is_binary(data) do
     parsers
     |> Enum.reduce_while(false, fn parser, acc ->
       case parser.accepts(data, content_type) do

lib/rssinjson/parser.ex

@@ -0,0 +1,61 @@
+defmodule FeedParser.RSSInJSON.Parser do
+  @behaviour FeedParser.Parser
+
+  @impl FeedParser.Parser
+  def accepts(data, content_type) do
+    with "application/json" <- content_type,
+         {:ok, json} <- Poison.decode(data),
+         %{"rss" => %{"version" => "2.0"} = rss} <- json do
+      {true, rss}
+    else
+      _ ->
+        false
+    end
+  end
+
+  @impl FeedParser.Parser
+  def parse_feed(rss) do
+    channel = rss["channel"]
+    title = channel["title"]
+    link = channel["link"]
+
+    image =
+      case channel do
+        %{"image" => %{"url" => url}} -> url
+        _ -> nil
+      end
+
+    items =
+      channel["item"]
+      |> Enum.map(fn item ->
+        guid = item["guid"]
+        link = item["link"]
+        title = Map.get(item, "title")
+        content = item["description"]
+
+        pubDate =
+          item["pubDate"]
+          |> Timex.parse("{RFC1123}")
+          |> case do
+            {:ok, date} -> date
+            _ -> nil
+          end
+
+        %FeedParser.Item{
+          guid: guid,
+          url: link,
+          title: title,
+          content: content,
+          date: pubDate
+        }
+      end)
+
+    {:ok,
+     %FeedParser.Feed{
+       site_url: link,
+       title: title,
+       image_url: image,
+       items: items
+     }}
+  end
+end