Code for step 3

lib/elixir_popularity/application.ex

@@ -7,6 +7,7 @@ defmodule ElixirPopularity.Application do
 
   def start(_type, _args) do
     children = [
+      :hackney_pool.child_spec(:hn_id_pool, timeout: 15000, max_connections: 100),
       ElixirPopularity.Repo
     ]
 

lib/hackernews_api.ex

@@ -0,0 +1,63 @@
+defmodule ElixirPopularity.HackernewsApi do
+  @moduledoc """
+  Fetches data from the Hackernews API, extracts the necessary fields,
+  and massages some data
+  """
+
+  require Logger
+
+  alias ElixirPopularity.HackernewsItem
+
+  def get_hn_item(resource_id) do
+    get_hn_item(resource_id, 4)
+  end
+
+  defp get_hn_item(resource_id, retry) do
+    response =
+      resource_id
+      |> gen_api_url()
+      |> HTTPoison.get([], hackney: [pool: :hn_id_pool])
+
+    with {_, {:ok, body}} <- {"hn_api", handle_response(response)},
+         {_, {:ok, decoded_payload}} <- {"payload_decode", Jason.decode(body)},
+         {_, {:ok, data}} <- {"massage_data", massage_data(decoded_payload)} do
+      data
+    else
+      {stage, error} ->
+        Logger.warn(
+          "Failed attempt #{5 - retry} at stage \"#{stage}\" with Hackernews ID of #{resource_id}. Error details: #{
+            inspect(error)
+          }"
+        )
+
+        if retry > 0 do
+          get_hn_item(resource_id, retry - 1)
+        else
+          Logger.warn("Failed to retrieve Hackernews ID of #{resource_id}.")
+          :error
+        end
+    end
+  end
+
+  defp handle_response({:ok, %HTTPoison.Response{status_code: 200, body: body}}) do
+    {:ok, body}
+  end
+
+  defp handle_response({_, invalid_response}) do
+    {:error, invalid_response}
+  end
+
+  defp gen_api_url(resource_id) do
+    "https://hacker-news.firebaseio.com/v0/item/#{resource_id}.json"
+  end
+
+  defp massage_data(data) do
+    {:ok,
+     HackernewsItem.create(
+       data["text"],
+       data["type"],
+       data["title"],
+       data["time"]
+     )}
+  end
+end

lib/hackernews_item.ex

@@ -0,0 +1,22 @@
+defmodule ElixirPopularity.HackernewsItem do
+  alias __MODULE__
+
+  defstruct text: nil, type: nil, title: nil, time: nil
+
+  def create(text, type, title, unix_time) do
+    %HackernewsItem{
+      text: text,
+      type: type,
+      title: title,
+      time: get_date_time(unix_time)
+    }
+  end
+
+  defp get_date_time(nil), do: nil
+
+  defp get_date_time(unix_time) do
+    {:ok, date_time} = DateTime.from_unix(unix_time)
+
+    DateTime.to_date(date_time)
+  end
+end