Replace site-specific pipeline stages with new extractor architecture

lib/frenzy/pipeline/extractor.ex

@@ -0,0 +1,3 @@
+defmodule Frenzy.Pipeline.Extractor do
+  @callback extract(String.t()) :: {:ok, String.t()} | {:error, String.t()}
+end

lib/frenzy/pipeline/extractor/daring_fireball.ex

@@ -0,0 +1,38 @@
+defmodule Frenzy.Pipeline.Extractor.DaringFireball do
+  alias Frenzy.Pipeline.Extractor
+  @behaviour Extractor
+
+  @impl Extractor
+  def extract(body) do
+    html_tree = Floki.parse(body)
+
+    case get_article_element(html_tree) || get_link_element(html_tree) do
+      nil ->
+        {:error, "no matching elements"}
+
+      elem ->
+        {:ok, Floki.raw_html(elem)}
+    end
+  end
+
+  defp get_article_element(html_tree) do
+    case Floki.find(html_tree, "div.article") do
+      [article_elem | _] ->
+        # articles include extra information in the div.article element
+        Floki.filter_out(article_elem, "h1, .dateline, #PreviousNext")
+
+      _ ->
+        nil
+    end
+  end
+
+  defp get_link_element(html_tree) do
+    case Floki.find(html_tree, "dl.linkedlist dd") do
+      [dd_elem | _] ->
+        dd_elem
+
+      _ ->
+        nil
+    end
+  end
+end

lib/frenzy/pipeline/scrape_stage.ex

@@ -4,8 +4,8 @@ defmodule Frenzy.Pipeline.ScrapeStage do
   @behaviour Stage
 
   @impl Stage
-  def apply(_opts, %{url: url} = item_params) do
-    case get_article_content(url) do
+  def apply(opts, %{url: url} = item_params) do
+    case get_article_content(url, opts["extractor"]) do
       {:ok, content} ->
         {:ok, %{item_params | content: content}}
 
@@ -16,17 +16,41 @@ defmodule Frenzy.Pipeline.ScrapeStage do
   end
 
   @impl Stage
-  def validate_opts(opts), do: {:ok, opts}
+  def validate_opts(opts) when is_map(opts) do
+    # todo: figure out why this errors when an empty map is provided
+    case opts["extractor"] do
+      nil ->
+        {:ok, %{opts | extractor: "builtin"}}
 
-  @spec get_article_content(String.t()) :: {:ok, String.t()} | {:error, String.t()}
-  defp get_article_content(url) when is_binary(url) and url != "" do
+      extractor when not is_binary(extractor) ->
+        {:error, "extractor must be a string"}
+
+      "builtin" ->
+        {:ok, opts}
+
+      extractor ->
+        try do
+          String.to_existing_atom("Elixir." <> extractor)
+          {:ok, opts}
+        rescue
+          ArgumentError ->
+            {:error, "extractor must be \"builtin\" or a module that exists"}
+        end
+    end
+  end
+
+  @impl Stage
+  def validate_opts(_), do: {:error, "options must be a map"}
+
+  @spec get_article_content(String.t(), String.t()) :: {:ok, String.t()} | {:error, String.t()}
+  defp get_article_content(url, extractor) when is_binary(url) and url != "" do
     Logger.debug("Getting article from #{url}")
 
     url
     |> HTTPoison.get()
     |> case do
       {:ok, response} ->
-        handle_response(url, response)
+        handle_response(url, response, extractor)
 
       {:error, %HTTPoison.Error{reason: reason}} ->
         {:error, "HTTPoison error: #{reason}"}
@@ -35,38 +59,46 @@ defmodule Frenzy.Pipeline.ScrapeStage do
 
   defp get_article_content(_url), do: {:error, "URL must be a non-empty string"}
 
-  @spec handle_response(String.t(), HTTPoison.Response.t()) ::
+  @spec handle_response(String.t(), HTTPoison.Response.t(), String.t()) ::
           {:ok, String.t()} | {:error, String.t()}
-  defp handle_response(_url, %HTTPoison.Response{status_code: 200, body: body}) do
+  defp handle_response(_url, %HTTPoison.Response{status_code: 200, body: body}, extractor) do
+    case extractor do
+      "builtin" ->
         article = Readability.article(body)
         {:ok, Readability.readable_html(article)}
+
+      module_name ->
+        apply(String.to_existing_atom("Elixir." <> module_name), :extract, [body])
+    end
   end
 
-  defp handle_response(_url, %HTTPoison.Response{status_code: 404}) do
+  defp handle_response(_url, %HTTPoison.Response{status_code: 404}, _extractor) do
     {:error, "404 not found"}
   end
 
-  defp handle_response(url, %HTTPoison.Response{status_code: status_code, headers: headers})
+  defp handle_response(
+         url,
+         %HTTPoison.Response{status_code: status_code, headers: headers},
+         extractor
+       )
        when status_code in [301, 302] do
-    {"Location", new_url} = Enum.find(headers, fn {name, _value} -> name == "Location" end)
-
     headers
     |> Enum.find(fn {name, _value} -> name == "Location" end)
     |> case do
       {"Location", new_url} ->
         Logger.debug("Got 301 redirect from #{url} to #{new_url}")
-        get_article_content(new_url)
+        get_article_content(new_url, extractor)
 
       _ ->
         {:error, "Missing Location header for redirect"}
     end
   end
 
-  defp handle_response(_url, %HTTPoison.Response{status_code: 403}) do
+  defp handle_response(_url, %HTTPoison.Response{status_code: 403}, _extractor) do
     {:error, "403 Forbidden"}
   end
 
-  defp handle_response(_url, %HTTPoison.Response{status_code: status_code} = response) do
+  defp handle_response(_url, %HTTPoison.Response{} = response, _extractor) do
     {:error, "No handler for response #{inspect(response)}"}
   end
 end

lib/frenzy/pipeline/site/daring_fireball_scrape_stage.ex

@@ -1,105 +0,0 @@
-defmodule Frenzy.Pipeline.Site.DaringFireballScrapeStage do
-  require Logger
-  alias Frenzy.Pipeline.Stage
-  @behaviour Stage
-
-  @impl Stage
-  def apply(_opts, %{url: url} = item_params) do
-    case get_article_content(url) do
-      {:ok, content} ->
-        {:ok, %{item_params | content: content}}
-
-      {:error, reason} ->
-        Logger.warn("Unable to get Daring Fireball article content for #{url}: #{reason}")
-        {:ok, item_params}
-    end
-  end
-
-  @impl Stage
-  def validate_opts(opts), do: {:ok, opts}
-
-  @spec get_article_content(String.t()) :: {:ok, String.t()} | {:error, String.t()}
-  defp get_article_content(url) when is_binary(url) and url != "" do
-    Logger.debug("Get Daring Fireball article from #{url}")
-
-    url
-    |> HTTPoison.get()
-    |> case do
-      {:ok, response} ->
-        handle_response(url, response)
-
-      {:error, %HTTPoison.Error{reason: reason}} ->
-        {:error, "HTTPoison error: #{reason}"}
-    end
-  end
-
-  defp get_article_content(_url), do: {:error, "URL must be a non-empty string"}
-
-  @spec handle_response(String.t(), HTTPoison.Response.t()) ::
-          {:ok, String.t()} | {:error, String.t()}
-  defp handle_response(url, %HTTPoison.Response{status_code: 200, body: body}) do
-    html_tree = Floki.parse(body)
-
-    case get_article_element(html_tree) || get_link_element(html_tree) do
-      nil ->
-        {:error, "no matching element"}
-
-      elem ->
-        readable_html =
-          elem
-          |> Floki.filter_out(:comment)
-          |> Readability.readable_html()
-
-        {:ok, readable_html}
-    end
-  end
-
-  defp handle_response(_url, %HTTPoison.Response{status_code: 404}) do
-    {:error, "404 not found"}
-  end
-
-  defp handle_response(url, %HTTPoison.Response{status_code: status_code, headers: headers})
-       when status_code in [301, 302] do
-    {"Location", new_url} = Enum.find(headers, fn {name, _value} -> name == "Location" end)
-
-    headers
-    |> Enum.find(fn {name, _value} -> name == "Location" end)
-    |> case do
-      {"Location", new_url} ->
-        Logger.debug("Got 301 redirect from #{url} to #{new_url}")
-        get_article_content(new_url)
-
-      _ ->
-        {:error, "Missing Location header for redirect"}
-    end
-  end
-
-  defp handle_response(_url, %HTTPoison.Response{status_code: 403}) do
-    {:error, "403 Forbidden"}
-  end
-
-  defp handle_response(_url, %HTTPoison.Response{status_code: status_code} = response) do
-    {:error, "No handler for response #{inspect(response)}"}
-  end
-
-  defp get_article_element(html_tree) do
-    case Floki.find(html_tree, "div.article") do
-      [article_elem | _] ->
-        # articles include extra information in the div.article element
-        Floki.filter_out(article_elem, "h1, .dateline, #PreviousNext")
-
-      _ ->
-        nil
-    end
-  end
-
-  defp get_link_element(html_tree) do
-    case Floki.find(html_tree, "dl.linkedlist dd") do
-      [dd_elem | _] ->
-        dd_elem
-
-      _ ->
-        nil
-    end
-  end
-end

lib/frenzy_web/controllers/account_controller.ex

@@ -1,6 +1,6 @@
 defmodule FrenzyWeb.AccountController do
   use FrenzyWeb, :controller
-  alias Frenzy.{Repo, User, FervorClient, Filter}
+  alias Frenzy.{Repo, User, FervorClient}
   alias FrenzyWeb.Router.Helpers, as: Routes
   alias FrenzyWeb.Endpoint
 
@@ -125,11 +125,7 @@ defmodule FrenzyWeb.AccountController do
         Enum.each(feeds, fn feed_url ->
           feed_changeset =
             Ecto.build_assoc(group, :feeds, %{
-              feed_url: feed_url,
-              filter: %Filter{
-                mode: "reject",
-                score: 0
-              }
+              feed_url: feed_url
             })
 
           {:ok, _feed} = Repo.insert(feed_changeset)

lib/frenzy_web/controllers/fervor/feeds_controller.ex

@@ -1,6 +1,6 @@
 defmodule FrenzyWeb.Fervor.FeedsController do
   use FrenzyWeb, :controller
-  alias Frenzy.{Repo, Feed, Filter, Item}
+  alias Frenzy.{Repo, Feed, Item}
   import Ecto.Query
   alias FrenzyWeb.Fervor.Paginator
 
@@ -85,11 +85,7 @@ defmodule FrenzyWeb.Fervor.FeedsController do
           group ->
             changeset =
               Ecto.build_assoc(group, :feeds, %{
-                feed_url: feed_url,
-                filter: %Filter{
-                  mode: "reject",
-                  score: 0
-                }
+                feed_url: feed_url
               })
 
             {:ok, feed} = Repo.insert(changeset)