WIP: Fast search based on ETS

kekend/lib/serial_killer/title_storage.ex

@@ -0,0 +1,78 @@
+defmodule SerialKiller.TitleStorage do
+  alias :ets, as: Ets
+
+  def start_link(_args) do
+    GenServer.start_link(__MODULE__, :ok, name: __MODULE__)
+  end
+
+  def init(:ok) do
+    Ets.new(:title_storage, [:bag, :protected, :named_table])
+
+    shows =
+      Postgrex.query!(
+        SerialKiller.DB,
+        "SELECT title, num_votes, id FROM shows ORDER BY num_votes desc LIMIT 100",
+        []
+      ).rows
+
+    build_letters_index(shows)
+    :ok
+  end
+
+  def get(letter) do
+    Ets.lookup(:title_storage, letter)
+    |> Enum.map(fn row ->
+      {_letter, [title, num, id]} = row
+
+      # TODO выглядит, буд-то бы можно сделать красивше, но я пока не придумал
+      [title, num, id]
+    end)
+  end
+
+  @doc """
+  shows -> [["Game of Thrones", 1668725, "tt0944947"]]
+  """
+  defp build_letters_index(shows) do
+    Enum.each(shows, fn row ->
+      show = Enum.at(row, 0)
+
+      String.split(show, " ")
+      |> Enum.each(fn word ->
+        first_letter = function_name(word, 0)
+        set_to_title_storage(first_letter, row)
+
+        second_letter = function_name(word, 1)
+        set_to_title_storage("#{first_letter}#{second_letter}", row)
+
+        third_letter = function_name(word, 2)
+        set_to_title_storage("#{first_letter}#{second_letter}#{third_letter}", row)
+
+        four_letter = function_name(word, 3)
+        set_to_title_storage("#{first_letter}#{second_letter}#{third_letter}#{four_letter}", row)
+      end)
+    end)
+  end
+
+  defp set_to_title_storage(index, show) do
+    Ets.insert(
+      :title_storage,
+      {index, show}
+    )
+  end
+
+  defp function_name(word, deep) do
+    word
+    |> String.at(deep)
+    |> prepare_letter
+  end
+
+  defp prepare_letter(letter) do
+    cond do
+      letter == nil -> ""
+      String.match?(letter, ~r/\w/) -> String.downcase(letter)
+      true -> ""
+    end
+  end
+end
+
+# SerialKiller.TitleStorage.init(:ok)