defmodule Esperantisto.MixProject do
  use Mix.Project
  def project do
    [
      app: :esperantisto,
      version: "0.1.0",
      elixir: "~> 1.11",
      start_permanent: Mix.env() == :prod,
      deps: deps()
    ]
  end
  def application do
    [
      extra_applications: [:logger],
      mod: {Esperantisto.Application, []}
    ]
  end
  defp deps do
    []
  end
end

defmodule Esperantisto do
  @moduledoc """
  Documentation for `Esperantisto`.
  """
  @doc """
  Hello world.
  ## Examples
      iex> Esperantisto.hello()
      :world
  """
  def hello do
    :world
  end
end

defmodule Esperantisto.Text do
  @priv_dir Application.app_dir(:esperantisto, "priv/books")
  def get_files() do
    File.ls!(@priv_dir)
  end
  def iter_files() do
    get_files()
    |> Stream.map(fn file -> File.stream!(Path.join(@priv_dir, file)) end)
    |> Stream.map(fn stream -> process_book(stream) end)
  end
  defp process_book(stream) do
    stream
    |> Stream.transform(&parse_title/1, fn line, parser ->
      if parser == nil do
        {:halt, nil}
      else
        case parser.(line) do
          {nil, new_parser} -> {[], new_parser}
          {value, new_parser} -> {[value], new_parser}
        end
      end
    end)
    |> Stream.take(50)
    |> Enum.to_list()
  end
  defp parse_title("Title: " <> title = _line) do
    {{:title, title}, &parse_author/1}
  end
  defp parse_title(_) do
    {nil, &parse_title/1}
  end
  defp parse_author("Author: " <> name = _line) do
    {{:author, name}, &identity/1}
  end
  defp parse_author(_) do
    {nil, &parse_author/1}
  end
  defp identity(line) do
    {line, &identity/1}
  end
end

defmodule Esperantisto.Application do
  # See https://hexdocs.pm/elixir/Application.html
  # for more information on OTP Applications
  @moduledoc false
  use Application
  @impl true
  def start(_type, _args) do
    children = [
      # Starts a worker by calling: Esperantisto.Worker.start_link(arg)
      # {Esperantisto.Worker, arg}
    ]
    # See https://hexdocs.pm/elixir/Supervisor.html
    # for other strategies and supported options
    opts = [strategy: :one_for_one, name: Esperantisto.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

# Used by "mix format"
[
  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
]