defmodule Frontmark do
  @moduledoc """
  Parses a frontmatter+markdown page
  """

  def parse_yaml(string) do
    case YamlElixir.read_from_string(string) do
      {:ok, yaml} ->
        yaml

      {:error, _error} ->
        nil
    end
  end

  def parse(text) do
    text
    |> String.split(Application.get_env(:frontmark, :separator), parts: 2)
  end

  def process([frontmatter, markdown]) do
    [Frontmark.parse_yaml(frontmatter), Earmark.as_html!(markdown)]
  end

  def page([yaml, html]) do
    Enum.reduce(yaml, %{"content" => html}, fn {key, value}, acc ->
      Map.put(acc, key, value)
    end)
  end

  def filepath(path) do
    partial = Application.get_env(:frontmark, :pages_folder) <> path

    if String.slice(partial, -3, 3) == ".md" do
      partial
    else
      partial <> ".md"
    end
  end

  def get(path) do
    path
    |> Frontmark.filepath()
    |> File.read!()
    |> Frontmark.parse()
    |> Frontmark.process()
    |> Frontmark.page()
  end
end