defmodule SukaatoWeb.Marker do
  @moduledoc """
  Manages markdown files or strings and their conversion to HTML pages or posts.
  """
  @rel_proj_root "."
  @markdown_root Path.expand(@rel_proj_root <> "/controllers/page_md", __DIR__)
  @markdown_pages Path.wildcard(@markdown_root <> "/*.md")
  @markdown_posts @markdown_root <> "/users"
  @site_config_file Path.expand("../../site.toml", __DIR__)
  @site_config Toml.decode_file(@site_config_file)
  @admin_username elem(@site_config, 1)["site"]["username"]

  @doc """
  Converts markdown and YAML frontmatter from files for pages or posts to HTML5.
  """
  def render_mark(filename, category \\ :markdown_page, username \\ @admin_username) do
    filename = if is_atom(filename), do: Atom.to_string(filename), else: filename
    filename = if !String.contains?(filename, ".md"), do: filename <> ".md", else: filename

    markdown_paths = case category, do: (:markdown_page -> @markdown_pages; :markdown_post -> Path.wildcard(@markdown_posts <> "/" <> username <> "/posts/*.md"))
    markdown_files = Enum.map(markdown_paths, fn p -> Path.basename(p) end)

    if Enum.member?(markdown_files, filename) do
      markdown_filepath = @markdown_root <> "/" <> filename

      if category == :markdown_post do
        markdown_filepath = if username != "" and username != nil, do: @markdown_root <> "/users/" <> username <> "/posts/" <> filename, else: Path.wildcard(@markdown_root <> "/users/*/posts/" <> filename)
        post_data = if is_list(markdown_filepath), do: Enum.map(markdown_filepath, fn m -> YamlFrontMatter.parse_file(m) end), else: YamlFrontMatter.parse_file(markdown_filepath)

        if is_list(post_data) do
          post_content = Enum.filter(post_data, fn m -> elem(m, 0) == :ok end)
          post_content = if length(post_content) > 0, do: Enum.map(post_content, fn m -> Panpipe.to_html5(elem(m, 2)) end), else: []
          post_content = Enum.filter(post_content, fn m -> elem(m, 0) == :ok end)
          frontmatter = if length(post_content) > 0, do: Enum.map(post_data, fn p -> elem(p, 1) end), else: []

          if length(frontmatter) > 0 and length(post_content) > 0 do
            {:ok, frontmatter, post_content}
          else
            {:error, frontmatter, post_content}
          end
        else
          if elem(post_data, 0) == :ok do
            post_content = Panpipe.to_html5(elem(post_data, 2))

            if elem(post_content, 0) == :ok do
              frontmatter = elem(post_data, 1)
              {:ok, frontmatter, post_content}
            end
          else
            frontmatter = elem(post_data, 1)
            markdown = elem(post_data, 2)
            {:error, frontmatter, markdown}
          end
        end
      end

      if category == :markdown_page do
        post_content = Panpipe.pandoc(input: markdown_filepath, to: :html5)

        if elem(post_content, 0) == :ok do
          markup = elem(post_content, 1)
          {:ok, markup}
        # else
        #   {:error, "something's up"}
        end
      end
    else
      {:error, "no such markdown file '" <> filename <> "'"}
    end
  end

  def backup_marks(), do: nil

  # defp create_page(), do: nil

  # @NOTE following two functions should integrate markdown file creation and db insertion

  # defp create_post(), do: nil

  def create_mark(), do: nil
end