defmodule Replica do
  @break "---\n"

  def read(key) do
    schema = key |> Path.extname
    address = case schema do
      ".md" -> key
      "" -> key <> ".md"
      "." <> _ -> key
    end
    body = replica() |> Source.Node.read(address)
    if address |> Path.extname() == ".md",
    do: body |> parse,
    else: body
  end

  def pages do
    {_, drops} = Cachex.fetch(:replica, "pages", fn key ->
      {:commit,
        replica()
        |> Source.Node.all
        |> Enum.map(& &1.address)
        |> Enum.filter(& not (&1 =~ ~r'^response/' or &1 =~ ~r'\.png$'))
        |> Enum.map(& &1 |> String.replace_suffix(".md", ""))
      }
    end, expire: 1 * 60 * 60 * 1000)
  end

  def replica, do: (Source.Index.scheme(:page) |> hd)
  def page(key), do: read(key).page

  def all do
    replica()
    |> Source.Node.all
    |> Enum.map(& &1.address)
    |> Enum.map(&read/1)
    |> Enum.reject(&is_nil/1)
  end

  def parse(page) do
    case page |> String.split(@break) do
      ["", header | page] ->  %{
        header: header |> YamlElixir.read_all_from_string! |> hd,
        page: page |> Enum.join(@break),
      }
      _ -> %{ header: %{}, page: page, }
    end
  end
end