# Templates will be filled by posts
index_template = File.read!("./templates/post_index_page.html")
post_template = File.read!("./templates/post_single_page.html")

post_feed_item_template = File.read!("./templates/post_item.xml")
post_feed_template = File.read!("./templates/posts.xml")

# Converting handlebars in template to values
fill_template = fn template, pairs ->
  ~r/{{(.*)}}/U
  |> Regex.replace(template, fn _, key -> Map.get(pairs, String.to_atom(key)) end)
end

fill_template_pretemplated = fn template -> &fill_template.(template, &1) end

filterCutFileExtension = fn files ->
  fn ext ->
    Enum.filter(files, &String.ends_with?(&1, "." <> ext))
    |> Enum.map(&String.replace_suffix(&1, "." <> ext, ""))
    |> (fn x -> %{String.to_atom(ext) => x} end).()
  end
end

isMeta = &String.starts_with?(&1, "#+")

posts_org =
  File.ls!("./posts_org")
  |> Enum.reject(fn x -> String.starts_with?(x, ".") end)
  |> (fn files -> Enum.map(["org", "html"], filterCutFileExtension.(files)) end).()
  |> Enum.reduce(%{}, fn x, acc -> Map.merge(x, acc) end)

post_contents_org =
  Enum.filter(Map.get(posts_org, :org), fn el -> Enum.member?(Map.get(posts_org, :html), el) end)
  |> Enum.map(
    &(File.read!("./posts_org/" <> &1 <> ".org")
      |> (fn fileContent -> String.split(fileContent, "\n") end).()
      |> Enum.take_while(isMeta)
      |> Enum.map(fn metaOrg ->
        [head | tail] = String.split(metaOrg, ":")

        %{
          (String.slice(head, 2..-1) |> String.downcase() |> String.to_atom()) =>
            String.slice(Enum.join(tail, ":"), 1..-1)
        }
      end)
      |> Enum.reduce(%{:content => File.read!("./posts_org/" <> &1 <> ".html")}, fn x, acc ->
        Map.merge(x, acc)
      end))
  )

months = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]

dateFolder = fn p ->
  Map.get(p, :date)
  |> String.slice(8..15)
  |> String.split(" ")
  |> (fn ([month, year]) -> year <> "/" <> Integer.to_string(Enum.find_index(months, &(&1 == month)) + 1) <> "/" end).()
end
normalize_title = fn title -> String.replace(String.downcase(title), " ", "-") end

constructLocalPath = fn p -> dateFolder.(p) <> normalize_title.(Map.get(p, :title)) end

post_contents = post_contents_org
  |> Enum.map(fn postMap -> Map.merge(postMap, %{localpath: (constructLocalPath.(postMap))}) end)

index_file =
  post_contents
  |> Enum.sort_by(
    &(Map.get(&1, :date)
      |> String.slice(5..6)
      |> Integer.parse())
  )
  |> Enum.reverse()
  # Group by month
  |> Enum.group_by(fn m -> Map.get(m, :date) |> String.slice(8..15) end)
  |> Enum.sort_by(fn {d, _c} -> ((length months) * elem(Integer.parse(String.slice(d, 4..7)), 0)) + Enum.find_index(months, &(&1 == String.slice(d, 0..2))) end)
  |> Enum.reverse()
  |> Enum.map(fn {month, posts} -> "\n<h1>" <> month <> "</h1>\n" <> (posts |>
      Enum.map(fn post -> "<h2 class=\"post-link\">" <> (Map.get(post, :date) |> String.slice(0..6)) <>
                        " - <a href=\"" <> Map.get(post, :localpath) <> ".html\">" <> Map.get(post, :title) <> "</a></h2>"
      end) |> Enum.join("\n")) end) 
  |> Enum.join("\n")
  |> (fn v -> %{index: v} end).()
  |> fill_template_pretemplated.(index_template).()

File.open!("./public/gen/index.html", [:write])
  |> IO.binwrite(index_file)
  |> File.close()


prepare_path = fn path ->
  File.mkdir_p!(Path.dirname(path))
  path
end

post_contents
  |> Enum.each(fn post -> post
      |> (fn p -> "./public/gen/" <> Map.get(p, :localpath) <> ".html" end).()
      |> prepare_path.()
      |> File.open!([:write])
      |> IO.binwrite(fill_template.(post_template, post))
      |> File.close()
  end)

stripForRSS = fn content -> content
  |> String.replace("\n", "")
end

post_feed =
  post_contents
  |> Enum.map(fn m -> Map.update!(m, :content, stripForRSS) end)
  |> Enum.map(fill_template_pretemplated.(post_feed_item_template))
  |> Enum.join("\n")
  |> (fn v -> %{items: v} end).()
  |> fill_template_pretemplated.(post_feed_template).()

File.open!("./public/gen/rss.xml", [:write])
  |> IO.binwrite(post_feed)
  |> File.close()