defmodule Microformats2.Items do
  @moduledoc false
  import Microformats2.Helpers

  alias Microformats2.Items
  alias Microformats2.Items.Implied
  alias Microformats2.ParserState

  def parse(nodes, doc, url, opts, items \\ [])
  def parse([head | tail], doc, url, opts, items) when is_bitstring(head), do: parse(tail, doc, url, opts, items)
  def parse([head | tail], doc, url, opts, items), do: parse(tail, doc, url, opts, parse(head, doc, url, opts, items))
  def parse([], _, _, _, items), do: items

  def parse({_, _, children} = root, doc, url, opts, items) do
    root_classes =
      [root]
      |> attr_list()
      |> Enum.filter(&is_rootlevel?/1)
      |> Enum.sort()

    if not Enum.empty?(root_classes) do
      item =
        %{normalized_key("type", opts) => root_classes, normalized_key("properties", opts) => %{}}
        |> maybe_put_id(root, opts)

      entry =
        parse_sub(children, doc, url, opts, item, %ParserState{})
        |> Implied.parse(root, url, doc, opts)

      items ++ [entry]
    else
      parse(children, doc, url, opts, items)
    end
  end

  defp maybe_put_id(item, root, opts) do
    id = Floki.attribute([root], "id") |> List.first()

    if present?(id),
      do: Map.put(item, normalized_key("id", opts), id),
      else: item
  end

  defp parse_sub([], _, _, _, item, state), do: {item, state}

  defp parse_sub([child | children], doc, url, opts, item, state) when is_bitstring(child),
    do: parse_sub(children, doc, url, opts, item, state)

  defp parse_sub([child = {_, _, child_children} | children], doc, url, opts, item, state) do
    p =
      if has_a?([child], "h"),
        do: parse(child, doc, url, opts, []) |> List.first(),
        else: []

    classes =
      [child]
      |> attr_list()
      |> Enum.filter(&non_h_type?/1)

    {props, state} = gen_prop(child, classes, item, p, doc, url, opts, state)

    {n_item, new_state} =
      if is_rootlevel?(child),
        do: {props, state},
        else: parse_sub(child_children, doc, url, opts, props, state)

    parse_sub(children, doc, url, opts, n_item, new_state)
  end

  defp maybe_parse_prop(type, child, doc, url, opts, state) do
    if valid_mf2_name?(type),
      do: parse_prop(type, child, doc, url, opts, state),
      else: {nil, state}
  end

  def parse_prop("p-" <> _, child, doc, url, _, state),
    do: Items.PProp.parsed_prop(child, doc, url, state)

  def parse_prop("u-" <> _, child, doc, url, opts, state),
    do: Items.UProp.parsed_prop(child, doc, url, opts, state)

  def parse_prop("dt-" <> _, child, _, _, _, state),
    do: Items.DtProp.parsed_prop(child, state)

  def parse_prop("e-" <> _, {_, _, children}, doc, url, opts, state) do
    updated_tree =
      Floki.traverse_and_update(children, fn element ->
        element
        |> update_url_attr("href", doc, url)
        |> update_url_attr("src", doc, url)
      end)

    {%{
       normalized_key("html", opts) => updated_tree |> Floki.raw_html() |> stripped_or_nil(),
       normalized_key("value", opts) =>
         updated_tree |> cleanup_html() |> text_content(doc, url, &replaced_img_by_alt_or_src/3) |> stripped_or_nil()
     }, state}
  end

  def parse_prop(_, _, _, _, _, state), do: {nil, state}

  defp update_url_attr({element, attributes, children}, attr, doc, doc_url) do
    updated_attributes =
      Enum.map(attributes, fn
        {^attr, uri} -> {attr, abs_uri(uri, doc_url, doc)}
        v -> v
      end)

    {element, updated_attributes, children}
  end

  defp update_url_attr(node, _, _, _), do: node

  defp gen_prop(child, classes, item, p, doc, url, opts, state) do
    {props, new_state} =
      Enum.reduce(classes, {item[normalized_key("properties", opts)], state}, fn class, {acc, state} ->
        {prop, new_state} =
          if is_rootlevel?(child) do
            {value, new_state} = Items.Value.get_value(class, p, child, doc, url, opts, state)
            {Map.put(p, normalized_key("value", opts), value), new_state}
          else
            maybe_parse_prop(class, child, doc, url, opts, state)
          end

        key = normalized_key(strip_prefix(class), opts)
        {Map.update(acc, key, [prop], &(&1 ++ [prop])), new_state}
      end)

    retval =
      if blank?(classes) and present?(p) and is_rootlevel?(child),
        do: Map.update(item, normalized_key("children", opts), [p], &(&1 ++ [p])),
        else: Map.put(item, normalized_key("properties", opts), props)

    {retval, new_state}
  end

  defp strip_prefix("p-" <> rest), do: rest
  defp strip_prefix("u-" <> rest), do: rest
  defp strip_prefix("dt-" <> rest), do: rest
  defp strip_prefix("e-" <> rest), do: rest
  defp strip_prefix(rest), do: rest

  def img_prop(img, url, doc, opts) do
    alt = Floki.attribute([img], "alt") |> List.first()
    src = Floki.attribute([img], "src") |> List.first()

    if present?(alt) and present?(src),
      do: %{normalized_key("alt", opts) => alt, normalized_key("value", opts) => abs_uri(src, url, doc)},
      else: abs_uri(src, url, doc)
  end
end