defmodule UsCongress.BillDtd.Shape do
  @doc """
  `&combine/2` is used to combine a sequence of nodes,
  once `end_element` is found.
  """
  def combine(
    %{scheme: "enum", body: enum} = former,
    %{label: "header", measure: [header], params: %{}} = current
  ), do:
    %{scheme: "header", enum: former.body, body: header}

  def combine(
    %{measure: measure} = former,
    %{scheme: s, body: b} = current
  ), do:
    former |> Map.put(:measure, [current | measure])

  def combine(
    %{scheme: a_scheme, body: a_body},
    %{scheme: b_scheme, body: b_body} = b
  ), do:
    b |> Map.put(a_scheme, a_body)

  def combine(
    %{measure: measure} = basis,
    %{measure: _measure} = current
  ) do
    current = Map.put(current, :measure, current.measure |> Enum.reverse)
    basis
    |> Map.put(:measure, [current | measure])
  end

  @doc """
  `&merge/2` is used to merge a sequence of nodes,
  before `end_element` is found.
  In practice this only seems to apply on the `characters` event.
  """
  def merge(%{measure: measure} = prior, current) when is_bitstring(current) do
    prior |> Map.put(:measure, [current | measure])
  end

  @doc """
  
  """
  def scheme(%{ label: name, measure: [body], params: params}) do
    %{ scheme: name, body: body }
  end

  def reshape(label) when is_atom(label), do: Atom.to_string(label)
  def reshape(label) when is_binary(label), do: label
  def reshape(l) when is_list(l), do: l |> Enum.map(&reshape/1)
  def reshape(record) when is_map(record) do
    record = if Map.has_key?(record, :params) and Map.size(record.params) == 0,
      do: Map.delete(record, :params),
      else: record
    record = if Map.has_key?(record, :measure) do
      if length(record.measure) == 0,
        do: Map.delete(record, :measure),
        else: Map.put(record, :measure, record.measure |> Enum.reverse)
      else
        record
      end
    record |> Map.new(fn {l, n} -> { reshape(l), reshape(n) } end)
  end
end