earmark_ast_dsl

defmodule EarmarkAstDsl do
  import __MODULE__.Table, only: [make_table_rows: 2]
  import __MODULE__.Atts, only: [make_atts: 1, only_atts: 1]

  use EarmarkAstDsl.Types

  @moduledoc """
  EarmarkAstDsl is a toolset to generate EarmarkParser conformant AST Nodes.

  Its main purpose is to remove boilerplate code from Earmark and
  EarmarkParser tests.
  Documentation for `EarmarkAstDsl`.

  ### `tag`

  The most general helper is the tag function:

      iex(1)> tag("div", "Some content")
      {"div", [], ["Some content"]}

  Content and attributes can be provided as arrays, ...

      iex(2)> tag("p", ~w[Hello World], class: "hidden")
      {"p", [{"class", "hidden"}], ["Hello", "World"]}

  ... or maps:

      iex(3)> tag("p", ~w[Hello World], %{class: "hidden"})
      {"p", [{"class", "hidden"}], ["Hello", "World"]}
        

  ### Shortcuts for `p` and `div`

      iex(4)> p("A para")
      {"p", [], ["A para"]}

      iex(5)> div(tag("span", "content"))
      {"div", [], [{"span", [], ["content"]}]}

  ### Tables

  Tables are probably the _raison d'être_ ot this little lib, as their ast is quite verbose, as we will see
  here:

      iex(6)> table("one cell only") # and look at the output 
      {"table", [], [
        {"tbody", [], [
          {"tr", [], [
            {"td", [{"style", "text-align: left;"}], ["one cell only"]}
          ]}
        ]}
      ]}

  Now if we want a header and have some more data:

      iex(7)> table([~w[1-1 1-2], ~w[2-1 2-2]], head: ~w[left right]) # This is quite verbose!
      {"table", [], [
        {"thead", [], [
          {"tr", [], [
            {"th", [{"style", "text-align: left;"}], ["left"]},
            {"th", [{"style", "text-align: left;"}], ["right"]},
          ]}
        ]},
        {"tbody", [], [
          {"tr", [], [
            {"td", [{"style", "text-align: left;"}], ["1-1"]},
            {"td", [{"style", "text-align: left;"}], ["1-2"]},
          ]},
          {"tr", [], [
            {"td", [{"style", "text-align: left;"}], ["2-1"]},
            {"td", [{"style", "text-align: left;"}], ["2-2"]},
          ]}
        ]}
      ]}

  And tables can easily be aligned differently in Markdown, which makes some style helpers
  very useful

      iex(8)> table([~w[1-1 1-2], ~w[2-1 2-2]],
      ...(8)>        head: ~w[alpha beta],
      ...(8)>        text_aligns: ~w[right center])
      {"table", [], [
        {"thead", [], [
          {"tr", [], [
            {"th", [{"style", "text-align: right;"}], ["alpha"]},
            {"th", [{"style", "text-align: center;"}], ["beta"]},
          ]}
        ]},
        {"tbody", [], [
          {"tr", [], [
            {"td", [{"style", "text-align: right;"}], ["1-1"]},
            {"td", [{"style", "text-align: center;"}], ["1-2"]},
          ]},
          {"tr", [], [
            {"td", [{"style", "text-align: right;"}], ["2-1"]},
            {"td", [{"style", "text-align: center;"}], ["2-2"]},
          ]}
        ]}
      ]}

  """

  @spec div(content_t(), free_atts_t()) :: ast_t()
  def div(content \\ [], atts \\ []), do: tag("div", content, atts)

  @spec p(content_t(), free_atts_t()) :: ast_t()
  def p(content \\ [], atts \\ []), do: tag("p", content, atts)

  @spec table(content_t(), free_atts_t()) :: ast_t()
  def table(rows, atts \\ [])
  def table(rows, atts) when is_binary(rows), do: table([rows], atts)

  def table(rows, atts) do
    tag("table", make_table_rows(rows, atts), only_atts(atts))
  end

  @spec tag(maybe(binary()), content_t(), free_atts_t()) :: ast_t()
  def tag(name, content \\ [], atts \\ [])
  def tag(name, nil, atts), do: tag(name, [], atts)

  def tag(name, content, atts) when is_binary(content) or is_tuple(content),
    do: tag(name, [content], atts)

  def tag(name, content, atts) do
    {to_string(name), make_atts(atts), content}
  end
end