defmodule EctoCooler.OptionParser do
  @moduledoc false

  alias EctoCooler.Helpers

  @functions [
    {"all", 1},
    {"change", 2},
    {"changeset", 0},
    {"create!", 1},
    {"create", 1},
    {"delete!", 1},
    {"delete", 1},
    {"get!", 2},
    {"get", 2},
    {"get_by!", 2},
    {"get_by", 2},
    {"update!", 2},
    {"update", 2}
  ]

  @spec parse(String.t(), list() | atom()) :: map()

  def parse(suffix, :read), do: parse(suffix, only: [:all, :get, :get!, :get_by, :get_by!])
  def parse(suffix, :delete), do: parse(suffix, only: [:delete, :delete!])

  def parse(suffix, :write) do
    parse(suffix,
      only: [:change, :changeset, :create, :create!, :update, :update!, :delete, :delete!]
    )
  end

  def parse(suffix, :read_write) do
    parse(suffix,
      only: [
        :all,
        :get,
        :get!,
        :get_by,
        :get_by!,
        :change,
        :changeset,
        :create,
        :create!,
        :update,
        :update!
      ]
    )
  end

  def parse(suffix, options) do
    @functions
    |> filter_functions(options)
    |> Enum.reduce(%{}, fn {function, arity}, acc ->
      Map.put(acc, String.to_atom(function), %{
        name: function_name(function, suffix),
        description: function_description(function, arity, suffix)
      })
    end)
  end

  @spec create_suffix(module, list()) :: String.t()
  def create_suffix(_, options) when not is_list(options), do: ""

  def create_suffix(schema, options) do
    if Keyword.get(options, :suffix, false),
      do: Helpers.underscore_module_name(schema),
      else: ""
  end

  defp build_function_name("all", suffix), do: "all_" <> Drops.Inflector.pluralize(suffix)
  defp build_function_name("get_by", suffix), do: "get_#{suffix}_by"
  defp build_function_name("get_by!", suffix), do: "get_#{suffix}_by!"
  defp build_function_name("changeset", suffix), do: "#{suffix}_changeset"

  defp build_function_name(function, suffix) do
    if String.ends_with?(function, "!"),
      do: String.replace_suffix(function, "!", "") <> "_" <> suffix <> "!",
      else: function <> "_" <> suffix
  end

  defp function_name(function, ""), do: String.to_atom(function)
  defp function_name(function, suffix), do: String.to_atom(build_function_name(function, suffix))

  defp function_description(function, arity, ""), do: function <> "/" <> Integer.to_string(arity)

  defp function_description(function, arity, suffix),
    do: build_function_name(function, suffix) <> "/" <> Integer.to_string(arity)

  defp filter_functions(functions, options) when is_list(options) do
    filter_functions(functions, Enum.into(options, %{}))
  end

  defp filter_functions(functions, %{except: excluded_functions}) do
    Enum.reject(functions, fn {function, _} ->
      function = String.to_atom(function)
      Enum.member?(excluded_functions, function)
    end)
  end

  defp filter_functions(functions, %{only: included_functions}) do
    Enum.filter(functions, fn {function, _} ->
      function = String.to_atom(function)
      Enum.member?(included_functions, function)
    end)
  end

  defp filter_functions(functions, _), do: functions
end