defmodule Mix.Torch do
  @moduledoc false

  alias Torch.Config

  def parse_config!(task, args) do
    {opts, _, _} = OptionParser.parse(args, switches: [format: :string, app: :string])

    format = convert_format(opts[:format] || Config.template_format())
    otp_app = opts[:app] || Config.otp_app()

    unless otp_app do
      Mix.raise("""
      You need to specify an OTP app to generate files within. Either
      configure it as shown below or pass it in via the `--app` option.

          config :torch,
            otp_app: :my_app

          # Alternatively
          mix #{task} --app my_app
      """)
    end

    unless format in ["eex", "slime"] do
      Mix.raise("""
      Template format is invalid: #{inspect(format)}. Either configure it as
      shown below or pass it via the `--format` option.

          config :torch,
            template_format: :slime

          # Alternatively
          mix #{task} --format slime

      Supported formats: eex, slime
      """)
    end

    %{otp_app: otp_app, format: format}
  end

  def ensure_phoenix_is_loaded!(mix_task \\ "task") do
    case Application.load(:phoenix) do
      :ok ->
        :ok

      {:error, {:already_loaded, :phoenix}} ->
        :ok

      {:error, reason} ->
        Mix.raise("mix #{mix_task} could not complete due to Phoenix not being loaded: #{reason}")
    end
  end

  def copy_from(source_dir, mapping) when is_list(mapping) do
    for {source_file_path, target_file_path} <- mapping do
      contents =
        [Application.app_dir(:torch), source_dir, source_file_path]
        |> Path.join()
        |> File.read!()

      Mix.Generator.create_file(target_file_path, contents)
    end
  end

  @doc """
  Copy templates files depending of the executed mix task.

  Torch currently supports both EEX and Slime templates.  The underlying mix tasks that
  Torch uses to generate the templates into a Phoenix projects source code expect to
  find templates with the `.html.eex` extension, regardless of actual template format.

  This is why this function invocation of `copy_from/2` changes the template file extensions
  to `.html.eex` reglardess of the original template format type.
  """
  def inject_templates("phx.gen.html", format) do
    copy_from("priv/templates/#{format}/phx.gen.html", [
      {"edit.html.#{format}", "priv/templates/phx.gen.html/edit.html.eex"},
      {"form.html.#{format}", "priv/templates/phx.gen.html/form.html.eex"},
      {"index.html.#{format}", "priv/templates/phx.gen.html/index.html.eex"},
      {"new.html.#{format}", "priv/templates/phx.gen.html/new.html.eex"},
      {"show.html.#{format}", "priv/templates/phx.gen.html/show.html.eex"}
    ])

    copy_from("priv/templates/common/phx.gen.html", [
      {"controller_test.exs", "priv/templates/phx.gen.html/controller_test.exs"},
      {"controller.ex", "priv/templates/phx.gen.html/controller.ex"},
      {"view.ex", "priv/templates/phx.gen.html/view.ex"}
    ])
  end

  def inject_templates("phx.gen.context", _format) do
    copy_from("priv/templates/phx.gen.context", [
      {"access_no_schema.ex", "priv/templates/phx.gen.context/access_no_schema.ex"},
      {"context.ex", "priv/templates/phx.gen.context/context.ex"},
      {"schema_access.ex", "priv/templates/phx.gen.context/schema_access.ex"},
      {"test_cases.exs", "priv/templates/phx.gen.context/test_cases.exs"},
      {"context_test.exs", "priv/templates/phx.gen.context/context_test.exs"}
    ])
  end

  def backup_project_templates(mix_task_name) do
    File.rename("priv/templates/#{mix_task_name}", "priv/templates/#{mix_task_name}_backup")
  end

  def restore_project_templates(mix_task_name) do
    File.rename("priv/templates/#{mix_task_name}_backup", "priv/templates/#{mix_task_name}")
  end

  def remove_templates(template_dir) do
    File.rm_rf("priv/templates/#{template_dir}/")
  end

  defp convert_format("slim"), do: "slime"
  defp convert_format(format), do: format
end