defmodule Mix.Tasks.CommandK.Init do
  use Mix.Task

  @shortdoc "Generates boilerplate code for a Command+K palette"

  def generator_paths(), do: [".", :command_k]

  @impl true
  def run(args) do
    if args != [] do
      Mix.raise("mix command_k.init does not accept any arguments")
    end

    if Mix.Project.umbrella?() do
      Mix.raise(
        "mix command_k.init must be invoked from within your *_web application root directory"
      )
    end

    ctx_app = Mix.Phoenix.context_app()

    base = Mix.Phoenix.base()
    web_module = Mix.Phoenix.web_module(base)
    binding = [assigns: [web_module: web_module]]

    commands_file = Mix.Phoenix.web_path(ctx_app, "commands.ex")
    core_components_file = Mix.Phoenix.web_path(ctx_app, "components/core_components.ex")

    Mix.Phoenix.copy_from(generator_paths(), "priv/templates/command_k.init", binding, [
      {:eex, "commands.ex", commands_file}
    ])

    inject_eex_before_final_end(
      Mix.Phoenix.eval_from(
        generator_paths(),
        "priv/templates/command_k.init/core_components_command_k_palette.ex",
        binding
      ),
      core_components_file
    )

    Mix.shell().info("""

    Configure CommandK in the `live_view` section in your #{inspect(web_module)} module:

        def live_view do
          quote do
            use Phoenix.LiveView,
              layout: {#{inspect(web_module)}.Layouts, :app}

            use CommandK,
              handler: #{inspect(web_module)}.Commands,
              component: &#{inspect(web_module)}.CoreComponents.command_k_palette/1

            unquote(html_helpers())
          end
        end

    Then, modify your assets/app.js code to capture meta key information on keydown:

        let liveSocket = new LiveSocket("/live", Socket, {
          params: {_csrf_token: csrfToken},
          metadata: {
            keydown: (e, el) => {
              return {
                key: e.key,
                metaKey: e.metaKey,
                repeat: e.repeat
              }
            }
          }
        })

    See the documentation on Key Events for more information:

        https://hexdocs.pm/phoenix_live_view/bindings.html#key-events
    """)
  end

  defp inject_eex_before_final_end(content_to_inject, file_path) do
    file = File.read!(file_path)

    if String.contains?(file, content_to_inject) do
      :ok
    else
      Mix.shell().info([:green, "* injecting ", :reset, Path.relative_to_cwd(file_path)])

      file
      |> String.trim_trailing()
      |> String.trim_trailing("end")
      |> Kernel.<>(content_to_inject)
      |> Kernel.<>("end\n")
      |> then(&File.write!(file_path, &1))
    end
  end
end