defmodule EditorConfig.CLI do
  @moduledoc "Escript entrypoint for the `editorconfig` command."

  @switches [f: :string, b: :string, version: :boolean, files: :boolean, help: :boolean]
  @aliases [f: :f, b: :b, v: :version, h: :help]

  @spec main([String.t()]) :: no_return()
  def main(argv) do
    {status, output} = run(argv)
    IO.write(output)
    System.halt(status)
  end

  @spec run([String.t()]) :: {non_neg_integer(), String.t()}
  def run(argv) do
    case OptionParser.parse(argv, strict: @switches, aliases: @aliases) do
      {opts, paths, []} -> dispatch(opts, paths)
      {_opts, _paths, invalid} -> {2, "invalid option: #{inspect(invalid)}\n"}
    end
  end

  defp dispatch(opts, paths) do
    cond do
      opts[:help] -> {0, help()}
      opts[:version] -> {0, version()}
      paths == [] -> {2, "missing FILEPATH\n\n" <> help()}
      true -> resolve_paths(paths, opts)
    end
  end

  defp resolve_paths(paths, opts) do
    config_name = Keyword.get(opts, :f, ".editorconfig")
    version = Keyword.get(opts, :b, EditorConfig.spec_version())
    show_files? = Keyword.get(opts, :files, false)

    results =
      Enum.map(paths, fn path ->
        if show_files? do
          EditorConfig.properties_with_sources(path,
            config_name: config_name,
            version: version
          )
        else
          EditorConfig.properties(path, config_name: config_name, version: version)
        end
      end)

    format_results(paths, results, show_files?)
  end

  defp format_results(paths, results, show_files?) do
    output =
      paths
      |> Enum.zip(results)
      |> Enum.map_join("", &format_result(&1, length(paths) > 1, show_files?))

    status = if Enum.any?(results, &match?({:error, _reason}, &1)), do: 1, else: 0
    {status, output}
  end

  defp format_result({path, {:ok, props}}, multi?, false) do
    header = if multi?, do: "[#{path}]\n", else: ""
    header <> format_props(props)
  end

  defp format_result({path, {:ok, props, sources}}, multi?, true) do
    header = if multi?, do: "[#{path}]\n", else: ""
    source_lines = Enum.map_join(sources, "\n", fn {file, section} -> "#{file}: [#{section}]" end)
    header <> source_lines <> "\n" <> format_props(props)
  end

  defp format_result({_path, {:error, reason}}, _multi?, _show_files?),
    do: "error: #{inspect(reason)}\n"

  defp format_props(props) do
    props
    |> Enum.sort_by(fn {key, _value} -> key end)
    |> Enum.map_join("", fn {key, value} -> "#{key}=#{value}\n" end)
  end

  defp version do
    "EditorConfig Elixir Core v#{EditorConfig.version()} - Specification Version #{EditorConfig.spec_version()}\n"
  end

  defp help do
    """
    editorconfig [options] <FILEPATH...>
      -f <path>       config filename other than .editorconfig
      -b <version>    target specification version
      -v, --version   print version
      --files         print the files and sections that contributed
      -h, --help      print help
    """
  end
end