defmodule Yemux do
  alias Yemux.{Error, Partial, Session}

  @moduledoc """
  ## Synopsis
  #
  Yemux creates a string of shell commands that create or connect to a TMUX session.

  It exposes a single function `main` which takes a symbol as first parameter which
  allows to dispatch to the according functions and a list of additional parameters.

  ## Subcommands


  ### `:yemux`

  """

  def main(dispatch, args)

  def main(:yemux, args) do
    _yemux(args)
  end

  def main(:partial, args) do
    case _partial(args) do
      [_ | _] = list -> list |> List.flatten() |> Enum.join("\n")
      string -> string
    end
  end

  defp _partial([partial_name, partial_filename]) do
    case YamlElixir.read_from_file(partial_filename) do
      {:ok, partials} -> _partial_from_hash(partial_name, partials, partial_filename)
      {:error, %{message: message}} -> raise Error.BadYamlFile, message
    end
  end

  def _partial_from_hash(partial_name, partials, partial_filename) do
    case Partial.render_partial(partial_name, partials) do
      {:ok, output} ->
        output

      {:error, message} ->
        raise Error.BadPartialDefinition, Enum.join([message, partial_filename], " ")
    end
  end

  defp _yemux(args)

  defp _yemux([yml_filename, cfg_filename]) do
    case YamlElixir.read_from_file(cfg_filename) do
      {:ok, config} -> _yemux([yml_filename], config)
      {:error, %{message: message}} -> raise Error.BadYamlFile, message
    end
  end

  defp _yemux([filename], config \\ nil) do
    case YamlElixir.read_from_file(filename) do
      {:ok, yaml} -> _yemux_create(filename, yaml, config)
      {:error, %{message: message}} -> raise Error.BadYamlFile, message
    end
  end

  defp _yemux_create(filename, yaml, config) do
    case Session.new(filename, yaml, config) |> Session.create() do
      {:ok, list} -> list |> List.flatten() |> Enum.join("\n")
      {:error, message} -> raise Error.BadSessionSpec, message
    end
  end
end

# SPDX-License-Identifier: Apache-2.0