defmodule Edeliver do


  def run_command([command_name, application_name = [_|_] | arguments]) when is_atom(command_name) do
    application_name = to_string(application_name)
    application_name = String.to_atom(to_string(application_name))
    {^application_name, _description, application_version} = :application.which_applications |> List.keyfind(application_name, 0)
    application_version = to_string application_version
    apply __MODULE__, command_name, [application_name, application_version | arguments]
  end

  def release_version(application_name, _application_version \\ nil) do
    releases = :release_handler.which_releases
    application_name = Atom.to_char_list application_name
    case (for {name, version, _apps, status} <- releases, status == :current and name == application_name, do: to_string(version)) do
      [current_version] -> current_version
      _ ->
        case (for {name, version, _apps, status} <- releases, status == :permanent and name == application_name, do: to_string(version)) do
          [permanent_version] -> String.to_char_list(permanent_version)
        end
    end
  end

  def list_pending_migrations(application_name, application_version, ecto_repository \\ '') do
    repository = ecto_repository!(application_name, ecto_repository)
    versions = Ecto.Migrator.migrated_versions(repository)
    pending_migrations = migrations_for(migrations_dir(application_name, application_version))
    |> Enum.filter(fn {version, _name, _file} -> not (version in versions) end)
    |> Enum.reverse
    |> Enum.map(fn {version, name, _file} -> {version, name} end)
    pending_migrations |> Enum.each(fn {version, name} ->
      warning "pending: #{name} (#{version})"
    end)
  end

  def migrate(application_name, application_version, ecto_repository, direction, migration_version \\ :all) when is_atom(direction) do
    options = if migration_version == :all, do: [all: true], else: [to: to_string(migration_version)]
    Ecto.Migrator.run(ecto_repository!(application_name, ecto_repository), migrations_dir(application_name, application_version), direction, options)
  end

  def migrations_dir(application_name, application_version) do
    # use priv dir from installed version
    lib_dir = :code.priv_dir(application_name) |> to_string |> Path.dirname |> Path.dirname
    application_with_version = "#{Atom.to_string(application_name)}-#{application_version}"
    Path.join([lib_dir, application_with_version, "priv", "repo", "migrations"])
  end

  defp ecto_repository!(_application_name, ecto_repository = [_|_] ) do
    # repository name was passed as ECTO_REPOSITORY env by the erlang-node-execute rpc call
    List.to_atom ecto_repository
  end
  defp ecto_repository!(application_name, _ecto_repository) do
    case System.get_env "ECTO_REPOSITORY" do # ECTO_REPOSITORY env was set when the node was started
      ecto_repository = <<_,_::binary>> ->
        ecto_repository_module = ecto_repository |> to_char_list |> List.to_atom
        if maybe_ecto_repo?(ecto_repository_module) do
          ecto_repository_module
        else
          error! "Module '#{ecto_repository_module}' is not an ecto repository.\n    Please set the correct repository module in the edeliver config as ECTO_REPOSITORY env\n    or remove that value to use autodetection of that module."
        end
      _ ->
        case ecto_repos_from_config(application_name) do
          {:ok, [ecto_repository_module]} -> ecto_repository_module
          {:ok, modules =[_|_]} -> error! "Found several ecto repository modules (#{inspect modules}).\n    Please specify the repository to use in the edeliver config as ECTO_REPOSITORY env."
          :error ->
            case Enum.filter(:erlang.loaded |> Enum.reverse, &ecto_1_0_repo?/1) do
              [ecto_repository_module] -> ecto_repository_module
              [] -> error! "No ecto repository module found.\n    Please specify the repository in the edeliver config as ECTO_REPOSITORY env."
              modules =[_|_] -> error! "Found several ecto repository modules (#{inspect modules}).\n    Please specify the repository to use in the edeliver config as ECTO_REPOSITORY env."
            end
        end
    end
  end

  defp ecto_repos_from_config(application_name) do
    Application.fetch_env(application_name, :ecto_repos)
  end

  defp maybe_ecto_repo?(module) do
    if :erlang.module_loaded(module) do
      exports = module.module_info(:exports)
      # :__adapter__ for ecto versions >= 2.0, :__repo__ for ecto versions < 2.0
      Dict.get(exports, :__adapter__, nil) || Dict.get(exports, :__repo__, false)
    else
      false
    end
  end

  defp ecto_1_0_repo?(module) do
    if :erlang.module_loaded(module) do
      module.module_info(:exports)
      |> Dict.get(:__repo__, false)
    else
      false
    end
  end

  # taken from https://github.com/elixir-lang/ecto/blob/master/lib/ecto/migrator.ex#L183
  defp migrations_for(directory) do
    query = Path.join(directory, "*")
    for entry <- Path.wildcard(query),
      info = extract_migration_info(entry),
      do: info
  end

  defp extract_migration_info(file) do
    base = Path.basename(file)
    ext  = Path.extname(base)
    case Integer.parse(Path.rootname(base)) do
      {integer, "_" <> name} when ext == ".exs" -> {integer, name, file}
      _ -> nil
    end
  end

  # defp info(message),    do: IO.puts "==> #{IO.ANSI.green}#{message}#{IO.ANSI.reset}"
  defp warning(message), do: IO.puts "==> #{IO.ANSI.yellow}#{message}#{IO.ANSI.reset}"
  defp error!(message) do
     IO.puts "==> #{IO.ANSI.red}#{message}#{IO.ANSI.reset}"
     throw "error"
  end


end