meili

defmodule Meili.Util do
  @moduledoc false

  @doc """
  Recursively camelizes map keys from snake_case to camelCase.
  Leaves existing camelCase keys unchanged.
  """
  @spec camelize_keys(map() | list() | term()) :: map() | list() | term()
  def camelize_keys(map) when is_map(map) do
    Map.new(map, fn {key, val} ->
      {camelize_key(key), camelize_keys(val)}
    end)
  end

  def camelize_keys(list) when is_list(list) do
    if Keyword.keyword?(list) do
      list |> Map.new() |> camelize_keys()
    else
      Enum.map(list, &camelize_keys/1)
    end
  end

  def camelize_keys(other), do: other

  @spec camelize_key(atom() | String.t()) :: String.t()
  def camelize_key(key) when is_atom(key) do
    key |> Atom.to_string() |> camelize_key()
  end

  def camelize_key(key) when is_binary(key) do
    if String.contains?(key, "_") do
      case String.split(key, "_") do
        [first | rest] ->
          rest_camelized = Enum.map_join(rest, &String.capitalize/1)
          first <> rest_camelized

        [] ->
          ""
      end
    else
      key
    end
  end
end